340 W. B. CLARK — UPPER CRETACEOUS FORMATIONS OF NEW JERSEY. 



section of the deposits of this horizon" is found. If the Yellow Sand 

 described by Professor Cook really constitutes a part of the Cretaceous 

 series, then a part of it should be referred to the basal portion of the 

 Manasquan formation. As above explained, it is highly probable that 

 the Yellow Sand, as described by Professor Cook, is really of Miocene 

 age, and does not belong to the Upper Cretaceous series at all. The 

 Manasquan formation embraces the lower and middle members of the 

 Upper Marl bed of Professor Cook, including what was described under 

 the name of the Green marl and the Ash marl of that division. 



Area! distribution.— The Manasquan formation is confined exclusively 

 to the northern portion of the New Jerse}^ area, extending from the 

 region just south of Long Branch, in Monmouth county, across the 

 northern portion of Ocean county into Burlington county, but entirely 

 disappearing a short distance beyond its border in Camden county. The 

 width of outcrop of the formation is very variable, on account of the en- 

 croachment of the Miocene deposits, which very frequently entirely bury 

 the strata of the Manasquan from view, thus temporarily interrupting 

 its continuity. Where the Miocene deposits have been stripped off by 

 streams, as along the line of the Manasquan river and its tributaries, it 

 may attain a width of 3 or 4 miles, but more often the width does not 

 exceed 1 or 2 miles, with frequent variations, as above cited. 



Character of materials. — The deposits of the Manasquan formation con- 

 sist typically of highly glauconitic greensands of a deep green color. 

 They may at times, by the admixture of argillaceous materials, have a 

 somewhat ashy color, which is characteristic of the beds to which Professor 

 Cook gave the name of ''Ash marl." This ash-colored marl is not always 

 confined to the upper portion of the Manasquan formation, however, 

 but more often found there. At the base of the Manasquan formation 

 there is often a layer of fine clay, very light in color, which is commonly 

 referred to under the name of " fullers earth." 



Strike, dip, thickness.— The strike and dip of the Manasquan formation 

 conform in general to the strike and dip of the preceding members of the 

 Upper Cretaceous series, so far as can be determined by a study of the 

 sections and of the well-borings. The topographic relations of the strata 

 are such as to preclude satisfactory measurements, such as were possible 

 in the case of the Rancocas and Monmouth formations. 



The thickness of the formation diminishes gradually from very nearly 

 50 feet in the northern portion of its area of occurrence to about 40 

 feet at the eastern border of Burlington county, beyond which it more 

 rapidly declines, reaching 30 feet in the southwestern portion of the 

 county, and entirely disappearing by the overlapping of the Miocene 

 shortly thereafter. 



