The Elbsandsteingebirge (Elbe Sandstone Mountains), as the name says, is a series of sandstone mountains. The rock is eroded forming vertical cliff faces, towers, and escarpments. This landscape is similar to canyonlands or badlands in the United States, although probably smaller in extent and less bombastic. The sandstone is a Cretaceous sandstone which formed in a shallow sea. Quartz rich sand with a lot of iron oxide in the matrix, which explains the red colour.
The Elbsandsteingebirge stretches on both sides of the Elbe, hence the name, and also on both sides of the national border, between Dresden and northern Bohemia. For this reason, we have also linked the two bordering Czech regions below. The Czech Republic is also home to the largest natural bridge in the area, the Pravčická Brána (Prebischtor), with a width of 26 m, height of 16 m and length of 8 m, not only the largest natural bridge in the region, but in all of Europe. On the German side, there is the second largest, the Kuhstall, and the third largest, the Kleinsteinhöhle. Schengen has united what has always belonged together. And the language of the locals is not understood on either side of the border. It is also remarkable that areas that are not at all alpine are often ennobled with the name Switzerland. Thus the German part is also called Saxon Switzerland, whereas the Czech part, you have already guessed, is called Bohemian Switzerland. Only in the case of real mountains, such as the High Tatras, does no one seem to have come up with the epithet Switzerland yet.
There are massive layers of hard sandstone with thin layers of siltstone inbetween. Those layers are often impermeable, so water is dammed and flows to the cliff face where it forms springs. The silt layers are both weaker and also subject to heavier erosion, because of the water. The result is the formation of horizontal wedges and even caves, until the rock above breaks down. The talus is continually conveyed to the sea by the Elbe river below. This continuous process sharpens the edge and keeps the cliff face vertical. Or in other terms: the erosional processes reached an equilibrium at which the formation of cliffs and towers is supported instead of them being eroded.
As we already mentioned, there are horizontal caves formed by the erosion along soft layers in the sandstone. They often have a small spring inside caused by the impermeable silt. But while they are wide, they are not very deep and the ceiling is often low, so it is necessary to crawl. With very few exceptions the caves of the area are known to be extremely narrow.
Another common type of caves in the area are tectonic caves, both fracture and talus caves. Both cave types are basically formed by movements of the rock. Fracture caves are the result of movements of the huge rocks. They may be open like the Himmelsleiter (Stairway to Heaven) or real caves. Talus caves are fissures inside the talus heaps at the foot of the cliffs.
The area, although rich in caves, is not a karst area, the caves are mostly very small. Some geologists tend to describe it as a sandstone karst area, which is actually an oxymoron. However, the discussion is mainly on the terminology, and not on the processes involved in the formation of the caves.