Page:Popular Science Monthly Volume 80.djvu/217

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213
THE GREAT AMERICAN DESERT

even the heaviest downpour. Because of the general porous nature of the soil the region is characterized by sub-surface drainage. The fluctuations in the ground water from time to time produce differences in the level of the lakes and ponds. During especially wet seasons the level of the lakes may be perceptibly elevated, due in all probability to seepage from the surrounding hills.

The most important stream of the Sand Hills is the Loup River, the three forks of which rise in low swampy flats toward the central portion of the region. Through the Sand Hills portion of its course the Middle Loup has a fall of about eight feet per mile and so develops considerable current which causes its bed and its channel to shift continually. The sand banks are cut and the channel veers from side to side along its course. This tendency culminates in the formation of many "oxbows"

PSM V80 D217 Middle loup river with sand hills in distance.png
Fig. 1. The Middle Loup River with Fringes of Woody Vegetation.
Sand Hills in the distance.

or loops. Some of these loops are most perfect and beautiful as viewed from far up in the hills. The streams of the region are all shallow, the Loup varying from one to six feet in depth with a channel about fifty yards wide. In many places such streams are extremely beautiful with their winding channels of clear swift water and fringes of vegetation.

The Dismal River is an important tributary to the Loup. Heading in the swamp and lake region of Hooker, Grant and McPherson counties, it continues eastward for about seventy-five or eighty miles, and pours into the Loup at Dunning. This river is an especially welcome sight as