Submarine Karst of Croatia - Evidence of Former Lower Sea Levels

Povzetek

Med zadnjo, to je pleistocensko-holocensko transgresijo, je naraščajoča morska gladina zalila velike dele dinarskega krasa. Ker porečja rek na vzhodni jadranski obali sestavljajo pretežno karbonatne kamnine, te reke prenašajo le okoli 20 % sedimentov v obliki suspenza, vse ostalo pa kot raztopljeni tovor. Zaradi tega je pod morsko gladino še vedno mogoče ugotavljati značilne kraške oblike, kot so škraplje, vrtače, polja, jame in brezna, kot tudi rečne doline in soteske. Poleg teh preprostih potopljenih oblik so zaradi dvigajoče se gladine nastale tudi nove: podmorski izviri imenovani vrulje, zaslanjeni obalni izviri in morska jezera. Najpomembnejši dokazi o nekdanjem kopnem okolju so kapniki v potopljenih jamah in lehnjak v potopljenih nekdanjih rekah. Te oboje je mogoče uporabiti za ugotavljanje nekdanje niæje morske gladine.

During the last, Late Pleistocene-Holocene transgression, rising sea flooded a vast part of the Dinaric karst. Due to prevalence of carbonate rocks in the drainage area of most of the rivers on Eastern Adriatic coast, those rivers carry only approximately 20% of particulates as suspended matter and the rest is dissolved. Consequently, many typical karst features such as karrens, dolines, poljes, caves, pits and river valleys and canyons as well, presently under the sea, can still be recognized. Beside these simply drowned features, some new ones were formed by the sea level rise. Those are submarine springs, so called vruljas, brackish coastal springs and marine lakes. The most significant evidences of former subaerial conditions are speleothems in submerged caves and calc tufa deposits of drowned paleo rivers. Both of them could be used for determination of the former low sea level stands.