Michael Retelle is a glacial and Quaternary geologist whose research and teaching interests include the studies of high arctic glacial, marine, and lacustrine environments and environmental change. He is also involved in research on the glacial and postglacial history in Maine. Most recently, his work has focussed on high resolution records of climate change preserved in annually laminated sediments in lakes on Ellesmere and Cornwallis Islands in the Canadian high arctic.

The principle objective of this research has been to reconstruct paleoclimatic conditions in the high arctic over the last few millennia using laminated sediments and diatom assemblages as climate proxies. To that end, intensive field and laboratory studies include recovery of sediment cores and analysis of laminated sediments combined with studies of climatological, hydrological and sedimentary processes in the watershed and lake. Understanding the link between modern processes and the sediment record is critical for interpreting the paleoclimate signal preserved in the lake sediments and ultimately reconstructing a detailed climatic history in the arctic.

Two main types of lakes have been studied in this program: (1) coastal meromictic lakes that are density stratified, containing a layer of fresh to brackish surface water overlying"old" seawater trapped in the basin during isostatic emergence of the marine inlet from the adjacent sea in the late Holocene, and (2) ice-marginal lakes fed by glacier meltwater and sediment. Although varved lake sediments offer the potential for high resolution paleoclimate reconstruction, climatologically significant records are just beginning to emerge from recent research initiatives in the arctic. The climate signal preserved in the lake sediments is often complex and may be influenced by temperature and precipitation, both of which strongly control stream discharge.

Recent research at Lake C2 at Taconite Inlet, northern Ellesmere Island (Bradley et al., 1996) showed that although depositional controls and processes are complex, varve thickness is ultimately driven by climate forcings. Work done in collaboration with colleagues and students from the University of Massachusetts is summarized in the Taconite Inlet Home Page. Reseach on paleoclimate records from other high arctic lakes on Ellesmere, Devon, and Cornwallis Islands is in progress.

In addition to work on lake sediment records in the Canadian high arctic Retelle is currently involved in an interdisciplinary geo-archaeological project in Shetland, U.K. with Gerald Bigelow and students ). This project will investigate the relationship between climate change and human settlement in coastal sand dune areas of the Shetland Islands. Many coastal sites in the region were settled by the Norse in the period 1000 to 1300 A.D., only to be abandoned around 1300 A.D. during the subsequent onset of the Little Ice Age. Our research will focus on the evidence of settlement and environmental changes represented in the geology of the dunes. Field work for this project began in June, 1997.