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NEW YORK STATE MUSEUM 



of the Little Falls dolomite, and is today best shown back of the 

 High Rock spring (plate 8). Small patches of basal Amsterdam 

 lying in contact with the Little Falls somewhat farther north show 

 that this is the very summit of the formation. At the Star spring 

 a wedge of Amsterdam limestone appears lying closely against the 

 fault face and with a tipped upper surface, rising toward the north, 

 falling toward the south. Back of the Red spring it has risen to 

 the full height of the fault scarp; at the High Rock spring it is 

 some 15 feet below the surface of the ground. Figures 6 and 7 

 clearly show the disposition of this wedge of Amsterdam. 



Fig. 7 Illustration of the manner in which the tipped block of Amsterdam] 

 limestone lies against the fault face, as seen in looking at" the fault from; 

 the downthrow side; tilt of block much exaggerated; i = Red spring, 2.'- 

 Star spring, 3 = High Rock spring. 



At the Star spring a drilled well gave 38 feet of drift and 62 

 feet of shale before reaching the summit of the Amsterdam lime- 

 stone. This well is only a very few yards east of the Amsterdam] 

 wedge outcrop and the fault line, showing clearly that the wedge' 

 is but a very narrow block caught in along the fault. Ignoring! 

 it and estimating the throw of the Saratoga fault from the ex- 

 posures and the well record at the Star spring, a result of about 160 

 feet is obtained, 100 feet of drift and shale, 40 feet of Amsterdam 

 limestone and the 20 feet of Little Falls shown in the fault scarp. 



The Amsterdam wedge seems to continue along the fault all 

 the way through Saratoga between the two swerves in its course. 

 This is indicated by the fact that it is the surface rock just east of 

 the fault at the Hathorn spring, and also is the surface rock at the 

 Congress spring, as shown by the drill core. It really amounts to a< 

 parallel fault lying very close to the main fault. South of the Con- 

 gress spring its course is lost under heavy drift. 



