4o8 CLAYS AND CLAY INDUSTRY. 



CUMBERLAND COUNTY. 



The clays examined in this county belong chiefly to the Co- 

 hansey and Cape May formations. One small deposit (Loc. 184) 

 north of Vineland is probably of secondary origin in late Pleisto- 

 cene times. 



Cohansey Clays. 



Of these the Cohansey clays are the more important in point 

 of development and have been opened at 6 or 7 localities, although 

 now dug at only 3 or 4 points. 



Clayville. — The most extensive openings are near Clayville, 

 north of Millville (Loc. 183), where clay was dug as early as 

 i860, and shipped to New York and Trenton. Later attempts to 

 produce common brick from it were unsuccessful, the reason 

 probably being that the clay was not burned hard enough. At the 

 time of writing the pit is owned by the Clayville Mining & Brick 

 Company, and worked by the Globe Fireproofing Company. 



The clay bank (PL XLIII, Fig. 2) lies about 1 mile east of 

 the factory, and the railroad is connected with them by a switch. 

 The clay is variable in thickness, ranging, it is claimed, from 7 to 

 24 feet, although 14 feet was the greatest thickness observed. 

 With such a variation we should look for irregularities in either 

 the upper or lower surface of the clay deposit, and it is found that 

 both occur, a characteristic not rare in the Cohansey clays. 



The area that has been dug over is considerable, and the amount 

 of stripping to be removed has varied from 5 to 12 feet. The 

 line of separation between overburden and clay is sharp wherever 

 seen. The clay itself is very tough and gritty, and has to be 

 worked by undermining and falling. In some parts of the bank 

 it grades horizontally into sand, and, where the base of the clay 

 was seen, sand was found to underlie it. In mining the clay, the 

 run of the bank is used, but there is said to be one layer at the 

 bottom which has a high shrinkage. 



On account of the size of this deposit a complete physical test 

 was made of it (Lab. No. 653) with the following results: 



