Geologii of Hudson County, JVe/i: Jersey. 35. 



directly northwest of Castle Point ; from this jooint north- 

 ward all the way to Bull's Ferry, these rocks are exposed, ex- 

 cept where cut out by dikes of trap or covered by debris ; 

 throughout this whole section we find thinly-bedded, dark- 

 colored shites, feldsjiathic sandstone, and shale, all of which have 

 been more or less metamorphosed by the heat of the associated 

 trap ; the dip throughout this section, except where plainly dis- 

 turbed by the intrusion of the trap, is N. W. 15°. The details 

 of this series of exposures will be more fully given in connection 

 Avitli the description of the trap-sheets. 



The economic importance of the Triassic sedimentary rocks 

 in Hudson County is very limited indeed ; the sandstone at 

 Snake Hill has been used for building-stone, but the supply is 

 small and the quality inferior. An attempt has been made to 

 utilize the slaty layer beneath the trap at Weehawken for roofing- 

 slate, but without success. The importance of the quarries of 

 Triassic "brown-stone'' in other portions of the State is very 

 great. Fj'om the extensive Newark quarjics, large quantities of 

 building-stone are furnished for New York and the neighboring 

 ciiies; great quantities also come from quarries of the same 

 chart cte:' and age in the Connecticut Valley. 



The Belleville copper-mine has already been mentioned ; but, 

 although worked more extensively than any of the other copper- 

 mines in the Trias of New Jersey, it has proved, like the rest, 

 little more than a delusion to those interested in its devel- 

 ojiment. 



In a sanitary point of view, the inclined strata of alternating- 

 layers of sandstone and shale present one of the best substratums 

 that could be desired ; not only do the character and inclina- 

 tion of the rock furnish a complete natural drainage, but it is 

 also a poor conductor of heat, and thus retains the warmth at 

 the surface. Unfortunately, this formation has been so deeply 

 eroded and covered by subsequent deposits, that its beneficial 

 influence is but little felt, except: in the high ridge bordering 

 the Passaic Eiver. 



Trap-Roch. — As already mentioned, trap-rock occurs in thin 

 layers, penetrating the sandstone at the Schuyler mine. In 

 the Newark meadows, midway between Bergen Hill and the 

 highland bordering the Passaic, are the trap-hills called Snake 



