© Author(s) 2024. CC Atribution 4.0 License Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain Tektonika in gravitacijski pojavi, drugi del: Trnovsko- banjško-šentviška degradirana uravnava Ladislav PLACER1*, Tomislav POPIT2 & Igor RIŽNAR3 1Geološki zavod Slovenije, Dimičeva ul. 14, SI–1000 Ljubljana, Slovenija; *corresponding author: ladislav.placer@telemach.net 2Univerza v Ljubljani, Naravoslovnotehniška fakulteta, Oddelek za geologijo, Aškerčeva 12, SI-1000 Ljubljana, Slovenija; e-mail: tomi.popit@ntf.uni-lj.si 3Geološke ekspertize Igor Rižnar s. p., SI-1000 Ljubljana, Slovenija; e-mail: igor.riznar@telemach.net Prejeto / Received 22. 3. 2024; Sprejeto / Accepted 29. 5. 2024; Objavljeno na spletu / Published online 11. 6. 2024 Key words: External Dinarides NW, geomorphology, gravitational phenomena, karst plains, degraded karst plains, Idrija fault Ključne besede: Zunanji Dinaridi NW del, geomorfologija, gravitacijski pojavi, kraške uravnave, degradirane kraške uravnave, Idrijski prelom Abstract The article describes the recent conditions at the Paleogene thrust contact between the External Dinaric Thrust Belt composed of carbonate rocks and the External Dinaric Imbricate Belt composed of f lysch rocks, geographically, between the Trnovski gozd (Trnovski gozd plateau) and the Vipava Valley at the northwestern end of the Dinarides. Fossil and recent gravity-related phenomena that indicate the uplift of the southwestern edge of the External Dinaric Thrust Belt and the larger complex in the hinterland are found there. However, these phenomena are not related to the reactivated Paleogene thrust tectonics, but to the Neogene-recent underthrusting as a consequence of the Microadria (Adriatic Microplate) movement towards the Dinarides. Only arguments for these processes are presented in this article. Izvleček V članku so opisane recentne razmere na paleogenskem narivnem stiku med Zunanjedinarskim narivnim pasom iz karbonatnih kamnin in Zunanjedinarskim naluskanim pasom iz f lišnih kamnin. Geografsko med Trnovskim gozdom (Trnovska planota) in Vipavsko dolino na severozahodnem koncu Dinaridov. Tu najdemo fosilne in recentne gravitacijske pojave, ki kažejo na dviganje jugozahodnega obrobja Zunanjedinarskega narivnega pasu in večjega kompleksa v zaledju, vendar to ni povezano z reaktivirano paleogensko narivno tektoniko, temveč z neogensko-recentnimi procesi podrivanja, ki so posledica pomikanja Mikroadrije (Jadranska mikroplošča) proti Dinaridom. V članku so predstavljene le posledice teh procesov. GEOLOGIJA 67/1, 129-156, Ljubljana 2024 https://doi.org/10.5474/geologija.2024.007 Introduction The Microadria (Adriatic microplate) is moving towards the Dinarides, which northwestern part is described by Blašković (1991); Weber et al. (2006; 2010); Placer et al. (2010); Vrabec et al. (2018). It has not been precisely determined when the con- vergence process began, but in general we assume that it started in the Middle Miocene and con- tinues today, which is why we use the term Neo- gene-recent activity of the Adriatic Microplate. Its characteristics have not yet been sufficiently stud- ied, but the result of this process is the narrowing of the Dinarides, which is kinematically different from the narrowing of the Dinarides in the Paleo- Uvod Mikroadrija (Jadranska mikroplošča) se po- mika proti Dinaridom, za njen severovzhodni del so o tem pisali Blašković (1991); Weber et al. (2006; 2010); Placer et al. (2010); Vrabec et al. (2018). Kdaj se je pričel proces približevanja ni natančneje ugotovljeno, v splošnem pa menimo, da v srednjem miocenu in traja še danes, zato uporabljamo termin neogensko-recentna dejav- nost Jadranske mikroplošče. Njene značilnosti še niso dovolj raziskane, posledica tega procesa pa je oženje Dinaridov, ki se kinematsko razli- kuje od oženja le-teh v paleogenu, v zaključnem obdobju nastajanja krovne zgradbe. Razlikuje se 130 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR K V A R N E R LJUBLJANAUDINE TRIESTE 0 50 km I S T R A Fig. 2 SAF IF RIJEKA S O U T H E R N A L P S D I N A R I D E S A D R I A A D R I A T I C S E A SF KF T H S 1 2 3 4 5 6 7 8 9 10 11 12 T IF 131Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain gene, in the final period of the formation of the nappe structure. It differs mainly in that, in addi- tion to successive deformations, new plicative and disjunctive structures also emerged. The Istran block is located between the Sesl- jan and Kvarner Faults, an integral part of the Mi- croadria which, in contrast to the other blocks of the Microadria, is noticeably pushed towards the northeast. Its visible part is Istra (Fig. 1). As a re- sult, an extensive Istra Pushed Area was formed in the Dinaric hinterland of the block, in which longi- tudinal morphostructural objects are laterally bent towards the northeast (Placer et al., 2010; 2023). This situation is illustrated by the morphostruc- tural trajectory in the figure. The two branches of the Dinaric thrust boundary in Istra are related by the Črni Kal Anomaly, which is substantiated in the article by Placer et al. (2023, p. 18–30). This article discusses the laterally bent Paleo- gene thrust boundary between the External Di- naric Imbricated Belt, composed predominantly of f lysch rocks, and the External Dinaric Thrust Belt, which is composed mostly of carbonate rocks. Ex- tensive, sub-recent and recent gravity-related phe- nomena have developed here, which significantly affect the geomorphology of the landscape (Komac & Ribičič, 2008; Kocjančič et al., 2019; Placer et al., 2021a). The described conditions are particu- larly pronounced on the northeastern part of the Vipava Valley beneath the carbonate brims of the Trnovski gozd and Nanos plateaus (Popit et al., 2022), where fossil gravity bodies are stacked in several consecutive levels, and the recent ones are spread out over them; such are e.g. the recent large Slano Blato and Razdrto planar landslides (Fig. 2). The conditions therefore show that the External Dinaric Thrust Belt is being uplifted in this area predvsem v tem, da so poleg nasledstvenih defor- macij nastale tudi nove plikativne in disjunktivne strukture. Sestavni del Mikroadrije je istrski blok med Sesljanskim in Kvarnerskim prelomom, ki je na- sproti drugim blokom Mikroadrije opazno potis- njen proti severovzhodu. Njegov vidni del je Istra (sl. 1). Zaradi tega je v dinarskem zaledju bloka nastalo obsežno istrsko potisno območje v kate- rem so longitudinalni morfostrukturni objekti bočno usločeni proti severovzhodu (Placer et al., 2010; 2023). To stanje ponazarja morfostruktur- na trajektorija na sliki. Dva kraka narivne meje Dinaridov v Istri povezuje črnokalska anomalija, ki je utemeljena v članku Placer et al. (2023, str. 17-30). V tem članku obravnavamo bočno usločeno narivno mejo paleogenske starosti med Zunanje- dinarskim naluskanim pasom, pretežno iz f lišnih kamnin in Zunanjedinarskim narivnim pasom pretežno iz karbonatnih kamnin. Tu so se raz- vili obsežni subrecentni in recentni gravitacijski pojavi, ki pomembno vplivajo na geomorfologijo krajine (Komac & Ribičič, 2008; Kocjančič et al., 2019; Placer et al., 2021a). Opisane razmere so posebej izrazite na severovzhodnem obrobju Vi- pavske doline pod karbonatnimi obronki planot Trnovski gozd in Nanos (Popit et al., 2022), kjer so fosilna gravitacijska telesa naložena v več nad- stropjih, recentna pa se prožijo preko njih; taka sta npr. velika recentna planarna plazova Slano blato in Razdrto (sl. 2). Razmere torej kažejo, da se enota Zunanjedinarskega narivnega pasu na tem območju dviga (Mihael Ribičič, ustna izjava 2010), kar povzroča nestabilnost pobočij, vendar dviganje ni posledica reaktivacije krovnega nariva Zunanjedinarskega narivnega pasu paleogenske Fig. 1. Structural sketch of the northeastern margin of Microadria. Compiled from: Geological map of Slovenia 1:250 000 (ed. Buser, S. 2009); Geological map of the Friuli Venezia Giulia 1:150 000 (ed. Giovanni Battista Carulli, 2006); Placer et al. (2021; 2023). Sl. 1. Strukturna skica severovzhodnega obrobja Mikroadrije. Sestavljeno po predlogah: Geološka karta Slovenije 1:250 000 (ured. Buser, S. 2009); Carta geologica del Friuli Venezia Giulia 1:150 000 (ured. Giovanni Battista Carulli, 2006); Placer et al. (2021; 2023). 1 Southern Alps / Južne Alpe. 2 External Dinaric Thrust Belt. Front part of thrust unit: T – Trnovo Nappe, H – Hrušica Nappe, S – Snežnik Nappe / Zunanjedinarski narivni pas. Čelni del krovne enote: T – Trnovski pokrov, H – Hrušiški pokrov, S – Snežniški pokrov 3 External Dinaric Imbricate Belt / Zunanjedinarski naluskani pas 4 Adria Microplate (Microadria) / Jadranska mikroplošča (Mikroadrija) 5 Thrust boundary of Southern Alps; thrust fault related to the dynamics of the Southern Alps / narivna mejna Južnih Alp; nariv povezan z dinamiko Južnih Alp 6 Thrust boundary of Dinarides / narivna meja Dinaridov 7 Boundary of the External Dinaric Imbricate Belt / meja Zunanjedinarskega narivnega pasu 8 Boundary of the nappe unit within the External Dinaric Thrust Belt / meja krovne enote znotraj Zunanjedinarskega narivnega pasu 9 Subvertical fault: SAF – Sava Fault, IF – Idrija Fault, SF – Sistiana Fault, KF – Kvarner Fault / subvertikalni prelom: SAF – Savski prelom, IF – Idrijski prelom, SF – Sesljanski prelom, KF – Kvarnerski prelom 10 Črni Kal Anomaly (Placer et al., 2023, pg. 17–30) / črnokalska anomalija (Placer et al., 2023, str. 17–30) 11 Area of large gravitational phenomena / območje velikih gravitacijskih pojavov 12 Morphostructural trajectory / morfostrukturna trajektorija 132 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR (Mihael Ribičič, oral statement 2010), which in- troduces instability into the slopes. However, the uplift is not the result of the reactivation of the Paleogene nappe thrust of the External Dinaric Thrust Belt, but the Neogene-recent activity of the Adriatic Microplate. Paleogene overthrusts in this starosti, temveč neogensko-recentne dejavnosti Jadranske mikroplošče. Paleogenski krovni na- rivi so v tem delu Dinaridov v smeri narivanja subhorizontalni in rahlo undirani (Placer et al., 2021a, str. 47; 2023, sl. 11), regionalno pa blago tonejo proti severozahodu. Fig. 8A Fig. 3, 6 Fig. 4, 11 SF P1 P1’ H T T T T/H T/H H S 1 2 3 4 5 6 7 8 9 10 11 12 13 T IF P1 P1’ TOLMIN IDRIJA NOVA GORICA Livek 0 10 km 2 1 K R A S 1 a a e c e b b dB a n j š i c e T r n o v s k i g o z d V i p a v s k a d o l i n a Š e n t v i š k ap l a n o t a N a n o s IF L iv šk a d ol ina 133Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain Geomorfološka stopnja med Trnovskim goz- dom z Nanosom iz karbonatnih kamnin v Zuna- njedinarskem narivnem pasu in Vipavsko dolino iz f lišnih kamnin v Zunanjedinarskem naluska- nem pasu bi lahko nastala tudi samo zaradi hi- trejše denudacije f liša, vendar so bili pri karti- ranju trase avtoceste po Vipavski dolini pod Nanosom in Trnovskim gozdom odkriti nedvou- mni znaki reverzne tektonike, ki kažejo na podri- vanje (neobjavljeno). Pomembno je tudi, da je več etaž gravitacijskih pojavov lažje razložiti s tek- tonskim dviganjem kot z denudacijo in da nasto- pa geomorfološka stopnja tudi tam, kjer sta obe omenjeni krovni enoti zgrajeni iz f lišnih kamnin (območje trenutnega kartiranja severozahodno od Vipavske doline). Kot strukturni model recentnega dogajanja na meji med Zunanjedinarskim naluskanim pasom in Zunanjedinarskim narivnim pasom v Vipa- vski dolini služi dogajanje na meji med avtohto- nom Istre in Zunanjedinarskin naluskanim pa- som, kjer so ob neogensko-recentnih podrivnih reverznih prelomih paleogenske narivne ploskve antiformno usločene (Placer et al., 2023, sl. 7). Zdi se, da stopničasta zgradba Dinaridov ni povezana samo s paleogensko krovno zgradbo, temveč tudi z neogensko-recentnimi podrivnimi reverznimi prelomi. To opažajo tudi Korbar et al. (2020) na območju Kvarnerja. Longitudinalni desnozmični prelomi Dinaridov imajo