14 



General section of the Cretaceous roclcs of the Northwest 



Divisions and subdivisions. 



Localities. 



S 3 





£ .2 



-S to 



'Gray, ferruginous, and yellowish sandstone, and arenaceous 

 clays, containing Belcmnitella bullosa, Nautilus dekayi, 

 Ammonites placenta. A. lobatus, Scapkites conradi, S. ni- 

 colletti, Baeulites grandis, Busycon bairdi, Fusus culbert- 

 son, F. newberryi, Aporrkais amcricana, Pseudo-buccinum, 

 nebrascensis, Mactra warrenana, Cardium subquadratum, 

 and a great number of other molluscous fossils, together 

 with bones of Mosasaurus missouriensis, d\c. 



Dark-gray and bluish plastic clays, containing, near the up- 

 per part, Nautilus dekayi, Ammonites placenta, Baeulites 

 ovatus, B. compressus, Scai^hites nodosum, Dentalium gracile, 

 Crassatella evansi, Ouculloea nebrascensis, Inoceramus 

 sagensis, I. nebrascensis, I. vanuxemi, bones of mosasau- 

 rus missouriensis, dc. 



Middle zone nearly barren of fossils 



Lower Fossiliferous zone, containing Ammonites complexus, 

 Baeulites ovatus, B. compressus, Helioceras mortoni, H. tor- 

 turn, M. umbilieatum, H. cochleatum, Ptychoceras mortoni, 

 Fusus vinculum, Anisomyon borealis, Amauropsis paludi- 

 niformis, Inoceramus subloevis, I. tenui-lineatus, bones of 

 Xlosasaurus missouriensis, d-c. 



Dark bed of very fine unctuous clay, containing much car- 

 bonaceous matter, -with veins and seams of gypsum, 

 masses of snlphuret iron, and numerous small scales, 

 fishes, local, filling depressions in the bed below. 



Lead-gray calcareous marl, weathering to a yellowish or 

 whitish chalky appearance above, containing large scales 

 and other remains of fishes, and numerous species of 

 Ostrea congesta attached to fragments of Inoceramus. 

 Passing down into light yellowish and whitish limestone, 

 containing great numbers of Inoceramus problematicus, 

 I. pseudo-mytiloides, I. aviculoidcs, and Ostra congesta, fish 

 scales, <fcc. 



Dark-gray laminated clays, sometimes alternating near the 

 upper part with seams and layers of soft gray and light- 

 colored bmestone, Inoceramus problematicus, I. tejiuiros- 

 tratus, I. latus, I./ragilis, Ostrea congesta, Yenila mortoni, 

 Fholadomya papyracca, Ammonites mullani, A. percari- 

 natus, A. vespertinus, Scapkites warrcni, S. larvo?formis, 

 S. ventricosus, S. vermiformis, Nautilus elegans, (?) d-c. 



Yellowish, reddish, and occasionally white sandstone, with, 

 at places, alternations of various colored clays and beds 

 and seams of impure lignite ; also eilicified wood and 

 great numbers of leaves of the higher types of dicotyle- 

 donous trees with casts of Pharella (?) dakotensis, Axi- 

 naea siouxensis, Cyprina arenaria. 



Fox Hills, near Moreau River, near 

 Long Lake, abo-s e Fort Pierre, 

 along base Big Horn Mountains, 

 and on North and South Platte 

 Rivers. 



Sage Creek, Cheyonno River, and 

 on White River, above the Mau- 

 vaise Terres. 



Fort Pierre and out to Bad Lands, 

 down the Missouri, on the high 

 country, to Great Bend. 



Great Bend of the Missouri, below 

 Fort Pierre. 



Near Bijou Hill, on the Missouri. 



Bluffs along the Missouri, below 

 the Great Bend, to the vicinity 

 of Big Sioux River; also below 

 there on the tops of the hills. 



Extensively developed near Fort 

 Benton, on the Upper Missouri ; 

 also along the latter from ten 

 miles above James River to Big 

 Sioux River, and along the east- 

 ern slopo of the Rocky Mount- 

 ains as well as at the Black 

 Hills. 



Hills back of the town of Dakota ; 

 alsoextensivelydeveloped in the 

 surrounding country, in Dakota 

 County, below the mouth of Big 

 Sioux River, thence extending 

 southward into Northeastern 

 Kansas and beyond. 



Feet. 

 500 



200 



800 



o 

 -A 



o O 

 © i-t 



