646 THE POPULAR SCIENCE MONTHLY. 



stratified rocks. Cooling in place, these trap-sheets are now conform- 

 able to the associated strata, and seem at first sight to be normal por- 

 tions of it, but the metamorphism which they have produced in the 

 beds above and below them show that they are intrusive. The erosion 

 which has since acted upon the surface of this region has cut away the 

 softer sandstones and shales, leaving the outcropping edges of the trap- 

 sheets in high-relief, and these are now known as the Palisade Range, 

 First and Second Newark Mountains, etc. 



It has been suggested that the New Jersey and Connecticut basins 

 were once connected by strata which occupied all the interval between 

 them, and that by the subsidence of the sides or the elevation of the 

 central portion an arch was formed the crown of which has been re- 

 moved by erosion. It seems, however, scarcely probable that some 

 thousands of feet of Triassic rocks, including thick beds of hard and 

 resistant trap, should have been so completely carried away from the 

 interval of 100 miles now separating the Triassic basins, that not a 

 trace of them should be anywhere left. There is apparently good evi- 

 dence also that the trap-sheets of the Connecticut Valley issued from 

 fissures there, and appertained to a distinct line of disturbance ; and, 

 further, that the materials composing the Triassic series in each belt 

 were derived from the adjacent highlands, and were spread by currents 

 which swept up and down two narrow troughs. 



To some persons, the most interesting fact in regard to the Trias 

 yet remains to be mentioned, and this is that from the quarries sunk in 

 its sandstone-beds of which the most important are at Bellville, New 

 Jersey, and Portland, Connecticut has been taken the brown-stone 

 to which we owe the architectural beauty and monotony of the best 

 portions of our city. Copper is also frequently found impregnating the 

 Triassic rocks, but it has generally proved only a snare to those who 

 have attempted to work it, the deposit being small and unreliable. 



a! 



Triassic Series. 



Tbowbriose Mt, 2??Mountain I?!Mountain Snake Hill Palisades 



Profile Section from Trowbridge Mt. to the Hudson River, 



Fig. 2. 



During the time in which the Jurassic rocks were deposited in other 

 places, the Atlantic coast of North America seems to lmve been above 

 the sea-level, for we find here no strata which are certainly of that age. 

 Some writers have called Jura-Trias the beds described as Triassic on 

 the preceding pages, but up to the present time no facts have been 

 brought to light which justify this usage. Possibly the uppermost 

 beds of the series may hereafter be found to contain Jurassic fossils, 



