1 6 NEW YORK STATE MUSEUM 



Paleozoic rocks 



Potsdam sandstone and Beekmantown limestone. The Potsdam 

 sandstone, which is the oldest of the Paleozoic formations bordering 

 the Adirondacks, is certainly nowhere present at the surface within 

 the map limits. There is evidence for believing that this sand- 

 stone is present along the southwestern border of the Adirondacks 

 under cover of later formations. This question has been carefully 

 discussed by Professor Gushing in his report on the Little Falls 

 district.^ 



It is also true of the Beekmantown limestone that no exposures 

 occur within the map limits. At Little Falls the Beekmantown 

 (Little Falls dolomite) is something like 400 feet thick, but it shows 

 a rapid thinning both northward and northwestward. In the vicinity 

 of Cold Brook and Poland, and only a little over a mile from the 

 southern boundary of the Remsen quadrangle, a considerable thick- 

 ness of Beekmantown is shown. Thus, more than likely, it extends 

 northward under the younger formations for a short distance at 

 least on the Remsen quadrangle. 



The Beekmantown comes close to where Black creek enters the 

 map limits, but it seems to have disappeared before that point was 

 reached. There is no evidence whatever to suggest the presence of 

 Beekmantown in the northwestern part of the district. 



Trenton formation. As here discussed the Trenton formation 

 includes the Lowville limestone at the base, then possibly the 

 Black River limestones and shales, with the Trenton limestone 

 proper at the top. 



The Lowville limestone shows in outcrop within the map limits 

 only in the northwest along Black river. The outcrops are in the 

 bed of the river and are well shown a short distance above the mouth 

 of Crystal creek. The rocks are fine grained, compact, of a light 

 bluish gray color and show many of the calcite filled tubes so 

 characteristic of the formation. The layers are generally from 6 

 inches to a foot thick and constitute a very pure limestone. The 

 exposed thickness of the Lowville here is about 10 or 12 feet and 

 although neither the top nor the bottom is visible the maximum 

 thickness can not be much over 30 feet. At the mouth of Crystal 

 creek there is a Precambric outcrop only a few rods from the Low- 

 ville,^ and a short distance west Trenton limestone is exposed. 



1 Geology of the Vicinity of Little Falls. N. Y. State Mus. Bui. 77. 1905. 



2 Along the western border of the Adirondacks the Lowville rests unconformably upon 

 the Pamelia formation of Gushing. The Pamelia has been traced across the Port Leyden 

 quadrangle by the writer and it is possible that just a trace of it may be present between 

 the Precambric and the Lowville at Crystal creek. 



