242 The American Geologist. October, 1905 
river all head at the top of the divide in the Loup Fork 
formation. They have water in their upper courses ; but, 
as these streams are building up their middle courses with 
Loup Fork sand, the water, on reaching this part of its re- 
spective channel, sinks beneath the surface. White river 
itself is a large stream and is scarcely fordable on account 
of its quicksand. In many places its banks are very steep 
forming canyon walls. The water of the stream in the 
rainy season is white, the color being due to the white 
Oligocene sediment carried in the water from the Bad 
Lands. At other seasons of the year the water is practic- 
ally clear. 
Why the southern, tributaries of White river are build- 
ing up their channels in their middle course The streams 
flowing north from the vicinity of the artesian well cut 
through both the Loup Fork and the Oligocene formations 
in the first six or eight miles of their respective .courses, 
falling in that distance from three hundred to three hundred 
and fifty feet. Then as the Cretaceous shales yield less 
readily to the erosive efforts, the fall is not maintained from 
there on. Hence a slack-water region is produced. In this 
the Loup Fork sands are deposited, except in high flood 
times when force enough is given to the water by its volume 
to carry the sediment with it to the master stream. The 
aridness of the region aids in building up this middle 
course. 
Change of Drainage Courses. In the early history of 
Antelope creek it seems to have flowed north as the head 
stream of Little Oak creek, as its direction of flow would 
tend to take it to-day. Finally the Kaya Paha tapped it 
above the site of the boarding school and captured its upper 
tributaries, leaving Little Oak, its lower channel, to dwindle 
to a dry stream. The wind-gap through which the original 
stream seems to have run together with the great bend on 
Antelope creek at this point bears out this conclusion. 
Antelope creek is now in danger of itself being tapped 
in the near future of geologic time by White Thunder 
creek. This creek runs, as it were, at right angles to the 
Antelope ; that is, it would form a pretty good perpendicular 
to the Antelope if continued to it. The Antelope is at least 
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