CLAYS OF GLOUCESTER COUNTY. 421 



Clarksboro. — Wells in the vicinity of Clarksboro indicate the 

 presence of 15 feet of clay, probably Clay Marl II, beneath a few- 

 feet of loamy sand. 1 



Swedesboro'. — At several points northwest of Swedesboro a 

 chocolate-colored clay occurs along the highway and banks of 

 Raccoon creek at points not unfavorably situated for opening pits, 

 but no attempt has been made to utilize it. 



Clay Marl III is usually a sand bed but at certain horizons con- 

 tains workable lenses of clay which have been used in Gloucester 

 county. 



Woodbury. — Such a deposit occurs at Thackara's brickyard, 

 one-half mile south of Woodbury on the road to Wenonah (Loc. 

 155, PI. XXVI, Fig. 1). The clay is loamy in character with 

 numerous mica scales, but makes a good red hand-molded brick. 

 Farther south on this same road, and about 1 mile from Wood- 

 bun- is an abandoned brickyard (Loc. 156). In the bottom of 

 the pit there is an extremely tough, bluish-black clay 4 feet in 

 thickness, overlain by 6 feet of weathered chocolate clay, and this 

 in turn capped by 4 feet of pebbly loam. It is claimed that the 

 toughness of the clay (Lab. No. 717) caused the abandonment of 

 the yard, for the deposit does not appear to be exhausted. The fol- 

 lowing are its physical characters : Water required for mixing, 

 40.5 per cent., which is rather high; air shrinkage, 9 per cent., 

 which is also high; average tensile strength, 134 pounds per 

 square inch. At cone 05, fire shrinkage was 4.3 per cent., and 

 absorption 1 1.28 per cent. ; color light red, and bricklet steel-hard. 

 At cone 01, fire shrinkage was 4.6 per cent. ; absorption, 8.7 per 

 cent., and color red. In- working this material it would probably 

 be necessary to add a considerable quantity of the sandy over- 

 burden. 



Alloway Clay. 



The Alloway clay is found in southern Harrison township at 

 several localities, and underlies considerable areas. (PI. XIII.) 



H arris onville. — Clay crops out along the roadside 1 mile east 

 of Harrisonville (Loc. 176). It is mottled yellow and red, and 



1 Annual Report of the State Geologist, 1901, p. 77. 



