The underground layers of rock are most often invisible to us, but they impact our daily lives in manifold ways. Our soils’ fertility largely depends on the mineral elements present in the geological substrata. For our water supply and for all of our building endeavours, too, geological factors play a vital part. For this reason, the Open Air Museum illustrates fundamental contexts of geological conditions with the Geology Trail.
At the outset of the trail, there are display boards on topics such as The Structure of the Earth and The Cycle of Stones. In the second part, visitors have the opportunity to take a walk through the various geological periods, inasmuch as they are represented in Hesse. The granites of the western Odenwald recall the first origin of earth and the solidification of the flowing mass of magma below the earth’s surface.
The Palaeozoic (500 to 230 million years ago) is represented by the chronological sequence of Silurian sericite gneiss, found in the southern Taunus, and Devonian slates, micaceous sandstones, quartzite and limestones from the Taunus proper. Carbon slates from the Lahn river region, sandstones from eastern Hesse and conglomerates from the Hesse-Thuringia border region, which come from the Permian, follow.
The only representative of the Mesozoic (230 to 65 million years ago) in Hesse is the Triassic. It contains red sandstones from the eastern Odenwald and the Reinhardswald, shell-bearing limestones from the Diemel region and the Eastern Rhön mountains and, finally, Keuper sandstones from the Netra valley. The Jurassic and Cretaceous periods cannot be shown as what is Hesse today was dry land at the time, so no sediments formed.
The Cainozoic (65 million years ago to today) is represented by stones from the Tertiary. These are coralline limestones, but also the softer sandstones of the Wetterau region and, in particular, basalts. The latter are of importance not only in the Westerwald, along the northern edge of the Odenwald and in the Knüll mountains, they also form the central Hesse Vogelsberg massif. This is the largest contiguous basalt mass in Europe. The end of the trail is marked by a sandstone column from Rockenberg (Wetterau) which consists of very young, not fully solidified fine sand sediment.