pri tem manjši pomen, pomembnejši so le nekateri, npr. Idrijski prelom, ki smo ga zato tudi vključili v članek. V tem članku ni opisan strukturni mehanizem neogensko-recentnega dviganja Zunanjedinar- skega narivnega pasu nad Zunanjedinarski nalu- skani pas v Vipavski dolini, temveč je obdelana le geomorfologija dvignjenih planot nad Vipavsko part of the Dinarides are subhorizontal and slight- ly undulating in the direction of thrusting (Placer et al., 2021a, p. 47; 2023, fig. 11), and regionally dipping gently to the northwest. The geomorphological step between Trnovski gozd and Nanos composed of carbonate rocks in the External Dinaric Thrust Belt and Vipava Val- ley composed of f lysch rocks in the External Di- naric Imbricate Belt could also have been created only due to a faster denudation of f lysch, howev- er, during the mapping of the route of the high- way along the Vipava Valley beneath Nanos and Trnovski gozd unequivocal signs of reverse tec- tonics indicating subduction (unpublished) were found. It is also important that several etages of gravity phenomena can be more easily explained by tectonic uplift than by denudation, and that a geomorphological step occurs also where both of the mentioned nappe units are composed of f lysch rocks (the area of the ongoing mapping northwest of the Vipava Valley). The events on the boundary between the Istra Autochton and the External Dinaric Imbricated Belt, where Paleogene thrust planes are antiformal- ly folded along the Neogene-recent underthrusting reverse faults (Placer et al., 2023, Fig. 7) serve as a structural model of the recent events on the bound- ary between the External Dinaric Imbricated Belt and the External Dinaric Thrust Belt in the Vipava Valley. The stepped structure of the Dinarides ap- pears to be related not only to the Paleogene nappe structure, but also to Neogene-recent underthrust reverse faults. This is also observed by Korbar et al. (2020) in the Kvarner area. Longitudinal right lateral strike-slip faults of the Dinarides are less important, only some are more important, e.g. the Idrija Fault, which it is included it in the article. Fig. 2. Major karst plains on the External Dinaric Thrust Belt and External Dinaric Imbricate Belt. Sl. 2. Večje kraške uravnave na Zunanjedinarskem narivnem in Zunanjedinarskem naluskanem pasu. 1 Southern Alps / Južne Alpe 2 External Dinaric Thrust Belt: T – Trnovo Nappe, H – Hrušica Nappe, S – Snežnik Nappe, T/H – area of the interjacent nappe slices between Trnovo Nappe and Hrušica Nappe (Placer, 1981, fig. 9) / Zunanjedinarski narivni pas: T – Trnovski pokrov, H – Hrušiški pokrov, S – Snežniški pokrov, T/H – območje vmesnih krovnih lusk med Trnovskim in Hrušiškim pokrovom (Placer, 1981, sl. 9) 3 External Dinaric Imbricate Belt / Zunanjedinarski naluskni pas 4 Microadria / Mikroadrija 5 Thrust boundary of the Southern Alps / narivna meja Južnih Alp 6 Thrust boundary of the Dinarides / narivna meja Dinaridov 7 Boundary of the External Dinaric Imbricate Belt / meja Zunanjedinarskega narivnega pasu 8 Boundary of the nappe unit within the External Dinaric Thrust Belt / meja krovne enote znotraj Zunanjedinarskega narivnega pasu 9 Important subvertical fault: IF – Idrija Fault, SF – Sistiana Fault / pomembnejši subvertikalni prelom: IF – Idrijski prelom, SF – Sesl- janski prelom 10 Larger karst plain: a – Aurisina Classical Karst Region, b – Doberdo del Lago, Kostanjevica, and Komen Classical Karst Region, c – Voglarska planota (Voglarji plateau), d – southeastern part of Banjšice (Banjšice plateau), e – eastern part of Šentviška planota (Šentviška Gora plateau) / večja kraška uravnava: a – Nabrežinski Kras, b – Doberdobski, Kostanjeviški in Komenski Kras, c – Voglarska planota, d – jugovzhodni del Banjške planote ali Banjšic, e – vzhodni del Šentviške planote 11 Active planar landslide: 1 – Slano blato, 2 - Razdrto / dejavni planarni plaz: 1 – Slano blato, 2 – Razdrto 12 Profile Nanos (hamlet) - Strane (village) / profil Nanos (zaselek) - Strane (vas) 13 Recording location of fig. 5A / stojišče snemanja sl. 5A 134 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR dolino. Dvig Trnovskega gozda, Banjšic in Šentviške planote se odraža v posebnostih njiho- ve geomorfologije, ta se ne odraža samo v gra- vitacijskih pojavih, temveč, poleg drugega, tudi v intenzivnosti korozivne degradacije kraških uravnav na Zunanjedinarskem narivnem pasu, v tem primeru na Voglarski planoti na severozaho- dnem delu Trnovskega gozda, na jugovzhodnem delu Banjške planote ali Banjšic in na vzhodnem delu Šentviške planote. Pojav korozivne degra- dacije omenjenih uravnav izpeljujemo iz predpo- stavke, da so nastale na nižji nadmorski višini od današnje. Povečana stopnja korozije je posledica ostrejših klimatskih razmer, kar se najlepše opa- zi, ko obravnavane uravnane dele Zunanjedinar- skega narivnega pasu (c, d, e) primerjamo z urav- nanim Krasom, ki leži na nižji nadmorski višini (a, b) (sl. 2). Trnovski gozd in Banjško planoto razmeju- je suha dolina Čepovanski dol, po Dierks et al. (2021) pradol. Slednja je od Šentviške planote lo- čena z Idrijskim prelomom ter ob njem dvignjena za okoli 200 m. Dviganje Trnovskega gozda in Banjške plano- te na današnji nivo se kaže že v samem obstoju Čepovanskega dola, ki ni mogel nastati na da- našnji nadmorski v išini, ker nima hidrografske- ga zaledja. Uravnano območje Trnovskega gozda in Banj- šic sta Stepišnik in Ferk (2024, str. 12–13, 17–18) opredelila kot korozivni kraški ravnik, ki naj bi nastal v času pred dvigom Trnovskega gozda. Enako je o dvigu menil že Habič (1968). V našem članku podajamo geološko-strukturni pogled na kraške uravnave Trnovskega gozda, Banjšic in Šentviške planote, ki potrjuje osnovne geografske ugotovitve, hkrati pa kaže na možnost, da je ime- lo uravnano ozemlje ob svojem nastanku bistveno večji obseg od današnjega. Gravitacijski pojavi Kvartarni gravitacijski pojavi so na seve- rovzhodnem robu Vipavske doline razmeroma dobro obdelani, dosedanje raziskave so pokazale, da je zgradba in geneza pobočnih sedimentov na tem območju izredno kompleksna. Pod čelom pa- leogenskega narivnega roba se nahajajo obsežne akumulacije pobočnih sedimentov, ki so nastali z različnimi mehanizmi transporta in sedimen- tacijskimi procesi (Popit in Košir, 2003; Popit et al., 2013; Popit, 2016). Poleg regionalnih geolo- ških razmer, na mesta pojavljanja in vrsto poboč- nih procesov neposredno vplivajo tudi krajevni strukturni, litološki, hidrološki in geokemični pogoji. This article does not describe the structural mechanism of the Neogene-recent uplift of the External Dinaric Thrust Belt above the External Dinaric Imbricated Belt in the Vipava Valley, only the geomorphology of the raised plateaus above the Vipava Valley is covered. The elevation of the Trnovski gozd, Banjšice and Šentviška Gora pla- teau is ref lected in the peculiarities of their geo- morphology. This is not ref lected only in the grav- itational, but also in the intensity of the corrosive degradation of the karstic plains on the External Dinaric Thrust Belt – in this case on the Voglar- ji plateau in the northwestern part of the Trnovs- ki gozd, in the southeastern part of the Banjšice plateau or Banjšice, and on the eastern part of the Šentviška Gora plateau. The phenomenon of cor- rosive degradation of the above-mentioned settle- ments is derived from the assumption that they were formed at a lower altitude than today. The increased corrosion is the result of harsher cli- matic conditions, which is most apparent when we compare the leveled parts of the External Dinaric Thrust Belt (c, d, e) with the leveled Karst, which lies at a lower altitude (a, b) (Fig. 2). The Trnovski gozd and Banjšice plateaus are delimited by the Čepovan dry valley, a pradol ac- cording to Diercks et al. (2021). The latter is sepa- rated from the Šentviška Gora plateau by the Idrija Fault and was uplifted by about 200 m along the length of it. The uplift of the Trnovski gozd and the Ban- jšice plateaus up to today’s level is already evident in the very existence of the Čepovan dry valley, which could not have been formed at today’s alti- tude because it does not have a hydrographic hin- terland. Stepišnik and Ferk (2023, p. 12–13, 17–18) defined the leveled area of the Trnovski gozd and Banjšice plateaus as a corrosive karst plain, which was thought to have been formed before the up- lift of the Trnovski gozd plateau. Habič (1968) already thought the same about the uplift. In our article, we present a geological-structural view of the Trnovski gozd, Banjšice, and Šentviška Gora plateaus, which confirms some basic geographical findings but at the same time points to the possi- bility that the levelled area extended significantly further at the time of its formation than it does today. Gravitational phenomena Quaternary gravity-related phenomena are rel- atively well studied on the northeastern edge of the Vipava Valley, and research so far has shown that the structure and genesis of slope sediments 135Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain Kvartarni pobočni sedimenti, ki so odloženi pod čelom narivnega roba se v najvišjih delih po- bočja pojavljajo v obliki meliščnih zaplat in pah- ljač. Ti so vezani na prevoje med višje ležečimi strmimi karbonatnimi stenami in položnejšim f lišnim pobočjem pod njimi. Melišča obsega- jo precejšnje območje in predstavljajo glavni vir karbonatnega grušča, ki se nadalje z različnimi mehanizmi transporta in sedimentacijskimi pro- cesi odlaga nižje po neprepustnem pobočju. V nižjih delih pobočja so odložena številna manjša in velika sedimentna telesa in bloki kvartarnih pobočnih sedimentov mestoma sprijetih v poboč- no brečo. Variabilnost kvartarnih sedimentov v posameznih sedimentnih telesih je glede na geo- loško zgradbo ozemlja izredno velika. Izvor ma- teriala predstavljata dva glavna litološka različ- ka: sediment sestavljen iz siliciklastičnih f lišnih kamnin (peščenjak, meljevec, laporovec in mulje- vec) iz f lišne podlage in karbonatni sediment iz karbonatne krovnine v zaledju. Na podlagi dveh litoloških različkov bi pričakovali, da bo sestava in zgradba kvartarnih sedimentov razmeroma enostavna. Po dosedanjih raziskavah pa se je v večini detajlno preiskanih profilov na območju Rebrnic pod Nanosom (Popit et al., 2013) in pla- zu Selo (Košir & Popit, 2002; Popit & Košir, 2003; Verbovšek et al., 2017) izkazala izjemna strati- grafska raznolikost in lateralna spremenljivost. Znotraj splazelih mas je bilo evidentiranih več iz- razito plastnatih sedimentov, ki kažejo na več faz sedimentacije oziroma dogodkov. Če se osredotočimo na območje med Ajdovšči- no in Novo Gorico (sl. 3), po velikosti in obliki močno izstopa 10 km2 velik kompleksni plaz Selo, po Koširju et al. (2015) imenovan podorni tok ve- likega dosega (ang. long runout rock avalanche). Plaz Selo meri približno 4,5km v dolžino, razdalja od odlomnega roba do največjega dosega plazu v dolini pa 5,8 km. Povprečna debelina sedimenta je ocenjena na 19 m, največja izmerjena debelina sedimenta v osrednjem delu pa 56 m (Popit & Ko- šir, 2003; Košir et al, 2015). Volumen plazu, ki je bil ocenjen s pomočjo terenskega dela, radarskega profiliranja in GIS-a, znaša 190 × 106 m3 (Ver- bovšek et. al., 2017). Poleg manjših in večjih sedimentnih teles pahljačastih in jezičastih oblik se na pobočjih na celotnem severnem robu severovzhodnega dela Vipavske doline pogosto pojavljajo tudi planarne izravnave karbonatnih breč, nastale kot posledica velikih rotacijskih plazov, in posamezni večji ali manjši karbonatni bloki nastali z rotacijsko-tran- slacijskimi zdrsi. Na podlagi plastnatosti breče na posameznih delih blokov lahko prepoznamo, in this area is extremely complex. Extensive ac- cumulations of slope sediments formed by various transport mechanisms and depositional process- es (Popit in Košir, 2003; Popit et al., 2013; Popit, 2016) are present beneath the front