GEOLOGY OF SARATOGA SPRINGS AND VICTXITY 167 



possibility of the continuation to the present time of these processes 

 that metamorphose the shales, limestone and sandstones into schists 

 and gneisses in the depths of the mountains is not at all disproved. 

 At the same time it is also possible that these same limestones and 

 sandstones come within the influence of deep-seated, still heated 

 igneous rocks, thence deriving their carbonic acid, and at the same 

 time that they gather ** connate " waters (original sea water de- 

 posited with the rocks) from a large area and held in the depths, 

 to which they descend, through the thick covering masses of shales. 



One naturally asks here why these waters only come up in the 

 Gurnspring-Saratoga-Ballston belt, a stretch altogether not more 

 that about 12 miles long. The geologic structure of the region is 

 responsible for this phenomenon (see diagram, text fig. 17). 



South of Ballston the shales again thicken rapidly on account of 

 the southward dip of the beds, until at Schenectady they reach no 

 doubt more than 3000 feet in thickness, thus shutting the waters 

 : off from the surface to the south of the Saratoga mineral springs 

 region. Northward of this region the structural relations are not 

 yet well understood and the reasons for the absence of the springs 

 not apparent. At Glens Falls the " Trenton " and Black River 

 limestones come again to the surface but without bringing any 

 mineral water. This outcrop is apparently the southern spur of 

 a fault block. It probably fails to intercept the mineral waters 

 coming from the east because it lies west of another large fault, 

 which is indicated by the Fort Ann spur of Precambric rocks and 

 ^ which extends close to or into the crumpled shales of the eastern 

 basin, thus shutting off the mineral waters from access to more 

 western regions or to the surface altogether. We have seen before 

 that the Precambric rocks west of the Spring fault form a barrier 

 for the waters in that direction and that the thick masses of shales 

 east of the area serve there as a competent cover. The Spring belt 

 is thus shut in on all four sides by either thick masses of shales 

 (east and south) or barriers of Precambric rocks (west and north) 

 and in the belt itself the waters are brought nearest to the surface 

 in following the routes of least resistance. 



