PALEOLIMNOLOGICAL COMPARISON OF THE LAURENTIAN GREAT-LAKES BASED ON DIATOMS

We used cluster analysis to compare records of diatom succession recor ded in dated cores from offshore basins of the five Great Lakes. Most recently deposited samples from Lakes Erie and Ontario are far removed from the cluster centroid, as are samples deposited in Lakes Huron an d Michigan during forest clearance. Most recently deposited samples fr om Lake Superior are also clearly segregated, but occupy the opposite end of the ordination. At a lower level, samples clustered by lake and time. For each lake, sample clusters from presettlement, early indust rialization, and postindustrialization were identified. Relationships of cluster structure allow inferences concerning the comparative state of the lakes at different periods in their history.