An Geological Overview of Glacial Accumulation And

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The Mining-Geology-Petroleum Engineering Bulletin A geological overview of glacial UDC: 550.8:552.1 accumulation and erosional occurrences DOI: 10.17794/rgn.2017.4.8 on the Velebit and the Biokovo Mts., Review scientiƤ c paper Croatia

Josipa Veli©1,3; Ivo Veli©2,3; Dubravka Kljajo4; Ksenija Protrka5; Hrvoje Škrabi©5; Zlatko Špoljar3 1University of Zagreb, Faculty of Mining, Geology and Petroleum Engineering, Pierottijeva 6, HR 10 000 Zagreb 2Croatian geological survey, Sachsova 2, HR10000 Zagreb; 3Croatian geological summer school, Panþiüeva 5, HR 10 000 Zagreb 4Public Institution Nationak Park Northern Velebit, Krasno 96, HR 53 274 Krasno 5Public Institution Nature Park Biokovo, Marineta - Mala obala 16, HR-21 300 Makarska

Abstract Numerous accumulation and erosional forms originating from the activity of small valley glaciers or cirque glaciers occur on the highest mountains in Croatia: Velebit (1757 m) and Biokovo (1762 m). They were produced during the Upper Pleistocene, in the Würm glacial stage of the Alpine classiƤ cation. Accumulation forms comprise ground, terminal and recessional moraines, drumlins, eskers, glacial erratics and glacio- ƪ uvial and glaciolacustrine sediments. Single ridge eskers are often associated with areas of kame and kettle topography. Among erosional occurrences roche moutonnée (sheepback rocks), U-shaped valleys ranging in size from meso-macro, arêtes, hanging valleys, meso-sized cirques, kettles, and striations were noted. In the Croatian Dinarides, such forms mainly occur at an altitude between 900 and 1400 meters. During the early to middle Würm glacial maximum, the snow line was above 900 m, perhaps even above 1000 m altitude, and sea levels were 120 meters lower than at present day. Considering the features of the present relief, the ice cover was probably 200 to 300 m thick. Features of drumlins, eskers and kettles point to warm-based glaciers. The drumlins are small – up to 100 meters long and 50 meters wide, with the most common long axis ranging orientation from 130o-310o. The near total absence of platy clasts, as well as their stratigraphic aƥ liation, largely reƪ ects features of source rocks.

Keywords glacial records, Würm, situmetry, stratigraphy of till clasts, Mt. Velebit, Mt. Biokovo, Dinarides, Croatia

1. Introduction 1909; Rogliü, 1931) on Pleistocene glaciations in the Croatian Dinarides. Discussions in Croatian literature about glaciation in The Rujno glacier existed on altitudes between 1300 the mountains Velebit and Biokovo took place through- and 1400 meters above sea level and eventually de- out the entire 20th century, mainly among geomorpho- scended to 920 meters (Nikler, 1973). This indicates a logists (Hraniloviü, 1901; Gavazzi, 1903a, 1903b; relatively wide geographic distribution of Pleistocene Rogliü, 1931). However, the ¿ rst to describe moraine glaciations on Velebit Mt. Later research has con¿ rmed deposits on Mt Velebit was a geologist, precisely Nikler these ¿ ndings, thus Belij (1985) wrote on the glacial re- (1973), who identi¿ ed glacial sediments on the Southern lief of Southern Velebit and illustrated its icebound top Velebit localities Oglavinovac, Javornik and Ribniþka ranging from Kozjak ridge in the northwest towards Vrata as parts of the Rujno moraine and depicted the pre- Dušice Plane in the southeast. According to some au- sumed boundaries of the glacier. Later, on the Basic thors, Middle Pleistocene glacial and periglacial depos- Geological Maps 1:100 000 and Explanatory notes for its even extend to the present day’s coast in the Novigrad Otoþac (Veliü et al., 1974; Sokaþ et al., 1976) and Sea and Karin Sea, as well as on the islands of Krk and Gospiü sheets (Sokaþ et al., 1974; Sokaþ et al., 1976) Pag and elsewhere on recent altitudes ranging from 75 to on Velebit Mt. and Imotski sheet(Raiü et al., 1977; Raiü 300 m (Marjanac et al., 1990; Marjanac & Marjanac, & Papeš, 1978) on Biokovo Mt., traces of glaciation are 2004). Based on geomorphological traces of glaciation, only generally and roughly stated. This is in accordan- e.g. exaration morphological features and forms of sedi- ce with the opinion of senior geoscientists (Schubert, ment accumulations, Bognar et al. (1991a, b), Bognar et al. (1997) and Bognar & Faivre (2006) presume that Corresponding author: Josipa Veliü Northern and Central Velebit were affected by glaciation [email protected] at altitudes above 1300 m. Hughes et al. (2011) stressed

77-96 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 78

V - VELEBIT B - BIOKOVO 1. Veliki Lom 2. Mali Lom 3. Ledena draga 4. Lubenovac 5. Tudorevo-Mirovo 6. Oglavinovac 7. Javornik 8. Struge 9. Rujno 10. Bukovaþka draga 11. Studenci

11 1 4 2 3 5

6 7 9 8

Figure 1: Situation map. V: Velebit Mt., B: Biokovo Mt. that “the Balkan ice caps are likely to have rivalled in (see Figure 1 B), some localities containing glacial sed- size the ice masses over Pyrenees and were certainly iments were merely registered and are scheduled for de- amongst the largest ice masses of the Mediterranean tailed investigation, those being primarily Oglavinovac, mountains”. Javornik and Struge in the Southern Velebit. During the research for preparation of the Geological Recently, Slovenian geomorphologists published arti- guides of the Northern Velebit National Park (Veliü & cles on glacioÀ uvial relief on North Velebit Mt. (Ste- Veliü, 2009), Paklenica National Park (Veliü et al., 2014) pišnik, 2015) and on pleistocene glaciation of the Biok- and Nature Park Biokovo (Veliü & Veliü, 2016) a series ovo Mt. (Žebre et al., 2013). of occurrences relating to glaciation were observed, which have not yet been the subject of detailed analysis 2. 2. Study area and geological setting and publishing in Croatian geological literature, or were partially published (Veliü et al., 2010; Veliü et al., 2011; The Velebit and Biokovo Mts. are amongst the high- Protrka et al., 2011; Veliü et al., 2013). Therefore it is est mountains in the Croatian part of the Karst Dinar- clear that geological exploration of traces of glaciation ides. Geomorphologically and climatologically, they on Mts. Velebit and Biokovo has intensi¿ ed over the last represent the boundary between the Continental and less than a decade, contributing to new ¿ ndings such as Mediterranean Croatia. Mt. Velebit forms a natural presented in this article. It is important to note that the boundary between continental and Mediterranean cli- degree of research, ¿ ndings and interpretation of data matic regions. In its peak areas, two different climate varies for the eleven localities described in this article. zones, the maritime and the continental, collide causing Many of these are inaccessible by roads and can only be unpredictable weather patterns. The average snowy win- reached by mountain tracks, undertaking steep climbs or ter lasts longer than seven months. In the valleys and simply “by azimuth”. Apart from the relatively well in- dolines (sinkholes) snow lingers much longer, and the vestigated, such as the Alan glacier of the valley type in so-called snow-holes retain snow throughout the whole Tudorevo and Mirovo in Northern Velebit (see Figure 1 year. Mt. Biokovo is also never ice-free in the deepest V) and Bukovaþka Draga and Studenac on Mt. Biokovo dolines (sinkholes), ice pits and ice caves. At altitudes

