146 



corroborate some fundamental doctrines recently advanced by 

 geologists. 



The first Newark mountain is an elevated range of trap, dis- 

 playing in many places south of Paterson, fine mural escarp- 

 ments of considerable height, especially along its eastern side. 

 The face of these cliffs is often remarkably smooth and regular. 

 Near Paterson, the trap rock is seen at the Falls of the Passaic 

 overlying the red sandstone, which displays near their contact a 

 modification of structure not unusual in such cases. 



The interesting waterfall at this spot, seventy feet in height, is 

 caused by the dike of trap which crosses the river in the form of a 

 fine natural dam. The entire mass of water precipitating itself over 

 the brink of this dam, passes first into a lateral cleft or chasm in 

 the dike, and thence descends into a deep pool or basin, which it 

 has excavated for itself in the subjacent softer sandstone. The 

 trap rock of the clifl^s around, presents a strong tendency to the 

 columnar structure. Within a few yards above the level of the 

 river, beneath the Falls, we behold the junction of the igneous and 

 the sedimentary rocks. Between the true trap rock above and 

 the altered sandstone below, there occurs a mass, of five or six 

 feet thickness, possessing the structure of a toadstone or amygda- 

 loid, enclosing geodes filled with prehniie, analcime, zeolite, and 

 several other minerals. Immediately beneath this, we discover 

 a layer of the sandstone, a few inches in thickness, bearing all 

 the marks of partial fusion, being filled with small vesicular cavi- 

 ties, as if from the extrication of steam, and looking like an over- 

 baked mass of brick or pottery. 



At a gorge in the same ridge, near Plainfield, the rock departs 

 somewhat from its ordinary aspect, being easily splintered, rather 

 metallic in its lustre, and containing frequent streaks or fine lines 

 of the red oxide of copper. Near another notch in the mountain, 

 a little north of Scotch Plains, a credulous miner seeking for the 

 precious metals, has disclosed an interesting mass of cellular or 

 amygdaloidal trap, of a peculiar light yellowish-green colour. In 

 this neighbourhood minerals of the zeolite family are frequently 

 founi. 



While mentioning the thin seam of limestone in the narrow 

 valley of Greenbrook, between the first and second trap moun- 

 tains, a few miles north of Scotch Plains, reference has been 



