HAWwoRTH. | Physiography of Western Kansas. 47 
called the Blue hills, in allusion to the bluish haze the atmosphere 
frequently presents when looking at the hills from a distance. These 
hills are composed principally of the Benton shales, the Blue Hill 
Shales, with a protecting cap of Fort Hays limestone in places. It 
is a prominent feature of the landscape and can be seen from the 
east for a distance of from 20 to 40 miles. West of this still is 
another escarpment likewise trending northeast and southwest, 
produced by the eastern limits of the Niobrara chalk formations. 
It passes southwest from Jewell county, reaching almost to the 
Arkansas river, gradually growing less prominent in the southern 
direction on account of the thickness of the Niobrara formation 
correspondingly decreasing. Frequently along these escarpments 
outstanding mounds or columns are left after erosion has removed 
ail surrounding materials. Plate VIL, Castle Rock, is a good illus- 
tration of this. It is situated on the north side of the Hackberry, 
near its mouth in Gove county. Plate VIII. represents such a mound 
in the process of formation. 
Beyond the Niobrara limits north of the Arkansas river the 
Tertiary formations are reached. The general character of the 
uplands throughout the whole of the Tertiary area is that of a broad 
level plain excepting where it has been cut into by a drainage 
channel. One of the peculiar features of this part of the state is, 
that no matter where one may be standing or in what direction 
one may be looking, it seems as though one is surrounded by higher 
ground on all sides. This is a feature of the landscape in all prairie 
countries where the surface is so nearly level. The general east- 
ward inclination of from five to fifteen feet to the mile which ob- 
tains throughout the whole of this western country is nowhere 
noticeable. . 
South of the Arkansas river the character of the uplands is 
materially different from that to the north. The broad plains area 
south of Great Bend is almost level, few streams having cut their 
channels exceeding 50 to 75 feet deep. One can travel by train 
across this area on the Santa Fe or the Rock Island, and can hardly 
notice any variation in the grades until Barber county is reached. 
Froin this locality westward the surface is very rugged, due to 
the great southern inclination. In the vicinity of Medicine Lodge 
