SIXTH REPORT OF THE DIRECTOR I909 II5 



dam and passage beds at this point and a more generalized section 

 of the dolomites above. 1 We were more concerned with the upper 

 part of the section than with the Potsdam and made the following 

 measurements down the south face of the hill, where the section 

 seemed most complete : 



SECTION OF LITTLE FALLS DOLOMITE AT SKENE MOUNTAIN NEAR 



WHITEHALL, N. Y. 



Feet 

 7 Whitish, rather coarsely crystalline dolomite, with a little 



chert at summit ; this material forms the summit of the 

 knob everywhere and is of greater thickness than 10 feet, 

 that being only what is shown where the section was meas- . 



ured 10 



6 Mostly very finely crystalline, dark gray magnesian limestone 

 somewhat cherty above ; full of irregular seams of more 

 coarsely crystalline material which weathers less readily 

 and forms projecting films on weathered surfaces; lower 

 portion very massive forming high cliff; at base a single 



trilobite fragment was found 90 



5 Very coarsely crystalline, whitish dolomite, somewhat oolitic 



and becoming steadily finer grained downward 30 



4 Gray blue, finely crystalline dolomite with calcareous cement, 

 weathering sandy looking, many calcite-filled cavities ; at 



base a Cryptozoon horizon 50 



3 Blackish, oolitic, magnesian limestone 20 



2 Measures concealed 50 



1 Passage beds : chiefly calcareous sandstone, but with alter- 

 nating beds of vitreous sandstone and blackish, crystalline, 

 sandy limestone; only a 15 foot thickness of these shows 

 on the south face but, followed around to the west side the 

 full thickness comes in with the large thickness of Pots- 

 dam underneath which Walcott measured, the dip being 

 strong to the east 80 



330 



This section is much like those at Saratoga and Ticonderoga. 

 The horizon of the Hoyt limestone is largely concealed, but the 

 black, oolitic beds above the gap are exceedingly like those as- 



1 U. S. Geol. Sur. Bui. 81, p. 345. 



