NIOBRARA CRETACEOUS. 
The divisional line between the Benton and Niobrara Creta- 
ceous beds is placed perhaps rather arbitrarily between the Blue 
Victoria of Cragin and the Fort Hays Beds. These latter strata 
vary somewhat in thickness—between fifty and sixty five or seventy 
feet—and are very persistent, both in lithological characters and in 
extent, reaching from Jewell county on the north to near Coolidge 
on the west, about ten miles north of the Arkansas river where it 
enters the state. It is composed of distinctly stratified, massive 
white chalk, or soft limestone, hardening somewhat on exposure. 
Its microscopical characters are similar to those of the upper Nio- 
brara. The rocks have yielded a few vertebrate fossils, especially 
a large Plesiosaur in Jewell county. Mosasaurs and Pterodactyls 
seem to be wholly wanting. The invertebrate fossils are for the 
most part, Ostrea and Haploscapha, together with Inoceramus: 
They are usually, however, in a more or less comminuted condition. 
The Blue Hill shales beneath them are entirely conformable, 
apparently, and are very easily distinguished by the large and 
numerous septaria which they contain. Crystals of selenite are 
often abundant in the shale, as is so usually the case in the blue 
shaly deposits of the Cretaceous throughout the succeeding forma- 
tions. 
An escarpment of the Fort Hays beds at the mouth of Hackberry 
ereek in Gove county has above it, and lying conformably, the less 
distinctly stratified chalk of the Upper Niobrara, which, though 
nearly barren in fossils, shows some of the characteristic fishes of 
that formation. The Fort Hays beds disappear beneath the upper 
beds some miles further west, near the post-office known as Ailan- 
thus. 
The thickness of the upper Niobrara beds, the Pteranodon Beds of 
Marsh, the Smoky Hill Beds of Cragin, are not less than 300 feet, and 
in all probability are nearly 400. At Elkader, in the valley of the 
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