of the Pale- ogene thrust margin. In addition to regional ge- ological conditions, local structural, lithological, hydrological, and geochemical conditions also di- rectly inf luence the places of occurrence and type of slope processes. Quaternary slope sediments deposited below the thrust front margin appear in the highest parts of the slope in the form of scree patches and fans. These are related to the passes between the higher lying steep carbonate walls and the gentler f lysch slope below them. The scree deposits cover a con- siderable area and are the main source of carbon- ate gravels, which is deposited further down the impermeable slope by various transport mecha- nisms and depositional processes. Numerous larg- er and smaller sedimentary bodies and blocks of Quaternary slope sediments cemented into slope breccia are deposited in the lower parts of the slope. The variability of Quaternary sediments in individual sedimentary bodies is extremely large, considering the geological structure of the territo- ry. The origin of the material is represented by two main lithological differences: sediment consisting of siliciclastic f lysch rocks (sandstone, siltstone, marl, and mudstone) from the f lysch base and car- bonate sediment from the carbonate hanging wall in the hinterland. Based on two lithological differ- ences, the composition and structure of Quater- nary sediments would be expected to be relatively simple. According to previous research, most of the profiles investigated in detail in the Rebrnice area beneath Mt. Nanos (Popit et al., 2013) and the Selo landslide (Košir & Popit, 2002; Popit & Košir, 2003; Verbovšek et al., 2017) revealed extraordi- nary stratigraphic variability and lateral diversity. Several distinctly layered sediments were record- ed within the landslide masses, indicating several phases of sedimentation or events. If we focus on the area between Ajdovščina and Nova Gorica (Fig. 3), the 10 km2 complex Selo landslide stands out in terms of size and shape, according to Košir et al. (2015) and is described as a long runout rock avalanche. The Selo landslide measures approximately 4.5 km in length, with the distance from the crown to the toe end meas- uring 5.8 km. The average sediment thickness is estimated at 19 m, and the maximum measured sediment thickness in the central part is 56 m (Popit & Košir, 2003; Košir et al., 2015). The vol- ume of the landslide, estimated with the help of 136 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR field work, GPR profiling, and GIS, is 190 × 106 m3 (Verbovšek et. al., 2017). In addition to smaller and larger sedimentary fan- and tongue-shaped bodies, planar levelings of carbonate breccias, formed as a result of large ro- tational landslides, and individual larger or small- er carbonate blocks formed by rotational-transla- tional landslides occur often on the slopes of the entire northern edge of the northeastern part of the Vipava Valley. Based on the layering of the breccia in individual parts of the blocks, we can recognize that the blocks rotated up to 60° towards the slope. Such an example occurs in the hinterland of the Šumljak landslide in Rebrnice (Popit, 2017). The leveled surface is developed mainly in the central parts of the planar surfaces, while steep margins appear on the outer parts of the levelings, which represent the main broken edges of the sedimen- tary bodies. These sedimentary bodies, especially in the upper part of the slope, were formed as a re- sult of the remobilization of material from the out- er parts of large rotational landslides, where the material was transported lower down the slope in the form of rock avalanches (Popit, 2017). In addi- tion to planar levelings, individual carbonate part- ly-brecciated gravity blocks are exposed on the slopes in large numbers in the wider vicinity of Lo- kavec, but towards Šempeter they become smaller and less numerous. The exceptional amount and frequency of the occurrence of slope processes is indicated by e.g. the area around Ajdovščina, where there are many large sedimentary bodies along the edge of the Vipava Valley, e.g. the Podrta Gora and Gradiška Gmajna fossil landslides (Popit et al., 2022) and many large gravity (collapsing) carbonate blocks. Based on preliminary research by Placer et al. (2008), and later by Kocjančič et al. (2019), 10 carbonate gravity blocks. The re- sults of the measurements showed that the lengths of the block movements along the slope ranged from 80 m to as much as 1,950 m (Kocjančič et al., 2019). The layered carbonate blocks changed their strike and dip when moving relative to the carbonate layers of the source area. Differences in the incidence of carbonate layers of the source area and carbonate blocks range from 4° to 59°. Larger gravity blocks that appear northwest of Lokavec are Zasod and Školj Sv. Pavla nad Vrtovinom (Ver- bovšek et al., 2019), Zasod pri plazu Selo, Kucl- ji nad Osekom, Vitovski hrib above the village of Vitovlje and many smaller translational gravity blocks (Fig. 6). To the northwest, the occurrence of carbonate blocks decreases considerably, and by the Lijak spring they are practically non-existent. da so bloki rotirali tudi do 60° proti pobočju. Tak primer nastopa v zaledju plazu Šumljak na Rebr- nicah (Popit, 2017). Izravnana površina je razvita predvsem v osrednjih delih planarnih površin, na zunanjih delih izravnav pa se pojavljajo strmi ro- bovi, ki predstavljajo glavne odlomne robove se- dimentnih teles. Ta sedimentna telesa, predvsem v zgornjem delu pobočja, so nastala kot posledica remobilizacije materiala z zunanjih delov velikih rotacijskih plazov, kjer se je material nato v obliki kamninskih plazov transportiral nižje po pobočju (Popit, 2017). Poleg planarnih izravnav so na po- bočjih močno izpostavljeni posamezni karbonat- ni, deloma brečirani, gravitacijski bloki, ki se v velikem številu pojavljajo v širši okolici Lokavca, proti Šempetru pa jih je na pobočju vse manj tako po velikosti kot po njihovi številčnosti. Na izje- mno količino in pogostnost pojavljanja pobočnih procesov kaže npr. območje v okolici Ajdovščine, kjer so vzdolž roba vipavske doline številna velika sedimentna telesa, npr. fosilni plaz Podrta Gora in Gradiška Gmajna (Popit et al., 2022) in števil- ni veliki gravitacijski (podorni) karbonatni bloki. Na podlagi predhodnih raziskav Placerja in so- delavcev (2008), ter kasneje Kocjančičeve s sode- lavci (2019), je bilo samo v okolici Lokavca iden- tif iciranih 10 karbonatnih gravitacijskih blokov. Rezultati meritev so pokazali, da so dolžine pre- mikov blokov po pobočju znašale od 80 m do kar 1950 m (Kocjančič et al., 2019). Vpadi plastna- tih karbonatnih blokov so pri premiku, glede na karbonatne plasti izvornega območja, spremenili smer in naklon. Razlike pri vpadu karbonatnih plasti izvornega območja in karbonatnih blokov pa znašajo od 4° do 59°. Večji gravitacijski blo- ki, ki se pojavljajo severozahodno od Lokavca so Zasod in Školj Sv. Pavla nad Vrtovinom (Verbov- šek et al., 2019), Zasod pri plazu Selo, Kuclji nad Osekom, Vitovski hrib nad Vitovljami in številni manjši translacijsko gravitacijski bloki (sl. 6). Se- verozahodneje se pojavnost karbonatnih blokov močno zmanjša in do izvira Lijaka jih praktično ni več. Geomorfologija Trnovskega gozda, Banjšic in Šentviške planote Ob pogledu na geološko karto Trnovskega gozda ter Banjške in Šentviške planote je že na prvi pogled jasno, da tvorita Trnovska in Ban- jška planota morfotektonski blok in da je bila nekoč Šentviška planota njegov del. Prvi dve geografsko ločuje Čepovanski dol, tretjo pa v geografskem in tektonskem pomenu od Banjšic ločuje dolina Idrijce, ki si jo je izdolbla po coni Idrijskega preloma (sl. 2). 137Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain Geomorphology of the Trnovski gozd, Banjšice, and Šentviška Gora plateaus Looking at the geological map of the Trnovski gozd and the Banjšice and Šentviška Gora plateaus, it is clear at first glance that the Trnovski gozd and Banjšice plateaus form one morphotectonic block, and that the Šentviška Gora plateau was once part Vse tr i planote so zgrajene pretežno iz kar- bonatnih kamnin (sl. 4), njihovo površje je razgibano, večji uravnani površini pa nastopata na Voglarski planoti na Trnovskem gozdu (c – zgornjejurski in spodnjekredni karbonati) in na jugovzhodnem delu Banjške planote (d – zgorn- jetriasni, jurski in spodnjekredni karbonati), rock fall initiation (hillslope depresion v/u-shaped) / izvor padanja kamenja (depresijske grape v/u-oblike) MORPHOLOGY (landforms) / MORFOLOGIJA (oblika površja) head scarp line / zgornji odlomni rob (edge of escarpment (height / višina) < 2 m shear plane / strižna ploskev talus cone / melišča stožčastih oblik SEDIMENT STORAGE TYPES / VRSTA SEDIMENTACIJE Selo landslide (Long runout rock avalanche) / Plaz Selo (podorni tok velikega dosega) carbonate slope deposit / karbonatni pobočni grušč fluvial deposit / fluvialen nanos hummock on landslide / izboklina znotraj plazine 2 - 5 m > 5 m rock fall initiation (hillslope depresion) / izvor padanja kamenja (depresijsko območje) 600 2400 m12000 Mesozoic limestone and dolomites / Mezozojske karbonatne kamnine STRUCTURE / STRUKTURA Paleogene flysch / Paleogenske flišne kamnine / Sedimentary body / Sedimentna telesa Nappe and thrust sheet border / Narivna meja Tectonic fault / Prelom Normal geological boundary / Geološka meja landslide in flysch / preperinski palz v flišu translational or rotational block carbonate (breccia) slide / translacijski ali rotacijski blokovni zdrs breče flatten area of carbonate brecias as a result of rotational landslides / izravnave karbonatnih breč, kot posledica rotacijskih plazov N Vogršček accumulation lake / Akumulacijsko jezero Vogeršček Li ja k Lij ak Vipava Vipava Slano blato landslide / Plaz Slano blato Selo landslide / Plaz Selo AJDOVŠČINA NOVA GORICA Lokavec Accumulation of Vogerček lake / Akumulacijsko jezero Vogeršček Fig. 3. Geomorphological map of the forehead of Trnovo Nappe between Lijak (spring) and Lokavec (village). Sl. 3. Geomorfološka karta čela Trnovskega pokrova med Lijakom in Lokavcem. 138 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR 1 2 3 4 5 6 c e NOVA GORICA AJDOVŠČINA IDRIJA Most na Soči c d e 0 10 km So ča Soča Bača Id ri jc a G o l a k i BF P2 P2’ SOF IF ZF 7 8 9 10 11 12 IF P2 P2’ SV SV VM Fig. 3, 6 Fig. 4. Structural-litholigical sketch of the Trnovski gozd, Banjšice, and Šentviška Gora plateaus. According to the Basic Geological Map of Yugoslavia 1:100 000 – OGK (sheet Gorica: Buser, 1968; sheets Tolmin in / and Videm (Udine): Buser, 1987; sheet Kranj: Grad & Ferjančič, 1974; sheet Postojna: Buser, Grad & Pleničar, 1967), Mlakar (1969, fig. 5, fig. 8), and Placer (1973, fig. 2). Sl. 4. Strukturno-litološka skica Trnovske, Banjške in Šentviške planote. Po podatkih Osnovne geološke karte SFRJ 1:100 000 - OGK (list Gorica: Buser, 1968; lista Tolmin in Videm: Buser, 1987; list Kranj: Grad & Ferjančič, 1974; list Postojna: Buser, Grad & Pleničar, 1967), Mlakarja (1969, sl. 5, sl. 8) in Placerja (1973, sl. 2). 