96 



SCIENCE 



[N. S. Vol. XXXII. No. 811 



has shown the area to be unusual for its 

 numerous faults, some of very considerable 

 displacement. Two of the largest of these are 

 the Noses and the Hoffman's ferry faults, 

 which have already been described, the former 

 cutting across the northwestern and the latter 

 the southeastern portion of the Broadalbin 

 quadrangle. The maximum throw of the 

 Noses fault is about 1,500 feet and that of the 

 Hoffman's ferry fault about 2,000 feet, with 

 downthrow in each case on the east side. Re- 

 cent work shows the Hoffman's ferry fault to 

 extend much farther northward than formerly 

 supposed, or from north of Galway to beyond 

 Corinth and with increasing throw northward 

 across the northwestern portion of the Sara- 

 toga quadrangle and producing the great 

 scarp of pre-Cambrian rock. The Noses fault 

 follows the base of the high (1,000 feet) es- 

 carpment of pre-Cambrian rock which extends 

 from west of Gloversville to northwest of 

 Northville. 



Another dislocation of unusual interest is 

 here briefly described for the first time and 

 should be called the Batchellerville fault. 

 From a point about two miles southeast of 

 Northampton it strikes north-northeast for at 

 least 8 miles along the Saeandaga river and 

 through the village of Batchellerville. The 

 maximum throw is nearly 1,500 feet and 

 the high (1,000 feet) escarpment of pre-Cam- 

 brian rock is a very pronounced topographic 

 feature. The most significant thing about 

 this new fault is the fact that it downthrows 

 on the west and is thus the only great Mo- 

 hawk valley fault showing this characteristic. 

 The Batchellerville and Noses faults run ap- 

 proximately parallel and are about six or 

 seven miles apart, the great escarpment of 

 pre-Cambrian rock of the one fault facing the 

 equally great escarpment of the other. In 

 other words we have here a fine illustration of 

 trough faulting, the whole country between the 

 Batchellerville and Noses faults being a great 

 depressed fault block much of which now lies 

 fully 1,000 feet below the level of the scarps 

 on either side. A glance at the Broadalbin 

 quadrangle will show the extent of this fault 

 block, whose northern extremity is not yet 



known but which occupies at least 75 square 

 miles or all of the region between the follow- 

 ing points : 3 miles north of Batchellerville ; 

 2i miles northwest of Northville; 2 miles west 

 of Mayfield, and 2 miles southeast of North- 

 ampton. On the state geological map the 

 deep indentation caused by the northward ex- 

 tension of the Paleozoic rocks to Northville 

 roughly corresponds to this depressed block, 

 although recent mapping by the writer shows 

 that the Paleozoic should extend at least 6 or 

 8 miles farther northward along the Saean- 

 daga River. The surface rock over this de- 

 pressed area is chiefly Little Falls dolomite, 

 with some pre-Cambrian rock towards the 

 north and some Trenton limestone and Utica 

 shale towards the south. The trough block is 

 not perfectly simple, because, on the west side 

 especially, a number of minor fractures have 

 considerably modified it and some of these 

 minor faults are so arranged, as at North- 

 ville, that small trough fault blocks are in- 

 cluded between them. 



Eastward from this trough block and lying 

 between the Batchellerville and Hoffman's 

 ferry faults is a great upraised block of pre- 

 Cambrian rock covering at least 100 square 

 miles and including all of the high country 

 in the northeastern portion of the Broadalbin 

 and the northwestern portion of the Saratoga 

 quadrangles. This uplifted block comprises 

 the great tongue of pre-Cambrian rock shown 

 on the state geologic map between Saratoga 

 Springs and Northville. 



The profound influence of trough faulting 

 upon the topography in this region strongly 

 suggests the occurrence of similar phenomena 

 well within the Adirondacks. As Professor 

 Cushing stated several years ago, the topog- 

 raphy of the eastern Adirondacks often sug- 

 gests faulting of this sort but positive proof 

 has heretofore failed. The finding of such a 

 large and clear-cut trough fault at the south- 

 ern margin of the pre-Cambrian rocks greatly 

 strengthens the belief that faulting of this 

 sort has had an important influence upon the 

 topography of the eastern Adirondacks. 



W. J. Miller 



Hamilton College 



