Oberschwaben (Upper Swabia) is the region between the Swabian Jura, which means the Donau (Danube) and the Bodensee (Lake Konstanz). The name of the area is derived from an old tripartition of Swabia, the part around Stuttgart divided from Upper Swabia by the mountain range of the Swabian Jura. The Swabian Jura has a 200 m high cliff face, an escarpmnet, towards north but not towards south. And so a traveller from Stuttgart might get the impression to climb a step. As a result the northern part was called Unterland (low country), the southern part Oberland (high country) which was then transformed into Oberschwaben (Upper Swabia).
The geographic region is also a geologic unit. The minimal dip of the sedimentary layers of the Swabian Jura continues southwards towards the Alps. Material from the north and the south was transported into the lowering basin and formed sedimentary rocks during millions of years. Those rocks are called Molasse. During this era the area was changing between dry land, sweetwater lake and saltwater inland sea called Molassemee. Remains of the marine periods are fossil cliffs at the southern rim of the Swabian Jura, bore holes of clams, and the fossilized turritellas of the Turritellenplatte near Ulm.
But todays landscape was formed by the glaciers of the Ice Age, which came from the Alps and covered the whole area to the southern rim of the Swabian Jura. The cold periods are well documented in the many end moraines and were categorized by early geologists. They named the four main glacials after four southern tributaries of the Danube, Günz, Mindel, Riß and Würm. And even when they were melting they formed the landscape: the enormous melting water river, the ancient Danube, cut the unique valley of the Blau and Schmeich rivers.
This region has almost no underground objects, as it was never lifted high enough to drain underground. The is another theory postulating huge cave systems, but not a single one has ever been found. If if they existed, they would be filled with hot ground water and thus be inaccessible. So the only underground sites we can visit are subterranea.