NARRATIVE. 13 



older deposits form strips around the granitic regions ; tlie beds of sedimen- 

 tary rock becoming continually narrower with the rise of the continent and 

 the consequent contraction of the ocean. From this time there were three 

 basins, viz., the coal basin of Pennsylvania, that of the West, and that of 

 Michigan. It is evident that the north-east region was the earliest dry ; to 

 the westward all the formations are more recent. 



" Wherever the water escaped towards the north-east, we have waterfalls 

 over precipices ; for instance, here at Niagara. Where depressions have 

 been formed in soft rocks between harder ones, we have valleys, as that of 

 the Mohawk. 



"It is a remarkable fact, that the leading changes in the geological 

 features of North America take place in a north and south direction. Thus 

 the fissures formino; the beds of the rivers, as those of the Connecticut, the 

 Hudson, the Mississippi, and the rivers of Maine. In the Old World, on 

 the contrary, most formations are parallel to the Equator, as the Alps, the 

 Atlas, and the Himalayas. Only two mountain chains run north and south, 

 the Ural, and the Scandinavian mountains, which are northern in their char- 

 acter. The longitudinal direction of fissures in this country is well shown 

 by the New York State Survey. The lakes of Western New York lie north 

 and south. So also Lake Huron and Lake Michigan. These longitudinal 

 fissures are sometimes traversed by others at right angles, as in the instances 

 of Lake Superior and Lake Erie. These fissures must have been formed 

 by the upheaval of the continent, the layers of already solidified rock being 

 lifted up or depressed. Elvers must have existed already in those early 

 ages, as is shown for instance in the ancient channel of the Niagara, (above 

 the Whirlpool,) which is filled with drift not found in the present channel. 



" All the formations before spoken of are more ancient than the coal, yet 

 many of them consist of soft clay. The hardness of rock is thus no proof or 

 criterion of its age. These soft slates are nowhere more developed than in 

 New York, and nowhere have they been more carefully examined and des- 

 cribed. These details of facts are to be looked upon in the same light as 

 a mere list of dates or occurrences in history. But geology aims at a full 

 illustration of all these details. 



" Passing to the vegetable kingdom : — As soon as we left the metamor- 

 phic rocks of Massachusetts, vegetation became much richer, because of the 

 limestone and marl deposits. It is remarkable how limestone favors not 

 only vegetable, but also animal life. In Switzerland, where the country is 

 divided between the limestone and marl region of the Jura, the sandstone of 

 the plain, and the granitic formations of the Alps, the cattle of the latter 

 region are not more than one-third of the size of those of the former. 



