Like the rest of the nummulite formation of the high Glarus Alps, the Hausstock contains fine-grained black sandstone. The mountain is part of the Glarus thrust, a major thrust fault; the top layer consists of Verrucano formations, 250-300 Ma old, on top of chalk, 100-150 Ma, and flysch, 35-50 Ma. In 2008, the thrust was declared a geotope, a geologic UNESCO world heritage site, under the name Swiss Tectonic Arena Sardona. The Glarus thrust can clearly be seen on the mountain at approximately .