12 NEW YORK STATE MUSEUM 



faults show a drag down to the southeast on the western side of 

 the break, and an upward drag on the eastern, or dropped side. 

 As the fault escarpments are the more prominent outcrops one 

 could easily gain the impression that the inclination was all to the 

 southeast, but Gushing and Ruedemann find the predominant dips 

 in between the faults to be flat to the west or northwest. The 

 sinking of the surface and of the strata themselves, toward the low 

 points of the region, Saratoga lake and the Hudson river, seems 

 therefore largely due to faulting and to the greater erosion of the 

 soft slates by the continental ice sheet. The geological age of the 

 faults is obscure. They may at least have been the scene of renewed 

 movement in fairly recent geological time. 



At some time in this long interval the volcanic plug at North- 

 umberland was developed, but the quarrying operations of the 

 years 1910-11 have revealed some obscure and puzzling relations 

 which will be fully discussed by Professor Gushing in a forthcoming 

 bulletin. 



The advent of the Gontinental glaciers from the north and in 

 very recent geological time has served to spread over the region 

 a heavy mantle of gravel and sand, such that the rocky strata are 

 often buried beneath as much as 150 feet of loose deposits. From 

 the bedrock the natural springs usually emerge into this gravel and 

 sand and then find their wa}^ to the surface. Doubtless there are 

 others which have never been discovered and which become lost 

 in the general ground waters. Where they have been observed it 

 has been usual to sink through the gravel to the bedrock, find the 

 orifice and conduct the water to the surface in some sort of a tube 

 which has been cemented tightly to the rock around the crevice. 



Various estimates have been made of the time which has elapsed 

 since the recession of the ice sheet. They vary from 10,000 to 

 50,000 years. If the section revealed in excavating beneath the 

 High Rock mound is correctly interpreted there must have accumu- 

 lated some 13 feet of tufa and muck since the aborigines built a 

 fire; apparently also since the great ice sheet had scraped the bed- 

 rock clear. 



THE FAULT AT SARATOGA SPRINGS 

 A structural feature of the local geology which early claimed 

 attention is the fault which runs along just west of the main line 

 of the springs in Saratoga village. It is revealed by a clif¥ of Little 

 Falls dolomite some 30 or 40 feet high and with precipitous front 

 except where partially or wholly covered by earth. The fault has 



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