2 14 KANSAS UNIVERSITY QUARTERLY. 



granites, somewhat mixed with the chalk beneath. Since the time of 

 the drying up of these Jakes the land has been again elevated and 

 the sandstones and sand deposits eroded down to the impervious 

 chalk and limestones beneath them in most of the valleys, leaving on 

 the uplands an immense area of remarkably flat lands with a gentle 

 inclination towards the east. I'he dip of the chalk and limestones is 

 markedly toward the northeast, but the old erosion is gently toward 

 the east, nearly parallel with the surface of the land above it. Lying 

 on this fairly uniform surface are the Tertiary sandstones of nearly 

 uniform thickness, from one to two hundred feet. Now, if I have 

 made my meaning clear, it will be seen that the water falling upon 

 the surface and percolating to the bottom of the pervious sandstones 

 and meeting the inclined surface of impervious chalk, will flow off 

 gradually to the east through the sand. It is this layer of water, of 

 unknown (piantity, which has received the name of sheet-water or 

 underflow. Where erosion in the valleys and along the eastern border 

 has exposed the line of contact between the sandstone and limestone, 

 water flows out, often in clear springs, usually under the later allu- 

 vium down into the valley. It thus happens that wherever in western 

 Kansas the valleys cut down through the sandstone there are pools of 

 water which never dry up, and even flowing streams. In earlier days 

 these pools were the favorite homes of many beavers and of countless 

 fishes. These streams or series of deep but narrow ponds, filled with 

 vegetation, are often ten, twenty or more miles in length, as in the 

 Saline river in Trego county, or the Smoky Hill at Wallace. After a 

 while, however, the water is absorbed through the adjacent soil and 

 the valleys are perpetually dry, or nearly so, save after rains. 



Simple as all this may be to one who has observed the cause, it has 

 been rarely understood in this part of the state, and I have seen 

 innumerable attempts to get water in the utterly barren chalk. There 

 is a considerable area of this waterless rock bordering the Tertiary, 

 as shown in the map, where irrigation from underground water is 

 simply out of the (juestion. The chief need of a geological survey 

 for irrigational purposes is to fix the limits of the water-bearing area 

 more closely. As given in the map, it is wholly derived from my 

 own observations, and can make no pretentions to close accuracy. 



In the comparatively limited area where this underflow sinks into 

 the alluvium, even good crops can often be raised wholly without 

 irrigation. In the dryest seasons I have seen excellent crops of wheat 

 on Butte Creek, near the western line of the state, that would have 

 done credit to eastern Kansas. And there is no doubt but that even 

 more of this underflow could be utilized by such crops as alfalfa, 

 which seek their moisture at considerable depths. 



