428 CLAYS AND CLAY INDUSTRY. 



MERCER COUNTY. 



The clay deposits in Mercer county can be referred to the 

 Raritan formation, the Clay Marls I and II and to the Pleistocene 

 clay loams. Owing, however, to the heavy accumulation of 

 Pensauken gravel over much of the area occupied by the Raritan 

 and the two lower Clay Marl beds, the localities at which these 

 beds are worked are not numerous. The Triassic red shale for- 

 mation, although also occurring in the county, has up to the 

 present time, not been found to be of any value there for the 

 manufacture of clay products. 



The Raritan- Clays. 



Trenton. — T0 1 the east of Trenton in the region known as Dog- 

 town, the Raritan clays are dug in a number of pits for sagger, 

 wad, and fire clay. One of the largest openings is that on the 

 property of J. J. Moon (Loc. 101), where a pit of considerable 

 depth was opened at the time of the writer's visit and illustrated 

 well the character of the materials obtained from the formation 

 in this vicinity (PI. VI). The section exposed in June, 1902, 

 was : 



Section at J. J. Moon's pit, Dogtozvn. 



Stripping, IS ft. 



White sandy clay, 2-3 ft. 



Black buff -burning clay (occasionally wanting). 



Red wad clay, 6 ft. 



No. 2 sagger clay, 4 ft. 



No. 1 sagger clay, 2 ft. 



Sand, 4 ft. 



Most of the product of these pits is hauled by wagon to Trenton 

 and used to a large extent by the potteries of that city. 



Another series of pits (Loc. 102), opened by Mr. Smith in the 

 woods to the southwest of Moon's pit, showed the following 

 section : 



