206 CLAYS AND CLAY INDUSTRY. 



brick or draintile are more likely to occur in the Brunswick shales, 

 rather than in the Lockatong or Stockton subdivisions, 1 and in 

 the Brunswick shales rather to the south of a line from Passaic to 

 Morristown than to the north of it, but there may be local excep- 

 tions to this rule. 



At Pedrick's brickyard, Flemington, the basal portion of the 

 clay used has been formed by the disintegration of the red shale 

 beneath, land it is expected to use the less disintegrated material 

 as sooo as suitable machinery for crushing it can be installed. 



The trap rock, where deeply weathered, gives rise to a yellow, 

 more or less stony clay, usually containing many fragments of the 

 less disintegrated portions of the rock. South of the drift-covered 

 area, i. e., southwest of a line from Morristown to Perth Amboy, 

 this residuary deposit often attains a thickness of several feet. 

 Locally, it has been utilized for clay, as at Daniel's brickyard, on 

 Sourland mountain, southeast of Lambertville (27 7), but it is 

 full of bowlders, which are left in the pit ( PI. XXIV, Fig. 1 ) . 



DEVONIAN. 



The Devonian formations of New Jersey are limestones, shales, 

 sandstones and conglomerates. They occur in Sussex county 

 along the Delaware river from Wallpack bend northward to the 

 State line, and also 1 in the Green Pond-Bearfort mountain region. 

 In the former region they are chiefly limestones with some shales; 

 in the latter, gritty shales, sandstones and conglomerates. In 

 some states the Devonian shales are a source of valuable materials 

 for paving brick, sewer pipe, drain and roofing tile, terra cotta, 

 etc. In New Jersey, however, they are nowhere used, and in view 

 of the unfavorable nature of most of the Devonian rocks, as well 

 as the present inaccessibility by railroad transportation of much 

 of the region covered by them, it is doubtful whether they will 

 prove of any immediate importance. 



SILURIAN. 



The Silurian formations in New Jersey consist chiefly of sand- 

 stones, with a few limestone . and shale strata. They occur in 



1 Annual Report of the State Geologist, 1897. 



