Sand pit Ballendorf
When the Swabian Alb was a coast
The former sand pit at Ballendorf offers an exceptional geological profile that takes visitors back 18 million years, to a time when the southern Swabian Alb was submerged beneath a subtropical prehistoric sea known as the Molasse Sea.
The light-coloured limestones that characterize the Swabian Alb were formed in a tropical sea during the Jurassic Period, the age of the dinosaurs. Afterward, the region remained dry land for more than 120 million years. The sea returned only in the middle of the Tertiary Period: as the Alps were uplifted, a broad, shallow depression known as the Molasse Basin formed south of the Alb. Around 20 million years ago, this basin was flooded by the sea. About 18 million years ago, the Molasse Sea reached the Ballendorf sand pit and covered the Jurassic limestone, which can still be seen today at the base of the pit.
In the shallow waters, oyster beds and boring bivalves became established. The latter left numerous round boreholes in the rock, which are still visible today.
As sea level continued to rise, coarse sands were deposited, forming the lower part of the exposed profile. Fine gravel and shell fragments indicate strong water movement and relatively shallow conditions. Higher up in the profile, the sand becomes progressively finer and shell remains become rarer, showing that the sea deepened over time and that the coastline migrated northwards.
When the Molasse Sea reached its maximum extent, a rocky cliff coast lay about three kilometres north of Ballendorf. This so-called cliff line was created by wave action and can still be traced today along the Swabian Alb as a long line of hills. It is particularly well visible from the parking area next to the sand pit.
Tip: At Heldenfingen and Altheim, visitors can see the rocks of this former cliff coast, still perforated by the boreholes of marine boring bivalves.
Address
Geopoint Sand pit Ballendorf
Ballendorf
(Alb-Donau-Kreis)