Climatic change evidence and lacustrine varves from maar lakes,Germany

Annually laminated, non-glacial lake sediments from Lake Holzmaar (Eifel, western Germany) were investigated using large Merkt thin sections. The absolute age of varve intervals with variations in thickness and composition were correlated to climatic changes recorded by glacier fluctuations in the Alps. Back to 8800 years VT (varve time = varve years before 1950) glacier advances coincide with sedimentation rate minima; prior to 8800 years VT they coincide with sedimentation rate maxima. The early and middle Holocene sediments suggest a periodicity of about 1000 years for cold/warm cycles. A sequence of 512 varve-thickness measurements was subjected to spectral analysis. These provide apparent evidence for a 11-year sun-spot cycle.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program.