GEOLOGY OF THE SCHROON LAKE QUADRANGLE 63 



Potsdam Sandstone Southwest of Schroon Lake Village 

 This area of Potsdam sandstone lies iJ/2 to 2 miles southwest 

 of Schroon Lake village, or about i mile west to southwest of 

 Grove Point. It was discovered by the writer in 1916. Just south- 

 west of the forks of the road three-fourths of a mile west of Grove 

 Point, there are four exposures, three of them in the road and 

 the other just across the fence to the south of the road. The 

 largest outcrop is several rods long. Paced at right angles across 

 the strike of these exposures the distance is 45 yards. Since the 

 dip is west 5, a thickness of about 12 feet of the sandstone occurs 

 here with neither top nor bottom visible. The strata strike 

 N 30 E. In the brook just north of these exposures there are 

 many angular fragments of the sandstone, but still farther north 

 neither fragments nor outcrops occur, so that the northern limit 

 of the area must be about as indicated on the accompanying geologic 

 map. For fully one-half of a mile to the south-southwest, within 

 the area mapped, a number of small exposures of the sandstone 

 were observed, and also hundreds of angular fragments up to sev- 

 eral feet across. Hundreds of angular fragments of the sand- 

 stone also occur on both the north and south sides of Thurman 

 pond, but a careful search failed to reveal an outcrop. Probably 

 these are simply fragments in the glacial drift. 



In all the outcrops the rock is in every way typical Potsdam 

 sandstone, being gray, well stratified, often cross-bedded, and not 

 very coarse grained. The layers are generally from a few inches 

 to a foot thick. No fossils were found. That these beds are very 

 close to the bottom of the Potsdam formation is evident from the 

 fact that granitic syenite, the immediately underlying rock, out- 

 crops close by on the east (see map). A fault passes along the 

 foot of the hills just west and this probably marks the western 

 boundary of the sandstone, though no exposures of any kind occur 

 close to the fault on its east side. 



Little Falls (?) Dolomite in and near Schroon Lake Village 

 Description of occurrences. In a paper dealing with the iron 

 ores of northern New York published by C. E. Hall 1 in 1879, men- 

 tion is made of this outlier. 



In his Preliminary Report on the Geology of Essex County, 2 

 Professor Kemp briefly describes the outlier and discusses its 

 significance. 



1 N. Y. State Mus. Rep't 32, p. 130-40. 1879. 



* N. Y. State Geol., isth Annual Rep't, 1895," p. 596-98. 



