The leaching and original content of calcium carbonate in till in northern Uppland, Sweden

Abstract

In a strip ranging c. 30 km inland from the northern coast of the province of Uppland (Sweden), south of the Bothnian Palaeozoic limestone area, till cuttings were studied with respect to calcareous matter. From the coast onward, the depth of the carbonate-free, leached zone was found to increase (as regarded exposed deposits above ground-water level) fromafewdecimetres to 3→ 6 m. In addition, in unleached till, the proportion of limestone grains in the fine gravel fraction diminishes from 25–35% to ≤1%, and the proportion of calcite in “fine material” drops from 15–17% by weight to 4–5% . Gillberg (this journal, Vol. 89) failed to find any calcareous matter (except for blank calcite values) in tills from most of our study area. However, he took samples at a fixed depth of 0.5–1 m, i.e. in most cases above the carbonate limit. Our findings agree well with the former and recent alkalinity conditions in the lakes within the study area.