Rinnen-karren with large grooves and crests on macrocrystalline gypsum
When the rock on the surface is attacked by karstification, the surface solutional features are called lapies or karren. The grooves, ridges, vacuoles and rounded dissolution features produced by this process confer the characteristic appearance on the rock and on the landscape.
In the gypsum karst we can find just as many karren features as occur in other karstic terrains, such as the limestone ones. Careful inspection of the surface of the Sorbas Karst easily shows up numerous different forms of karren. Solution flutes and rillen, with their small grooves separated by crests, parallel ridges appear frequently where the gypsum is more microcrystalline. Karren with large ridges and grooves (rinnenkarren) are more common where the gypsum is composed of larger, macrocrystalline crystals (Figure 4). When the dissolution has taken place below a cover of soil both the crests and the form of the lapies tend to be rounded (roundkarren). On occasions, where the ground is very flat, the karren take on a sinuous form (meanderkarren), with grooves that wind over the surface of the gypsum. Sometimes the action of the water on the walls of the dolines (wallkarren) means that these form the large grooves of a solution pipe, which often lead into the interior of the sinkholes and caves.
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Rinnen-karren with large grooves and crests on macrocrystalline gypsum
Karren with rounded crests developed under soil cover
Rillen with small grooves and crests on mycrocristalline gypsum
Meander-karren with sinuous channels
Figure 3