Karst Uncovered during the Bič- Korenitka Motorway Construction (Dolenjska, Slovenia)

Abstract

Na trasi avtoceste so na dnu morfoloških depresij oziroma uval med kraškimi pojavi najbolj vidni požiralniki in estavele. Pri gradbenih delih so se razkrile tudi podtalne škraplje ter jame. Izjemnih oblik so tiste, ki so nastale v dnu podolij in ki jih podtalne vode pogosto poplavijo. Imajo povsem svojevrsten, kot vemo tokrat prvič opisani skalni relief. Stare jame, skozi katere so se nekoč pretakali vodni tokovi, pričajo o znižanju gladine podzemeljske vode, ki površje dosega le v najnižjih podoljih ter o verjetnem tektonsko pogojenem členjenju kraškega površja. Dobršen del jam je zapolnjen z drobnozrnato naplavino in pod njo tudi preoblikovan. Oblikovanje špranjastih jam, ki so večinoma ob navpičnih razpokah, pa bi lahko opredelili kot podtalno. Razkrivajo se nam značilnosti plitkega in z naplavinami pokritega krasa, kjer je podzemeljska voda blizu površja. Te značilnosti bi bilo potrebno kar v največji meri upoštevati pri nadaljnjih poseganjih v kras, saj so nam na prvi pogled skrite, vsakršno poseganje v kras pa nam jih razkrije. Mnogi kraški pojavi predvsem jame, podtalne škraplje ali kamniti gozdovi so vredni, da jih zaščitimo in ohranimo.

The most conspicuous karst formations uncovered at the bottom of morphologic depressions or uvalas along the motorway route include swallow holes and estavelles. Also uncovered during the construction were underground karrens and caves of exquisite shapes, situated at valley bottoms and often flooded by groundwater. They have a specific rock relief that, to the best of our knowledge, is now described for the first time. Old caves through which streams were once flowing testify to the lowering of the level of groundwater, which reaches the surface only in the lowest-lying valleys, and to probable tectonic dissection of the karst surface. A good part of the caves are filled with fine-grained sediment and have been transformed underneath it. The shaping of fissure caves, located predominantly along vertical fissures, can be defined as having occurred subterraneously. They exhibit features of a shallow, sediment-covered karst where groundwater is close to the surface. These features are not visible at first sight, but they become apparent at any encroachment on karst and should therefore be taken fully into account in any such activity in the future. Many karst formations, above all caves, underground karrens or stone forests, are worthy of protection and preservation