4-6 NEW YORK STATE MUSEUM 1 



region has not yet been published, but it is hoped that.it will soon I 

 appear. A preliminary statement concerning it has already been 

 made.^ 



Within the Saratoga quadrangle this limestone is seldom exposed, 

 owing to heavy covering of glacial drift. The best and most com- 

 plete section of it is at Rock City Falls, where the contact with the 

 underlying Little Falls dolomite is exposed. At Saratoga the base 

 is thinly exposed and a wedge of the formation is infaulted along 

 the Saratoga fault, exposed back of the Star spring and for a short 

 distance northward. There is a good exposure at Rowlands mill, 

 which, however, does not show the base ; and there are other 

 exposures through North Milton, the best folded into a little syn- 

 cline. There is also a small exposure of basal Amsterdam and 

 summit Little Falls, drop-faulted along the West Galway fault, 

 south of East Galway. Nowhere within the quadrangle has the 

 summit been seen exposed, except perhaps at Rowlands mill. 



The best section and the one exposing the lowest beds, is that 

 at Rock City Falls (plate ii). The section here had been pre- 

 viously measured by Prosser.^ There is some 14 feet of Little Falls 

 dolomite in the face of the fall, gray, finely crystalline dolomite for 

 the most part, full of black seams, occasional nodules of crystalline 

 calcite, and with much chert midway. The horizon seems beneath 

 that of the coarser, light colored beds, such as form the summit 

 about Saratoga, and they have likely been removed by erosion. The 

 contact shows slight irregularity, as it does at Saratoga. The lower 

 3 feet of the overlying beds have a look of the Lowville and were 

 referred to that formation by Prosser. We collected some fossils 

 from them, however, which seemed to belong to the Amsterdam, 

 though we are somewhat in doubt in the matter. If this be Lowville 

 it is the only occurrence of this formation seen within the quad- 

 rangle limits. Above follow 38 feet of Amsterdam, somewhat thin-; 

 bedded, crystalline fossiliferous limestone of blue color. Not only! 

 are the Lowville-looking beds absent elsewhere but the succeedin 

 15 feet is also absent in the North Milton sections, the higher bed 

 resting directly on the Little Falls there. At Rowlands mill and 

 in the North Milton sections the summit shown is thinner bedded 

 and likely above anything in the Rock City Falls section. About 

 North Milton are a half dozen exposures, chiefly pinched into a 

 little syncline with the upper Little Falls, as shown on the areal 

 map. 



^Am. Jour. Sci., 31 :i43. 



2 N. Y. State Mus. Bui. 34, p. 476. 



