348 CLAYS AND CLAY INDUSTRY. 



southeast of the Delaware the clay loams are much used to mix 

 with the underlying clays, The sample from Bordentown (Loc. 

 109, Lab. No-. 171 ) is an example of this type of material. Other 

 localities at which these clays are being' worked are Edgewater 

 Park, Woodbine, Buckshutem and Belle Plain. 



At several localities the stiff-mud process of molding is used, 

 and while a good marketable brick is obtained, a better product 

 could noi doubt be turned out with the use of more care in temper- 

 ■ ing and molding or by re-pressing. As can be seen by reference 

 to the table of brick tests (p. 256) the products made from these 

 clays show a crushing strength equal to : that of the other common 

 building bricks. Layers are occasionally found of sufficient fine- 

 ness and plasticit}^ to> make common red earthenware, some clay 

 for this purpose having been dug in Hatch & Sons' pit at Fish 

 House. Many of the less gritty clays could also' be used for 

 draintile. 



COHANSEY CLAYS. 



The Cohansey clays represent an important group of deposits 

 whose value has become prominently known since the issuance of 

 the first New Jersey Clay Report, in 1878. 



The deposits show considerable variation in thickness. Many 

 openings were seen, showing from 6 to 8 feet of clay; 12 feet 

 were also observed, and in one instance, viz., at Clayville, the bed 

 of clay is said to be 24 feet thick. At some localities the bank may 

 be fairly uniform from top to> bottom, while at others there may 

 be several layers, varying in character, and in the latter case, if 

 the run of the bank is to 1 be used, thorough mixing is necessary. 



In mining the clay the deposit is sometimes large enough to 

 be worked with a steam shovel, especially if much clay is to< be 

 dug and shipped daily. This method is not commonly used, how- 

 ever, but instead the clay is usually dug with mattocks, and loaded 

 either onto tram cars or two-wheeled horse carts. ( PI. VII, Figs. 

 1 and 2.) 



The amount of overburden ranges from 4 to 6 feet at most 

 localities, but in one or two- instances 12 to 15 feet of stripping' 



