The characteristic pale grey mountains which surround Altaussee are made of limestone, a carbonate rock. The age of these rocks are Triassic and Jurassic. The mountains themselves did not form until the Cenozoic, when immense forces between the colliding African and Eurasian plates caused the mountains to be uplifted. The limestones which make up the mountains are white to pale grey in colour, and formed relatively deep in the ancient Tethys ocean. Because the rocks formed so deep, fossils are rare. However, corals are reported from the lower slopes of Loser mountain.