The Formation of the Traun Gorge
A Window into Earth's History
Decisive for the formation of the present-day lakes in the Salzkammergut region was the last, or Würm, Ice Age. While not the most significant, as it was undoubtedly surpassed in its shaping effect by the preceding ice ages, the current appearance of our beautiful region is undoubtedly attributed to this era.
In the late glacial period and during the final retreat of the valley glaciers, local lake formations occurred in many places in the Salzkammergut. Ice lakes and ice-margin lakes were dammed up in the marginal parts of the sinking, large ice streams, especially in the side valleys of the present Traun Valley, which had become ice-free early on. Occasionally, water collected in the sunken, funnel-shaped depressions on the surface, known as "Pingen." The largely silted Krottensee near Cumberland Castle in Gmunden is an example of such a Pingen or Söll lake.
With the complete disappearance of the ice, the large, deepened glacier basins filled with meltwater. In the tongue basins of the large valley glaciers, there was still damming of lakes during the glacier retreat, in the late glacial period. Lake drainage occurred over the end moraine ridges, and since these moraines, especially in higher elevations, consist mostly of loose deposits and permeable gravel, overflow breakthroughs and lowering of the dammed lakes soon occurred. These lowerings and deepening of lake outflows continued until a corresponding slope of the outflows was established.
On Lake Traun, the gradual lowering of the lake can be well observed in the city area of Gmunden. The highest drainage channel is at an elevation of 480 meters above sea level, approximately 60 meters above the current lake level, and a very pronounced, broad drainage valley is visible at an elevation of 460 meters above sea level.
The next lower channel at 450 meters above sea level corresponds to the current main level of the Traun Valley. The most recent lowering occurred in any case extremely abruptly, as the valley was too narrow and did not allow space for the water to spread. Due to this rapid, explosive overflow, the masses of water carried away the deposits and gravel. The present-day Traun thus carved its way into the landscape, and the Traun Gorge was formed. About 14 kilometers downstream from the lake outflow in Gmunden, the Traun plunges 12 meters deep at Traunfall, giving a glimpse of the forces that shaped the entire region around 15,000 years ago.
