The Mittelaletsch glacier emanates nestled between Geisshorn and Dreieckhorn on the eastern flank of the Aletschhorn (4193 m), the highest elevation of the Aletsch area. The ice stream formerly called "Ahnen glacier" flowed in the Aletsch glacier until the beginning of the 1970s, forming a middle moraine that reached down to Ze Baechu. Most historical visual documents of this glacier were taken from the Eggishorn, often with people in the foreground. From there you have as well a good view into the Mittelaletsch valley. During the last glaciation high extension around 1850, the length of the Mittelaletsch glacier was around 6 km and its surface 8.5 km2. To date it shrunk to a length of 5 km and a surface of almost 7 km2.