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 79 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia above 1200 m, there are no summer months without Development of glaciation on Velebit Mt. was partly frost occurrences. In the higher parts of Mt. Biokovo inÀ uenced by the relief with relatively large valleys (regularly above 800 m), precipitation throughout the (snow-dolines), reÀ ecting the structure and composition cooler seasons (from late autumn to early spring) is of the substrate and results with karsti¿ cation during the mostly in the form of snow. Here snow preserves regu- Middle and Late Pleistocene. Low temperatures were larly until the beginning of the summer. This is in ac- very important in this process - the average annual tem- cordance with the results of the studies conducted on Mt. perature was -2oC during the Würm Glacial Maximum, Durmitor, located 150 km away from Mt. Biokovo which is 10 to 12oC lower than recently (Šegota, 1966), (Gachev et al., 2016), where on altitudes above 1910 m as well as the abundant rainfall in uppermost Würm. Ac- a number of small but permanent ¿ rn-ice patches, which cording to the calculations presented by Bognar et al. can be classi¿ ed as small glaciers, can be found. (1991a,b), Perica & Orešiü (1999) and Bognar & Geological composition and structural framework Faivre (2006), the total average precipitation was 4662 have greatly inÀ uenced the formation of relief suitable mm, which was enough to create large snow accumula- to the genesis of glaciers and its traces. The geological tions and regional glaciations. The snow line was at structure of both of these mountains is composed of about 1300 m, and the estimated thickness of ice was scaly structures formed by reverse faulting of the origi- 200 m (Bognar et al., 1991a, b). nal anticlines (see Figure 2). They were formed by sev- Glacial deposits on the Northern Velebit Mt. (see Fig- eral structural mechanisms, as evidenced by the mor- ure 2 A) were created and deposited by the movement of phology of their slopes – the northeastern slope being small valley glaciers over the Jurassic carbonates and steepened on Velebit Mt. as opposed to the steep south- Velebit carbonate brecciaIn Veliki and Mali Lom valleys western slope on Biokovo Mt. (see Figure 2 A, VL, ML) they are overly Upper Juras- Velebit Mt. was uplifted by the reverse faulting of sic limestones and dolomites and Velebit breccia., but in northeastern vergencies. As the result of such tectonic Ledena Draga (=Cold Valley; Figure 2 A, LD) they are movements, Northern Velebit is recently a large faulted overly Middle Jurassic and Upper Jurassic carbonate anticline with Middle Triassic deposits in its core, and rocks. In the Lubenovac Valley (see Figure 2 A, LU) Jurassic and Cretaceous deposits in its limbs. In contrast, bedrocks are of the Upper Jurassic age. The Tudorevo- Southern Velebit is composed of the reversely elevated Mirovo Glacier (see Figure 2 A, TM) was moving southwestern limb of an anticline. Its Late Carbonifer- across the Lower Jurassic and Middle Jurassic carbon- ous and Permian clastic-carbonate deposits are reversely ates on which its glacial sediments recently lay. uplifted above the Triassic-Jurassic deposits of Liþko In Southern Velebit Mt. (see Figure 2.B), at the Polje. Thus is the northeastern limb of the Southern Vel- Oglavinovac (see Figure 2 B, OG) and Javornik (see ebit anticline was cut off and eroded. In the southwest- Figure 2 B, JA) cirques, moraine deposits overly Lower ern limb, a continuous Middle Permian to Middle Juras- and Middle Jurassic carbonates. Out of these cirques the sic sedimentary sequence appear, concordantly from the glacier moved through the U-valley Ribniþka Vrata to- base to the highest peaks above 1700 m. Higher parts ward the Rujno Plane (see Figure 2 B, RU). There, mo- and the topmost peaks of the Mt. Velebit are composed raine sediments were deposited over the Upper Triassic of Jurassic carbonates, apart from the northern parts dolomites and Jurassic limestones. Eastwardly, on the (Rožanski and Hajduþki Kukovi) and southeastern parts mountain valley and Pass of Struge (see Figure 2 B, (Crnopac), which are composed of unique Oligocene- Miocene tectogenic limestone breccias, known as Vele- ST), glacial sediments overly Middle Jurassic and Up- bit breccia (Veliü & Veliü, 2009).The breccia were per Jurassic carbonates. formed during the uplift of Mt. Velebit in the most active Glacial deposits from Bukovaþka Draga at Biokovo fault zones within the Jurassic and Cretaceous carbon- Mt. (see Figure 2 C, BD) overly the Upper Cretaceous ates, along the horizontal faults. The Velebit breccia on Kotišina carbonates and Eocene Flysch deposits. In the Mt. Velebit and Lika Region are a unique phenomenon Studenci karst depression (see Figure 2 C, SC), glacial in the world (Veliü & Veliü, 2009; Veliü et al., 2014). deposits were deposited over the Lower Cretaceous Biokovo Mt. was uplifted by reverse faulting and limestones of Aptian age. Valleys, on which sedimentary thrusting of southwestern vergencies. Its scaly structures bodies of glacial origin and erosional forms were identi- resulted from the subduction of the Paleogene lime- ¿ ed (from the North towards the South) are: stones and Flysch deposits below the Upper Cretaceous 1. Veliki Lom (mark VL; Figure 1 V, Figure 2 A) and Middle Jurassic carbonates. Thus its seaward slope, 2. Mali Lom (mark ML; Figure 1 V, Figure 2 A) which is pronouncedly steep, contains two thrust sheets 3. Ledena Draga (mark LD; Figure 1 V, Figure 2 A) – a lower sheet, with the Upper Cretaceous Kotišina de- 4. Lubenovac (mark LU; Figure 1 V, Figure 2 A) posits (carbonate breccia. and calcarenites), overlying Eocene À ysch deposits, and a higher (upper) sheet, with 5. Tudorevo and Mirovo (mark TM; Figure 1 V, the Middle and Upper Jurassic limestones, whose sharp Figure 2 A) edge comprises peaks ranging from 1400 to 1600 meters 6. Oglavinovac (mark OG; Figure 1 V, Figure 2 B) in height, located only 3 to 4 km away from the sea. 7. Javornik (mark JA; Figure 1 V, Figure 2 B)

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 80

Figure 2: Geological maps with the occurrences of glacial deposits. A: Northern Velebit Mt., B: Southern Velebit Mt., C: Biokovo Mt.