1 Thrust boundary of Southern Alps / narivna meja Južnih Alp 2 Boundary of the External Dinaric Thrust Belt / meja Zunanjedinarskega narivnega pasu 3 Boundary of the nappe unit within the External Dinaric Thrust Belt / meja krovne enote znotraj Zunanjedinarskega narivnega pasu 4 Fault: SOF – Sovodenj Fault, IF – Idrija Fault, ZF – Zala Fault, BF – Belsko Fault (Placer et al., 2021, fig. 6, p. 44; Buser, 1976, p. 50, Predjama Fault) / prelom: SOF – Sovodenjski prelom, IF – Idrijski prelom, ZF – Zalin prelom, BF – Belski prelom (Placer et al., 2021, sl. 6, str. 44; Buser, 1976, str. 50, Predjamski prelom) 5 Geological boundary / konkordantna geološka meja 6 Unconformity / diskordantna geološka meja 7 Predominantly carbonates / pretežno karbonati: T3 2+3, J, K1, Pc, E1 8 Predominantly clastites / pretežno klastiti: C, P1, K2, Pc, E 9 Carbonates and clastites / karbonati in klastiti: P2, T1+2, T3 1, K2 10 Karst plain: c – Voglarska planota (Voglarji plateau), d – southeastern part of Banjšice (Banjšice plateau), e – eastern part of Šentviška planota (Šentviška Gora plateau) / kraška uravnava: c – Voglarska planota, d – jugovzhodni del Banjške planote, e – vzhodni del Šentviške planote 11 Position of profile P2 – P2´ / lega profila P2 – P2´ 12 Top / vrh: VM – Veliki Modrasovec (1355 m), SV – Streliški vrh (1266 m) 139Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain manjša pa na vzhodnem delu Šentviške planote (e – zgornjetriasni karbonati). Del obravnavane- ga uravnanega sveta, ki je v geografski literaturi poimenovan tudi Banjško-trnovski ravnik, sta Stepišnik in Ferk (2023, str. 13–14) obravnavala kot korozijsko kraško uravnavo, ki je zaradi tek- tonskih procesov dvignjena nad primarni nivo. Enako je menil tudi Habič (1968). Za kompleksno razumevanje geomorfologije je poleg korozivnega vpliva potrebno upoštevati tudi strukturni in tektonski v idik geneze ozem- lja, ki sta glede na starejše interpretacije bistve- no dopolnjena. Zato si oglejmo Trnovski gozd ter Banjško in Šentviško planoto z v idika novej- ših raziskav. Kot najpomembnejše se postavlja vprašanje ali so bila neuravnana območja obrav- navanih planot nekoč uravnana. Na senčenem digitalnem modelu v išin (DMV) pridobljenem iz l idarskih podatkov je na omenjenih planotah opazit i tr i osnovne strukturno-morfološke t ipe površja (sl. 4): 1. sicer uravnano toda korozivno prizadeto površje, na katerem so opazne morfo- loško slabo odzivne razpoke v smeri SSW-NNE, 2. ostro razbrazdano površje po sistemu razpok v smeri SSW-NNE na Trnovskem gozdu, ki se razteza od meje uravnane Voglarske planote do Velikega Modrasovca (1355 m) in Streliškega vrha (1266 m) in 3. mehkejše nepravilno koro- dirano in erodirano površje na zahodnem delu Banjške in Šentviške planote, na katerem je opa- zit i različne strukturne oblike kot gube, plasti in prelome. Ožji pas uravnanega ozemlja na jugo- zahodni strani Trnovske planote od Predmeje do Vodic v tem članku ni zajet, ker bi to zahtevalo širšo strukturno razlago. Iz splošnih podatkov vemo, da so korozi- ji najbolj podvržene karbonatne kamnine, bolj apnenci kot dolomiti, manj k lastične kamnine, vendar so erozijsko manj odporne, zato je na sl. 4 prikazana strukturno-litološka skica na kateri so izr isane meje treh skupin kamnin, pretežno karbonatnih, pretežno klastičnih in mešanih. Razdelitev je groba in namenjena le predsta- vitv i v tem članku obravnavanih vprašanj. Če se omejimo samo na Trnovski gozd, Banjšice in Šentviško planoto, je uravnano površje razvito pretežno na karbonatnih kamninah zgornjetr i- asne, jurske in kredne starosti. Enako velja za močno razgibano površje. Mehkejše razgibano površje pa je razvito na območjih z mešanimi in k lastičnimi kamninami zgornjekredne in paleo- genske starosti. of it. The first two are geographically separated by the Čepovanski dol (dry valley), and the third is separated from Banjšice in a geographical and tec- tonic sense by the Idrijca River Valley, which was carved out along the Idrija fault zone (Fig. 2). All three plateaus are built mainly of carbonate rocks (Fig. 4), their surface is rugged, and larg- er level surfaces occur on the Voglarji plateau in the Trnovski gozd plateau (c – Upper Jurassic and Lower Cretaceous carbonates) and on the south- eastern part of the Banjšice plateau (d – Upper Triassic, Jurassic and Lower Cretaceous carbon- ates), and a smaller one in the eastern part of the Šentviška Gora plateau (e – Upper Triassic car- bonates). Stepišnik and Ferk (2023, p. 13–14) con- sidered the leveled part in question (which is also called the Banjšice-Trnovski gozd plain in the geo- graphical literature) a corrosive karst plain, which rises above the primary level due to tectonic pro- cesses. Habič (1968) also thought the same. For a complex understanding of the geomor- phology, in addition to the corrosive inf luence, it is also necessary to take into account the structural and tectonic aspects of the genesis of the territory, which are significantly supplemented with respect to older interpretations. Therefore, we examine Trnovski gozd, and the Banjšice and Šentviška Gora plateaus from the point of view of recent re- search. The most important question is whether the non-peneplained areas of the plateaus under consideration were once peneplained. On the shad- ed digital elevation model (DMV) obtained from lidar data, three basic structural-morphological surface types can be observed on the mentioned plateaus (Fig. 4): 1. an otherwise leveled (pene- plained) but corrosively affected surface, on which morphologically poorly responsive cracks in the SSW-NNE direction are noticeable, 2. sharply fur- rowed surface along a fracture system in the SSW- NNE direction in Trnovski gozd, which stretches from the boundary of the leveled (peneplained) Voglarji plateau to Veliki Modrasovec (1355 m) and Streliški vrh (1266 m) and 3. the softer, irreg- ularly corroded and eroded surface on the western part of the Banjšice and Šentviška Gora plateaus, on which various structural forms such as folds, layers, and fractures can be observed. The narrow strip of peneplained territory on the southwestern side of the Trnovski gozd plateau from Predmeja to Vodice is not covered in this article, as such would require a broader structural interpretation. We know from general data that carbonate rocks are more prone to corrosion, limestones more than 140 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR dolomites, and clastic rocks less so, but they are less resistant to erosion; so in Figure 4 a struc- tural-lithological sketch on which the boundaries of three groups of rocks, predominantly carbon- ate, predominantly clastic and mixed, are drawn. The division is rough and intended only to pres- ent the issues discussed in this article. If we limit ourselves to Trnovski gozd, and the Banjšice and Šentviška Gora plateaus, the f lat surface is devel- oped mainly on carbonate rocks of Upper Triassic, Jurassic, and Cretaceous age. The same applies to highly uneven surfaces. A softer rugged surface is developed in areas with mixed and clastic rocks of Upper Cretaceous and Paleogene age. How then do we approach the question of whether the entire area of the Trnovski gozd pla- teau and the Banjšice and Šentviška Gora plateaus was completely levelled before some certain time, or before the uplift of the territory? On all three S čim torej utemeljujemo vprašanje ali je bi lo celotno območje Trnovskega gozda ter Banjške in Šentviške planote pred določenim časom, ozi- roma pred dvigom ozemlja, v celoti uravnano? Na vseh treh planotah, kjer nastopajo karbonat- ne kamnine, izstopa sistem enako usmerjenih razpok v smeri SSW-NNE, ki pa je na uravnanih delih komaj ali slabo v iden, na razgibanih delih pa predstavlja glavno strukturno diskontinuite- to po kateri se je oblikovalo površje. V tem smis- lu je najbolj povedno ozemlje Voglarske plano- te in Čavna do Velikega Modrasovca (1355 m) za katerega je izdelana geomorfološka karta na sl. 3. Pri predpostavki, da je bi lo celotno obmo- čje uravnano na nižjem nivoju in pozneje dvig- njeno, postavljamo domnevo, da je bi lo dviga- nje neenotno, uravnani del Trnovskega gozda (Voglarska planota) se je dvigal enakomerno, območje jugovzhodno od tod pa neenakomerno P L A I N R U G G E D K A R S T S U R F A C E P R O F I L E P 2 - P 2 ’ A 1 2 43 0 3 km Fig. 5. Geomorphological profile P2 – P2 :́ Voglarska planota (Voglarji plateau) – Čaven (ridge) – Veliki Modrasovec (1355 m) – Lokavec (village). Position of profile in fig. 4. Sl. 5. Geomorfološki profil P2 – P2 :́ Voglarska planota – Čaven – Veliki Modrasovec – Lokavec. Lega profila na sl. 4. A – Panoramic shot of the thrust face of Trnovo Nappe. Recording location in fig. 2 / Panoramski posnetek narivnega čela Trnovskega pokro- va. Stojišče snemanja na sl. 2. B – Geomorphological profile P2 – P2´ as a kinematic model of this part of the Trnovo Nappe. Profile runs perpendicular to the regional sub-vertikal fractures in direction SSW-NNE / Geomorfološki profil P2 – P2´ kot kinematski model tega dela Trnovskega pokrova. Profil poteka pravokotno na regionalne subvertikalne razpoke v smeri SSW-NNE. 1 Carbonates / karbonati 2 Clastites (flysch) / klastiti (fliš) 3 Thrust fault surface of the Trnovo Nappes / narivna ploskev Trnovskega pokrova 4 Kinematics of regional sub-vertical fractures in direction SSW-NNE / kinematika regionalnih subvertikalnih razpok v smeri SSW-NNE 141Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain plateaus where carbonate rocks occur a system of similarly oriented fractures in the SSW-NNE di- rection stands out, which, however, is only bare- ly visible on the levelled parts, and on the rugged parts represents the main structural discontinuity along which the surface was formed. In this sense, the most telling area is the territory of Voglar- ji plateau, Mt. Čaven and Mt. Veliki Modrasovec (1355 m), for which the geomorphological map in fig. 3. is elaborated. On the assumption that the entire area was levelled at a lower level and later uplifted, we suggest that the uplift was uneven, the levelled part of Trnovski gozd (Voglarji plateau) uplifted evenly, and the area southeast of it uplifted faster and unevenly, which resulted in successive movements along the exposed fracture system and a certain degree of crushing. This was followed by in hitreje, zaradi česar je prišlo do nasledstve- nih premikov po izpostavljenem sistemu razpok in določene stopnje drobljenja. Temu je sledi- la izdatnejša korozija. Učinek tega procesa je prikazan na sl. 5, panoramskemu posnetku na sl. 5A je pri ložena grobo shematizirana kine- matska skica opisanega dogajanja v prof i lu med Voglarsko planoto in Velikim Modrasovcem na sl. 5B. Bloki (makrolitoni) med razpokami sis- tema SSW-NNE so na Voglarski planoti ostali nepremaknjeni, jugovzhodno od tod pa je med njimi prišlo do premikanja. Posledice opisanega stanja so prikazane na sl. 6, kjer so večji gravi- tacijski karbonatni bloki posejani le po pobočju pod robom planote z razgibanim reliefom, med- tem ko jih pod robom uravnane Voglarske plano- te ni. Meja med obema tipoma reliefa je zazna- planation surface / uravnano površje rugged surface / razgibano površje 600 2400 m12000 boundary between planation and rugged surface / meja med uravnanim in razgibanim površjem large carbonate blocks / večji karbonatni bloki 1 - Mala gora, 2 - Visoko, 3 - Zasod, 4 - Školj Sv. Pavla, 5 - Kuclji, 6 - Vitovski hrib Accumulation of Vegeršček lake / Akumulacijsko jezero Vogeršček Li ja k Lij ak Vipava Vipava Slano blato landslide / Plaz Slano blato Selo landslide / Plaz Selo AJDOVŠČINA NOVA GORICA Lokavec Vitovski vrh 919 m Jančerijski vrh 1155 m Veliki Modrasovec 1356 m 1 5 3 6 2 N 4 Fig. 6. Relation between geomorphology of Trnovski gozd (Trnovski gozd plateau) and gravitational phenomena. Sl. 6. Povezava med geomorfologijo Trnovskega gozda in gravitacijskimi pojavi. 