ABSTRACTA review of the deglaciation history of one of the large lake basins in Sweden, the Lake Siljan basin is given. A quantitative approach to the deglaciation of the area is applied with respect to the discharged amounts of water. To establish the palaeodischarges a formula based on the process of sedimentation and sorting of fluvially transported suspended matter is applied. The sediments for which the formula is used are annually varved silty sediments deposited as very distal delta sediments during the deglaciation of the southern part of the Lake Siljan basin. Connection to an absolute time scale and correlation of the new varve diagrammes is performed with a computer-based programme in order to eliminate subjectivity. Computations of palaeodischarges indicate that the water discharges during the melting season at the time of deglaciation were approx. 10 times greater than the present day mean annual discharges in the RiverÖsterdalälven that now drains the basin.