CRETACEOUS AND TERTIARY FORMATIONS. 9 



sive in structure, weathering to an indurated brown earth. Its 

 thickness is about 60 feet. It is conformable to the Magothy 

 formation below and the Woodbury clay above. Its inverte- 

 brate fauna is large and varied, and although it contains many 

 forms common to the beds above and below, its most character- 

 istic species are conspicuous for their absence or great rarity 

 in the adjoining strata. The Merchantville clay represents the 

 lower part of the Crosswicks clay of Clark, forms the base of 

 the Clay-marl series of Cook, and is the lowest of the five forma- 

 tions in New Jersey which are correlated with the Matawan for- 

 mation of Maryland. 



Woodbury clay. — The Woodbury is a black, non-glauconitic, 

 jointed clay about 50 feet thick, which weathers to a light choco- 

 late color, and when dry breaks into innumerable blocks, fre- 

 quently with a conchoidal fracture. Its invertebrate fauna of 

 95 marine species is more closely allied to that of the Magothy 

 than to the subjacent Merchantville. It is conformable both 

 with the Merchantville below and the Englishtown sand above. 

 It is the upper part of the Crosswick clay of Clark, and forms 

 part of the Clay-marl series of Cook. It is also one of the 

 formations correlated with the Matawan of Maryland. 



Bnglishtown sand. — The Englishtown is a conspicuous bed of 

 white or yellow quartz sand slightly micaceous and sparingly 

 glauconitic. Locally it contains thin laminae of fine brittle clay. 

 So far as known it contains no fossils. It decreases in thickness 

 from 100 feet near Atlantic Highlands to less than 20< feet in 

 the southern portion of the State. It represents the lower part 

 of the Hazlett sand of Clark, and forms a part of Cook's Clay- 

 marl series. It was formerly called the Columbus sand and is 

 the equivalent of a part of the Matawan formation. 



Marshalltown clay-marl. — The Marshalltown ranges from a 

 black sandy clay to an argillaceous greensand marl. Locally it is 

 abundantly fossiliferous, its characteristic invertebrate species 

 being in part recurrent forms from the Merchantville, and in 

 part a new element, which recurs again in a higher formation, 

 although absent or inconspicuous in the immediately succeeding 

 beds. Its thickness is 30 to 35 feet. It is a portion of the 

 "laminated" sands which formed the upper part of the Clay marl 



