Large boulders at the base of the summit of Mt Učka

Prospekt Gea, Intresting facts

Photo 1. A group of large boulders above Vela Učka (Photo by M. Randić)

Large boulders at the base of the summit of Mt Učka

More and more evidence suggests that during the Pleistocene (the ice ages) the mountains in the hinterland of Rijeka Bay were covered with thick sheets of ice and glaciers that transported huge quantities of broken rocks. Does this apply to Mt Učka as well?

On the mountains around Rijeka Bay, for example on Mt Učka and Mt Kamenjak, we can find large, massive boulders of rock, alone or in groups (Photo 1 and 2). They appear to have broken off the nearby cliffs and rolled until coming to a stop at the base of the cliffs.  But when looking closely at some of these boulders, however, it seems rather doubtful they could have simply broken off, rolled down a cliff and come to a stop in their present positions solely as a result of free fall and the force of gravity. Some are located quite a distance from the cliffs. So, the question arises: Could their movement have been caused by the flow of ice during the Pleistocene glaciations? The groups of boulders found around the summit of Mt Učka are generally associated with massive accumulations of mostly small rock debris. The quantity of accumulated rock debris is evident from the profiles of several open quarries (locally called kava, Photo 3) where this material was dug up. Based on the visible remains of accumulated rock debris we can imagine that during the glaciation the summit slopes of Mt Učka were bound by ice that stretched to the foothills of the mountain. The ice carried huge amounts of rock debris stripped from the slopes and it broke off and transported large boulders of rock as well.

M. Randić

Photo 2. A detail: Did the rock husk (seen in the middle of the photo) break off from the larger boulder? (Photo by M. Randić)

Photo 3. A quarry above Vela Učka. Large amounts of small rock material were dug from this quarry. (Photo by M. Randić)

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