Ries — Physical Tests of Devonian Shales. 



693 



to make a workable paste, (2) shrinkage in drying, (3) shrinkage in burning, 

 (4) plasticity, (5) tensile strength of air-dried briquettes, (6) temperature of 

 incipient fusion, (7) vitrification, (8) viscosity. 



The localities from which samples that were tested came, are Jamestown, 

 Angola, Hornellsville, Alfred Centre and Cairo. 



Hamilton. The Hamilton is one of the great shale bearing formations 

 of New York state. It is also widely distributed, extending from the Hud- 

 son river to lake Erie, and at these two points shows w ide 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 length, in the shales of this group." (Geology of the 

 Fourth 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 five miles wide, and then swing 

 westward from a point a few miles w 7 est of Albany, to Buffalo. In the 

 central part of the state the Hamilton belt is about twenty miles wide, and 

 thins to about twelve miles in the western half. The Finder-lakes are 

 largely bounded on the north by the Hamilton shale area. 



Along the banks of Seneca and Cayuga lakes the full section of the 

 Hamilton group may be seen. The lower members are the most northern, 

 and dip to the south under the higher ones. Professor Hall makes the 

 following divisions : 



1. Dark, slaty fossiliferous shale, resting on the Marcellus shale. 



2. A compact, calcareous blue shale, of little thickness. 



3. An olive or blue shale, which in its upper layers is stained by 

 oxide of manganese. This is one of the best adapted for clay products. 



4. Ludlowville shales, often sandy in their nature. 



5. A limestone. 



6. Moscow shales, of greyish blue color, and slightly calcareous in 

 places. 



These subdivisions can all be seen along the eastern shore of Cayuga 

 lake from Springport to Ludlowville. 



Cairo, Greene county. This is the only locality at which the Hamilton 

 shale is mined. The material which is shipped to the works of the Catskill 

 Shale Paving Brick Company at Catskill, is a reddish gritty clay possessing 

 little plasticity- This material was at first used alone, but found difficult 

 to work on account of its excessive leanness, and consequently is now mixed 

 with fifty per cent, of common red clay also obtained from Cairo. Samples 



