Case Studies from the Dinaric Karst of Slovenia

films flowing down inclined surfaces and thedissolution kinetics of the CO 2-containing rainwater(Dreybrodt & Kaufmann 2007). Some ofthese features and widely spread so they gotspecial names.According to Ford and Williams (2007) themain groups are circular plane forms like micropits,pits, pans, heelprints. Linear formsthat are fracture-controlled are microfisures,splitkarren and grikes. Linear forms that arehydrodynamically controlled are microrills, solutionchanels or rillenkarren, solution runnels,decantation runnels and flutings.Polygenetic formsare mixtures of solutionchannels or assamblages of karren: karenfeld,limestone pavement (clints and grikes),stepped pavements, pinnacle karst, corridorkarst, costal karren.Common features on the bare horizontalrock surfaces exposed to rain are solutionpans. This is circular or irregular depression inthe surface of the rock with flat bottom andoften undercut edges. They are from few cmto 1 m large. Corrosion in them is encouragedby biologic processes like decay of organicmatter where organic acids form. Water fromthem evaporates; crystals of calcite are blownby wind or washed out by rain. Shepards oftenused for watering the animals (Perica 2009).Characteristic form of corrosion is rillenkarren.They are formed by channelled flow ofthe rain water on steep slopes on the tops oflimestone blocks. They are few cm wide anddeep, semi-circulars in cross section and havesharp edges of crests between them. On thelower side they often transform into plat, nondissected surface.Down the slope of the exposed rock largerchannels, runnels form. They are few tens ofcentimeters wide and can be several metersFig. 22: Kamenitza on Velebit mountain (photo: N. Zupan Hajna).31