Two Phase Development of the Upper Cerkniščica basin

Porecje Cerkniscice obsega 46,8 km2 in je reliefno precej pestro. Reliefna pestrost ni posledica velike kamninske pestrosti, saj vecino porecja gradi zgornjetriasni dolomit. Glavno vlogo pri tem ima razlicna pretrtost dolomita. Vec raziskovalcev meni, da se recne terase v porecju Cerkniscice nahajajo v vecih nivojih. Z rekonstrukcijo vzdolžnih recnih profilov Cerkniscice oz. njene predhodnice in njenih glavnih pritokov pa se je pokazalo, da v porecju Cerkniscice pravih vecstopenjskih teras ni. Vzdolž toka se namrec pojavljata le dva znacilna nivoja: starejsi in mlajsi. Starejsi nivo je 10-40 m visje od mlajsega in predstavlja uravnavo, ki jo je izdelala predhodnica Cerkniscice, ko je le-ta ponikala pri Begunjah in vodo podzemsko odvajala se v smeri proti Logatcu. Mlajsi nivo predstavlja dno danasnje Cerkniscice in se je zacel oblikovati ob koncu Wurma v trenutku, ko je voda iz porecja preusmerila tok in zacela odtekati proti Cerkniskemu polju. Takrat je bilo ravnotežje zaradi spremembe razmer (nova erozijska baza, krajsa odtocna razdalja in s tem vecji strmec) v porecju poruseno in prisiljeno se je bilo prilagajati novim razmeram. Da bi ustvarila novo ravnotežje, se je Cerkniscica zacela vrezovati v starejsi nivo. The Cerkniscica catchement area covers about 46.8 km 2 , and most of the area is built of upper Triassic dolomite. So, the differences in the surface roughness are mostly not due to variable lithology, but to diffent degrees of tectonically injurred rock. Reconstruction of longitudinal profiles of the main river and of its tributaries revealed that there do not exist multiple terraces, as believed before. Rather, the river formed only two distinct levels. The older one is about 10-40 m higher, a wide, well equilibrated valley. It was formed by the predecessor of the present Cerkniscica, at the time when the river sank in the area of Begunje and continued  its way towards Logatec underground. The younger level is controlled by the inrush of the river into Cerknisko polje. Sudden lowering of the erosion base, by the end of Wurm, provoked rapid incision into the earlier surface, and the formation of canyon-like entrenchment.