156 NEW YORK STATE MUSEUM 



Northward from Saratoga the broad belt of Hudson Valley 

 shale narrows rather rapidly, and north of Fort Edward but little 

 of it remains. In the Champlain valley but a few patches of shales 

 remain, nothing like a continuous cover. Judging by the Saratoga 

 vicinity, such a cover is necessary both to prevent the free escape 

 of the mineral water and to prevent its admixture with overwhelm- 

 ing quantities of surface water. This fact would seem to account 

 for the nonappearance of these carbonated waters to the north. 



The rocks of the general region dip to the south, hence the shale 

 cover thickens southward and the mineral waters, if present, are 

 at a steadily increasing depth below the surface. In the village 

 the driller reported for the Star spring bore, only a short distance 

 east of the fault line, that the bottom of the shale was 100 feet 

 below ground, 38 feet drift, 62 feet shale, then limestone. The 

 Natural Company wells on South Broadway show an average of 

 140 feet of drift and 50 to 100 feet of shale before reaching lime- 

 stone. At the Geysers the limestone is still deeper. The Hathorn 

 No. 2 well reported 23 feet of drift and 432 feet of shale above the 

 limestone. At Ballston the shale is 200 feet thicker than this, and 

 the limestone correspondingly deeper. The waters then extend to 

 the south of Saratoga under the shales, but the depth of drilling 

 necessary to reach them steadily increases in that direction, and 

 away from the Saratoga vicinity they do not come to the surface 

 naturally. They likewise extend probably far to the east under the 

 thickening shale cover. 



It is by no means unlikely that to the south of Saratoga, the 

 water may extend to the west of the Saratoga fault. As has been 

 previously stated, the course of this particular fault south of Sara- 

 toga is conjectural, but on the assumption that it runs down to 

 Ballston, as provisionally mapped, it would be quite possible for 

 the waters to pass beyond it and appear west of it. About Ballston 

 shales are the surface rocks on both sides of the fault, with the 

 Little Falls dolomite below ground on each side under a protect- 

 ing shale cover. Along the south margin of the Saratoga quad- 

 rangle the shales extend entirely across the sheet from east to west, 

 the southerly dip of the rocks giving rise to shales at the surface 

 in each of the successive fault strips. The dias^ram, figure 16, 

 will explain the assumed course of the underground water, better 

 than can be done verbally. 



It is possible to account for the presence of these waters, held 

 imprisoned beneath the shales, in one of two ways. They may 



