r70 



NEW YORK STATE MUSEUM 



locally lacking in the gabbroic intrusions, and wholly absent in 

 the later dikes. 



The direction of strike of the foliation planes is quite uniform 

 throughout the area of the sheet and beyond, being in general to 

 the northeast. The more common direction is n 35° e, though 

 the readings range between the extremes of n 10° e and n 50° e; 

 variations of more than 10° from the usual direction are, however, 

 uncommon. The prevailing direction of dip is to the northwest, 

 this being uniformly true at the east and the west, while in the 

 center of the sheet these are replaced by southeast dips. In gen- 

 eral the dip is not high, seldom exceeding 45°, and usually flatter 

 than that, often only 10° to 15°. The few^ good exposures show 

 that the dip sometimes becomes momentarily high, quickly flat- 

 tening again to the usual amount. The direction and dip of the 

 foliation are common to gneiss and gabbro alike and must have 

 a common origin. The foliation has a general parallelism to the 

 longer axis of the intrusive mass of gabbro, yet continues un- 

 changed so far to the south of that, with no apparent tendency 

 to curve around its southern end, as to cause hesitancy in assum- 

 ing that the compressive effect of the intrusion has been mainly 

 instrumental in the production of the foliation. Farther, though 

 observations on the foliation of the later hyperite-gabbro are 

 somewhat unsatisfactory, they point to its parallelism with that 

 in the other rocks and indicate that, in so far at least, the cause 

 of the foliation is in no way to be ascribed to the larger intrusion. 

 It is of course a possibility that the Kand hill gabbro is merely 

 the bared, upper part of a great intrusive mass, much more 

 widely extended beneath than the surface exposures give any 

 indication of. The character of the rock, so like peripheral por- 

 tions of the great anorthosite masses to the south, may be as well 

 explained by this supposition as by the idea that it is a small, 

 outlying intrusion, its character due to differentiation prior to its 

 movement to its present position. The gently folded character of 

 the foliation planes may give weight to the idea of a widely ex- 

 tended igneous mass not far beneath. In general it may be said, 

 therefore, that the evidence is far from decisive as to the gabbro 



