HAWORTH. | Physical Properties of the Tertiary. Zils 
Cimarron sandhills rivaling those along the Arkansas river cover 
-wide areas. Jikewise north of the river in different parts of the 
country sandhills are by no means unknown, although they are not 
so abundant as south of the Arkansas. 
Origin of Sand Dunes.—it is probable that the first essential in 
the formation of sand dunes was the somewhat irregular depo- 
sition of sandy material during Tertiary time. One can hardly be- 
lieve that the distribution of sand throughout the Tertiary over 
the whole state was uniform. The cause of this lack of uniformity 
must be looked for in connection with the character of the drainage 
which brought the materials from the mountainous area and spread 
it over the great plains. A second factor which is doubtless im- 
portant, and which has heretofore received but little attention, is 
the action of water during recent times in carrying away the finer 
and more easily movable particles of clay and silt, leaving sand 
behind as a residual product. There are so many examples of this 
process producing accumulations of sand that one can not doubt 
its efficiency. In order to accomplish this result the surface of the 
country must have sufficient inclination to produce a comparatively 
rapid drainage. The greater portion of the great plains of Kansas 
does not possess such drainage, but we find it in almost ideal form in 
the southern part of the state from Meade county eastward to 
Barber county. Here the inclination to the southeast is frequently 
as much as 20 to 25 feet to the mile. Every stream that rises in the 
upland has cut its channel to a depth of from 100 to 200 feet. At 
its mouth the little stream has reached its base level and the deep- 
ening of the channel has long ago ceased, and a widening process 
has been carried to a considerable extent. This wide valley ‘or flood 
plain invariably is covered with sand which is simply a residual 
product left behind when the finer materials were carried away. The 
whole Tertiary from north to south contains a sufficient amount of 
sand to produce such residual masses were the proper drainage 
carried on. The production of many of the arroyos by sub-surface 
creeping, as already described in the article on drainage, would carry 
sand along with the silt and clay so that such sand washes or sand 
areas could not be produced by this kind of erosion. But'the sand 