8. Struge (mark ST; Figure 1 V, Figure 2 B) to the ¿ rm knowledge of the geological composition, 9. Rujno (mark RU; Figure 1 V, Figure 2 B) stratigraphy and structures of the Mts. Velebit and Biok- 10. Bukovaþka Draga (mark BD; Figure 1 B, Figu- ovo, based on the stratigraphic determination of a large re 2 C) number of clasts, it was possible to reliably determine 11. Studenci (mark SC; Figure 1 B, Figure 2 C). the ciques, travel routes and travel distances of the glaciers. In further presentation, the review of glacial occurrences and research results, are described from the 3. Materials and methods North (from the Velebit Mt.) towards the South (to the Biokovo Mt.). Research was predominantly realized by the ¿ eld investigations, with initial observations and determination of geomorphological occurrences which indicated gla- 4. Results cial conditions, as illustrated by panoramic photographs of the Mirovo (see Figure 3 A), Struge (see Figure 3 B) During the Late Pleistocene (Würm) glaciation, nu- and Rujno (see Figure 3 C) localities. Accumulation merous glaciers existed on Velebit Mt. According to the forms were located by GPS (coordinates), their depths, available and gathered data, two areas are distinguished: widths and heights were measured, their “peaks” were Northern Velebit Mt. and Southern Velebit Mt. In chap- positioned and the direction of form axes were deter- ters 4.1. to 4.5. Northern Velebit Mt. area, and in chap- mined – mainly numerous drumlins and several eskers. ters 4.6. to 4.9. Southern Velebit Mt. area are described. Afterwards, a detailed analysis of till was done by col- 4.1. Veliki Lom lecting a representative number of fragments/clasts of various sizes from all the bodies (situmetry, Schreiner, Veliki Lom (see Figure 1 V, Figure 2 A) contains a 1992), measuring of three perpendicular dimensions of ground moraine (see Figure 4 A), drumlins (see Figure the clasts, determination of petrographic composition 4 B, 4 C) and kettles (see Figure 4 D). This drumlin ¿ eld and stratigraphic ages of fragments and cobbles. A lim- is situated at 1300 meters above sea level. The largest ited number of samples, granulometry was performed in drumlin (see Figure 4 C) stretches about 100 m along its a laboratory. Values were calculated in the cabinet, longer axis striking 120°-200° (130°-310°). Two exca- which, on the basis of Zingg diagram (Zingg, 1935), vations were done here (see Figure 4 E) up to depths of were the base for the determination of clast sizes. Strati- 90 cm. Below the 20 cm thick black-brownish soil lies a graphic ages were statistically processed, and presented light-coloured ¿ ne-grained gravel/sand 40 cm thick, and in histograms. Data on clast sizes were used for correla- below it, clasts of different sizes, including blocks, ap- tion within three groups of localities (Northern Velebit pear. Deposits are poorly sorted, and clasts are differ- Mt., Southern Velebit Mt., Biokovo Mt.), and for the ently rounded, ranging from sharp-edged to relatively precise identi¿ cation of the source area of glaciers. Due well-rounded. Based on the results of situmetry for 133

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 81 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia

Figure 3: A: Glacial deposits of a “drumlin Ƥ eld” on Mirovo Valley, Northern Velebit Mt., B: Glacial deposits of Struge Pass, Southern Velebit Mt., C: Glacial deposits of Veliko Rujno Plane, Southern Velebit Mt. clasts, they are mostly spherical, discoidal and spindle tion were determined after the excavation. The longer shaped (see Figure 4 F). By age/lithology they are most- axis of the largest esker has a strike of 3000-1200. Its ly clasts of the Oligocene-Miocene Velebit breccia. and average width is 15 m, and it is 60 m long. to the Upper Jurassic gray limestones. The diameter of the kettle is 7 m. 4.3. Ledena Draga Ledena Draga (see Figures. 1 V, 2 A) lies at 1050 4.2. Mali Lom meters altitude. A “¿ eld” of glacial accumulations is In Mali Lom (see Figures. 1 V, 2 A), at the altitude of situated within a deep forest with several small drum- 1230 meters, a À attened drumlin ¿ eld is found, contain- lins. They are 40 x 90 m in size, with strikes 60°-240° o ing a ground moraine, with several smaller drumlins (see and 135 -315°, respectively (see Figure 6 A). Clasts of Figure 5 A), kettles (see Figure 5 B) and eskers. Clasts the Upper and Middle Jurassic limestones predominate in the drumlin are predominantly Jurassic mudstones (77 in the composition (56 % and 23 % respectively, Figure %), the majority of which (62 %) are of the Middle and 6 C). The lengths of the three axes were measured at 127 Upper Jurassic ages, and the rest are the Upper Creta- clasts and the grain shape diagram was produced. Platy ceous clasts (8 %) (see Figure 5 C) and various shapes forms are the rarest, while the spherical forms are the of Oligocene-Miocene Velebit breccia. (15 %) (see Fig- most common (see Figure 6 B). ure 5 D). They originate from the Middle and Upper 4.4. Lubenovac Jurassic limestones of the nearby Mali Rajinac Mount. The bedrock is the Upper Jurassic limestone. The strike Lubenovac locality (see Figures. 1 V, 2 A) includes of the largest drumlin is 3100-1300, the lengths of their two valleys – Veliki Lubenovac Valley and Mali Luben- two perpendicular axes are 91 m and 50 m respectively, ovac Valley. Veliki Lubenovac lies at an altitude of 1350 and the height (thickness) is about 5 m. As it was cov- meters. It is by shape a cirque, with the clusters of till ered with the soil and the grass, details of its composi- laying in elongated, decametric, tongue-like shapes lain

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 82

Figure 4: Veliki Lom Valley, Northern Velebit Mt. A: ground moraine with the erratics, B, C: drumlins, D: kettle, E: burrow in the ground moraine till, F: grain shape diagram of the till clasts.

Figure 5: Mali Lom Valley, Northern Velebit Mt. A: drumlin with erratics, B: kettle, C: histogram of the stratigraphic age distribution of the clasts, D: grain shape diagram of the till clasts.

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 83 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia

Figure 6: Ledena Draga Valley, Northern Velebit Mt. A: drumlin, B: grain shape diagram of the till clasts, C: histogram for the stratigraphic age distribution of the clasts. one over another alongside its edges (see Figure 7 A). al., 2011). It lies between 1330 and 1400 meters altitude Glacial deposits are represented by a ground moraine, (see Figures. 1 V, 2 A, 3 A). The area of Mirovo, due to i.e. till, with partially rounded clasts of the Jurassic lime- the appearance of numerous drumlins, represents a true stones and Oligocene-Miocene Velebit breccia, ranging drumlin ¿ eld (see Figures. 3 A, 8 A). It contains an accu- in size between 0.5 and 20 cm (see Figure 7 B). Numer- mulation of forms and shapes, such as a ground moraine ous kettles are present, especially in Mali Lubenovac, as (see Figure 8 B), a terminal (see Figure 8 C) and a reces- well as erratic blocks (see Figure 7 C). Most notable is sional (stadial) moraine (see Figure 8 D), about 100 m the drumlin that lies between 1300 and 1315 meters of long and 6 m high drumlins (see Figures 8 A, 8 C, 8 D, 8 altitude in Veliki Lubenovac, which is 15 m thick 100 m E) with strikes 100o-280o and 130o-310o, 200 m long and long, and about 30 m wide (see Figure 7 D). It is com- 50 m wide esker (see Figure 8 F) with the strike direction posed of the fragments from Velebit breccia. Its longer 350o, erratic blocks (see Figure 8 E), and kettles as the axis has a strike 130°-310°. Erratic blocks, composed erosional forms (see Figure 8 C) as well. mainly of Velebit breccia, are scattered around. The re- Granulometric composition of the till is heterogene- sults of the measurement of 25 clasts shows that they are ous (see Figure 9 D), yet of uniform lithological compo- predominantly of spherical and discoidal forms, with sition. It is composed exclusively of debris from the some being spindly and none as platy form (see Figure Lower Jurassic and Middle Jurassic carbonates, mostly 7 E). In Mali Lubenovac, at an altitude of 1280 meters, limestones, ranging from the sand-sized grains to blocks a 200 m long and about 50 m wide esker is located with as large as 1m3 (Veliü & Veliü, 2009). the direction of strike towards 350°. The Middle Jurassic clasts compose approximately 83 % of the total till mass, with the remaining 17 % be- 4.5. Mirovo and Tudorevo long to the Lower Jurassic clasts (see Figures. 9 A, 9 B). The best investigated features near Alan are at a small All shapes are represented, most of them being discoidal valley glacier in Mirovo (Bognar et al., 1991a, b; Veliü et (see Figure 9 C).

