GEOLOGIC FORMATIONS OF NEW YORK 171 



TRIASSIC SYSTEM 



This system received its name in Germany where it consists 

 of three distinct members. In England it is known as the New 

 Red Sandstone and contains the salt deposits of that country. 

 West of the Mississippi river the Triassic is well represented in 

 the United States, but in the east it is found only in narrow 

 troughs on the east side of the Appalachian chain and approxi- 

 mately parallel to it. It is well developed in the Connecticut 

 valley and is again found near Stony Point, New York, from 

 which locality it extends southw r est across Rockland county into 

 New Jersey, thence through Pennsylvania and Virginia. In the 

 latter state it includes the Deep and Dan river coal basins which 

 are of considerable importance. 



The Triassic deposits of New York and New England were 

 apparently formed in estuaries and consist of shales and sand- 

 stones. These bear ripple marks, sun cracks, rain prints and 

 the foot prints of enormous biped reptiles with three toes. These 

 were at first supposed to be bird tracks. Fishes are also abund- 

 ant in the sandstones of New York and New Jersey. 



The eastern Triassic rocks are important as having furnished 

 the greater part of the brown sandstone, which is used so exten- 

 sively for building houses in our eastern cities. The Triassic 

 period was also characterized by eruptions of igneous rock, which 

 formed the well known trap dykes of Connecticut and New Jer- 

 sey. In the latter state the most prominent is that known as 

 the ' Palisades of the Hudson/ which extend along the west 

 shore of the Hudson river from Staten Island to a point north- 

 west of Nyack. At the level of the river the rock is a nearly 

 horizontally stratified red sandstone; but between the bedding 

 planes a vast volume of melted rock has been injected, and 

 in cooling has assumed the rudely crystalline or columnar struc- 

 ture so common in basaltic or trap rocks. The broken edge of 

 this enormous sheet of trap, fronting on the river, forms the 

 precipice so well known as ' the Palisades.' The Orange moun- 

 tains are also of the same formation. 



