310 



em coast of South America. Other facts relevant to this subject might 

 be introduced, connected with the earthquakes in the Mississippi valley, 

 had I not been already enticed to greater length than may seem called 

 for in this place. 



It may be added, that the unusually marked character of the ridge 

 on the west end of Lake Erie, is a consequence of the even surface and 

 extent of the limerock, and its overlying clays, which here form its base. 

 It may be doubted whether any similar ridge, at least so distinct, may 

 be traced over the more broken country which circumscribed the eastern 

 limits of the waters in New York, 



LAKE ALLUVION. 



The facts and suppositions above stated, lead to several important 

 conclusions, in determining the alluvial deposits of the Peninsula. 



Under the name of diluvium, were classed all those alternating de- 

 posits of sands, gravels and clays, which envelope the upper rock for- 

 mations of the Peninsula. As we descend from the'^more elevated in- 

 terior, and come within that area which I have supposed circumscribed 

 by the waters of the ancient lakes, a different character of surface, and 

 of soil, prevails. The great deposit of blue and yellow clays, since 

 they underlie and extend beyond the ridge, must be of a date anterior 

 to the era under consideration. Nor do they seem to have been much 

 disturbed during that comparatively quiet state of the waters. An evi- 

 dent disarrangement, however, took place among the more loose sands 

 and gravels, which assumed the character of alluvion; being subjected 

 to a less disturbed and longer continued action than the diluviums, and 

 deposited with fewer inequalities of surface. This alluvion consists, in 

 the main, of ia covering of sand, or of sand^ridges, with the underlying 

 clays outcropping at intervals. Bouldei's are thinly dispersed, and few 

 local beds of clay are found, like those embraced in the diluvium. Most 

 of the alluvion is clothed with a dense growth of timber. 



Similar results, from the same cause, are found strikingly exemplified 

 in the State of New York, over an area described by Mr. Vanuxem, as 

 occupying " a portion of Oneida, the northern part of Madison, Onon - 

 daga and Cayuga, and the western and southern portions of Oswego." 

 The area included within these limits, will be found to correspond with 

 that which I have supposed occupied by the waters when raised to the 

 assumed level. " Were the whole of this ancient level or area," he 



