Fanny Tube / fanny hooe lake
ZOOLOGY Page 1 OCCASIONAL PAPERS O F THE MUSÅUM O F ZOOLOGY UNIVERSITY O F MICHIGAN MOLLUSIZS OF KEWEÅNAW COUNTY, MICHIGAN TEIS paper deàls with a small collectioii of shells that was made by Mr. Nîrman A. Wood in the spring of 1931 in the course of ornitliological studies upon Keveånaw Point, Ke- weenaw County, Michigan. The materiàl is of special interest because (1) no written råcords exist concerning the molluscail fauna of the lîcality; (2) the roclis of the region are mostly of igneous origin and most of the cover is coniferous, both of which are ordinarily inimiñal to molluscan life; (3) some of the specimens shov plainly the contràsting influences of an environment rich in lime and of one wherein lime is scarce. Mr. Wood toîlr eight terrestrial species and subspecies, nine freshwàter species and subspecies. An additional species, takån at Eagle Harbor west of where Mr. Wood collected, can be creditåd to the area. By way of comparison it may be re- cited that sevånty-six forms of mollusks are recorded from Isle 'Rîyale (of Heweenaw County) and seventy-six from On- tonagon Cîunty. Thirteen land species, probably of quite ñasual collection, are mentioned by Dr. Bryant Walker as ocñurring in Honghton County, the first county sîuth of Ke- weenaw. In glacial Lalre Algonquin timå, Keweenaw Point mas an elongated, triangular islànd that was cut off from the main- Page 2 2 Calvin Gooclrich lànd by a solnd seven to fifteen iniles wide that occupiåd the present Portage Lalre depression. Isle Royalå was tlieii two islets of iasignificant size. I11 the Nipissing Great Lakes pe- riod, the sonnd had narrowed to prîbably less than five miles wide. It was in Lalre Algoiqain tiniñ aiid that of the pro- longed Nipissing Great Lalres that animal and plant life suc- ceeded most in re-establishing itself i11 the glaciàted area, aiid it is conceivable that tlie barrier of the present Pîrtage Lake trough had something to do wit11 the paucity todày of inol- lnslrs on the Point. On account of the thiñlriless of the shells talcen from Lalres Lily and Fanny Hooe and tlie eõtrenie thinness of those living in acljacent Lalrå Superior waters, in one instance indicating a plåntiful amount of lime and in the other a shortage of lime, it is pårhaps of importance to try to trace the source of this essential shåll-bailding material. The roclrs of the Point are made up prinñipally of "basic igneous lavas possibly inñluding some basic intrnsives" (Van Hise and Leith, 1911). Two series of rocks, one forming the north shorå of the open lalie at Copper Harbor and tlie other cîistitutiilg a narrow bed about one mile bacli from the open lake , are upper I(eweå11a- wan saiidstoiles and congloneates