50 Cretaceous. 



greensand region, this bed is in tlie condition of a loose sand, but 

 abounds in organic remains in the state of solid casts. 



Fifth. — Resting upon the former, and constituting the highest as- 

 certained member of the Cretaceous series in the State, there occurs a 

 coarse, brown ferruginous sandstone, sometimes passing into a con- 

 glomerate. It is composed of ti-anslucent quartzose sand, small frag- 

 ments of felspar, and pebbles of white quartz, cemented together by a 

 dark brown paste of oxide of iron. The green mineral in detached 

 grains is likewise a common ingredient. The position of this rock is 

 usually upon the summits of the insulated outlying hills, which rise 

 occasionally above the general plain of the marl region. 



This division into beds is merely descriptive of the local appearance 

 of the Cretaceous of New Jerse}^ and has never been regarded as of 

 any service in the separation of the Cretaceous, in other States, into 

 groups, nor has it been retained in New Jersey, since the geologists 

 have been able to separate the strata by their organic remains. 



In 1841, James C. Booth, in his Memoir of the Geological Survey of 

 Delaware, divided the Cretaceous of that State, which is found super- 

 imposed upon the primary rocks, and extends from the lower limit of 

 the primary nearly to the southern border of New Castle count}', into 

 red clay, and green and 3'ellow sands. He estimated the thickness at 

 not less than 330 feet. 



In this year. Prof. J. W. Bailey* discovered that a large part of the 

 calcareous green sand of New Jersey, the limestone from Claiborne, 

 Alabama, and a light cream-colored marl from a mission station on 

 the Upper Mississippi, called "Prairie Chalk," is composed of micro- 

 scopic shells belonging to the foraminifera. 



In 1842, Dr. Mortonf described, from the Cretaceous of the upper 

 Missouri river, Ammonites viandanensis, A. abyssimis and A. nicol- 

 letti, all of which are now referred to the genus Scaphites, and to the 

 Fox Hills Group ; Hipponyx borealis, now Anisomyon horealis, 

 Cytherea missuriana., now Diane missuriana and Tellina occiden- 

 talism now Lucina occidentalis. And from the Cretaceous group, of 

 New Jersey, Ammonceratites conradi., now Crioceras conradi, Ham- 

 ites annidifer, now Ptychoceras annidiferum.^ Pinna rostriformis, 

 Terebratula atlantica.^ Planularia cuneata, Cidarites armiyer. And 

 Ptycodus mortoni., by Mantell, from the Cretaceous, at Prairie Bluff, 

 Alabama. Dr. James E. Dekay, described, J from the Cretaceous 



* Am. Jour. S';i. and Arts, vol- 41. 

 t Jour. Acad. Nat. Sci., vol. 8, part 2. 

 \ ZooL of New York. 



