GEOLOGY OF SARATOGA SPRINGS AND VICINITY 65 



is commonly elevated territory, the Paleozoic contrastingly at 

 low altitude. The abrupt way in which such Precambric ridges 

 as those of French and Putnam mountains, and of Sugar Loaf, on 

 the Glens Falls nuadrangle, break off at the south, with an abrupt 

 drop in level of from 500 to 800 feet, would seem of necessity to 

 imply cross faulting in the fault slices concerned. 



On the Saratoga quadrangle the evidence for cross breaks at 

 the contact between the Amsterdam limestone and the over- 

 lying Canajoharie shale seems quite conclusive. The Amsterdam 

 dips to the south are always higher than those of the Little Falls 

 dolomite, showing downfolding or downdragging in that direction, 

 and in the shales the dips are even higher for a time, so that even 

 close to the Amsterdam border the thickness of shale over the 

 limestone is considerable. Exposures do not suffice to determine 

 whether we are dealing with monoclinal folding or with faulting; 

 but since the former could be considered merely an initial phase 

 of the latter, either one would indicate the horizon as a likely one 

 for cross breaks. 



Joints. Our readings on joint directions on the Saratoga quad- 

 rangle are not sufficiently numerous to make it worth while to plot 

 them. The Precambric rocks cover but a small portion of the 

 quadrangle. They are as usual much jointed nearly everywhere 

 and appear to be referable to four sets, a north-south, an east- 

 west, a northeast and a northwest set. But they do not hold their 

 direction true, curving through considerable arcs. In the Gren- 

 ville strike joints are prominent, in this case the east- west set. Of 

 the vertical joints the northeast set is the most prominent, the 

 north and the northwest less so and more irregular. The Paleozoic 

 rocks are not ver}^ sharply jointed in the main, and the joint direc- 

 tions are Ytry irregular. 



