The extent of middle Pleistocene ice cap in the coastal Dinaric Mountains of Croatia

Solitary limestone blocks and groups of blocks occur on Risnjak and Velebit Mountains and on the northern Adriatic islands of Krk and Rab. Previous researchers have interpreted some of these as a) erratic blocks, b) corrosional remnants, or c) rockfalls. We have studied their mode of occurrence and composition, and revised previous interpretations of their origin in the light of transport mechanism and depositional processes. After analyzing the context of the block positions and the physical processes responsible for their emplacement, and taking into account their sedimentological context (their association with glaciogenic sediments), we herein propose a glacial origin for most of these blocks. However, some blocks are indeed shaped by sub-soil corrosion, as evidenced by their structure. The interpreted erratic blocks on the inner northern Adriatic Sea islands document the presence of middle Pleistocene glaciation of Dinaric Mountains though not its maximal extent, which is still unclear as the ice terminus was in the area that is inundated by postglacial rise of Adriatic Sea. The reconstructed ice cap area, which extended along the coastal mountains from Risnjak Mt. to south Velebit Mt. and across the range from Lika Polje to Rab Island, is conservatively estimated to be 5400 km2.