OF THE UNITED STATES. 15 



cially in some places overlaid by deep deposits of clay 

 and sand, as at Bordentown, White Hill &c. In other 

 localities, the older Pliocene (Upper marine) overlies 

 the secondary, as is the case a few miles from Salem. 

 Above all these deposits is mostly found a uniform covering 

 of gray sand', referred by Mr. Vanuxem to alluvial ori- 

 gin; yet we often observe the marl, with its peculiar 

 fossils, immediately beneath the soil. 



These fossils, as will hereafter be shown, are of a very 

 striking character, occasionally grouped in vast numbers, 

 and in other instances almost wholly absent. The genera 

 Gryphsea, Exogyra and Belemnites, are found abun- 

 dantly throughout. Near Egypt; on the margin of Cross- 

 wick's creek, and at Ralph's mill, near Hornerstown, 

 TerebratulaB occur in prodigious numbers, but under 

 different appearances : at Egypt, for instance, is a series 

 of thin strata, some filled exclusively by Terebratulae, 

 others by Gryphsea, so disintegrated as mostly to fall to 

 pieces on removing them from the marl. Near Horners- 

 town, on the contrary, the Terebratulse are found in a 

 very indurated matrix in the bottom of a rivulet, and in 

 perfect preservation. Near Walnford, Exogyrse and 

 Belemnites predominate : at Arneytown, these genera 

 are associated with Ammonites, Baculites &c. The 

 marls of the whole of Monmouth county are similarly 

 characterized, especially those near Middletown, the 

 Nutt swamp &c. 



Mullica hill, in Gloucester, presents a naked elevation 

 of forty or fifty feet, composed of sand and small quartz 