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 84

Figure 7: Cirque of the Veliki Lubenovac Valley, Northern Velebit Mt. A: till accumulations on the cirque slopes, B: till composed from the clasts of the Upper Jurassic limestones and the Oligocene-Miocene carbonate Velebit breccia., C: drumlin with an erratic; D: drumlin, E: grain shape diagram of the till clasts – mainly spheroidal and discoidal, and subordinated spindly clasts.

Figure 8: The Mirovo Valley, Northern Velebit Mt. A: drumlins and recessional moraine (top right), B: ground moraine, C: drumlins, kettles and the terminal moraine, D: small drumlins and the recessional moraine (top left), E: erratics on the small drumlin, F: esker.

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 85 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia

Figure 9: Mirovo valley, Northern Velebit Mt. A: clasts of the terminal moraine – Lower Jurassic Lithiotid ƪ oatstone (l), Brachiopod ƪ oatstone (b), Spotty bioturbated limestone (s), and predominantly Middle Jurassic mudstones, B: histogram for the stratigraphic age distribution of the till clasts, C: grain shape diagram of the till clasts, D: granulometric diagram of the sand and gravel distribution in till from burrows (SS-1 to SS-4), E: Tudorevo Cirque Valley, Northern Velebit Mt.

Glacial deposits can also be found in the Tudorevo of the Lower Jurassic and the Middle Jurassic limestones karst depression (see Figure 9 E), located N-NE from (see Figure 10 B). The Middle Jurassic clasts predomi- Mirovo. The till is represented by clasts similar to those nate, but the Lower Jurassic, Pliensbachian Lithiotid in Mirovo. Tudorevo was a cirque valley, from which ice Limestones (see Figure 10 C) and Toarcian Spotty Lime- moved cca 3.5 km towards theS-SW through Mirovo stones (see Figure 10 D) originated from the slopes N-NE Valley into the Bariþeviü Dolac Valley, where the termi- of Oglavinovac at a distance up to 2 km were also ob- nal moraine was deposited. served. A detailed investigation is in progress. The Mirovo and Tudorevo glacier was named as Alan 4.7. Javornik Glacier by Bognar et al. (1991a, b). Javornik Valley (see Figures. 1 V, 2 B) lies on the 4.6. Oglavinovac Lower and Middle Jurassic carbonates at 1300 m altitude. In its western part there is a cirque (see Figure 11 Oglavinovac.Valley (see Figures 1 V, 2 B) lies at 1250 A, 11 B), and towards the east there is a drumlin ¿ eld meters altitude. Middle Jurassic limestones are at the (see Figures 11 B, 11 C) as well as several kettles (see base, and the middle part of the valley is a typical cirque Figure 11 D) and erratic blocks are located. The till is (see Figure 10 A). Its till is composed from the fragments composed of the Lower Jurassic and Middle Jurassic

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 86

Figure 10: Oglavinovac Valley, Southern Velebit. A: cirque, B: till, C: a clast of the Pliensbachian Lithiotid rudstone, D: a clast of the Toarcian bioturbated Spotty limestone. clasts, originating from the nearby slopes of this karst in the western part of the Plane. The ¿ rst glacial deposits depression. Similar to the Oglavinovac Valley glacial ever described in Southern Velebit were found at the lo- deposits, detailed investigation of glacial occurrences on cality of Veliko Rujno, where they form the Rujanska the Javornik Valley is in progress as well. Kosa Ridge, at altitudes between 800 and 950 meters (see Figures 1 V, 2 B, 3 C). They were described by 4.8. Struge Nikler (1973), who de¿ ned them as a lateral moraine, a Struge Pass (see Figures 1 V, 2 B, 3 B) is a locality large, over 1.5 km long, and 150 m high body. Our re- hitherto undescribed, but recently its glacial accumula- search rede¿ ned Rujanska Kosa Ridge as a large drum- tion and erosional occurrences are under detailed inves- lin (see Figure 13 A), with smaller drumlins of 90o-270o tigation (see Figures 12 A, 12 B, 12 C). These can be strikes, positioned alongside its À anks (see Figure 13 B, found between 1350 and 1390 meters altitude. The till is 13 C), as well as eskers and numerous erratic blocks (see extremely poorly sorted (see Figure 12 D) and it is Figure 13 A) of several Jurassic stratigraphic units. In mainly composed of the Middle Jurassic clasts and sub- Figure 13 C a strongly pronounced U- valley can be ordinately of Upper Jurassic clasts. seen. Altogether 155 clasts from till (see Figure 13 D) of A small cirque, with the clusters of till laying in elon- the largest drumlin were analysed. The results are shown gated, decametric, tongue-like shapes lain one over an- in the Figure 14. Platy clasts are subordinated (see Fig- other alongside its edges could be recognized (see Fig- ure 14 A) and the Upper Jurassic and Middle Jurassic ure 12 A) as well as drumlins (see Figure 12 B) and er- clasts predominate (see Figure 14 B). Several clasts of ratics (see Figure 12 C). the Upper Triassic age were also found. Highly signi¿ - cant are the ¿ ndings of cca 5 % of the Upper Jurassic 4.9. Rujno clasts, because they undoubtedly prove their previously- Rujno is a karst Plane in Southern Velebit Mt. com- mentioned origins from the Oglavinovac and Javornik prising Veliko Rujno in the eastern part, and Malo Rujno Cirques (OG and JA on Figure 2 B). Glaciolacustrine

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 87 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia

