276 NEBRASKA STATE HORTICULTURAL SOCIETY. 



Such a loose sandy soil soaks up moisture very readily, so that after 

 a heavy fall of rain scarcely any water is drained from the surface into 

 the valleys, but all of it goes into the porous soil. Now and then rain- 

 storms of such torrential fierceness occur in the hills that a great quan- 

 tity of the sand is brought down from high on the hills and carried into 

 the valleys. Such storms are, however, exceptional, since the usual 

 heavier rains of about 1.0 — 1.5 in. are completely taken up by the sand, 

 with no surface drainage at all. 



In connection with the distribution of soil water in the Sand Hills 

 it is interesting to note that, although the sui'face of the sand is com- 

 monly as dry as powder, the sand but a few inches beneath the surface 

 is quite moist. The average of many soil samples taken during July, 

 1911 (a wet month for that year), in widely isolated stations at a depth 

 of twelve inches, showed the water content to be 3.27 per cent. The 

 Sand Hills rest upon a series of relatively impermeable clays and strati- 

 fied rocks. These layers of more solid materials crop out from the sur- 

 face along streams and on the lower slopes of some hills quite remote 

 from the deeper valleys. The soil is always moister upon a slope with 

 these outcrops than in situations where such are absent. 



The annual precipitation over the main body of Sand Hills varies 

 from twenty-three inches in the east to about fifteen Inches on the 

 western border. April, May and June are usually the wettest months of 

 the year, while the dry season frequently continues from August to 

 March or the first of April.^ In the central Sand Hills during the 

 month of July, 1911, five and one-half inches of rain fell. At the gov- 

 ernment forest nursery near Halsey (Thomas County) during this month 

 there was scarcely a day that rain did not fall. The showers were usu- 

 ally light, but a few were soaking rains. Hail sometimes accompanies 

 these thunderstorms in such quantity that a great amount of damage 

 is done to gardens, crops and other property. 



Most of the precipitation disappears into the soil at once. It is a 

 rare sight, if indeed it ever happens, that any of the streams or lakes of 

 the region show an increase in volume resulting from the run-off from 

 even the heaviest downpour. Because of the general porous nature of 

 the soil the region is characterized by sub-surface drainage. The fluc- 

 tuations 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" 



3 Data from official rccorcls of U. S. Forest Service at Halsey, Nebr., for last 

 seven years. 



