GEOLOGY OF SARATOGA SPRINGS AND VICINITY 57 



a small fraction of its original throw, the remainder being taken up 

 apparently by the branch faults (West and East Galway faults). 

 Across the Saratoga quadrangle the main fault rapidly regains its 

 original amount of throw. This would naturally suggest a loss of 

 throw in the case of the two branch faults, and such meager evidence 

 as we have in regard to them is corroborative of this suggestion. 



West Galway fault. The West and East Galway faults enter 

 the Saratoga quadrangle near its southwestern corner and not greatly 

 over half a mile apart. They are easily traced for 3 or 4 miles 

 when they run into heavily drift-covered territory in which their 

 course, and even their existence, is quite uncertain. Where outcrops 

 reappear, in the northern portion of the quadrangle, two faults are 

 found which are on the trend of these two, and they are assumed 

 to be their prolongations ; but the uncertainty of this must be em- 

 phasized. If the assumption is correct, interesting consequences 

 follow. 



South of East Galway the ravine that runs across the West Galway 

 fault, and which cuts down into the Precambric just west of the 

 fault line (see areal map), gives the data for an approximate esti- 

 mate of the fault's throw at that point. The Precambric is on one 

 side, the upper portion of the Theresa formation on the other, so 

 that the throw is just about equivalent to the combined thicknesses 

 of the Potsdam and Theresa formations, or from 250 to 300 feet. 



Near this point, one and one-half miles south of East Galway, 

 there is a dropped wedge of rock, or 

 horse, along the \A>st Galway fault, 

 which is interesting because the rock 

 concerned is much younger than on 

 either side of the fault. Potsdam sand- 

 stone adjoins it on the west or upthrow 

 side of the fault, and the upper beds of 

 the Theresa formation on the other side, 

 the downthrow. The rock of the in- 

 cluded wedge is upper Little Falls and Fig. 5 Plan of outcrops on 



basal Amsterdam, hence higher in the the West Galway fault, show- 



'^ ing the wedge with Little 



section than the Theresa on the down- Falls dolomite at the north 



throw side by the full thickness of the t\t IXtuh'T^f adi- 

 Little Falls dolomite, at least 300 feet, tional outcrops, no. i of 

 Figure 5 shows a plan of the outcrops ?XT™ sa^ndstrnl"" ' °' 

 and our interpretation of the relations. Scale 1 inch = 350 yards. 

 The wedge of Little Falls and Amsterdam shows abundant out- 

 crops. At the north end of the wedge and apparently on the 