Figure 11: Javornik Valley, Southern Velebit Mt. A: cirque, B: drumlins, C: the largest drumlin, D: kettle (arrow). deposits are also present in the Veliko Rujno Plane (see 330o–150o. The middle drumlin is 71 m long, 26 m wide Figure 14 C). They are composed of silt and ¿ ne-grained and has the same strike as the previous one. The south- sand, with sporadic occurrences of larger (up to 15 cm) ern drumlin (see Figure 15 C) is smaller: it is only 12 m clasts. The till of Rujanska Kosa Ridge and nearby long and10 m wide, showing the same strike as well. On drumlins had been redeposited in the beginning of the the highest point, at 1180 meters, a 40 m long and 12 m Holocene, as glacioÀ uvial deposits at Malo Rujno Plane. wide drumlin is located, (see Figure 15 D) with a strike On Biokovo Mt., two localities were relatively thor- 165o-345 o oughly processed, despite being hard to reach. They are Glacial sediment in drumlins contain till (see Figure located in the northwestern part of Biokovo Mt. (see 16 A) formed from sharp-edged to semi-rounded chipped Figures 1 B, 2 C). debris and fragments of Middle Jurassic and Upper Cre- taceous limestones originated from Bukovaþka Draga 4.10. Bukova«ka Draga bedrock. From each drumlin, several dozen rock frag- In the northwestern part of the Biokovo Mt., in the ments were measured and their stratigraphic age and Bukovaþka Draga Valley (BD in Figures. 1 B and 2 C), rock type was determined as well (see Figure 16 B). on altitudes between 1030 to 1200 m, between the Buko- Various types of the Middle Jurassic limestones prevail vac Mountain hut and the Bukovac Pass, occurrences (above 75 %), and the Upper Cretaceous Kotišina clasts relating to the Würm glaciation were thoroughly investi- are subordinated (up to 25 %). The share of the frag- gated in the ¿ eld. A panoramic view shows the U-shape ments from the Kotišina breccia. and calcarenites in- of the Valley, as well as arêtes rising on its SW side. creases from the North towards the South: out of 6 % in These were formed by the erosion and abrasion caused the northern drumlin, over 19 % in the middle and up to by a local small valley glacier (see Figure 15 A). Sev- 25 % in the southern one. The trend in the share of the eral drumlins between 3 and 5 m thick, were identi¿ ed. Middle Jurassic clasts is quite opposite: from 94 % in the The northern drumlin (see Figure 15 B), near the Moun- northern drumlin, the share decreases to 75 % in the tain hut, is 61 m long and 27 m wide, with a strike of southern one. According to the grain shape diagram,

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 88

Figure 12: Struge Pass, Southern Velebit Mt. A: ground moraine and drumlins, B: drumlins, C: erratics, D: till. spindly and discoidal clasts prevail (see Figure 16 C). (1978). The bottom of the valley is covered with mo- This occurrence is interpreted as a consequence of gla- raine deposits (see Figure 17 A). In the eastern part, sev- cier movement through the Bukovaþka Draga Valley, eral small drumlins appear (see Figure 17 B). Till com- where the bedrock of the glacier was of different strati- prises fragments ranging from 0.5 cm long to erratic graphic units. The immediate bedrock is composed blocks of 2 m (see Figure 17 C). On the surface, there mostly of the Kotišina deposits, which, due to the small are fragments between 20 and 30 cm, and below them is thicknesses of drumlins, outcrop at numerous locations, debris from 0.5 up to 5 cm in size. These are very small displaying so-called “sheepback rocks” or “roche mou- drumlins; sized 60 x 35 m and 37 x 22 m respectively, tonnée” (see Figure 15 E). In the higher part of the with the longer axis strike at 350o-170o. Based on the northeastern slope of Bukovaþka Draga Valley, the gla- analysis of the shapes for 40 clasts, those of discoidal cier additionally encompassed the Middle Jurassic car- and spherical shape prevail (see Figure 17 D). Several bonates – mostly micritic limestones and carbonate kettles were noted (see Figure 17 A). In the northern breccia. On the top of the Valley bedrocks are Maas- part of the valley “sheepback rocks” or “roche mouton- trichtian Kotišina deposits and Eocene Flysch. née” on the Lower Cretaceous limestones age were dis- covered (see Figure 17 E). 4.11. Studenci 5. Discussion In the karst depression Studenci, north of the mountain hut Lokva, at an altitude of 1350 m, a small valley is Based on the analysis and interpretation of gathered laid out containing remains of glacial accumulation data, as well as the results of former exploration of the forms (SC in Figures. 1 B and 2 C). Very highly pro- Velebit and Biokovo Mts. (see Figure 1) numerous ac- nounced erosional forms are situated alongside its À anks cumulation and erosional forms caused by the activity of and in the north, with an extension into a U-shaped val- small valley glaciers and cirque glaciers are described. ley (see Figure 17 A). This locality was ¿ rst cartograph- According to the published data (Nikler, 1973; Bognar ically presented by Raiü et al. (1977) and Raiü & Papeš et al., 1991a, b; Bognar et al., 1997; Bognar & Pru-

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 89 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia

Figure 13: Veliko Rujno Plane, Southern Velebit Mt. A: drumlin of the Rujanska Kosa Ridge with erratics, B: drumlin south of the Rujanska Kosa Ridge, C: drumlins below the Ribni«ka Vrata – glacial “U“ valley; a northward view from the Rujanska Kosa Ridge, D: till of the Rujanska Kosa Ridge. goveþki, 1997; Belij, 1985; Marjanac & Marjanac, raine on Bilo Ridge and Pliensbachian Lithiotid lime- 2004) due to glacial occurrences in the Croatian part of stone, more than 2 km from Dundoviü Mirovo Valley to the Karst Dinarides, these were placed in the Upper Bilo Ridge as well. The relations between the sedimen- Pleistocene, according to the Alpine temporal classi¿ ca- tary bodies, such as the position of the recessional mo- tion in the Würm period. raine on the older drumlin and ground moraine, the fact Both the shape of drumlins in Lubenovac and the that the younger drumlin lies over the older one in Mi- strike of its longer axis at 130°-310°, indicate that the rovo and the formation of younger cirques in Tudorevo, direction of glacier movement was at 130°, towards the all indicate for the multiphase thaw and freeze events of Lika Region. Mirovo and Tuderevo were completely in- the Alan Glacier. vestigated and represent a unique model case containing Since the beginning of the ¿ nal phase of glacier melt- more or less all occurrences formed by the inÀ uence of ing, drumlins and an eskers were formed on the ground glacier. The strikes of the drumlins, eskers and the gla- moraine, and inside the moraine itself kettles were hol- cial U-valley, as well as the terminal and recessional mo- lowed out with ice blocks. Along with the advanced raines, indicate movement of the glacier from the North- melting and retreat of the ice sheet from Mirovo towards east towards the Southwest and the South, generally in Tudorevo, on the weakly permeable ground moraine of the direction of 2100, from Tudorevo and Mirovo Valleys Mirovo and terminal moraine of Bilo Ridge serving as a towards the Bariþeviü Dolac depression. Alongside this dam, it is assumed that a glacier lake existed in Mirovo route, fragments, boulders and blocks were deposited on (Veliü et al., 2011), like for the Central Velebit proposed a several kilometre long trail, the furthest of these Lower Boþiü et al., 2012. As water gradually leaked from the Jurassic Toarcian Spotty limestones up to 3,5 km, from lake, and ground moraine deposits eroded all the way to the north part of Tudorevo Valley to the terminal mo- the Middle Jurassic karsti¿ ed carbonate base, all the wa-

