156 CLAYS AND CLAY INDUSTRY. 



locally conspicuous. Towards the southwest, however, the marl 

 content increases, and in the vicinity of Marshalltown, Salem 

 county, the bed was once extensively dug for fertilizer. It has 

 also been opened at many other points for the same purpose. The 

 marly portions are abundantly fossiliferous. 



This member of the Clay Marl series outcrops north and north- 

 west of the Wenonah sand bed, into which it passes somewhat 

 abruptly. In Monmouth county, where alone it is likely ever to 

 prove of any value for clay, it occurs on the lower slopes of the 

 Mount Pleasant hills from Atlantic Highlands westward through 

 New Monmouth, Morganville, Robertsville and Englishtown. 

 It lies between two thick sand beds, No. V above and No. Ill 

 below, so that it can be readily identified. Its position for a por- 

 tion of this distance above mentioned is shown upon the large 

 scale of the Matawan district, Plate XII. 



Clay Marl IV is not at present utilized for clay at any point, 

 although a black laminated clay, belonging to this bed was for- 

 merly dug in a small pit near the railroad one and one-half miles 

 west of Atlantic Highlands. At two small brickyards west of 

 Mount Holly (Loc. 123) a loamy surface clay 2 or 3 feet thick 

 may perhaps be the weathered portion of this formation, al- 

 though it seems equally likely that it is a late Pleistocene deposit. 

 The clay was, also, noted at Belmar (Loc. 148) and east of Ran- 

 cocas (Loc. 124). Although not now used, there is no apparent 

 reason, however, why portions of it migHt not be employed for 

 common brick, equally as well as many of the black micaceous 

 clays now utilized at many points. Its thickness is probably be- 

 tween 30 and 40 feet. 



CLAY MARL III ( COLUMBUS SAND). 



The middle member of the Clay Marl series is a very conspic- 

 uous bed of quartz sand. It is white or yellow and sometimes 

 marked by delicate lines of red, giving it a highly variegated 

 appearance. Locally, the iron has cemented it into rather mas- 

 sive beds of stone. Although the bed for the most part is clean 

 quartz sand, often closelv resembling the sand on the present 



