311 



adds, " stripped of its alluvial materials, we should find tliat the surface 

 presented a lake bottom, appearing as though Ontario and Oneida once 

 had a higher level, their waters uniting and covering the whole sur- 

 face." 



Very important practical conclusions are drawn by Mr. Vanuxem from 

 these facts. 



It is in this alluvion that we find buried, trunks of trees, the remains 

 of the Mastodon, and fresh water shells, and I am not aware that any 

 of these have been found, under similar circumstances, in the diluvial 

 deposits. 



Instances in our State, though rare, are all confirmatory of the posi- 

 tion assumed. Bones of the Mastodon were two years since found on 

 the Paw Paw River, in Berrien county, beneath twelve feet of sand and 

 gravel. A few of these are preserved in the State collection. In the 

 same manner, trees may be seen imbedded in the gravel which overlies 

 the clays on St. Clair River, at the foot of Lake Huron, and at a depth 

 of ten to twenty feet from the surface. The discovery of fresh-water 

 shells, under similar conditions, has been made in Saginaw county, and 

 elsewhere in this State, and in the Niagara valley, at a height far above 

 the present stream. 



We do not by any means consider these facts conclusive that this in- 

 land sea was one of fresh water, nor do we see much difficulty in the way of 

 so important a conclusion. If such was the case, the barriers which cut 

 oflt' the influx of the ocean must have existed during the quiescent state 

 of the waters. For had the present passages of the ocean been then 

 opened, no such accumulation of fresh water could have taken 

 place ; but we must necessarily suppose the inland sea to have been at 

 the same level with the briny Atlantic. Assuming our theoiy of the 

 erection of these barriei"s, as proposed above, we may then conceive the 

 uplifting of the continent to have been still in progress, until the whole 

 became elevated far above the influence of the ocean, and could receive 

 accessions only from fresh water streams. 



In conclusion of this subject, the aspect of the surface throughout 

 this region seems to indicate three great eras since the formation of >he 

 newest vocks : 



1st. After the elevatory process had commenced, and land appeared 

 above the surface of the ocean. At this period many of the secondary 



