(48) 



tral and southern Maryland, upon the lower members of the 

 Potomac group which are not represented in New Jersey. 

 Elsewhere in New Jersey the upper Raritan consists of white 

 sands or fine gravel and the line of contact is sharp, except 

 where it is obscured by Tertiary or later deposits. The Mat- 

 awan is conformably overlain by the lower Monmouth forma- 

 tion ; the lithological differences are clearly marked, however. 



In its northern portion the Matawan is readily separable 

 upon lithological grounds into Crosswicks Clays and Hazlet 

 Sands ; outside of New Jersey in Delaware and Maryland 

 these divisions cannot be recognized with any certainty. 

 The Crosswicks Clays consist of slate or drab-colored clays 

 with thin seams and pockets of glauconite, becoming dark, 

 almost black, locally interstratified with white sand, contain- 

 ing much lignite and beds of leaves on Raritan Bay. The 

 lignified trunk of a large tree was found in the clays in this 

 vicinity, as well as many fragments. Further southward the 

 clays become brittle, more arenaceous and micaceous and 

 contain less iron sulphide. The Hazlet Sands are highly 

 ferruginous, brown in color, with indurated crusts in their 

 lower layers ; above these there is frequently a well-developed 

 layer of dark-colored clay, overlain with very micaceous 

 sands, which are sometimes dark-colored, especially toward 

 the south where they are also argillaceous. 



In his report on surface geology Professor R. D. Salisbury 

 states * that his assistant, Mr. G. N. Knapp, distinguished five 

 layers in the clay-marls and traced them across the state. 

 These he designates Merchantville bed (marly clay), Wood- 

 bury bed (dove-colored clay), Columbus bed (sand), Mar- 

 shalltown bed (marly-clay sand), and Wenonah bed (sand). 

 These features, although more or less marked, are not sharply 

 defined throughout the entire area of the Matawan, and Pro- 

 fessor Clark has never attempted to name or map any subdi- 

 visions other than the lower clay member and the upper sandy 

 member. 



The Matawan is abundantly fossiliferous, especially along 



*Ann. Rep. State Gcol. N.J. 1898: 35. 1899. 



