456 MESOZOIC TIME. 



taceous occurs in the Coast ranges, and along the foot-hills of the Sierra Nevada, 

 from Placer County to Shasta; and in Oregon, east of the Cascade range (Marsh). 



As the Cretaceous formation is very fully represented in the region of the Upper 

 Missouri, a detailed section of it, by Meek & Hayden, is here given, beginning 

 below : — 



1. Earlier Cretaceous. 



1. Dakota Group. — Yellowish, reddish, and whitish sandstones and clays, with 



lignite and fossil Angiospermous leaves: thickness, 400 feet. Location, 

 near Dakota, and reaching southward into northeastern Kansas. This 

 division may require to be united with No. 2 (M. & H. ). 



2. Benton Group. — Gray laminated clays, with some limestone: thickness, 800 



feet. Location, near Fort Benton, on the Uppwr Missouri, also below the 

 Great Bend ; eastern slope of the Rocky Mountains. 



3. Niobrara Group. — Grayish calcareous marl : thickness, 200 feet. Location, 



Bluffs on the Missouri, below the Great Bend, etc. 



2. Later Cretaceous. 



4. Pierre Group. — Plastic clays: thickness, 700 feet; —middle part barren of 



fossils. Located on the Missouri, near Great Bend, about Fort Pierre and 

 out to the Bad Lands, on Sage Creek, Cheyenne River, White River above 

 the Bad Lands. 



5. Fox-Hills Group. — Gray, ferruginous, and yellowish sandstones and arenaceous 



clays: thickness, 500 feet. Location, Fox Hills, near Moreau River, above 

 Fort Pierre near Long Lake, and along the base of Big Horn Mountains. 



No. 1 occurs at different points in New Mexico (Newberry). No. 2, on the north 

 branch of the Saskatchewan, west of Fort a la Corne, lat. 54° N. ; in New Mexico 

 (Meek). No. 3, over the region from Kansas through Arkansas to Texas: in the 

 Pyramid Mountain. No. 4, in British America, on the Saskatchewan and Assiniboine ; 

 on Vancouver Island; Sucia Islands, in the Gulf of Georgia. No. 5, at Deer Creek, 

 on the North Platte, and not identified south of this. (Meek & Hayden.) 



With regard to the Cretaceous strata of Utah and Wyoming (8,000 to 10,000 feet 

 thick), Meek remarks that the lower beds represent in their fossils No. 2 of the Upper 

 Missouri section, and that the later beds, Nos. 3, 4, 5, cannot be identified, although 

 probably present. 



In Mississippi, Hilgard has made out the following subdivisions : — 



1. (Lowest) Eutaic group (Coffee group of Safford), consisting of clays, with usually 

 some sand beds above, and containing beds of lignite and rarely other fossils, the thick- 

 ness 300 to 400 feet. 



2. Rotten-Limestone group, not less than 1,200 feet thick, made up of soft, chalky, 

 white limestones, underlying the prairies, and containing Placuna scabra Mort., Neithea 

 Mortoni Gabb, Gryphma convexa Mort., G. mutabilis Mort., G. Pitcheri Mort., Ostrea 

 falcata Mort., Rudistes, Mosasaurus, and including the " Tombigby Sand," in which 

 occur many Selachian relics and the gigantic Ammonites Mississippiensis. 



3. The Ripley group, Ijard white limestones, often glauconitic and sandy, underlaid 

 by black or blue micaceous marlytes, 300 to 350 feet thick, and containing Cuculkea 

 capax Con., Gervillia ensiformis Con., Baculites SpiUmani Con., Scaphites Conradi 

 D'Orb., Ammonites placenta Dekay, etc., forming the Pontotoc ridge in Mississippi, the 

 Chunnenugga ridge in southeastern Alabama, and occurring also at Eufaula, Ala. 1 

 is Hayden's No. 1; 2, his No. 4; and 3, his No. 5 (Hilgard, Am. J. Sci., III. ii. 392). 



In Tennessee, there are the Coffee Sand, 200 feet thick; the Green-sand or Shell bed 

 (Rotten Limestone), 200 to 350 feet; the Ripley group, 400 to 500 feet thick, consisting 

 mostly of stratified sands. 



In Alabama, the thickness of the Cretaceous is 2,000 feet, 900 to 1,100 of it the Rotten 

 Limestone. 



In Texas, the beds consist mainly of compact limestone, and the larger part are of the 

 Later Cretaceous. Shumard gives the following subdivisions: Marly clay, 150 feet 



