FEATURES OF TRAP EXTRUSIONS IN NEW JERSEY 319 



filled with zeolites. It should be noted that the surface trap at this 

 quarry is of the dense variety for a thickness of several feet and gives 

 no hint of the structure underneath. A short distance west of this 

 point, just below the main line of the N. Y. and Greenwood Lake 

 R. R. is the entrance to a water-supply tunnel, which was driven 

 under the mountain a number of years ago. It entered trap on the 

 western side and came out in the sandstone country on the east, and 



Fig. 14 



in its course passed almost directly beneath the Francisco quarry just 

 described, but at a much lower level. At the time that work was in 

 progress much of the material brought out and thrown on the dump 

 was of the characteristic structure which we recognize as being asso- 

 ciated with the portion of the lava flow which plunged into the old 

 lake. Glassy crusts, crystal-lined vugs, and sandstone inclusions were 

 all common. 



The two localities described, the one at West Paterson and the 

 other at Great Notch, give us the general line of the lake valley and 



