Gould — Tertiary Springs of Western Kansas, etc. 263 



Art. XXI. — Tertiary Springs of Western Kansas and 

 Oklahoma; by Charles J^ewton Gould. 



The western third of Kansas and a good part of north- 

 western Oklahoma are covered with the Tertiary formation. 

 This rock consists for the most part of a white or yellowish 

 clay with ledges and lenses of coarse sand and gravel inter- 

 spersed between. Ordinarily this formation covers the 

 level uplands of the region to the depth of from twenty to 

 that of several hundred feet. The streams have in many 

 cases cut their way through this rock into the underlying 

 formations, usually the Cretaceous or Permian. In many 

 instances the Tertiary may be recognized by one of two typ- 

 ical kind of rocks. Perhaps the most common of these con- 

 sists of rather precipitous chalky-white cliffs, often known 

 locally as gyp. cliffs (although there is no gypsum in their 

 composition). These are typical in northern Clark County 

 along the heads of Bluff, Bear and Sand Creeks. The other 

 kind is that of a very coarse, pebbly sandstone conglomerate. 

 This is often found along the bluffs of small streams and 

 sand-draws throughout the region. The pebbles are of all 

 sizes, shapes and colors, with white and pink predominating. 

 They are usually smooth and water-worn, having been washed 

 down from the Rocky Mountains during late geological time. 

 It is these pebbles, set free from their matrix by the disinte- 

 gration of the rock, that cover the slopes and form the gravely 

 points on so many of our western hillsides. 



The two kinds of rock spoken of above will serve to illus- 

 trate the character of the entire formation. It consists of 

 alternating layers of clay, sand and gravel. Perhaps the clay 

 occupies the greater part of the thickness, but the two kinds 

 of rock do not occupy a definite position with regard to each 

 other. They are arranged in alternating layers one above the 

 other, now the clay predominating, now almost the entire 

 thickness being composed of sand and gravel. Sometimes 

 wells will penetrate more than 100 feet without encountering 

 gravel ; again gravel and sand will be found all the way down. 



Now it is well known that clay is impervious to water while 

 sand (and much more readily gravel) permits the compara- 

 tively rapid flow of water through its particles. The rain 

 water falling upon the surface of the soil will sink into the 

 ground until it strikes a ledge of gravel when it slowly seeps 

 through the porous material until it finds its way to a con- 

 siderable depth. If a well penetrates this gravel bed, water 

 will accumulate and furnish a supply relative to the thickness 



