72 STUART WELLER 



two essential differences between his classification and that of Cook 

 are in the position of the major dividing line between what are, 

 roughly speaking, Cook's "clay-marl" and "marl" series, and in 

 the interpretation of the "yellow sand" formation above the "middle 

 marl." In place of Cook's lithologic names, however, Clark sub- 

 stituted a series of geographic names in accordance with more modern 

 usage. In a more recent paper Clark 1 has made some modification 

 of his earlier interpretation of the beds, notably in the position of the 

 lower boundary line of his lower or Matawan division in the region 

 adjacent to Raritan Bay. In this paper he has excluded the 

 Cliffwood clays from the Matawan, thus bringing the basal line of 

 the Matawan to conform exactly with the base of Knapp's Merchant - 

 ville clay. 



During his study of the Pleistocene deposits under the direction 

 of Professor R. D. Salisbury, Mr. G. N. Knapp found it necessary 

 to make close study of the underlying formations of Cretaceous age. 

 In the course of this study he was able to discriminate a series of five 

 distinct formations in the old "clay-marl" series of Cook. Each one 

 of these formations was found to be marked by constant lithologic 

 characteristics, but at that time the paleontologic characters of the 

 beds had not been investigated. These formations were traced by 

 Knapp and carefully mapped entirely across the state from Mon- 

 mouth to Salem Counties. A description of the beds, especially in 

 relation to the soils to which they give rise, was first published by 

 Professor Salisbury in the 1898 Report of the Survey, 2 and geographic 

 names were applied to them, viz., Merchant ville, Woodbury, Colum- 

 bus, Marshalltown, and Wenonah. A fuller description of the 

 lithologic characters of these formations has been given by Dr. H. B. 

 Kiimmel in the recent Clay Report of the Survey. 3 



1 American Journal of Science, 4th series, Vol. XVIII, pp. 435-40. 



2 Annual Report of the State Geologist of New Jersey, 1898, pp. 35, 36. It may 

 be said that the tracing out of the Cretaceous beds was no part of Professor Salisbury's 

 plan. It was done by Mr. Knapp because the several beds of the "clay-marl" series 

 sustained very definite relations to the Pleistocene formations. The names published 

 at this time were not published by Professor Salisbury for the purpose of making a 

 new classification of the Cretaceous, but merely because the soils could best be described 

 in connection with these several subdivisions. 



3 Geological Survey of New Jersey, Final Report, Vol. VI, pp. 152-61. 



