Ordovician limestone in Hälsingland, Sweden
Limestone boulders of Early and Middle Ordovician age occur along the Baltic coast of Sweden from c. 59 degrees N to c. 62.5 degrees N, apparently at a considerable distance from any known source rocks on land. We have investigated a limestone block from Lake Kultebo, at 61 degrees N, not far inland. The conodont elements enclosed in the rock are of Mid-Ordovician age and show that the block could