142 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR more extensive corrosion. The effect of this pro- cess is shown in Figure 5. A roughly schematic ki- nematic sketch of the described event in the profile between Voglarji plateau and Veliki Modrasovec in Figure 5B is attached to the panoramic snapshot in Figure 5A. The blocks (macrolithons) between the fractures of the SSW-NNE system remained unmoved on the Voglarji plateau, but movement took place between them southeast of the area. The consequences of the described condition are shown in Figure 6, where larger gravity carbonate blocks are only scattered along the slope below the edge of the plateau with rugged relief, while they are absent below the edge of the f lat Voglarji pla- teau. The border between the two types of relief is marked by a yellow dashed line running in the SSW-NNE direction of fractures, which is why it is almost f lat and, in our opinion, indirectly proves movana z rumeno prekinjeno črto, ki poteka v smeri razpok SSW-NNE, zaradi tega je skoraj ravna in po našem mnenju posredno dokazuje, da je na tem mestu razpoklinski sistem glavni usmerjevalec geomorfološke podobe površja. Kot navidezna izjema deluje plazišče severoza- hodno od Vitovlja, vendar leži pod Vitovskim vrhom (919 m), za katerega menimo, da je nastal kot posledica selektivne korozije. Osameli gr iči so namreč pogost pojav velikih kraških uravnav. Profil P2 – P2´ na sl. 5B je v kinematskem smis- lu soroden vzdolžnemu profilu P1 – P1́ (sl. 7) na jugovzhodnem delu bližnjega Nanosa (sl. 2), kjer obstoja enak sistem regionalnih razpok v smeri SSW-NNE (Placer et al., 2021a, sl. 11, profil 1a). Enake razmere obstojajo tudi na ostalem delu Trnovskega gozda do Streliškega vrha (1266 m) (sl. 4). Nanos NW Kinematic sketch SE Suhi vrh 1313 m Strane 1 2 3 4 5 6 7 8 9km 50 0 10 00 m 1 2 3 4 5 Fig. 7. Geomorphological profile P1 – P1́ as a kinematic model of Hrušica Nappe unit at the southeastern end of Nanos plateau. The profile runs perpendicular to the regional sub-vertical fractures SSW-NNE. After Placer et al. (2021, fig. 11, profile 1a), Nanos (hamlet) – Strane (village). Position of profile in Fig. 2. Sl. 7. Geomorfološki profil P1 – P1́ kot kinematski model krovne grude Hrušiškega pokrova na jugovzhodnem koncu planote Nanos. Profil poteka pravokotno na regionalne subvertikalne razpoke SSW-NNE. Povzeto po Placer et al. (2021, sl. 11, profil 1a), Nanos (zaselek) - Strane (vas). Lega profila na sl. 2. 1 Carbonate / karbonati 2 Clastites (flysch) / klastiti (fliš) 3 Thrust surface of the Hrušica Nappe / narivna ploskev Hrušiškega pokrova 4 SSW-NNE system fracture / razpoka sistema SSW-NNE 5 Kinematics of regional subvertical fractures SSW-NNE / kinematika regionalnih subvertikalnih razpok SSW-NNE 143Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain that the fracture system is the main guide of the geomorphological surface image at this place. As an apparent exception, there is a landslide north- west of Vitovlje, but it lies below Mt. Vitovski vrh (919 m) which we believe was formed as a result of selective corrosion. Inselbergs are a frequent fea- ture of large karst formations. Profile P2 – P2´ in fig. 5B is kinematically re- lated to the longitudinal profile P1 – P1´ (Fig. 7) in the southeastern part of nearby Mt. Nanos (Fig. 2), where the same system of regional fractures in the SSW-NNE direction exists (Placer et al., 2021a, Fig. 11, profile 1a). The same conditions also exist in the rest of the Trnovski gozd plateau up to Mt. Streliški vrh (1266 m) (Fig. 4). In the area of rugged relief, the ridge of Mt. Ve- liki Golak and Mt. Mali Golak (Fig. 4) stands out, along with some peaks or groups of peaks raised above the surroundings. The Mt. Veliki and Mali Golak ridge was formed during a long period of se- lective corrosion because it lies in the area of Low- er and Middle Jurassic carbonates, which in some places are relatively less soluble than those from the Upper Jurassic. Individual peaks or groups of peaks outside the ridge are the result of the gen- eral post-thrust structural and geomorphological development of the Trnovski gozd plateau, when successive and new deformations occurred. Glaci- ation also had a part in shaping the surface (Ko- delja et al., 2013). Čepovanski dol (Dry Valley) The Čepovanski dol dry valley is a witness to the tectonic events in the wider area. The valley’s essential characteristics consist in a river that ran along it, and that it is tectonically raised together with the Trnovski gozd and Banjšice plateaus in the northeast above the Šentviška Gora plateau and in the southwest above the Vipava Valley. Above the Šentviška Gora plateau, it is raised along the Idrija Fault, and above the Vipava Valley the uplift is the result of a temporally, dynamically, and kinemati- cally complex post-thrust Neogene-recent process. In this article the process itself is not discussed, only its consequences are pointed out. As a result, the relief elevation above the Vipava Valley is not comparable to the elevation of the relief along the Idrija Fault. Let’s take a look at the Idrija fault. According to Mlakar (1964), the horizontal component of the offset along the fault is about 1950 m in Idrija. The horizontal component of the offset according to Placer (1982, p. 57) is about 2360 m, but this length also includes offsets along the Zala Fault and parallel faults between Zala and Idrija Faults Na območju razgibanega reliefa izstopa npr. greben Golakov (sl. 4), ki leži v smeri slemenitve plasti NW-SE in nekaj vrhov ali skupin vrhov dvignjenih nad okolico. Greben Golakov je nastal skozi dolgo obdobje selektivne korozije, ker leži v območju spodnje in srednjejurskih karbonatov, ki so ponekod relativno slabše topni od zgornje- jurskih. Posamezni vrhovi ali skupine vrhov iz- ven Golakov pa so posledica splošnega postna- rivnega strukturnega in geomorfološkega razvoja Trnovskega gozda, ko so nastale nasledstvene in nove deformacije. Svoj delež pri oblikovanju površja je imela tudi poledenitev (Kodelja et al., 2013). Čepovanski dol Čepovanski dol je pričevalec tektonskega dogajanja na širšem prostoru. Njegovi bistveni značilnosti sta, da je po njem tekla reka, in da je skupaj s Trnovsko in Banjško planoto tektonsko dvignjen; na severovzhodu nad Šentviško pla- noto, na jugozahodu nad Vipavsko dolino. Nad Šentviško planoto je dvignjen ob Idrijskem pre- lomu, nad Vipavsko dolino pa je dvig posledica časovno, dinamsko in kinematsko kompleksne- ga postnarivnega neogensko-recentnega proce- sa, ki ga v tem članku ne obravnavamo, temveč le opozarjamo na njegove posledice. Dvig nad Vipavsko dolino zaradi tega ni primerljiv z dvi- gom ob Idrijskem prelomu. Oglejmo si Idrijski prelom, v Idriji zna- ša horizontalna komponenta premika ob njem po Mlakarju (1964) okoli 1950 m, po Placer ju (1982, str. 57) okoli 2360 m, vendar so v to dol- žino všteti tudi premiki ob Zalinem prelomu in vzporednih prelomih med Zalinim in Idrijskim prelomom. Torej premiki ob glavni prelomni coni in ob prelomih ožjega dela idr ijske izrav- nalne zgradbe (Placer et al., 2021b, 239). Ce- lotni premik ob idrijski izravnalni zgradbi pa je nekaj večji, saj bi morali vrednosti 2360 m priš- teti še premike širšega dela izravnalne zgradbe, kot sledi iz podatkov Geološke karte idrijsko-ži- rovskega hribovja med Stopnikom in Rovtami 1:25 000 (Čar, 2010). Velikost teh pa ni znana, le sklepamo lahko na okoli 100 do 200 m. Mla- karjev podatek je vezan le na premik ob glavni prelomni coni. V Idriji je severovzhodno kri lo ugreznjeno, v išina strukturnega skoka znaša v Idriji okoli 480 m (Placer, ibid.), vendar je ta po- datek navidezen, prava v išina je bistveno manj- ša, vendar ni bi la določena. V našem primeru opisujemo razmere med Tol- minom in Dolenjo Trebušo (sl. 8A). Pri Dolenji Trebuši (sl. 9) poteka Idrijski prelom po dolini 144 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR d1 d 4 d 3 d 2 d 1 TOLMIN Dolenja Trebuša Š e n t v i š k a B a n j š i c e p l a n o t a Fig. 10 Fig. 9 VF IF LF IF Idrijca Bača paleo - Bača pa le o - I dr ijc a pa leo - Ba ča So ča paleo - Idrijc a 1 2 3 4 5 6IF A B 0 5 km d 0 145Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain Fig. 8. The influence of the Idrija Fault on the formation of the relief between Tolmin (town) and Dolenja Trebuša (village). Position of figure in fig. 2. Sl. 8. Vpliv Idrijskega preloma na oblikovanje reliefa med Tolminom in Dolenjo Trebušo. Lega slike na sl. 2. A – Current situation / Sedanje stanje. B – Situation before the formation of the Idrija Fault / Stanje pred nastankom Idrijskega preloma. 1 Fault: visible, covered or assumed: IF – Idrija Fault, VF – Volče Fault, LF – Livek Fault / prelom: viden, prekrit ali domneven: IF – Idrijski prelom, VF – Volčanski prelom, LF – Livški prelom 2 Hlevnik ridge (886 m) - Senica (576 m) / greben Hlevnik (886 m) - Senica (576 m) 3 Bučenica ridge (498 m) / greben Bučenica (498 m) 4 Selski vrh ridge (588 m) - Mrzli vrh (590 m) / greben Selski vrh (588 m) - Mrzli vrh (590 m) 5 Senica ridge (658 m) / greben Senica (658 m) 6 Horizontal component of the dextral movement of the valleys and ridges that were transversely cut by the Idrija Fault: d0 – Idrijca Valley, Dolenja Trebuša ↔ Čepovanski dol (Čepovan dry valley), d1 – Idrijca Valley, Mt. Prvejk ↔ Čepovanski dol, d2 – Bača Valley ↔ Soča Valley, d3 – Senica (658 m) ridge ↔ Selski vrh (588 m) – Mrzli vrh (590 m) ridge, d4 – Bučenica (498 m) ridge ↔ Hlevnik (886 m) – Senica (576 m) ridge; d1 ≈ d2 ≈ d3 ≈ d4 ≈ 2200 m / vodoravna komponenta desnega premika dolin in grebenov, ki jih je prečno presekal Idrijski prelom: d0 – dolina Idrijce, Dolenja Trebuša ↔ Čepovanski dol, d1 – dolina Idrijce, Prvejk ↔ Čepovanski dol, d2 – dolina Bače ↔ dolina Soče, d3 – greben Senica (658 m) ↔ greben Selski vrh (588 m) - Mrzli vrh (590 m), d4 – greben Bučenica (498 m) ↔ greben Hlevnik (886 m) - Senica (576 m); d1 ≈ d2 ≈ d3 ≈ d4 ≈ 2200 m d1 Dolenja Trebuša Č e p o v a n s k i d o l 1 2 3 d 1 Prvejk 358 m 0 2 km d 0 Fig. 9. Corrosive record of the Čepovanski dol (Čepovan dry valley) floor in the left slope of the Idrijca Valley indicating a connection with the Idrijca Valley under the northwestern slope of the Prvejk hill (358 m). Position of figure in fig. 8A. Sl. 9. Korozivni odtis dna Čepovanskega dola v levem pobočju doline Idrijce, ki kaže na povezavo z dolino Idrijce pod severozahodnim pobo- čjem Prvejka (358 m). Lega slike na sl. 8A. 1 Idrija Fault, approximate position of the main fault zone / Idrijski prelom, približna lega glavne prelomne cone 2 Čepovanski dol (Čepovan dry valley) floor / dno Čepovanskega dola 3 Horizontal componente of displacement along the Idrija Fault: d0 – the entire movement, d1 – segment movement / vodoravna kompo- nenta premika ob Idrijskem prelomu: d0 – celotni premik, d1 – segmentni premik 146 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR and represents the sum of offsets along the Idri- ja main fault zone and the offsets in the narrower zone of the Idrija adjusting structure (Placer et al., 2021b, 239). The total offset along the Idrija ad- justing structure is somewhat larger, as the offsets of the wider part of the adjusting structure, should be added to the value of 2360 m as follows from the data of the Geological map of the Idrija-Žirovs- ki vrh between Stopnik and Rovte in the 1:25,000 scale (Čar, 2010). The size of these is not known, but we can only conclude that they sum to around 100 to 200 m. Mlakar’s information is only related to movement along the main fault zone. In Idrija, the northeastern block (of the Idrija Fault) is sub- sided, the height of the structural offset in Idrija is around 480 m (Placer, ibid.), but this information is easily available; the true height is significantly lower, but was not determined. For our purposes, the situation between Dolenja Trebuša and Tolmin is described (Fig. 8A). At Do- lenja Trebuša (Fig. 9) the Idrija Fault runs along the Hotenja Valley, across the saddle on Mt. Prvejk (358 m) and further towards Tolmin along the Idri- jca Valley. The horizontal displacement along it has two measurable values, the first one is the distance between the axis of the outlet of Čepovanski dol in the left slope of the Idrijca Valley, and the axis of the Idrijca Valley northwest of Mt. Prvejk, which is denoted by d1 (around 2200 m), the second is the distance between the bottom of Čepovanski dol and the extension of the Idrijca Valley southeast of Mt. Prvejk, which is marked with d0 (around 2650 m). The distance of 2650 m is close to the total dis- placement in Idrija 2360 + 100 to 200 m = 2460 to 2560 m and represents the entire displacement in the area of Dolenja Trebuša, however, we will see that the 2200 m displacement is more important