Holocene lake-level rise in the Upper Peninsula of Michigan, USA, as indicated by peatland growth

Abstract

We examined one sediment core from Kerr Lake and eight cores from the adjacent peatland in the Sylvania Wilderness Area of the Upper Peninsula of Michigan, USA. Radiocarbon dating of the interface between peat and the underlying glacial till showed that the peatland grew by paludification of the surrounding uplands, implying a rising water level in the lake. Pollen analysis of the cores showed that the peatland began expanding just before the arrival of Tsuga in the surrounding forests. The most rapid growth of the peatland occurred between 3900 and 3000 BP. This is also the time when the forests were being transformed from dry Pinus strobus-dominated woodlands to moister Tsuga- and Acer saccharum-dominated northern hardwoods. Our results imply an increase in available moisture at the time of Tsuga colonization.