GEOLOGY. 239 



materials have been transported and scattered over the bottom 

 and along the south shore of our ancient inland sea, just as 

 similar materials are now being scattered over the banks and 

 shores of Newfoundland. 



" These boulders include representations of nearly all the rocks of 

 the Lake Superior country, conspicuous among which are granites 

 with rose-colored orthoclase, gray gneiss and diorites, all charac- 

 teristic of the Laurentian series ; hornblendic rocks, massive and 

 schistose, and dark greenish or bluish silicious slates, probably 

 from the Huronian dolorites, and masses of native copper, appar- 

 ently from the Keweenaw Point copper region. 



*' In the drift gravels I have found pebbles and small boulders 

 of nearly all the paleozoic rocks of the lake basin containing 

 their characteristic fossils, namely, Calciferous sandstone with 

 Maclurea ; Trenton and Hudson with Ambonychia radiata, Cyrto- 

 lites ornatus; Medina with Plcurotomaria litorea ; Corniferous with 

 Conocardium trigonale, Atrypa reticularis, Favosiles polymorpluji ; 

 Hamilton with Spirifer mucronatus, etc." 



In remarks on the origin of the great lakes, Dr. Newberry 

 states, as " facts and deductions :" 



" 1st. Lake Superior lies in a synclinal trough, and its mode of 

 formation therefore hardly admits of question, though its sides 

 are deeply scored with ice-marks, and its form and area may have 

 been somewhat modified by this agent. 



" 2d. Lakes Huron, Michigan, Erie and Ontario are excavated 

 basins, wrought out of once continuous sheets of sedimentary 

 strata by a mechanical agent, and that ice or water or both." 

 Annals Lyceum Natural History, New York, 1869. 



POST-TERTIARY PHENOMENA. 



Prof. "Winchell, of the Michigan Geological Survey, read a paper 

 at the Troy meeting of the American Association for the Advance- 

 ment of Science upon the Post-Tertiary Phenomena in Michigan. 

 The paper, he said, was intended simply to make note of three 

 classes of phenomena recently observed in Michigan. The first 

 note was in reference to the relics found in and beneath the numer- 

 ous peat-beds of the State. These beds are the sites of ancient 

 lakelets that have been slowly filled by the accumulation of sedi- 

 ments. They enclose numerous remains of the mastodon and 

 mammoth. These are sometimes found so near the surface that 

 one could believe they have been buried within 500 or 1,000 

 years. For the first time, too, the remains of the gigantic extinct 

 beaver of North America have been recently found in Michigan. 

 What is perhaps most interesting of all is the discovery of a iiint 

 arrow-head in a similar situation. This arrow-head was found 7 

 feet beneath the surface, in a ditch excavated in the southern part 

 of Washtenaw County. The mastodon remains found near 

 Tecumseh, but a few miles distant, lay but 2i feet beneath the sur- 

 face. The Adrian mastodon was buried but 3 feet deep. 



The second note made related to the occurrence of enormous 



