PLEISTOCENE CLAYS. 135 



Unio and Anodonta, which bear a close resemblance to living- 

 forms. Teeth and portions of the skull of an extinct horse have 

 also been found, as well as a few other vertebrate remains and 

 some plant forms. The fossil evidence is all indicative of the 

 comparative late age of those clays, but is not sufficiently refined 

 to do more than corroborate in a general way the evidence of age 

 derived from the stratigraphy. 



THE BRIDGETON FORMATION. 1 



The next older formation than the Pensauken recognized in 

 Xew Jersey is the Bridgeton. Like the Pensauken, it represents 

 a period when the State was depressed below its present level, so 

 that areas now 200 feet and less above sea were for the most part 

 submerged. Like the Pensauken, it is also chiefly gravel and 

 sand ; like the Pensauken, it occurs in a series of isolated patches, 

 large and small, which are but remnants of what was once a 

 continuous formation. These remnants are most extensive in 

 the southeast parts of Burlington, Camden, Gloucester, and 

 Salem counties and the northern portion o<f Cumberland. Here 

 the formation in general caps the hills and forms considerable 

 deposits on the broad interstream surfaces. 



The formation locally contains a few thin seams of clay near 

 its base, interbedded with coarse sands and even gravel. So far 

 as known, however, these are never of commercial importance 

 and are nowhere worked. 



1 The exact age of the Bridgeton formation is not beyond question. It 

 has not been positively determined whether it is Pleistocene or earlier, and, 

 perhaps, never can be definitely settled. The weight of available evidence 

 favors its correlation with the earlier or high-level Columbia of the District of 

 Columbia. 



