GEOLOGY OP THE VICINITY OP LITTLE FALLS 47 



fault is a small one of unknown throw, at the crest of a low anti- 

 clinal fold, with sharp drag on the east side. It is a fair sample 

 of the insignificant faults of the vicinity. 



All the Mohawk valley faults, so far as known are normal faults 

 with nearly vertical hade. Nearly all of them downthrow to the 

 east, the only exceptions to this rule known in the region being 

 two of the faults which occur here, the Dolgeville, and the small 

 fault at Little Falls. These both downthrow to the west. 



Foliation 



The excessive metamorphism to which the pre-Cambrian rocks 

 were early subjected has produced in them a foliated structure, 

 in a varying degree of perfection ; varying not only with change 

 in the character of the rock, but from place to place in the same 

 rock. Igneous and aqueous rocks are alike foliated, though com- 

 monly the latter are much more distinctly so than the former. 

 The old bedding planes of the aqueous rocks are so obliterated 

 that they have not been made out and it can not be stated what 

 relationship, if any, they bear to the foliation planes. Of the 

 old igneous rocks the syenite at Middleville shows the least folia- 

 tion of any. The, corresponding rock at Little Falls is however 

 excessively foliated, though varying much in amount from place 

 to place. The syenites and granites to the northward are thor- 

 oughly gneissoid. 



The foliation planes of the district have a nearly east and west 

 strike. Of the very large number of readings taken on them about 

 G^fo lie between n. 70° e. and n. 90° e., and the larger part of the 

 remainder do not exceed these limits by more than 10°. Locally 

 however there is considerable variation, largely due to folding. 



The dips of the foliation planes are now to the north, now to 

 the south, showing that they have been folded. Sometimes 

 changes in dip direction are frequent showing small folds, but in 

 the main the folding is on a large scale. In the majority of cases 

 the dips are gentle, not exceeding 20°, but there are many in- 

 stances of steeper dips, even reaching 90°, and in many places 

 the rocks are excessively and minutely folded and crumpled. 



