. An ecological survey of Isle Royale, Lake Superior. Animal ecology; Botany; Zoology; Plant ecology. ECOLOGY OP ISLE ROYALE. 33 â wall continued to retreat toward the northeast, these ponded waters increased in area and formed the highest beach lines now preserved on the north shore of Lake Superior. The evidence for this is found on Mt. Josephine, located on this shore just north of the southwestern end of Isle Eoyale, which reaches an elevation of about 800 feet above the Lake. Par up on its slopes, according, to Lawson ('93, p. 253), evidence of beach lines are found, about which he says:
. An ecological survey of Isle Royale, Lake Superior. Animal ecology; Botany; Zoology; Plant ecology. ECOLOGY OP ISLE ROYALE. 33 â wall continued to retreat toward the northeast, these ponded waters increased in area and formed the highest beach lines now preserved on the north shore of Lake Superior. The evidence for this is found on Mt. Josephine, located on this shore just north of the southwestern end of Isle Eoyale, which reaches an elevation of about 800 feet above the Lake. Par up on its slopes, according, to Lawson ('93, p. 253), evidence of beach lines are found, about which he says: "These two terraces at 685 and 607 feet are remarkable for being the highest strand lines which #j?r^:;s^'^\ .rV. Fig. 51. Showing origin of the Glacial Lakes, their relation to the ice sheet and their Miss- issippi drainage. have thus far been observed on the coast of Lake ; Under such conditions it seems that Isle Eoyale would undoubtedly have been sub- merged. The ice retreat continued and finally Isle Eoyale, freed from the ice and in part from the lake waters, emerged as a narrow rocky ridgeâthe crest of the Greenstone Eange which today rises, at the northeastern end of the island, to a maximum elevation of about 550 feet. As the ice wall retreated the Michigan and Huron basins became confluent, and an outlet to the east (Trent valley, Ontario) at first, later the Port Huron and possibly the Chicago outlet (Goldthwait, '09, p. 65) became available, Fig. 52, and at about this time the Glacial Great 5. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Adams, Charles Christopher, 1873-; Gleason, Henry A. (Henry Allan), 1882-1975; McCreary, Otto; Peet, Max Minor; University of Michigan. University Museum; Michigan. Geological Survey. Lansing, Mich. , Wynkoop Hallenbeck Crawford Co. , Stat
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