86 NEW YORK STATE MUSEUM 



The other belt of thick and prominent outcrops of white-weath- 

 ering cherty beds extends across Willard mountain and forms the 

 backbone or top of the high ridge extending north from Willard 

 mountain, obviously one of the causes that this steep landmark 

 has withstood weathering so much better than the surrounding 

 land. On top of Willard mountain itself, a ridge about 150 feet 

 wide of white-weathering, vertical or steeply inclined synclinal 

 beds is found. The high cliffs on the west brow of Willard moun- 

 tain consist principally of this chert, which is again finely exposed 

 on the road crossing the ridge north of Willard mountain. It 

 extends here along the crest of the ridge to the north point. An- 

 other ledge strikes about a mile east of Willard mountain. 



A ridge of white beds begins also north of Snake hill at the 

 shore of Saratoga lake and can be recognized again 2 to 3 miles 

 farther northeast. At the lake shore a solid 3 foot bed of black 

 chert was found intercalated in fissile dark shales. This 

 chert contained Climacogtraptus bicornis, Glosso- 

 graptus, Climacograptus modestus, but not the 

 Dicellograptus nicholsoni that occurs all along the 

 lake shore in the shales. It would thus seem to be also of Nor- 

 manskill age, although it is surrounded by Snake Hill beds. Far- 

 ther northeast a thickness of over 20 feet of this chert has been 

 observed on top of the ridge. 



The graptolites in the chert are not preserved as carbonaceous 

 or pyritized remains as in the argillaceous shales, but are as white 

 as the weathered surface of the rock and, wherever present, show 

 a striking contrast with the dark rock. It is possible that they 

 are also kaolinized, but they may also be composed of the mineral 

 giimbelite, a greenish white silicate which has been found in 

 Bavaria to have sometimes replaced the carbonaceous tests of 

 graptolites. 



The Normanskill grit. The white-weathering chert beds are al- 

 ways associated, on the Schuylerville quadrangle at least, with the 

 Normanskill grit. As in the case of the cherty beds, grit beds 

 are also present, though in much less development, in the Snake 

 Hill formation. These grits of both formations have been care- 

 fully described as Hudson grit by Dale (1899, P^^^ 187), from 

 whom we quote : 



The Hudson grit is a rock so marked in its characteristics as to be 

 easily identified. It is coarse, grayish, sandy looking. Fresh fracture sur- 

 faces are very dark and show glistening glassy quartz grains and very 