for the interpretation of the relief between Dolen- ja Trebuša and Tolmin. The discussion about the structure of the fault zone of the Idrija Fault and the formation of the valley network around Dolenja Trebuša is beyond the scope of this article, but the important fact is that the displacement d1 (2200 m) is also ref lected in the relief around Tolmin. When the axis of the Idrijca Valley on the northwestern side of Mt. Prvejk is placed opposite the bottom of the corrosive imprint of Čepovanski dol, the mouth of the Bača River is positioned opposite the middle part of the Soča Valley near the village of Most na Soči (Fig. 8B). This probably means that the Idrija Fault was originally segmented, with two segments meeting at Dolenja Trebuša, which today are com- bined into a single zone. This question cannot be solved without detailed mapping, which is why the area around Dolenja Trebuša in Fig. 8B is structur- Hotenje, čez sedlo na Prvejku (358 m) in naprej proti Tolminu po dolini Idrijce. Horizontalni premik ob njem ima dve izmerljiv i vrednosti, prva je razdalja med osjo izteka Čepovanskega dola v levem pobočju doline Idrijce in osjo do- line Idrijce severozahodno od Prvejk, kar je označeno z d1 (okoli 2200 m), druga je razdal- ja med dnom Čepovanskega dola in podaljškom doline Idrijce jugovzhodno od Prvejka, kar je označeno z d0 (okoli 2650 m). Razdalja 2650 m je blizu skupnemu premiku v Idriji 2360 + 100 do 200 m = 2460 do 2560 m in predstavlja ce- lotni premik na območju Dolenje Trebuše, k ljub temu pa bomo videli, da je za razlago reliefa med Dolenjo Trebušo in Tolminom pomembnejši premik 2200 m. Razprava o zgradbi prelomne cone Idrijskega preloma in o nastanku dolinske mreže okoli Dolenje Trebuše presega okvir tega č lanka , pomembno pa je dejstvo, da se premik d1 (2200 m) odraža tudi v reliefu okoli Tolmina, ko namreč postavimo os doline Idrijce na severoza- hodni strani Prvejka nasproti dna korozivnega odtisa Čepovanskega dola, se ustje Bače postavi nasproti sredine doline Soče pri Mostu na Soči (sl. 8B). To ver jetno pomeni, da je bi l Idrijski prelom prvotno segmentiran pri čemer sta se v Dolenji Trebuši srečala dva segmenta, ki sta danes združena v enotno cono. Tega vprašanja ni mogoče rešit i brez detajlnega kartiranja, zato je prostor okoli Dolenje Trebuše na sl. 8B struk- turno neobdelan. Ko stoji dolina Bače nasproti doline Soče (sl. 8B) se; greben Selski vrh (588 m) - Mrzli vrh (590 m) se postavi nasproti grebena Seni- ce (658 m) nad Modrejem (sl. 8A, d3), greben Bučenice (498 m) nad Modrejcami se posta- vi v vzhodno-jugovzhodni podaljšek grebena Hlevnik (886 m) - Senica (576 m) nad Volčami (sl. 8A, d4). Iz slike 8B je torej mogoče povzeti, da je paleo-Idrijca tekla po Čepovanskem dolu in da je paleo-Bača tekla po sedanji dolini Soče južno od Mosta na Soči. Na podlagi gornjih ugo- tovitev smatramo razdaljo okoli 2200 m za refe- renčni premik ob Idrijskem prelomu na območju Tolmina in Dolenje Trebuše. To lahko izrazimo z zapisom d1 ≈ d2 ≈ d3 ≈ d4 ≈ 2200 m. Do kvalitativno enake ugotovitve o vplivu Idrijske- ga preloma na odnos doline Idrijce do Čepovan- skega dola in doline Bače do doline Soče južno od Mosta na Soči, so prišli Miklavž Feigel (ustna izjava, 1973) in Moulin et al. (2016, sl. 5). Podatka o premiku d1 in d2 sta v isoko pri- čevalna, medtem ko ima d3 ob d2 le vzporeden pomen. Podatek d4 je lahko realen ali sluča- jen, saj glede na nadaljnje izvajanje ne moremo 147Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain ally not resolved. The course of the Fault in the Tol- min area is described in more detail, which is why a topographical sketch is attached for easier orienta- tion (Fig. 10). The terms “total displacement” for d0 and the “segmental displacement” for d1 in Figure 9 are only relevant for explaining the situation in the Dolenja Trebuša area. When Bača Valley is positioned opposite the Soča Valley Mt. Selski vrh ridge (588 m) – Mt. Mr- zli vrh (590 m) is located opposite the Mt. Senica ridge (658 m) above Modrej village (Fig. 8A, d3), the Mt. Bučenica ridge (498 m) above Modrej is lo- cated in the east-southeastern extension of the Mt. Hlevnik ridge (886 m) – Mt. Senica (576 m) above Volče (Fig. 8A, d4). It can therefore be concluded from Figure 8B that the paleo-Idrijca f lowed along the Čepovanski dol and that the paleo-Bača f lowed along the present Soča Valley south of the village of trdit i, da je greben Hlevnik - Senica - Bučenica obstajal že pred nastankom Idrijskega preloma. Trasa preloma na sl. 8 sloni na interpretaciji kot jo je podal Buser (1986; 1987) na Osnovni geološki karti, l ista Tolmin in Videm; od sedla med Bučenico in Kukom nad Kozarščem poteka proti severozahodu, oziroma proti Kobaridu, ne pa proti zahodu-severozahodu proti Volčam, kot menijo Moulin et al. (2016, sl. 5). Za tako odlo- čitev obstoja več razlogov: 1. razvoj pliocenske- ga porečja Soče po Meliku (1956), 2. geološki podatki na Osnovni geološki karti 1:100.000, l ista Tolmin in Videm (Buser ibid.), 3. ugrez severovzhodnega kri la Idrijskega preloma in 4. kr iter ij desnozmičnega premika 2200 m na ob- močju Tolmina in Dolenje Trebuše, kot je prika- zan v tem članku. 0 2 km VF LF IF IF Fig. 10. Topographic map of the wider area around the Soča confluence, Tolminka, and Idrijca rivers. According to Geopedia – interactive online atlas and map of Slovenia. Explanation in Fig. 8. Sl. 10. Topografska karta širše okolice sotočja Soče, Tolminke in Idrijce. Povzeto po Geopedia - interaktivni spletni atlas in zemljevid Slove- nije. Legenda na sl. 8. 148 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR Most na Soči. Based on these findings, we consider a distance of around 2,200 m as a reference offset along the Idrija fault in the area of Tolmin and Do- lenja Trebuša. This can be expressed as d1 ≈ d2 ≈ d3 ≈ d4 ≈ 2200 m. Miklavž Feigel (oral statement, 1973) and Moulin et al. (2016, Fig. 5) came to the same qualitative conclusion about the impact of the Idrija Fault on the relationship between the Idrijca Valley, the Čepovanski dol, the Bača Valley, and the Soča Valley south of Most na Soči (2016, Fig. 5). The data on the d1 and d2 offsets are highly tes- timonial, while d3 has only a parallel meaning with d2. The d4 data may be representative or coinciden- tal, since according to further implementation we cannot claim that the Hlevnik - Senica - Bučenica ridge already existed before the formation of the Idrija Fault. The Idrija Fault trace in Figure 8 is based on the interpretation given by Buser (1986; 1987) on the Basic Geological Map, sheet Tolmin and Videm; from the saddle between Mt. Bučenica and Mt. Kuk above the village of Kozaršče, it runs towards the northwest, or rather towards Kobar- id, but not WNW towards Volče, as Moulin et al. (2016, Fig. 5) suggested. There are several reasons for such a decision: 1. the development of the Plio- cene Soča basin according to Melik (1956), 2. geo- logical data on the basic geological map 1:100,000, the Tolmin and Videm sheets (Buser, ibid), 3. the subsidence of the northeastern block of the Idrija Fault, and 4. the criterion of a 2,200 m dextral off- set in the area of Tolmin and Dolenja Trebuša, as shown in this article. Ad 1. Melik (1956, Fig. II) in his discussion about the Middle Pliocene assumes that the pa- leo-Soča f lowed through the valley between Ko- barid and Robič, and then through the present-day Nadiža gorge towards the south. Melik (ibid) also assumed that the paleo-Idrijca river f lowed through the Čepovanski dol valley, and that today’s hanging Livek Valley SE of the village of Livek (Fig. 2) had a wide watershed in its hinterland, which was fed from the area northeast of Livek and today appears completely denuded. The description applies to the situation before the formation of the Idrija Fault. It is also indirectly proven by the f low of the Soča River, which f lows north of Kobarid across the fron- tal part of the Southern Alps thrust independently of the bundle of faults that were created later and which we believe are related to the Idrija Fault. The assumption is supported by the 1:100,000 scale Ba- sic geologic map, Tolmin and Videm sheet (Buser, 1986; 1987). The Livek hanging valley is the main geomor- phological object that indicates the f low of the pa- leo-Soča River towards the present-day Nadiža Ad 1. Melik (1956, sl. II) v svoji razpravi za obdobje srednjega pliocena domneva, da je pa- leo-Soča tekla po dolini med Kobaridom in Ro- bičem, nato pa po današnji soteski Nadiže proti jugu, da je paleo-Idrijca tekla po Čepovanskem dolu in da je imela danes v iseča Livška doli- na (sl. 2) tedaj široko zaledje. Napajala se je z območja severovzhodno od Livka, ki je danes povsem denudirano. Opis velja za stanje pred nastankom Idrijskega preloma, kar posredno dokazuje tudi tok Soče, ki severno od Kobarida teče preko čelnega dela nariva Južnih Alp ne- odvisno od pozneje nastalega snopa prelomov, za katere menimo, da so povezani z Idrijskim prelomom. Podlaga za to domnevo so podatki Osnovne geološke karte, l ista Tolmin in Videm (Buser, 1986; 1987). Viseča Livška dolina je glavni geomorfološki objekt, ki kaže na tok paleo-Soče proti današ- nji dolini Nadiže. Na območju Livka ima med Kolovratom in Matajur jem značilnosti pradoli- ne, katere pobočja dosežejo do 500 m višine, pri Čepovanskem dolu pa največ okoli 400 m. Na podlagi tega je moč sklepati, da je imelo denu- dirano porečje zgornjega dela l ivške paleoreke znaten obseg. V času nastanka Melikove razprave so Idrij- ski prelom obravnvali kot disjunktivno deforma- cijo, ki naj bi imela ponekod učinek reverznega, ponekod normalnega preloma. Rakovec (1956, str. 79) ga je potegnil do Kobarida in Učje. Des- nozmično komponento Idrijskega preloma je utemelji l Mlakar (1964). Ad 2. Po podatkih Osnovne geološke karte (OGK), l ista Tolmin in Videm (Buser, ibid.), je trasa Idrijskega preloma od sedla med Bučenico in Kukom nad Kozarščem (sl. 10), usmerjena pro- t i severozahodu. Naprej poteka pod severovzho- dnim pobočjem grebena Hlevnik - Senica in po Soški dolini do Kobarida ter po severovzhodnem pobočju grebena Mali vrh (1405 m) - Starijski vrh (1146 m) proti spodnjemu delu doline Učje nad Žago (Čar & Pišljar, 1993; Gosar, 2022). Pri Libušnjah se na severovzhodno stran cone Idrij- skega preloma naslanja narivna meja Južnih Alp, ki se pri Kobaridu od nje odcepi. Zahodno od tod se nadaljuje pod imenom prelom Barcis - Staro selo. Premik narivne meje Južnih Alp ob Idrijskem prelomu je desnozmičen, navidezna dolžina premika znaša okoli 3,5 km, vendar gre za učinek, ki je posledica ugreza severovzhodne- ga kri la Idrijskega preloma in položnega vpada narivne meje Južnih Alp. Dejanski desnozmič- ni premik je manjši, vendar njegove velikosti ni mogoče ugotovit i. 149Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain Valley. In the area of the village of Livek, between Mt. Kolovrat and Mt. Matajur, it has the charac- teristics of a deep valley, with slopes that reach a height of up to 500 m, while the maximum valley depth at Čepovanski dol is around 400 m. With this in mind, we can conclude that the denuded basin of the upper part of the Livek paleo-river had a signif- icant extent. At the time of Melik’s treatise, the Idrija Fault was treated as a brittle deformation, which was supposed to have the effect of a reverse fault in some places, and a normal fault in others. Rakovec (1956, p. 79) drew it to Kobarid and Učja. The dex- tral offset component of the Idrija Fault was estab- lished by Mlakar (1964). Ad 2. According to the Basic Geological Map 1:100,000 (OGK), sheet Tolmin and Videm (Bus- er, ibid.), the Idrija Fault trace from the saddle be- tween Mt. Bučenica and Mt. Kuk above Kozaršče village (Fig. 10) is directed towards the northwest. It continues under the northeastern slope of the Mt. Hlevnik – Mt. Senica ridge and along the Soča Valley to Kobarid and along the northeastern slope of the