engleski

Olimp Pit at North Velebit - an Example of Deep Pit in Deep Karst of Croatia

Till today in region of Croatian karst more than 8 000 speleological features are explored. Most ofthem are pits. Two pits are deeper than 1000 m, and 12 are deeper than 500 m. Olimp pit, 531 m deep is located in region of Begovački kukovi on east border of NP Sjeverni Velebit. This area is consisted ofpaleogenic breccias (Jelar breccia). Olimp pit had been found 1998, but exploration last till 2000. Speleological explorations has been organized by members of Speleological Society Karlovac with help of colleagues from same other speleological societies from Croatia. . Pit entrance (dimension 6x3.5 m) is on 1370 m from sea level. At entrance there is fixed stone block. It stopped accumulation of snow and ice which are common in other pits in this area. Olimp pit is simple and knee form type. It consist of seriai with 14 vertical channel s (shafts). Between them arejust small horizontal parts (shelfs). Average deepness ofshafts is 38 m. The deepest shafts in this pit are 92 and 90 m deep. This shafts are extend from 50th till 142nd m, and from 216th till306th m deepness from the entrance level. The most of the shafts are narrow in the beginning and after become widther. Each shaft is widthest on its bottom. Here shafts are formed. They are partly denudated in rock and party accumulated of falling blocks. Upper part of the pit (till350th m deepness) was form in unbedded pale'ogenic limestone's breccias and lower part was form in limestone (probably from upper jurrasic period). In upper part of pit, long, shallowand widely gro ove-like karren was observed. In lower part of pit net-like karren are prominent which genesis are conditioned by bedding planes tOG. In this part falling blocks and rocks are most common because fissures and specially beddings planes. In deeper part of this pit swallow-holes on shelfs are observed. This is probably because share of erosion in speleogenetic process are increase with deep. Speleogenesis of this pit control s by fractures, with extending N-S and NW-ES. Actually bottom of Olimp pit is consist of collapsed blocks. Explorations will be continued by digging. ..

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