230 CEMENT MATERIALS AND INDUSTRY. [bull. 243} 
Auburn, Tecumseh, Dunbar, Nehawka, Weeping- Water, and along 
Platte River near Louisville. The Cottonwood limestone, a mass™ 
bed full of Fusulina, was recognized west of Auburn about Glenj 
rock and Johnson, and the same beds extend over the higher lands Mm 
western Richardson and Pawnee counties. a In the deep borings which 1 
have been made at various points in the southeastern corner of the< 
State it has been found that the Carboniferous formations have a total i 
thickness of about 1,200 feet, of which about 200 feet are Permian. 
• 
NIOBRARA AND BENTON FORMATIONS. 
as 
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Underlying the Pierre clay is a series of shales and chalky limestoneaJ 
The shales are known as the Benton formations and the limestone, a) 
the Niobrara formation. They have a thickness of about 450 feet 
the east, but thicken to the west. At the base there are about 20lN 
feet of dark shales, overlain by slabby limestones of the Greenhorr/ 
formation containing Inoceramus, which are followed by a series oJJj 
shales with few thin sandy layers, and at the top the Niobrara foal 
mation with its chalky deposits, characterized by thin, hard beds tillec< 
with Ostrea congesta. The formations cross the eastern part of theij 
State, and underlie all of the area west of the vicinity of the ninety 
seventh meridian, but are so deeply buried under drift and loesnj 
that outcrops are rarely visible. The most extensive exposures anifl 
along the Missouri River, extending from near the ninety-seventh fall 
the ninety-ninth meridian, and along the Republican Valley from Allium 
to near Superior. The formations are exposed at intervals across th< 
eastern portion of the State in each of the larger valleys and some I 
the branches. The more notable of these small outcrops are at Genoa 
north of German town, near Crete, at Pleasan thill, and in Beavl 
Creek north of Dorchester. There is an exposure of dark shale 
under some ledges of Greenhorn limestone in Big Blue River at Milford 
which are Benton. Benton and Niobrara beds also occur in a promi 
nent anticline along White River in the vicinity of Beaver and Alkal 
creeks, in the northwestern portion of the State. 
PIERRE CIA Y. 
All of Nebraska west of the ninet}^-eighth meridian is underlain b; 
the Pierre cla}^. Its surface outcrops are in the lower portion of th 
Niobrara Valley, the Republican Valley, and the extreme northwes 
corner of the State, but it is probable that careful search will reves 
outcrops in the valley of the Platte River in the vicinity of the ninety 
sixth meridian. The formation is a thick mass of dark-gray or bluis 
clay or soft shale. Its thickness is probably at least 2,000 feet in th 
west-central portion of the State. 
"Jour. Geol., vol. 5, 1897, pp. 1-16. 