Mt. Mali vrh (1405 m) – Mt. Starijski vrh (1146 m) ridge towards the lower part of the Učja Valley above the village of Žaga (Čar & Pišljar, 1993; Gosar, 2022). Near Libušnje, the thrust boundary of the Southern Alps leans on the northeastern side of the Idrija Fault zone, which splits off near Ko- barid. To the west it continues as the Barcis - Staro selo Fault. The offset of the thrust boundary of the Southern Alps along the Idrija Fault is dextral, with an apparent offset of about 3.5 km. The actual dex- tral displacement is smaller due to the subsidence of the northeastern block of the Idrija Fault and the gentle dip of the Southern Alps boundary thrust. The true offset, however, cannot be ascertained. On the saddle between Mt. Bučenica and Mt. Kuk, before Volče, the stratigraphically and geo- morphologically responsive Volče Fault (Fig. 8) splits off from the Idrija Fault, which runs along the southwestern slope of the Mt. Hlevnik – Mt. Senica ridge. Due NW it continues across the saddle be- tween Mt. Hlevnik (886 m) and the Mt. Kolovrat ridge into the Soča Valley. Between Mt. Kuk and Mt. Mengore ( just south of it), another fault branch- es off from the Idrija Fault (Jamšek Rupnik et al., 2022), whose route, in our opinion, passes the vil- lage of Livek and continues due NW towards Robič. The fault between Robič and Livek was mapped by Buser, who marked it due southeast to the upper Idrijca River and named it the Livek Fault. How- ever, the structural and remote detection data indi- cate a connection from Livek to the aforementioned saddle above Kozaršče, so we suggest that the lat- Na sedlu med Bučenico in Kukom se pred Vol- čami od Idrijskega preloma odcepi stratigrafsko in geomorfološko jasno odziven Volčanski pre- lom (sl. 8), ki poteka po jugozahodnem pobočju grebena Hlevnik - Senica. Nato se prevesi pre- ko sedla med Hlevnikom (886 m) in grebenom Kolovrata v Soško dolino. Med Kukom in Men- gorami nad Kozarščem se od Idrijskega prelo- ma odcepi drugi prelom (Jamšek Rupnik et al., 2022), katerega trasa po našem mnenju poteka mimo Livka in naprej proti Robiču. Prelom med Robičem in Livkom je kartiral Buser, potegnil ga je proti jugovzhodu na zgornjo Idrijco in ga poimenoval Livški prelom. Toda strukturni po- datki in zaznambe daljinske detekcije, kažejo na povezavo od Livka proti omenjenemu sedlu nad Kozarščem, zato predlagamo, da se slednja va- r ianta obravnava kot Livški prelom (sl. 8). Naše mnenje temelji na primerjavi podatkov Geološke karte Benečije Julijske krajine (Carulli, 2006) in Osnovne geološke karte Jugoslavije merila 1: 100.000, l istov Tolmin in Videm (Buser, 1986; 1987). Ta je pokazala, da se zahodno od Idrij- skega preloma uveljavlja drugačna dinamika neogensko-recentnih deformacij. To se odraža v njihovi smeri in kinematiki, vendar razprava o tem presega okvir tega č lanka. Ad 3. Sklepamo, da je Idrijski prelom odre- zal zgornje povir je l ivške paleoreke od njenega osrednjega in spodnjega toka. Rez je bi l učinko- v it zato, ker se je severovzhodno kri lo preloma ugreznilo, oziroma jugovzhodno kri lo dvignilo in s tem preprečilo odtok voda zgornjega povod- ja l ivške paleoreke proti jugozahodu. Te so se potem lahko odvajale le proti severozahodu ali jugovzhodu. Pričel se je proces nastajanja doline med Kobaridom in Tolminom, ki je bi l učinko- vit tudi zaradi bližine narivne meje Južnih Alp. Najprej sta nastali porečji dveh potokov od ka- ter ih je eden napajal paleo-Sočo, drugi paleo- -Bačo. Sčasoma je nastala dolina, v katero se je iz doslej še neraziskanih razlogov preusmerila Soča. Dolina med Kobaridom in Tolminom bi lah- ko nastala tudi zaradi same narivne meje Juž- nih Alp brez Idrijskega preloma, vendar kažeta Volčanski prelom in desni premik narivne meje Južnih Alp med Kobaridom in Libušnjami na traso, kot so jo razumevali Rakovec (1956), Ar- sovski & Feigel (1973) in Buser (1986, 1987). 150 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR ter variant be considered the Livek Fault (Fig. 8). Our opinion is based on a comparison of the data of the Geological Map of the Veneto Julian Region (Carulli, 2006) and the Basic Geological Map of Yu- goslavia, 1:100,000 scale, Tolmin and Videm sheet (Buser, 1986; 1987). This showed that a different dynamic of Neogene-recent deformations is taking place west of the Idrija Fault, which is ref lected in their direction and kinematics, but discussion of this is beyond the scope of this article. Ad 3. We conclude that the Idrija Fault cut off the upper headwaters of the Livek paleo-river from its central and lower course. The cut was effective because the northeastern f lank of the fault subsid- ed, or the southeastern f lank rose, thereby prevent- ing drainage of the waters of the upper catchment of the Livek paleo-river towards the southwest. These waters could then be discharged only towards the northwest or southeast. Thus, the process of for- mation of the valley between Kobarid and Tolmin began, which was also effective due to the proxim- ity of the Southern Alps Thrust Boundary. First, the basins of two watersheds were formed, one of which fed the paleo-Soča, the other the paleo-Bača River. Over time, a valley was formed into which the Soča River diverted for as yet unexplained and unexplored reasons. The valley between Kobarid and Tolmin may also have been formed by the Southern Alps Thrust Boundary without the Idrija Fault, but the Volče Fault and the right lateral shift of the Southern Alps Thrust Boundary between Kobarid and the village of Libušnje show the trace as understood by Rakovec (1956), Arsovski & Feigel (1973), and Buser (1986; 187). Ad 4. The displacement criterion of 2200 m can be used for displacements d2, d3, and d4 in the Tolmin area (Fig. 8A), while the of valley network between Tolmin and Sela pri Volčah indicates a multiphase development. This only reinforces the assumption that before the formation of the Idri- ja Fault, the paleo-Soča did not f low here and that the area between Tolmin and Sela pri Volčah was formed by several streams that fed the paleo-Bača River from the northwestern side. In Figure 8B, no variant on the geomorphological development of this area is given, but we would like to draw atten- tion to the Mt. Selski vrh – Mt. Mrzli vrh – Mt. Sen- ica (658 m) ridge, which was probably continuous, before the formation of the Idrija Fault, so the water of all the streams f lowed into the paleo-Bača River in the area of Sela pri Volčah exclusively. The above four considerations lend a relative- ly high probability to the interpretation of the pa- leo-Soča f low from Kobarid to the west and to the Ad 4. Kriter ij zmika 2200 m je na območju Tolmina mogoče uporabit i pr i premiku d2, d3 in d4 (sl. 8A), medtem ko splet dolin med Tol- minom in Selami pri Volčah kaže na večfaz- ni razvoj. To le utr juje domnevo, da pred nas- tankom Idrijskega preloma paleo-Soča tu še ni tekla in da je prostor med Tolminom in Selami pri Volčah oblikovalo več potokov, ki so napaja- l i paleo-Bačo s severozahodne strani. Na sl. 8B ni podane nobene variante o geomorfološkem razvoju tega prostora, opozorili bi pa na greben Selski vrh - Mrzli vrh -Senica (658 m), ki je bi l pred nastankom Idrijskega preloma ver jetno sklenjen, zato je voda vseh potokov odtekala v paleo-Bačo le na območju Sel pri Volčah. Navedeni št ir je premisleki dajejo sorazmer- no v isoko stopnjo ver jetnosti interpretaciji toka paleo-Soče od Kobarida proti zahodu in inter- pretaciji trase Idrijskega preloma od sedla med Bučenico in Kukom proti severozahodu. Ven- dar je potrebno obe tezi k ljub temu preverit i. Katera reka je urezala dolino med Robičem in Kobaridom bi se dalo ugotovit i s sondiranjem, s katerim bi določili smer imbrikacije plošča- t ih prodnikov; če je ta nagnjena proti zahodu je dolino izdolbla Soča, v nasprotnem primeru Nadiža. Sondiranje bi moralo odgovorit i tudi na vprašanje morebitne ojezeritve in njene starosti. Traso Idrijskega preloma je mogoče preverit i z razkopi ali geof izikalnim prof i l iranjem v dolini Soče, najprimernejše mesto preverbe je prostor pod severovzhodnim pobočjem grebena Hle- vnik - Senica. Raziskave v Modrejcah (Jamšek Rupnik- et al., 2022) so bile izvedene korektno, niso pa mogle dati odgovora na to vprašanje. Prispevek o genezi rečnega reliefa na območju zgornje Nadiže (Diercks et al., 2021) ne posega v to razpravo, čeprav je v njem uporabljena inter- pretacija Moulin et al. (2016, sl. 5), da je Nadiža urezala dolino med Robičem in Kobaridom. Pred nastankom Idrijskega preloma sta Banj- ška in Šentviška planota tvorili enovito »Banj- ško-Šentviško planoto« (sl. 8B). Če bi hoteli bolj dosledno rekonstruirati takratno stanje, bi mora- li Šentviško planoto dvigniti za okoli 150 m, ali obratno, in odmisliti dolino Idrijce med njima. V tem članku ne opisujemo strukturnih razmer na jugozahodni strani Banjške in Trnovske planote nad Vipavsko dolino, ugotavljamo pa, da so litolo- ška sestava (eocenski f liš ter kredni, paleocenski in eocenski karbonati), razporeditev (f liš v talni- ni, karbonati v krovnini, meja med njimi subhori- zontalna krovna narivna ploskev) in kinematika, primerljivi z istrsko-furlansko narivno-podrivno cono (Placer et al., 2023, sl. 1, str. 13). V profilu 151Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain interpretation of the route of the Idrija Fault from the saddle between Mt. Bučenica and Mt. Kuk to the northwest. However, it is still necessary to ver- ify both theses. Which river cut the valley between Robič and Kobarid could be determined by probing, which would determine the direction of imbrication of f lat pebbles; if it is inclined to the west, the valley was carved out by the Soča River, and if inclined otherwise by the Nadiža. Sounding should also an- swer the question of possible lake formation there and the age of such. The Idrija Fault trace can be verified by trenching or geophysical profiling in the Soča Valley; the most suitable place for verification is the area under the northeastern slope of the Mt. Hlevnik – Mt. Senica ridge. Research at the village of Modrejce (Jamšek Rupnik et al., 2022) was car- ried out correctly but did not provide a conclusive answer to the question. The paper on the genesis of the river relief in the area of the upper Nadiža River (Diercks et al., 2021) does not play a role in this discussion, though it does use the interpretation of Moulin et al. (2016, Fig. 5) that the Nadiža cut the valley be- tween Robič and Kobarid. Before the formation of the Idrija Fault, the Banjšice and Šentviška Gora plateaus formed a single plateau (Fig. 8B). If we wanted to recon- struct a more consistent picture of the situation at the time, we would have to raise the Šentviška, Gora plateau by about 150 m, or vice versa, and discard the Idrijca Valley between them. In this article we do not describe the structural conditions on the southwestern side of the Banjšice and Trnovski gozd plateaus above the Vipava Valley, but we note that the lithological composition (Eo- cene f lysch and Cretaceous, Paleocene, and Eocene carbonates), distribution (f lysch in the footwall, carbonates in the hanging wall and subhorizontal thrust plane between them) and kinematics are comparable to the Istra-Friuli Thrust-Underthrust Zone (Placer et al., 2023, Fig. 1, p. 13). In the profile of the Istra-Friuli Thrust-Underthrust Zone (ibid., fig. 8), two types of deformations stand out: under- thrust reverse faults and antiformally bent Paleo- gene thrust surfaces located next to them; both are related to the uplift of the hanging wall of the un- derthrust reverse faults. The equivalent of the anti- formally bent nappe thrust plane on the boundary between the Vipava Valley (External Dinaric Im- bricated Belt) and the Trnovski gozd plateau with Mt. Hrušica (External Dinaric Thrust Belt) is the Nanos-Čaven antiform (Placer et al., 2021a, p. 56- 58; 2023, p. 38), the equivalent of the underthrust