Spår längs Hökensås av Tidanissjöns utveckling och existens

Abstract

During deglaciation, ice-dammed lakes formed in front of the retreating ice margin. Between Billingen and Hökensås, and south of the middle Swedish end-moraine-zone, a depression exists. In this area an ice-dammed lake was formed called Tidanissjön. This ice-dammed lake had several outflows along the western side towards Billingen and to the east over Hökensås during its existence. The water level in Tidanissjön dropped as the ice retreated north. To increase the understanding of Tidanissjöns development and water levels, sandar, deltas, moraines, stream channels and dead ice pits have been studied. The level of height for the sandur and deltas are graded to the different water levels during their formation. At the same time as Lake Tidan existed, the depression in Vättern also consisted of an ice lake, Vätternissjön. During certain periods the ice lakes were connected to each other but also to the Baltic ice lake. Waterflow between the ice lakes are studied and identified along Hökensås. During an early stage of Tidanissjön, Vätternissjön was dewatered to Tidanissjön, conversely during a later period. After the ice had retreated north of lake Mullsjö, Tidanissjön became connected to the Baltic Ice Lake and ceased to exist. Tidanissjön had then existed for over 1000 years.