A plan for a geochemical study on weathered bedrock in Northern Finland

Systematic geochemical mapping based on till sampling has revealed an almost continuous layer of weathered material under the till cover in North­ern Finland. Differential leaching and enrichment of elements during weath­ering have changed the element contents and ratios so significantly that the varying quantity of weathered material mixed with any other sample material can produce false anomalies. For the present the sample materials are identified at the sampling point and different identifications by separated field groups are unavoidable. The Geochemistry Department of The Geologi­cal Survey of Finland has started a program for collecting all available infor­mation about the weathered bedrock occurrences in Finland including a literature study on the geochemistry of weathering