reverse faults are represented by structures whose description requires extensive substantiation, so istrsko-furlanske narivno-podrivne cone (ibid., sl. 8) izstopata dva tipa deformacij, podrivni re- verzni prelomi in ob njih antiformno usločene pa- leogenske narivne ploskve; oboje je povezano z dvigom krovninskega krila podrivnih reverznih prelomov. Ekvivalent antiformno usločene krovne narivne ploskve na meji med Vipavsko dolino (Zu- nanjedinarski naluskani pas) in Trnovskim goz- dom s Hrušico (Zunanjedinarski narivni pas), je nanoško-čavenska antiforma (Placer et al., 2021a, str. 56–58; 2023, str. 38), ekvivalent podrivnih reverznih prelomov pa predstvavljajo strukture, katerih opis zahteva obširno utemeljevanje, zato bodo predstavljene v posebnem prispevku. Za dokaz dviga uravnanega območja Trnovskega gozda in Banjške planote zadostu- je že sam obstoj Čepovanskega dola, saj dol kot nekdanja rečna dolina ni mogel delovati na se- danji nadmorski v išini, urezovanje v primarno uravnavo na začetku njegovega nastajanja pa se je moralo dogajati na še nižjem nivoju. Sklep Nad severovzhodnim obrobjem Vipavske do- line, ki je zgrajena iz f lišnih kamnin Zunanjedi- narskega naluskanega pasu, se dvigajo karbonat- ne kamnine Zunanjedinarskega narivnega pasu (planote Banjšice, Trnovski gozd, Nanos), ki so bile tja narinjene v paleogenu v zaključnem ob- dobju narivne faze nastajanja Dinaridov. Nari- njene karbonatne kamnine se danes gravitacijsko sprožajo v Vipavsko dolino, ta proces traja že sub- recentno in recentno obdobje, zato sklepamo, da se omenjene planote postopoma dvigajo. Dviganje ob severovzhodnem obrobju Vipa- vske doline se ne dogaja ob paleogenskih krovnih narivnih ploskvah, ki so tu subhorizontalne in blago tonejo proti severozahodu, temveč ob pod- rivnih reverznih prelomih smeri NW-SE, ki pa so šele v fazi proučevanja. Ti so posledica pomi- kanja Jadranske mikroplošče (Mikroadrija) proti Dinaridom. Desnozmični prelomi v smeri NW-SE imajo v tem primeru podrejeno vlogo. Premikanje Mikroadrije proti Dinaridom pote- ka domnevno vse od srednjega miocena, zato ga obravnavamo kot neogensko-recentno dogajanje. Poleg splošnih geomorfoloških pojavov na širšem prostoru severozahodnih Dinaridov (istrsko po- tisno območje) to dokazujejo tudi pojavi na Banj- šicah in Trnovskem gozdu: 1. Kraških uravnav na Trnovskem gozdu (Voglarska planota) in Banjši- cah ( jugovzhodni del) ne moremo razlagati s kra- jevno omejenimi procesi. 2. Korozivna degradacija teh uravnav je povezana s poostritvijo klimat- skih razmer zaradi dviganja Zunanjedinarskega 152 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR they are to be presented in a special, separate paper. The very existence of the Čepovanski dol is enough to prove the elevation of the peneplained area of the Trnovski gozd and the Banjšice plateaus, since the Čepovanski dol, as a former river valley, could not function at its current altitude, and the cutting into primary regulation at the beginning of its formation had to take place at a level even lower that of today. Conclusions The carbonate rocks (Banjšice and Trnovs- ki gozd plateaus, Nanos) that were overthrusted there in the Paleogene during the final period of the thrust phase of the formation of the Dinarides rise above the northeastern edge of the Vipava Valley, which is built from the f lysch rocks of the External Dinaric Imbricated Belt. The eroded car- bonate rocks are now gravitationally launched into the Vipava Valley, which process has been going on over the course of the sub-recent and recent pe- riods, so we conclude that the mentioned plateaus are gradually rising. The uplift along the northern margin of the Vipava Valley does not take place along the sub- horizontal Paleogene nappe thrust planes, dipping slightly to the northwest, but rather along the NW- SE trending underthrust reverse faults which are still in the study phase. These are a consequence of the Microadria movement towards the Dinarides where the right lateral NW-SE trending strike-slip faults play a subordinate role. The movement of the Microadria towards the Dinarides has presumably been going on since the Middle Miocene, so we treat it as a Neogene-re- cent event. In addition to the general geomorphic phenomena in the wider area of the northwest- ern Dinarides (Istran Pushed Zone), this is also proven by phenomena in the Banjšice and Trnovs- ki gozd plateaus: 1. The karstic peneplanation in the Trnovski gozd plateau (Voglarji plateau) and the Banjšice plateau (southeastern part) cannot be explained by locally limited processes. 2. The cor- rosive degradation of these peneplains (plateaus) is related to the aggravation of climatic conditions due to the uplift of the External Dinaric Thrust Belt. 3. Čepovanski dol was active (hosted a river) at a lower altitude, and at the beginning of cutting into the levelled karst surface it must have lay even lower. We note that in addition to the existing karstic peneplanations in the Banjšice and Trnovski gozd plateaus, the rest of the Trnovski gozd area was also peneplained from the Voglarji plateau in the southeast to Mt. Veliki and Mt. Mali Modrasovec narivnega pasu. 3. Čepovanski dol je bil pretočno aktiven na nižjem nadmorskem nivoju, na začet- ku urezovanja v uravnano kraško površje pa je moral ležati še nižje. Ugotavljamo, da je bil poleg obstoječih kra- ških uravnav na Banjšicah in Trnovskem gozdu, uravnan tudi preostali del Trnovskega gozda od Voglarske planote proti jugovzhodu do Velikega in Malega Modrasovca nad Lokavcem in Streliškega vrha nad Podkrajem pri Colu. Enako domnevamo tudi za danes neuravnani del Banjšic in Šentviške planote. Zato uvajamo termin trnovsko-banjško- -šentviška degradirana uravnava. Obseg trnovsko-banjško-šentviške degradira- ne uravnave je prikazan na sliki 11. Pri nižji nad- morski višini je bilo celotno območje uravnano, med dviganjem pa je strukturno in denudacijsko degradiralo. Degradacija ni bila enotna temveč podrejena litološki sestavi, strukturi in dinamiki dviganja. Danes so na tem prostoru razviti trije različni tipi reliefa, ki so nastali po načinu degra- dacije prvotne uravnave. Na relativno umirjenem delu iz karbonatnih kamnin, kjer strukturna de- gradacija ni imela vpliva, so vidne le posledice ostrejših klimatskih pogojev, ta del je označen kot korozivno degradirana kraška uravnava (I); del iz karbonatnih kamnin, ki je danes razgiban, je označen kot strukturno in korozivno degradirana kraška uravnava (II); del iz mešanih kamnin, ki je danes umirjeno razgiban je označen kot struk- turno degradirana in denudirana uravnava (III), tu je delež korozivne degradacije podrejen zaradi prisotnosti klastičnih kamnin. Vplivno območje korozivno degradiranih kraških uravnav (I) je identično z vplivnimi območji c, d in e (I ≡ c, d, e) (sl. 2, 4). Trnovsko-banjško-šentviška degradirana ura- vnava leži na najvišjem območju Trnovskega po- krova, ki je zgrajeno iz karbonatnih kamnin. Ta del je proti jugovzhodu ohranjen le do Streliškega vrha (1266 m), od tu naprej pa je erodiran; na mestu je torej domneva, da je bila obravnavana uravnava ob svojem nastanku večja od površine kot je predstavljena na sl. 11, zato bi sodila po definiciji Stepišnika in Ferkove (2023, 12–13) v razred korozijskih uravnav. Temu pritrjuje tudi sodobni pogled na njihovo genezo (ibid. 17–18). V tem članku ni obdelan geološki pomen Poni- kvanske tektonske krpe na Šentviški planoti. Ob- delan ni tudi pomemben podatek, da je Šebreljska planota vzhodni podaljšek Šentviške planote na drugi strani doline Idrijce. Vsa našteta dejstva in domneve terjajo teme- ljit premislek o ponarivni, oziroma popaleogenski genezi Dinaridov. 153Tectonics and gravitational phenomena, part two: The Trnovski gozd-Banjšice-Šentviška Gora degraded plain 1 2 3 4 5 6 NOVA GORICA AJDOVŠČINA IDRIJA Most na Soči Šebrelje 0 10 km So ča Soča Bača Id ri jc a G o l a k i SOF IF ZF 7 8 9 10 11 IF SV SV III III III II II III I I I III BF VM Fig. 11. Trnovski gozd-Banjšice-Šentviška planota degraded plain. Sl. 11. Trnovsko-banjško-šentviška degradirana uravnava. 1 Thrust boundary of Southern Alps / narivna meja Južnih Alp 2 Boundary of the External Dinaric Thrust Belt / meja Zunanjedinarskega narivnega pasu 3 Boundary of the nappe unit within the External Dinaric Thrust Belt / meja krovne enote znotraj Zunanjedinarskega narivnega pasu 4 Fault: SOF – Sovodenj Fault, IF – Idrija Fault, ZF – Zala Fault, BF – Belsko Fault (Placer et al., 2021, fig. 6, p. 44; Buser, 1976, p. 50, Predjama Fault) / prelom: SOF – Sovodenjski prelom, IF – Idrijski prelom, ZF – Zalin prelom, BF – Belski prelom (Placer et al., 2021, sl. 6, str. 44; Buser, 1976, str. 50, Predjamski prelom) 5 Concordant geological border / konkordantna geološka meja 6 Discordant geological border / diskordantna geološka meja 7 Predominantly carbonates / pretežno karbonati: T3 2+3, J, K1, Pc, E1 8 Predominantly clastites / pretežno klastiti: C, P1, K2, Pc, E 9 Carbonates and clastites / karbonati in klastiti: P2, T1+2, T3 1, K2 10 Area of the Trnovski gozd-Banjšice-Šentviška planota degraded plain / območje trnovsko-banjško-šentviške degradirane uravnave. Type of dominant degradation: I – corrosive degradation (I ≡ c, d, e: see fig. 2, fig. 4), II – structural and corrosive degradation, III – structural degradation and denudation / tip prevladujoče degradacije: I – korozivna degradacija (I ≡ c, d, e: glej sl. 2, sl. 4), II – strukturna in korozivna degradacija, III – strukturna degradacija in denudacija 11 Top / vrh: VM – Veliki Modrasovec (1355 m), SV – Streliški vrh (1266 m) 154 Ladislav PLACER, Tomislav POPIT & Igor RIŽNAR above Lokavec and Mt. Streliški vrh above Pod- kraj pri Colu. We assume the same for the cur- rently non-peneplained part of Banjšice and the Šentviška Gora plateaus – which is why we here introduce the term Trnovski gozd-Banjšice-Šent- viška Gora degraded peneplain. The extent of the Trnovski gozd-Banjšice-Šent- viška Gora plateaus degraded peneplanation is shown in Figure 11. At a lower altitude the entire area was levelled, but during the uplift it degraded structurally and denudationally. The degradation was not uniform but subordinated to the litholog- ical composition, structure, and uplift dynamics. Today, three different types of relief have been de- veloped in this area, formed according to the type of degradation of the original peneplain. On the relatively unactive part built of carbonate rocks, where structural degradation had no effect, only the consequences of harsher climatic conditions are visible; this part is designated as corrosively degraded karst plain (I); the part built of carbon- ate rocks, which is uneven today, is designated as a structurally and corrosively degraded karst plain (II); the part made of various (carbonate and clas- tic) rocks, which today is moderately rugged, is designated as structurally degraded and denuded plain (III); here the proportion of corrosive degra- dation is subordinate due to the presence of clastic rocks. The inf luence zone of corrosively degraded karst plains (I) is identical to the inf luence zones c, d, and e (I ≡ c, d, e) (Figs. 2, 4). The Trnovski gozd-Banjšice-Šentviška Gora degraded plain lies on the highest part of the Trno- vo Nappe, which is composed of carbonate rocks. This part towards the southeast is preserved only up to Mt. Streliški vrh (1266 m), while from here on it is eroded. It is appropriate, therefore, to as- sume that at the time of its formation the consid- ered level was more extensive than the surface as presented in Figure 11; according then to the definition of Stepišnik and Ferk (2023, p.12–13) it would belong to the class of corrosion plains. This is also confirmed by the modern view of their gen- esis (ibid. p.17–18). The geological significance of the Ponikve klippe on the Šentviška Gora plateau is not dis- cussed in this article. 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