222 The Physical History of the Trias 



appearance of red shales and sandstones, with thick beds of 

 intruded igneous rocks, the whole system dipping eastward at 

 an angle averaging between 15 and 20 degrees. 



We shall have more to say regarding the geological history 

 of this area, in connection with the Trias of New Jersey. 



The western bank of the Hudson River, from Jersey City north- 

 ward to Stony Point in Rockland Co., New York, a distance of 

 thirty miles, is composed of Triassic rocks. This is the beginning 

 of a great extent of strata of this age, which stretch southward 

 across the state of New Jersey, through Pennsylvania and 

 Maryland, and far into Virginia, — a length of over three 

 hundred and fifty miles. This belt has its greatest width on 

 the Delaware, where it is thirty miles broad ; it is six miles wide 

 on the Susquehanna, and eight on the Potomac. Smaller 

 detached areas of these rocks occur farther south in Virginia 

 and North Carolina, in these states carrying the Richmond 

 coal-beds, and those of Deep and Dan river. Thoughout the 

 whole distance from the Hudson to North Carolina, this 

 formation is composed mainly of soft red shales and red and 

 gray sandstones, together with extensive ridges of trap. . In 

 the northern portion of this area, the beds dip towards the 

 northwest at an angle of from ten to fifteen degrees. In many- 

 cases, owing to local causes, the angle of inclination is much 

 less than this, and sometimes much greater.* In North Caro- 

 lina the inclination is toward the southwest at an angle of 

 from 10 to 22 degrees. f 



In New Jersey, the Triassic formation is separated into 

 three natural divisions; (a) the first of these is a system 

 of bed shales and sandstones, which compose the great bulk 

 of the formation ; (b) on the western border of these there 

 occur several detached areas of coarse variegated conglomer- 

 ate ; and both these beds of derivative origin are traversed 

 by (c) dikes and sheets of eruptive rocks. 



* See table of dips, Cook's Geology of N J., p. 195. 

 t Emmons's Qeol. Kep. N. Carolina, p. 231. 



