CHAPTER XIII. 



THE VINCENTOWN FORMATION. 



The Vincentown formation has two distinct Hthologic facies. 

 In Monmouth County it is the "yellow sand" bed of Cook, and 

 is typically a bright yellow quartz sand, frequently with a small 

 percentage of glauconite grains. Sometimes the formation is 

 more ferruginous, with a redder color, with thin, irregular, iron- 

 cemented beds and peculiar tubular iron concretions. The thick- 

 ness of the formation in eastern Monmouth County is 40 to 50 

 feet. In tracing the formation towards the southwest, certain 

 calcareous beds are seen to be included in it. Whether these 

 beds are lenticular sheets or continuous layers cannot be deter- 

 mined from the limited exposures which are available for obser- 

 vation, but they continue to become more conspicuous in the 

 direction indicated, until in Salem County the calcareous beds 

 essentially replace the yellow sand beds of the northeast. This 

 calcareous facies is what was called the Vincentown limesand by 

 Clark, the name Vincentown being here extended to include also 

 the sand facies. These calcareous beds are at times, especially 

 in Monmouth County, a crumbling limesand, often with some 

 quartz and glauconite grains, but in its more southwestern ex- 

 tension they usually consist of firm limestone layers with softer 

 material interbedded. At several localities these harder layers 

 have been quarried and burned for lime. 



FAUNA OF THE VINCENTOWN FORMATION. 



Fossils are usually rare or entirely absent in the exposures of 

 the arenaceous facies of the formation, but somewhat full faunas 

 have been collected from several localities. The calcareous facies 

 of the formation is more often fossiliferous, and one locality near 

 Vincentown has afforded a very large fauna. 

 II PAE (161) 



