We are talking about the youngest rocks of the Lechtal Alps. They were formed in the Cretaceous period (90 million years) . During the first mountain-building phase, erosion/weathering had already set in and eroded away the mountains. Unordered, small and large fragments of different source rocks were pressed together and solidified. These rocks are assigned to the Gosau layer .
If you take a closer look at a representative of the Gosau layer, you will find in one stone, possibly all rock types that occur in the Lech valley. If the fragments are round, one speaks of a conglomerate, if they are angular, it is a matter of breccias. If the components are very small, they are called sandstone.
If the stones of the Gosau layers are polished, they present themselves as decorative ornamental stones. Therefore, they are processed in many buildings (castles and churches) of Tyrol and Bavaria.