Xo.. 136.] 



83 



summits of the hills themselves, and from larg6 tracts of plain 

 country. The whole vast basin of Lake Ontario is an excava- 

 tion in rocks, which still lie nearly as level as when first deposi- 

 ted ; and there seems no reason to doubt that the northern edges 

 of the enormous piles of slate rocks above the Helderberg lime- 

 stones once overspread what are now the level plains of the 

 countries bordering on that inland sea. 



Such long lines of blufis as the Niagara " mountain ridge," or 

 the steep escarpments of the Helderberg limestones, seem to 

 indicate the action at some period of waves from a broad expanse 

 of sea, to which they stood as coast-precipices. The existence 

 of old beaches, such as the Lake Ridge near Rochester, seems to 

 prove that the waters of the lakes once stood far higher than 

 now : perhaps the land may have stood much lower, and they 

 were inland bays or gulfs of the ocean. 



This whole subject is obscure, and we have mentioned it only 

 from a desire to embrace in this sketch a glance at every point 

 of interest connected with the surface of the State, as well as 

 with the strata of which it is built up ; and to direct wider and 

 more general study and observation to the Natural Monuments of 

 the Past. 



Among the most recent of geological monuments, which seem to 

 link together the vanished forms of the past with the conditions 

 of the present, are the bones of the Mastodon and Fossil Elephant, 

 which are occasionally disinterred in various parts of the State, 

 found buried only in recent accumulations of muck, peat, or 

 other earthy materials. They appear to be relics of a very modern 

 period of geological history, and their owners seem to have lived 

 since the existence in this region of many of our still-remaining 

 wild animals; possibly even since it was inhabited by man. 

 Specimens of these are in the Collection ; and there is also a 

 plaster cast of the skull of the Castoroides ohioensis^ a gigantic 

 extinct species of beaver, which was probably of the same period 

 with the mastodon. It was found near the village of Clyde, in 

 earth, during the excavation of a canal. 



The petrified wood, leaves, moss, etc., which are so common in 

 our limestone districts, are of modern date, and are being formed 

 at the present time. The rainwater which percolates through 



