Evidence of Climate Change over the Last 10,000 Years from the Sediments of Lakes in the Upper Mississippi Basin
http://pubs.usgs.gov/fs/fs-0059-99/

Walter E. Dean, United States Geological Survey

This USGS fact sheet discusses paleoecological records derived from sediments in the upper midwestern US (e.g. Minnesota). The paleoecological record was derived from varved (seasonally-laminated) sediment cores, geochemical data, and pollen.

This resource is referenced here:

• Microbial Life:Topics of Interest:Climate Proxies: Advanced Collection

Subject: Biology, :Ecology:Metabolism, Biology:Microbiology, Geoscience:Atmospheric Science:Climatology , Environmental Science:Ecosystems:Biogeochemical cycling
Resource Type: Scientific Resources:Overview/Reference Work
Grade Level: Graduate/Professional, College Upper (15-16), College Lower (13-14), High School (9-12)
Topics: Biosphere:Ecology:Habitats:Freshwater, Biosphere:Microbiology, Energy/Material cycles, Biosphere:Ecology, Climate