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 90

Figure 14: Veliko Rujno Plane, Southern Velebit Mt. A: grain shape diagram of till clasts at the Rujanska Kosa Ridge drumlin, B: histogram for the stratigraphic age distribution of the till clasts at the Rujanska Kosa Ridge drumlin, C: glaciolacustrine deposits of the Veliko Rujno Plane. ter had drained out and the recent relief of Mirovo was m to 900 m), which is a distance of approx. 5 km. Termi- formed. At the same time, in Tudorevo a glacier still ex- nal moraine is missing, probably being eroded, and the isted, and its activity created a recessional moraine at the material redeposited into glaciolacustrine and glacioÀ u- Mirovo/Tudorevo Pass, but similarly as in Mirovo itself, vial deposits today present on the Malo Rujno Plane it was melted at the very beginning of the Holocene. (Sokaþ et al., 1974., Veliü et al., 2014). Till in The Oglavinovac and Javornik Cirques is com- The share of Upper Cretaceous fragments in the till of posed of the Lower Jurassic and Middle Jurassic lime- Bukovaþka Draga on the Biokovo Mt. increases from stone clasts, originating from the nearby slopes of these the north towards the south, or the share of Middle Ju- karst depressions. Till on the Struge locality is composed rassic clasts decrease (see Figure 16 B). This occurrence mainly of the Middle Jurassic clasts and subordinately is interpreted as a consequence of glacier movement of the Upper Jurassic clasts. Drumlin orientation (see through the Bukovaþka Draga Valley, following the lith- Figure 12 A, 12 B) points to the movement of the gla- ological and stratigraphic changes of the bedrock units ciers towards the N-NE. in the Valley. The immediate bedrocks are Kotišina brec- The orientations, relationships and superposition of cia and calcarenites. The glacier was moving from the drumlins as well as their different sizes on the Veliko Southeast towards the Northwest, descending along a Rujno Plane point to multiple melting and glacier forma- relatively steep slope towards the lower valleys of Ko- tion phases at the same site. The glacier source was in rito and Bukva, South of the church of St. Nicholas. At the cirques Oglavinovac (1250 m) and Javornik (1300 the Studenci locality, the direction of movement is most m), and it moved through the U-valley Ribniþka vrata likely northwards. Namely, the Studenci locality is at an (see Figure 13 C) towards the Veliko Rujno Plane (830 altitude of 1330 m, the southern edge of the valley is

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 91 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia

Figure 15: Bukova«ka Draga Valley, Biokovo Mt. A: “U” valley of the Bukova«ka Draga and arete of the Bukovac Ridge (arrow), B: Northern drumlin, C: Southern drumlin, D: the highest drumlin, E: “sheepback rocks” or “roche moutonnée”.

Figure 16: Bukova«ka Draga Valley, Biokovo Mt. A: till of the Northern drumlin, B: histogram of clasts stratigraphy in till of the I.-northern drumlin, II.-middle drumlin, III.-southern drumlin, C: grain shape diagram of the till clasts of the drumlins.

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 92

Figure 17: The Studenci Valley, Biokovo Mt. A: Panoramic northward view of the Studenci “U” valley with drumlins, kettles and roche moutonnée, B: drumlins in the eastern part of the valley, C: till and erratics, D: grain shape diagram of till clasts, E: southward view of the valley: showing sheepback rocks or roche moutonnée (arrow) in the Aptian limestones. situated at 1425 m, and the northern edge at 1365 m. A ies) was de¿ nitely above contemporary 900 or 1000 me- number of smaller depressions and sinkholes in the north ters at the time. Since the sea level in the Northern Adri- are located at altitudes between 1260 m and 1300 m. atic in Croatia in Pleistocene, during glacial times, was Observed glacial occurrences on Velebit Mt. are up to about 120 m lower than today, and a signi¿ cant found above an altitude of 1050 meters, except on the part of the Adriatic was land (Mikulþiü Pavlakoviü et Rujno locality, which is situated at 850 m to 920 m. On al., 2011), glaciers were formed at a contemporary range Biokovo Mt., glacial occurrences are situated above of approximately 1000 do 1100 metres above sea level. 1200 meters. The glaciation range for Croatian Dinar- Suriü et al. (2014) pointed out that “in spite of very fa- ides is approximately from 900 to 1400 meters altitude. vourable coastal features, late Pleistocene-Holocene Therefore, during the glacial maximum ranging from relative sea-level changes along the eastern Adriatic Early to Middle Würm, the snow boundary (glacial bod- coast are still not completely resolved, mostly due to

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 93 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia

Figure 18: SW slope of the Biokovo Mt. A: Glacioƪ uvial fan of the Upper Pleistocene-Lower Holocene breccia (within red ellipse) of the Brdo Ridge, B: icefall ƪ utes above the Bast Village (arrows). the intensive and complicated regional and local neotec- Investigations of loess sediments of Vukovar and its tonics”. surroundings, approximately 300 km E-SE from Velebit However, Marjanac & Marjanac (2004) considered Mt., show that the loess/palaeosol sequence has a very the existence of glacial deposits on very low-altitudes in detailed record correlating with MIS 2-MIS 6, and MIS the coastal Dinaric Alps in comparison with the rest of 4-MIS 5 respectively (Galoviü et al., 2011; Wacha & the Mediterranean. The authors found evidence of low- Frechen, 2011; Banak et al., 2016). Thus, the paleo- land glaciation along the Adriatic coast ambiguous, sim- climatologic picture of glacial and periglacial areas of ilar to Hughes et al. (2006). Considering the height of Croatia during the Upper Pleistocene is completed, as the inÀ uence zone on the formation of recent relief (es- well as its inÀ uence on glaciations of Velebit and Bio- pecially arêtes on Biokovo Mt.), ice thickness has been kovo Mts. estimated at 200 to 300 m. According to the data on con- The near absence of platy clasts greatly reÀ ects the temporary altitudes of numerous cirques, the most in- features of source rocks. Rocks lacking lamination and tense generation of glacial bodies occurred above con- of thin strati¿ cation, such as Mesozoic and Cenozoic temporary altitudes of 1200 m. limestones in Velebit and Biokovo Mts. by abrasion and By the features of drumlins, eskers and kettles, the transport produce clasts of spherical, discoid and spindly glaciers in the investigated areas can be classi¿ ed as forms. Spherical forms indicate longer transport and a warm-based glaciers (Bennett & Glasser, 2003). This is higher energy of transporting medium (Zingg, 1935; in agreement with the paleoclimatic features presented Tišljar, 1994). Thus, it was possible to determine clast in the paper Perica & Orešiü (1999). It is presumed that sources and the directions and lengths of movement of the mean temperature was lower than contemporary by particular glaciers. Movement was relatively short – a about 10° C. The cooling occurred gradually, and the op- few kilometers towards the direction of topographically timal conditions occurred prior to (approximately) lower regions. Due to the amount of spherical clasts, the 70000 years. In the ¿ rst phase, the climate was cool and longest transport could be ascribed to tills in Ledena humid, at the end very cold and arid, and the maximum Draga and Veliki Lom (Velebit Mt.) and Studenci (Biok- cooling occurred 25000-18000 years ago (Perica & ovo Mt.). On other localities, discoid forms predomi- Orešiü, 1999). The summers were relatively warm due nate, indicating relatively shorter transport routes. to the inÀ uence of the sea which suited the forming of GlacioÀ uvial deposits are most widely distributed on warm-based glaciers. Malo Rujno Plane, and were also identi¿ ed on Alan Pass Furthermore, exploring the Quaternary sediments of and Krasno village in Northern Velebit Mt. (Sokaþ et the island of Susak located 60 km to the west of Velebit al., 1974, Veliü et al., 1974, Stepišnik, 2015) as well as Mt., Wacha et al. (2011) and Mikulþiü Pavlakoviü et on Libinje on Southern Velebit Mt. al. (2011) concluded that loess and loess derivatives rep- Several curiosities should also be mentioned. At two resent a very detailed record correlating to the Marine localities on very steep seaward slopes of Biokovo Mt. Isotope Stage MIS 3, precisely the major part of the aeo- sediment bodies 1 x 1.5 km in size, resembling fans, lian deposits, including the tephra layers, correlates to were formed (see Figure 18 A). The authors consider MIS 3 – MIS 5 interval. Cooler MIS 4 began 74000 them as products of icefall during the melting. Further- years ago, the age which can be correlated with results of more, on the same side of Biokovo Mt., well developed Perica & Orešiü (1999) who estimated the timing of op- À utes 75 to 200 m were identi¿ ed, with a height of about timal conditions at 70000 years. 850 m (see Figure 18 B), reaching from the base to the

