NIAGARA FALLS AND VICINITY 



119 



This dike, which can be clearly traced in the wall of the quarry for 

 a distance of perhaps 30 feet in an east and west direction, was 



Fig. 23 Channel in Manlius limestone with Oriskany sandstone and conglomerate layers, capped 

 by Onondaga limestone, Buffalo cement quarry. 



caused by the filling of an ancient fissure in the Siluric strata, by 

 sands forcibly injected from above. The fissure had a total depth 

 of about 10 feet; its walls were very irregular, and at intervals lateral 

 fissures extended in both directions. (Sec Fig. 24) All of these are 

 now filled with pure quartz sand, firmly united into a quartzose 

 sandstone by the deposition of additional silica in the interstices be- 

 tween the sand grains. 



Fig. 24 Sandstone dike in the Siluric strata of the Buffalo cement quarries. (After Clarke) 



The dike penetrates the " bullhead " rock and enters the water- 

 hme to a depth of from 2 to 3 feet. It is squarely cut off at the 

 top, where the Onondaga limestone rests on its truncated end and 

 on the limestone flanking it. The Onondaga limestone is entirely 

 unaffected by the dike, being evidently deposited after the formation 

 and truncation of this remarkable mass of sandstone. The width of 



