CLAY-BEARING FORMATIONS. 363 



at times to find certain layers in the bank that are sufficiently 

 fine-grained and plastic to be used in the manufacture of common 

 earthenware flowerpots. 



The scattered grains of glauconite found in Clay Marl I fuse 

 very easily, so that bricklets burned at as low a temperature as 

 cone 01 show small fused specks dotting the surface. These were 

 especially noticeable in the samples from localities 140, 194 and 

 143. The fusion point of the samples from Clay Marl I is com- 

 monly about cone 10 to 12, indicating that it is a nonrefractory 

 clay, and in no sense a fire clav. 



RARITAN <XAYS. 



The Raritan formation is by far the most important clay- 

 bearing formation in New Jersey, containing as it does the best 

 clays of the State, as well as some of the poorest. They range 

 from clays that are highly refractory to others that are easily 

 fusible, from fat to- lean ones and from those of high tensile 

 strength to others of exceedingly low bonding power. 



Even a hasty consideration of the uses to- which they are put 

 indicates in a measure what a wide range of materials must be 

 contained within the limits of the Raritan strata, for the pro- 

 ducts made from these clays include common brick, fireproofing, 

 draintile, conduits, terra cotta, front brick, fire brick, stoneware, 

 earthenware, tubs and sinks, foundry materials, paper filling, etc. 

 For these reasons, it is rather a difficult matter to discuss these 

 clays collectively. 



Extending, as the Raritan formation does, across the State 

 from Perth Amboy to Trenton, and down the Delaware river, 

 its clay beds are well located for working and shipment, either 

 by water or by rail. The question of shipping facilities is, 

 indeed, an important one, since so much of the clay mined is 

 sent to distant points. Unfortunately the formation is heavily 

 covered by later gravel deposits over a large portion of its area, 

 so that, except in a few favored regions, mining this clay is either 

 very difficult or impossible. 