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 94 peaks of its peripherals, also produced as a consequence Bennett, M. R., Glasser, N. F. (2003): Glacial geology. Ice of the relatively rapid melting of large quantities of ice sheets and landforms. Wiley, XI + 354 p. from the peaks of Biokovo Mt. and icefalls, precisely Boþiü, N., Faivre, S., Kovaþiü, M., Horvatinþiü, N. (2012): water and clast falls alongside a steep slope. Investiga- Cave development under the inÀ uence of Pleistocene gla- tion of the glaciolacustrine deposits of Mts. Velebit and ciation in the Dinarides – an example from Štirovaþa Ice Biokovo should be vital for the more precise determi- Cave (Velebit Mt., Croatia), Z. Geomorph. N. F., 56/4, nation of conditions and timeframe of glaciation and 409-433. its end. Bognar, A., Faivre, S. (2006): Geomorphological Traces of the Younger Pleistocene Glaciation in the Central Part of the Velebit Mt. Hrvatski geografski glasnik, 68, 2, 19-30. 6. Conclusions Bognar, A., Faivre, S. & Paveliü, J. (1991): Tragovi oledbe u Numerous accumulation and erosional occurrences of Sjevernom Velebitu (Glaciation traces in the North Vele- glacial deposits can be found in the coastal Dinarides in bit). Geografski glasnik, 53, 27- 39. Croatia, on Velebit and Biokovo Mts., originating from Bognar, A., Faivre, S. & Paveliü, J. (1991): Glacijacija Sjever- the activity of small valley and cirque glaciers. They are nog Velebita (Glaciation of the Northern Velebit). Senjski zbornik, 18, 181-196. situated on altitudes of approximately 900 to 1400 meters. Bognar, A., Faivre, S. & Paveliü, J. (1997): Tragovi oledbe na Srednjem Velebitu (Traces of glacial deposits on the Cen- The snow boundary was at least at 900 meters above tral Velebit). Senjski zbornik, 24, 1-16. sea level. That corresponds to contemporary 1000 me- Bognar, A., Prugoveþki, I. (1997): Glaciation Traces in the ters, as the sea level was 120 meters lower at the time of Area of the Risnjak Mountain Massif. Geologia Croatica, glaciation (the Würm glacial). 50, 2, 269-278. Ice thickness was estimated at 200 to 300 m, and the Gachev, E., Stoyanov, K., Gikov, A. (2016): Small glaciers on most intense generation of glacial bodies occurred above the Balkan Peninsula: State and changes in the last several contemporary altitudes of 1200 m. Drumlins, eskers and years. Quaternary International, 415, 33-54. kettles point to warm-based glaciers. Galoviü, L., Frechen, M., Peh, Z., Durn, G., Halamiü, J. Lengths of their movements were from 2 to 6 km, and (2011): Loess/palaeosol section in Šarengrad. Croatia – A directions of movement alongside the continental and qualitative discussion on the correlation of the geochemi- seaward slopes of Velebit and Biokovo Mts. cal and magnetic susceptibility data. Quaternary Interna- On the seaward slopes no glacial features were found tional, 240, 1-2, 22-34. at altitudes below 900 meters above sea level. Investi- Gavazzi, A. (1903a): Tragovi oledbe u našem kršu. Glasnik gated forms are remains of the ¿ nal (Würm) glaciation Hrvatskog naravoslovnog društva, 14, 174-175. in the Late Pleistocene. Gavazzi, A. (1903b): Tragovi oledbe na Velebitu. Glasnik Hr- Among the accumulation forms ground, terminal vatskog naravoslovnog društva, 14, p. 459. and recessional moraines, drumlins, eskers, erratic blocks Haq, B. U. (2007): The geological time table, sixth revised and glacioÀ uvial and glaciolacustrine deposits were de- enlarged and updated edition. Elsevier. termined. Hraniloviü, H. (1901): Geomorfološki problemi iz hrvatskoga Eskers are of the single ridge variety, which are often krasa. Glasnik Hrvatskog naravoslovnog društva, 13, 1-3, associated with areas of kame and kettle topography. 93-133. Hughes, P. D., Woodward, J. C., Gibbard, P. L. (2006): Quater- Among the erosional forms sheepback rocks (roche nary glacial history of the Mediterranean mountains. Pro- moutonnée), U-shaped valleys of meso-macro sizes, gress in Physical Geography, 30, 334-364. arêtes, hanging valleys, icefall À utes, meso-sized Hughes, P. D., Woodward. J. C., Calsteren, P. C., Thomas, L. cirques, kettles and striations were de¿ ned. E. (2011): The glacial history of the Dinaric Alps, Monte- Predominant quantity of discoidal types of clasts re- negro. Quaternary Science Review, 30, 3393-3412. À ects the relatively shorter lengths of glacier À ow. How- Marjanac, LJ., Marjanac, T. (2004): Glacial history of Croa- ever, due to the topographical features of the Mts. Vele- tian Adriatic and Coastal Dinarides. In: Quaternary Glacia- bit and Biokovo, it would be valuable to investigate tions – Extent and Chronology (Ehlers, J. & Gibbard, P. L., other prospective sites containing not only glacial but eds.). Developments in Quaternary Science, 2a, Elsevier, proglacial and periglacial features as well. 19-26. Marjanac, T., Marjanac, Lj., Oreški, E. (1990): Glacijalni i 7. References periglacijalni sedimenti u Novigradskom moru (Glacial and periglacial sediments in Novigradsko more, Northern Banak, A., Mandic, O., Sprovieri, M., Lirer, F., Paveliü, D. Dalmatia, Yugoslavia). Geol. vjesnik, 43, 35-42. (2016): Stable isotope data from loess malacofauna: Evi- Mikulþiü Pavlakoviü, S., Crnjakoviü, M., Tibljaš, D., Šoufek, dence for climate changes in the Pannonian Basin during M., Wacha, L., Frechen, M., Lackoviü, D. (2011): Mineral- the Late Pleistocene. Quaternary international, 415, 15-24. ogical and Geochemical Characteristics of Quaternary Belij, S. (1985): Glacijalni reljef južnog Velebita (Glacial re- Sediments from Island of Susak (Northewrn Adriatic, Cro- lief of Southern Velebit). Geografski glasnik, 47, 71-85. atia. Quaternary international, 234, 1-2, 32-49.

