34 GEOLOGY OF THE THIRD DISTRICT. 



CHAPTER V. 



NEW-YORK SYSTEM; 



WITH A DBTIILED ACCOONT OF THE ROCKS AND GROUPS TREATED, IN THE ORDER ENUME- 

 RATED IN THE SECOND CHAPTER. 



Few countries, if there be even any, are so happily circumstanced as New- York, for the 

 inrestigation of the rocks of the system which bears its name. The greater part of the Mis- 

 ■issippi valley, and more especially the cast side, is composed of its rocks. These rocks 

 extend thence through Ohio and Pennsylvania in a northeast direction, enter and cover the 

 whole of the northwest half of New- York, and retain the same undisturbed and horizontal 

 position, so characteristic of them in that valley. On the east side of the Mississippi, from 

 Alabama to the northern part of Pennsylvania, no higher rocks are seen upon their surface 

 than those of the Coal series ; and this series is found in the States of Tennessee, Virginia, 

 Kentucky, Ohio and Pennsylvania, the series terminating in the latter State, but reappearing 

 in the British possessions-in a northeast direction. 



In the west, few or no profound excavations exist ; and a considerable extent of country 

 generally must be travelled, in order to obtain knowledge of more than a few of them. In 

 New- York it is widely different. By the same cause which excavated Lake Ontario, excava- 

 tions at higher levels were made, disclosing the ends, or the outcrop of the rocks, giving rise 

 to a succession of surfaces and cliffs, unparalleled in number, magnitude and range, extending 

 from Niagara river in an east line, beyond the Hudson. The cliffs attain, in Herkimer and 

 Otsego counties, the aggregate height of nearly one thousand five hundred feet, their rocks 

 slightly inclining to the southwest. These are followed by others to the south, in regular 

 succession, but no regularity of surface outline, the terminal one of the whole series being 

 the rock upon which the coal of Pennsylvania is placed ; the nearest locality of this fossil 

 production, or its series, to the third district, being about twenty-five miles south of the line 

 of the two States. 



These excavations cast and west, by which the outcrop of the whole range of southwestern 

 rocks of the Union were exposed, have been no less advantageous to the industry of the State 

 than to the geologist. They have given to New- York, in connecting the eastern with the 

 western waters, a reduction of level fully equal to one thousand two hundred feet. 



