Notes: | Depths shown by isolines. " ... to accompany The Great Lakes: an Environmental Atlas and Resource Book." Indexed for Canadian and U.S. ecoregions. Includes notes and 3 graphs titled, "Summary of ecoregion characteristics [U.S.]," "Great Lakes factsheet," and "Summary of ecoregion characteristics [Canada]." Ancillary maps: Waterborne commerce -- Winter temperatures and ice conditions -- Summer temperatures -- Pollution sources and trophic status -- Recreation and sports -- Frost free period and air masses -- Precipitation and snowbelt areas -- Land use, fisheries and erosion.
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