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 95 A geological overview of glacial accumulation and erosional occurrences on the Velebit and the Biokovo Mts., Croatia

Nikler, L. (1973): Nov prilog poznavanju oledbe Velebita (Ein Veliü, I., Bahun, S., Sokaþ, B., Galoviü, I. (1974): Osnovna neuer Beitrag zur Kenntnis der Vereisung im Velebit Ge- geološka karta SFRJ, list Otoþac 1:100 000, L 33-115; Ba- birge). Geol. vjesnik, 25, 109-112. sic Geological Map SFRJ, The Otoþac sheet 1:100 000, Perica, D., Orešiü, D. (1999): Klimatska obilježja Velebita i Institute of geology Zagreb, Federal institute of geology, njihov utjecaj na oblikovanje reljefa. Senjski zbornik, 26, Beograd. 1-50. Veliü, I., Veliü, J. (2009): Od morskih pliüaka do planine. Protrka, K., Veliü, J., Škrabiü, H., Veliü, I. (2011): Glacijalna Geološki vodiþ kroz Nacionalni park Sjeverni Velebit (Ge- sedimentna tijela u Bukovaþkoj dragi, SZ Biokovo. U: ological guide through National park Northern Velebit). Protrka, K., Škrabiü, H. & Srziü, S. (ur): Znanstveno- National park Northern Velebit, Krasno, 1-143. 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Hrvatski geo- (a) project ¿ nanced by the Ministry of Science, Edu- grafski glasnik,77/2 85-99. cation and Sports of the Republic of Croatia entitled Suriü, M., Korbar, T., Juraþiü, M. (2014): Tectonic constraints “Stratigraphical and geomathematical researches of pe- on the late Pleistocene- Holocene relative sea-level change troleum geological systems in Croatia” (project no. 195- along the north-eastern Adriatic coast (Croatia). Geomor- 1951293-0237); phology, 220, 93-103. (b) “Microfossil assemblages in carbonate deposits Šegota, T. (1966): Quaternary temperature. Changes in Cen- of the Karst Dinarides“ (project no 195- 1953068-0242); tral Europe. Erdkunde, 20, 2, 110-118. (c) project ¿ nanced by the National Park Northern Tišljar, J., 1994. Sedimentne stijene (Sedimentary rocksin Velebit entitled “Investigation of moraine sedimentary Croatian). Školska knjiga, Zagreb, 422 p. (in Croatian) bodies in the National Park Northern Velebit”;

The Mining-Geology-Petroleum Engineering Bulletin and the authors ©, 2017, pp. 77-96, DOI: 10.17794/rgn.2017.4.8 Veli©, J.; Veli©, I.; Kljajo, D.; Protrka, K.; Škrabi©, H.; Špoljar, Z. 96

(d) projects “Geological guide through National park Supports (a) – (d) were lead by J. Veliü and (e) by T. Northern Velebit”, “Geological guide through National Malviü. park Paklenica” and “Geological guide through Natural We would like to thank for the permission to publish park Biokovo”; part of our results. The authors are grateful to younger (e) ¿ nancial support „Mathematical methods in geol- colleagues Tomislav Mašiü, Branimir Šajatoviü and Teo ogy II“ given by University of Zagreb, Faculty of Min- Jašaragiü-Rako, who helped with the ¿ eld work in the ing, Geology and Petroleum Engineering in 2017 (no. various stages of this research. M048xSP17).

SAŽETAK Geološki pregled glacijalnih naslaga i erozijskih pojava na planinama Velebitu i Biokovu, Hrvatska Brojne su pojave naslaga i erozije podrijetlom iz aktivnosti u malim ledenja«kim dolinama ili cirkovima, a koje su posto- jale na najvišim hrvatskim planinama – Velebitu (1757 m) i Biokovu (1762 m). Takve pojave nastale su tijekom gornjega pleistocena, u virmu (dobu prema alpskoj klasiƤ kaciji). Akumulacijski oblici obuhva©aju površinske, terminalne i rece- sijske morene, drumline, eskere, glacijalne prekide te glacijalno-rije«ne i glacijalno-jezerske taložine. Pojedina«ni ledenja«ki talozi, grebeni tipa eskera, «esto su udruženi s topografskim oblicima, tj. podru«jima kama (brežuljaka) i kotli©a (udubina). Tako¯er se pojavljuju i oblici roche moutonnée, tj. oblici stijena nastali prolaskom ledenjaka, te doline U-obli- ka koje variraju od mezoveli«ina do makroveli«ina. Zatim su opažene arête, uski grebeni koji dijele dvije doline, urezane doline, mezocirkovi, ledenja«ke udubine te pojave strija. Unutar hrvatskih Dinarida takve pojave opažene su na visinama od 900 do 1400 metara. Tijekom ranoga do srednjega virma, u vrijeme ledenja«koga maksimuma, snježna granica nala- zila se iznad 900, a možda i 1000 metara, dok je morska razina bila 120 metara niža od današnje. Promatraju©i današnji reljef, zaklju«eno je kako je ledeni pokriva« bio vjerojatne debljine 200 – 300 metara. Pojave poput drumlina, eskera i kotli©a upu©uju na ledenjake iznad ili blizu to«ke topljenja leda uz podlogu (engl. warm-based). Drumlini su mali, dimenzija do 100 m dužine i 50 m širine, dok im duža os uglavnom ima orijentaciju 130o – 310o. Gotovo potpuno nedosta- ju ravni klasti što, uz njihovu stratigrafsku pripadnost, upu©uje na svojstva ishodišnih stijena.

Klju«ne rije«i: dokazi oledbi, virm, situmetrija, stratigraƤ ja nesortiranih klasta, Velebit, Biokovo, Dinaridi, Hrvatska

Author(s) contribution Josipa Veli©: leader of the Ƥ eld investigations on all presented localities; analysed, synthesized and interpreted Ƥ eld and laboratory data; wrote the most of text of the article. Ivo Veli©: participated in Ƥ eld investigations on all localities; determined stratigraphic age of clasts of till, erratics and bedrocks; wrote a part of text on stratigraphy and tectonics of the all localities; made geological sketch maps of all localities with positions of glacial deposits. Dubravka Kljajo: participated in Ƥ eld investigations on the North Velebit Mt., especially in analysing of lithology of glacial sediments in burrows, and dimension of clasts. Ksenija Protrka: participated in Ƥ eld investigations on the Biokovo Mt., in analysing of lithology of glacial sediments, measured dimensions of clasts, orientations and size of drumlins; collected published data on the Biokovo Mt. glaciation. Hrvoje Škrabi©: participated in Ƥ eld investigations on the Biokovo Mt., in analysing of lithology of glacial sediments, measured dimensions of till clasts, erratics and drumlins. Zlatko Špoljar: gathered till clasts for situmetry, measured „a/b/c“ axes of clasts for graphics of grain shape diagrams.