W. B. Clark — The Matawan Formation. 435 



Art. XLY. — The Matawan Formation of Maryland, Dela- 

 ware, and New Jersey, and its relations to overlying and 

 ~ dng Formations ; by Wm. Bullock Clark. 



The name Matawan was proposed by the author in an 

 article published in the Journal of Geology in 1894 and was 

 there described as equivalent in a general way to the term Clay 

 Marls of Professor Cook. The chief characteristics of this 

 series of strata had been briefly discussed, however, two years 

 earlier in the Annual Report of the State Geologist of New 

 Jersey for 1892. In this earlier publication the separation of 

 the deposits into a lower clayey and an upper sandy member 

 was indicated, although the names Crosswicks clays and Hazlet 

 sands were not introduced until 1897 in an article published in 

 the Bulletin of the Geological Society of America. 



The work of the writer on the Cretaceous stratigraphy 

 of the Middle Atlantic Coastal Plain has been conducted 

 primarily for the U. S. Geological Survey, and was started in 

 Monmouth County, New Jersey, beginning in 1891. The 

 results of these early investigations, published the following 

 year in the Annual Report of the State Geologist of New 

 Jersey for 1892, which was accompanied by a "preliminary 

 geological map," represent mainly the conclusions which were 

 reached from a study of that local district. A wider extension 

 of the studies after 1891, both in New Jersey and Maryland, 

 led to the preparation of the fuller article published in the 

 Bulletin of the Geological Society of America in 1897, in 

 which certain modifications were made in earlier views. The 

 practical completion of the detailed mapping of the Cretaceous 

 formations in New Jersey and in Maryland the present season 

 has now led, it is believed, to a fairly close approximation to a 

 correct interpretation of the conditions represented in the entire 

 province between the Potomac and the Raritan rivers. In the 

 light of the Maryland work, the earliest maps prepared in New 

 Jersey have been more or less modified in local details, although 

 the general results remain the same. 



In a discussion of the Coastal Plain formations of Maryland 

 and New Jersey, it should be borne in mind that the entire 

 series of Upper Cretaceous deposits amount to scarcely five 

 hundred feet in total thickness, and that the beds, as far as 

 known, are practically conformable throughout. Beginning 

 with clays and sands slightly glauconitic, they pass over into 

 greensand marls. Five formations have been defined and 

 mapped, and several subdivisions of most of these formations 

 described by the writer. 



In order that the conclusions reached by the author and his 

 associates may be clearly understood, the following discussion 

 of the stratigraphic relations of the Matawan formation is 



Am. Jour. Sci. — Fourth Series, Vol. XYIII, No. 108.— December, 1904. 

 30 



