A drilling at Sundet on the Southern shore of Lake Siljan (Fig. 1) ended 107.5 m below the surface without reaching the bedrock. Analyses of samples taken at regular intervals have shown the presence between, 72.5 m and 74.5 m of diamicton which covers glacio-fluvial deposits containing ground-water under pressure. In a later drilling at a place located 18 m east of the former a similar diamicton was penetrated between 74 m and 76.5 m before the glacio-fluvial deposits with ground-water were reached.