The history of the Danube valley begins with the elevation of the Bohemian mass 17-18 million years ago in the Tertiary period. Already in the early history of the earth in the Precambrian 1000 million years ago, the structures and directions still recognizable in the construction of the mountains were laid out.
On both sides the valley is formed by old crystalline rocks, which can be distinguished into gneiss and granite. The gneiss, which represent rocks deformed by pressure and heat, can be divided into two groups: a so-called “monotone group”, which originates from a metamorphic transformation of sandstone, clays or marls, and a “colourful group”, which is interspersed with volcanic deposits (e.g. the graphite slate in the Obernzell area).
In the course of the Variscan mountain formation in the Carboniferous, in which granites were intercalated, the Bavarian Forest developed into a high mountain range. The formation of the pile (e.g. the Aicha-Halser secondary pile from Iggensbach to Passau), a quartzitic fissure filling, also falls into this time.
In the following geological epochs Perm and Triassic the high mountains were eroded by deep erosions to a Rumpfgebirge. In the Jurassic period only the “Bohemian Island”, surrounded by shallow seas and coral reefs, remained.
The emergence of the Alps was reflected in the beginning collision of the African and European plates, which led to an uplift of the Bohemian mass, and multiple sea floods in the basins in front of the emerging Alps still affected the basement. The remains of these marine sediments, now known as molasses, are still present on the bedrock body, and the tectonic disturbances that run through the space play an important role in the course of the Danube.
The Danube rift, which deviates to the south near Hofkirchen, is a fault line at which the bedrock was raised to over 1000 m compared to the southern tertiary foreland. A forerunner of the primeval Danube probably cut the valley further to the west by receding erosion and thus determined the present course of the Danube.
The Danube probably only found its present bed at the end of the Tertiary.Below Passau, the Danube today follows the Danube guidance disturbance in direct continuation of the Danube border disturbance and the Aicha-Halser side pile.During the Ice Age, the valley deepened at the same time as the mountains were raised, which contributed to the formation of today’s Danube valley.
The levelling areas, on which the river has deposited gravel and sand, represent important settlement areas as well as important groundwater reservoirs.