18 University of Kansas Geological Survey. 
The climatic conditions are such that precipitation is greatly limited, 
and the ground is usually so thoroughly desiccated that but little 
moisture is found near the surface. The general shape, or appear- 
ance, of the immediate source of the various arroyos are in many 
respects different from any heretofore observed in other parts of 
the state. However, they are most nearly approached in the eastern 
part by the little ravines the immediate source of which is on a 
hillside where a relatively thin mass of limestone protects a heavy 
bed of shale. Under such conditions, even in a humid climate, the 
peculiar shape of the arroyos is similar to the commonly occurring 
forms in the western part of the state. 
The main peculiarities referred to consist in the great width of 
the channel at its immediate source, and in the unusual abruptness 
of its banks. It is by no means rare to find an arroyo carrying a 
widih of a hundred feet or more to its immediate source, so that 
the very uppermost part of it will simply be the upper somewhat 
rounded end of a plat a hundred feet wide. The banks on either side 
of such arroyos frequently are so abrupt that one can with difficulty 
ride across them. Plate I is made from a photograph representing 
the peculiar shape of such a bluif-line along an arroyo in Meade 
county. while plate IJ likewise represents the side of an arroyo in 
Meade county. This peculiar shape prevails everywhere in the 
west, not a single instance having been found of the ordinary 
V-shaped ravine so common in humid climates where soft materials 
are eroded. 
The upper tributaries of the drainage channels in the west 
rarely have water in them more than a few weeks in the year. 
Therefore they evidently have not been eroded by the ordinary 
corrasive action of running water. This is further indicated by the 
fact that in nearly all cases the mat of grass covers the entire floor 
of the arroyo, the same as it does on the plains above. Such a cover- 
ing of grass could not exist did erosion occur in the bottom of the 
arroyos at the present time. | 
The question may then well be asked: How were such channels 
formed? It has appeared to the writer that probably we have here 
an origin of drainage channels differing from that ordinarily pro- 
duced elsewhere. It is certain that large quantities of material 
