The story starts in the ocean, where tropical reefs grew in shallow water hundreds of millions of years ago (Loser summit). Long before that, salt layers were left behind from prehistoric seas that dried out on hot coastlines, eventually forming the mountains (Sandling) and carbonates deposited on the ocean floor (Trisselwand). Later, Africa pushed these rocks onto the southern edge of Europe and created a mountain belt – the Alps. Soon after, rivers developed (like the Enns river) and cut deep valleys into the plateaus of the still young Alps.
Later, glaciers flooded these mountains and eroded them during the penultimate glaciation, with up to 1,000 m deep holes which were refilled by rivers like the Enns. During the last glaciation, ice from the plateau of the Totes Gebirge streamed through the valley.
As the ice melted, several lakes developed and the recent Lake Altaussee was formed by the Augstbach alluvial fan, landslides from the slopes, and lake sediments.
