134 



NEW YOKE STATE MUSEUM 



PHYSIOGRAPHY AND STRUCTURE 



In order to appreciate the position and attitude of the geologic 

 formations in New York, it is necessary to form a mental picture 

 of its physiography. For the purpose of reference the following 

 terms may be adopted to describe the principal physiographic 

 divisions of the state : 



I The Adirondack upland, comprising the Adirondack moun- 

 tain region and the adjacent territory. 

 II The southern upland; west of the Hudson river and south of 

 the line of the Mohawk valley prolonged to Buffalo. 



III The Highland-Taconic range; the mountains of granite cross- 



ing the Hudson river near West Point, and those of mica 

 schist along the New England border. 



IV The Central valley, consisting of the valley of the Mohawk 



and the low land extending from it to the Niagara river. 

 V The Hudson-Chamiplain valley, including the basin of Lake 

 Champlain. 



VI The Coastal plain, including Long Island and southern Staten 

 Island. 



As the geologic map shows, the principal Palaeozoic outcrops 

 in New York have three principal positions and directions: 



1) In zones encircling the Adirondack upland. These zones are 

 much disturbed locally hj faults, so that the outcrops are irregu- 

 lar. 2) In lines parallel with the Highland-Taconic range. This 

 mountain axis has a northeast direction in the Highlands of the 

 Hudson, changing gradually to north in the Champlain valley, 

 where the Green mountain uplift is tangent to that of the Adi- 

 rondacks. 3) In east and west lines across the southern upland 

 from Albany county to the Niagara river and Lake Erie, locally 

 intersected by river and lake valleys. 



That portion of the state bordering on the Pennsylvania boun- 

 dary is a high plateau, with summits about 2000 feet above tide. 

 Its surface slopes gradually northward toward Lake Ontario and 

 its component rock strata slope or dip southward. 



