GEOLOGY. 271 



municated with each other by many valleys, such as the Wabash and 

 the Illinois ; so that the basin of the lakes, which is now separated 

 from that of the Mississippi, at that epoch discharged its waters into 

 the basin of this great river. Mr. Hubbard, of the Michigan Survey, 

 says, there exists a depression between Lakes Huron and Michigan, 

 through the valley of Saginaw Bay, where there was a connection of 

 the waters. 



The existence of these fresh water deposites being now demon- 

 strated, it becomes necessary to give them a specific name, to distin- 

 guish them from the marine, or Laurentian formation. The geological 

 corps of the United States, in Michigan, propose to call them Algonquin, 

 from a powerful nation of Indians, who heretofore inhabited the region 

 of the lakes, and the heads of the Mississippi. It has not been defi- 

 nitely adopted, because there are doubts whether the drift proper that 

 occupies the central and elevated parts of Ohio, Wisconsin and Mich- 

 igan, is not of the same age. It was at first admitted, that the lacus- 

 trine deposites of Lake Erie, (on which Cleveland is situated,) although 

 at a lower level, was nevertheless more recent than the " drift," and 

 perhaps, contemporary with the " Laurentian." More recent researches 

 have not confirmed this view ; and many geologists, at the head of 

 whom is Mr. Whittlesey, are now inclined to think, that the lacustrine 

 or the " Algonquin " beds, are members of the " drift proper," modi- 

 fied by local action and circumstances, and that they pass insensibly 

 into each other. If this is really so, it will follow, not only that the 

 Laurentian is more recent than the lacustrine formation ; but what is 

 more important, the whole drift beds of the TVest must be regarded as 

 a fresh water deposit. The difficulty in this case arises, in conceiving 

 of banking, or highlands sufficiently elevated, to hold the waters of 

 such a basin, for the drift deposites attain the height of 1,600 feet 

 above tide, between Lake Superior and Lake Michigan, without 

 including the erratic blocks, or " boulders " that are found still higher. 

 Unfortunately, there have no shells been found in the elevated coarse 

 drift. The only fossils that these beds have furnished, are parts of 

 trees, leaves, &c. It is to be hoped that shells may be discovered ; 

 but until then, the identity of the drift with the Algonquin, or lacus- 

 trine formation, must remain in suspense. I should remark, that there 

 is found on the surface of the lacustrine, as well as on the Laurentian, 

 and on the proper " drift," boulders of all dimensions. The mere 

 statement of this fact, proves that they were not transported by the 

 same agent that has scratched, striated and polished, the rocks in 

 place. If this agent was a ylacier, we can no longer attribute to it the 

 transportation of boulders, for in that case, their transportation should be 

 contemporary with the polishing of the rocks ; but there is between them 

 the whole period, during which the lacustrine beds were being depos- 

 ited. There are also, on the surface of the lacustrine of Lake Erie, (and 

 other lakes) ridges and elongated hillocks, like the " osars " of Sweden, 

 showing like them, traces of stratification, which proves that they were 

 all formed under water. Neither the lacustrine or the Laurentian 

 contain the bones of mammiferous animals, such as the Mastodon, Ele- 

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