MUSKUM OF COMrARATlVE ZOOLOGY. 



275 



from the mouth, so as to descend (geologically) below the trap surface, 

 the rock appears firm and hard in the stream bed : slialj sandstone 

 often outcrops on the banks of the ravine, but at no point within five 

 feet of the trap, and generally ten or fifteen feet from it. Eeturning 

 down stream, the trap becomes amygdaloidul, and shows rounded 

 bosses or knobs similar to those described by Eussell; but as seen here 

 they are not directly at the upper surface of the trap. Nearly at the 

 entrance of the ravine, a bank of much-weathered vesicular and frag- 

 mental trap suggests a trap breccia, but the surface is too much rusted 

 for determination. The most important exposure licrc was found in the 

 side of a short adit made some years ago on a small vein in the trap ; it 

 is known in the district as the "Copper Mine." It shows (fig. 49) a 

 number of oval masses of trap, up to two feet or more in diameter, con- 

 tained in a peculiar red and black matrix. The trap masses vary iu 

 their texture and color with the distance from their surface; the outer 

 part is black and dense, then amygdaloidal for a few inches with con- 

 centric bands of color, and rather dense near the centre. The matrix 

 (fig. 50 a, b) has all the appearance of being a disorderly mixture of 

 small, angular scraps of trap, up to an inch long, held in a soft reddish 

 shaly mass, that shows no signs whatever of metamorphism. Its con- 

 trast with the over-lying sandstones at Englcwood is very marked, and 

 it is diflicult to understand how this could have been formed except on 

 the surface of a pre-existent sheet of lava. 



Russell says (a, 280), ''The section at Feltviilc furnishes indisputable 

 evidence that the igneous rocks composing the first Newark Mountain 

 were intruded in a molten state between the layers of the stratified 

 rocks subsequent to their consolidation." He describes (6) another 

 upper surface of the trap on the back of the same mountain farther 

 south, back of Plainficld, where there is "an amygdaloidal trap passin 

 into a metamorphosed shale," so tliat it is frequently difiicult to detect the 

 difierence between the two rooks. I was unable to visit this point. 



Feltville can bo reached by a pleasant walk of four miles from Fan- 

 wood Station, Central Hailroad of New Jersey ; the Triassic Map of New 

 Jersey, 18G7, gives the roads very clearly. It is to be hoped that further 

 observations will soon be made to give evidence for one or the other of 

 the above discordant conclusions. At Fanwood Station, the railroad 

 cuts the unstratified terminal moraine of the quaternary ice sheet (New 

 Jersey Geol. Survey, Annual Reports, 1877, 10; 1878, 10); and good 

 specimens of foreign angular and scratched stones, large and small, are 

 easily found. 



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