CLAYS OF KEW YOKK 831 



workers. It is generally slaty, gritty, and contains not infre- 

 quently mucli iron pyrite and bituminous matter. Tlie rock is 

 well exposed in the bed of the river at Leroy. 



As tke Hamilton, Portage and Ckemung are the most promising 

 and most extensive of the skale formations occurring in this state, 

 a series of physical tests was made on samples from several locali- 

 ties, to determine their characters as related to each other, also as 

 compared with other deposits. 



The samples were ground to pass through a 30 mesh sieve^. The 

 determinations made on these samples were: 1) amount of water 

 required to make a workable mass, 2) shrinkage in drying, 3) shrink- 

 age in burning, 4) plasticity, 5) tensile strength of air-dried bri- 

 quettes, 6) temperature of incipient fusion, 7) vitrification, 8) vis- 

 cosity, 9) per cent of soluble salts. 



The localities from which samples that were tested came are 

 Jamestown, Angola, Hornellsville, Alfred center, Cairo and 

 Coming. 



Hamilton. The Hamilton is one of the great shalet-b earing 

 formations of ISTew York state. It is also widely distributed, ex- 

 tending from the Hudson river to Lake Erie, and at these two 

 points shows wide extremes in its lithologic character. In the east 

 it is a true sandstone, in the west a clay shale. "The valleys of 

 Seneca and Cayuga lakes are both excavated, for more than half 

 their leng-th, in the shales of this group ". (Hall. Geology of the 

 4:th district of New York, p. 187) 



The Hamilton shales extend from Port Jervis northeastward 

 along the edge of the Chemung area in a belt about 5 miles wide, 

 and then swing westward from a point a few miles west of Albany to 

 Buffalo. In the central part of the state the Hamilton belt is about 

 20 miles wide, and thins to about 12 miles in the western half. The 

 Finger lakes are largely bounded on the north by the Hamilton 

 shale area. 



1 Of most of the shales ground up by disintegrators, about 60% of any- 

 sample will pass through a 30 mesh sieve, and the balance through a i 

 or % inch mesh. 



