1890.] NEW YORK ACADEMY OF SCIENCES. l41 



through the hills, and, flowing over the basaltic clijGfs, forms 

 those beautiful falls so well known as the Passaic or Paterson 

 Falls. 



The quarry from which they were obtained is within the city 

 of Paterson, and a few hundred yards north of the falls. 



To me it has been a most interesting region, though I have 

 had little time to study it, my visits having been hasty excur- 

 sions taken with the Mineralogical Club last summer. 



This quarry is in what would normally be the trap-rock, just 

 over its junction with the red sandstone, on the north side of 

 what I think is called Morris Hill, which is crowned with true 

 columnar basalt, specimens of which I show you in three-, four-, 

 and five-sided columns. The rock at the quarry is a breccia of 

 trap, with copper minerals, mostly pseudomorphous in charac- 

 ter, mingled with masses of porphyrite of a boulder-like shape, 

 often several feet in diameter; the trap-rock itself is also much 

 changed from that at the summit of the hill, approaching the 

 porphyrite in appearance. 



The original copper mineral has probably been chalcocite, the 

 decomposition of which has possibly had much to do with 

 changes which have evidently been produced in the mineral 

 constituents of the quarry. 



Not only is the copper broken down, but the trap-rock, which 

 in other parts of the hill has the characteristic hardness, is also 

 so softened and decomposed that it is readily quarried with the 

 bar and pick, without much if any resort to blasting. This 

 rotten rock is taken to the crusher near by and broken up, and 

 used for road-making purposes in the city of Paterson. 



Beneath this there is a layer of amygdaloid containing nu- 

 merous nodular cavities filled WMth various minerals, such as 

 prehnite, certain zeolites, etc. 



In some places the amygdaloid is entirely decomposed, so that 

 these little nodules of prehnite and pectolite can be gathered in 

 quantities, free from the surrounding rock. 



Beneath tiiis is the red sandstone, baked hard and containing 

 jasper-like masses showing the effect of heat where it is in con- 

 tact with the overlying rock. 



Here, it will be seen, we have one of nature's mysterious lab- 

 oratories, of more than usual interest, opened at our very doors. 



We have to do especially witli tiie brecciated trap, which con- 

 tains numerous cavities, from the size of the smaller vesicular 

 nodules of the amygdaloid to several inches, or even a foot or 

 more, in diameter. In fact, it resembles the amygdaloid on a 

 larger scale, except that the cavities, instead of being close 

 together, forming a sponge-like mass, are in some cases several 

 feet apart. 



