l64 THE JOURNAL OF GEOLOGY. 



thin and of very narrow geographical extent. The deposits are 

 largely fragmental, with here and there an admixture of carbonate 

 of lime derived from the shells of organisms. 



The most extensive section is afforded by the bluffs on the 

 shores of the Raritan Bay, between the mouth of Cheesequake 

 Creek and the Navesink Highlands. From this point the forma- 

 tion extends southwestward across the state, the best exposures 

 being found along the stream channels entering the Delaware 

 River from the east. Both along Crosswicks and Pensauken 

 Creeks the strata are highly fossiliferous, at the latter locality 

 over a hundred species having been identified. In the main the 

 forms are the same as those in the overlying Navesink formation, 

 although some are distinctive. 



From the surface outcrops the Matawan formation has been 

 estimated to have a thickness of 275 feet. 



The most striking differences both in the character of the mate- 

 rials and the thickness of the beds, are shown by well borings 

 along the line of dip. A recent boring at Asbury Park pen- 

 etrated the Navesink formation (Lower Marl Bed) at 400 feet, 

 beyond which for a distance of over 400 feet typical Clay Marls 

 were encountered. From 750 to 780 feet glauconitic layers were 

 found, while the deposits in general are finer and more regularly 

 stratified than in the surface outcrops to the westward. 



Navesink formation. (Lower Marl Bed). — The lower Marl 

 Bed has an extensive development throughout the region of the 

 Navesink Highlands, in the vicinity of the village of Navesink, 

 and along the north bank of the Navesink River, so that the name 

 of Navesink formation may be with propriety employed. 



Greensand forms the distinguishing feature of the deposits. 

 The lower portion is frequently quite sandy, in this respect show- 

 ing the change from the sandy layers of the upper portion of the 

 Matawan formation, upon which it lies conformably, to the typical 

 greensands of the Navesink formation. The upper portion again 

 shows the presence of much land derived material ; it is highly 

 argillaceous and just at the top frequently arenaceous. The green- 

 sands along the thinned out western edge of the Navesink forma- 



