INTRODUCTION. 17 



beginning- at the base; Merchantville, Woodbury, Columbus,' 

 Marshalltown and Wenonah. 



In carrying- these subdivisions across the State it was found 

 that some modifications in constitution and thickness occurred. 

 For example, the Wenonah sand which approached 100 feet in 

 thickness in S'alem County decreased to about 40 feet at Atlantic 

 Highlands and became finer and more micaceous to the north- 

 east. The Englishtown (Columbus) sand, 100 feet thick at 

 Hazlet in Monmouth County, pinched out in the vicinity of 

 Auburn, Salem County. The Marshalltown bed, while maintain- 

 ing a nearly uniform thickness, changed from a sandy marl in 

 Salem County to a clay and sand with beds of marl in Monmouth 

 County. The Merchantville and Woodbury beds continued fairly 

 uniform in thickness and constitution across the State. 



The shell bed at the base of the Lower Marl was traced in 

 1894 from Crosswicks Creek to Rancocas Creek near Smithville, 

 and it was also recognized at Mount Holly in the side of the hill 

 just north of the town at an elevation of 105 feet, where the 

 Lower Marl appeared as an outlier. The State Geological map, 

 however, represented these marl beds as part of the Middle 

 Marl (Hornerstown)^, and the sand which underlay them as the 

 Red Sand (Redbank) of Monmouth County, while the Lower 

 Marl (Navesink) was shown as a bed outcropping at Mount 

 Holly at an elevation much lower than the shell bed. It was 

 apparent that the earlier workers were in error, since the Lower 

 Marl and Red Sand as mapped southwest of Mount Holly were in 

 reality the Marshalltown and Wenonah beds respectively, and 

 could be traced without much difficulty to the section along Cross- 

 wicks Creek. To' settle this question beyond any doubt, the 



^ The term Columbus as here used has been found to conflict with its prior 

 use in OhiO' for a formation of the Devonian, and hence in this report the 

 term. Englishtown will be used instead, as the formation is well developed 

 near that place in Monmouth County. [H. B. K.] 



° This name was used by Knapp in unpublished reports about the same time 

 that the term Sewell was proposed in print by Clark for the same formation. 

 The term Sewell is, however, now abandoned since its application to the 

 Cretaceous of New Jersey has been found to conflict with its prior use in 

 Virginia and West Virginia or beds in the Carboniferous, and Dr. Clark 

 acquiesces in the substitution of the term Hornerstown. [H. B. K.] 



2 PAL 



