Introduction to Kansas Geology. 5) 
state. The streams usually have a considerable current due to the 
great incline of the surface as a whole, which, from west to east, 
averages nearly eight feet to the mile for the whole state. Toward 
the east part of the state they have broad and level valleys filled in 
for from 20 to 60 feet with alluvial material, while in the far west 
some of them have scarcely reached base level. 
The general physiographic conditions of the state are not as 
regular as is usually supposed. Although the surface is a great 
plain sloping eastward, its minuter topography is often varied and 
rugged; valleys 200 feet deep, bluffs and mounds with precipitous 
walls 300 feet high, overhanging rocky ledges, and remnants of 
cataracts and falls in numerous streams, giving a variety of scenery, 
are to be observed almost all over the eastern part the state, and 
to even a greater extent in some parts of the west. The physi- 
ography of a country is dependent upon its geologic structure, so 
that we may begin physiography by a study of structural geology. 
The rocky portions of the earth accessible to the student of 
geology are confined to the surface of the sphere. Mountain chains 
are elevated, deep gorges and river channels are worn, and vast 
faults, or dislocations, are made in various places, whereby the 
rocky strata are exposed so that an accurate knowledge can be 
gained of the surface to considerable depth provided the field of 
observation is sufficiently extended. It is now generally under- 
stood that the oldest rocks of the globe are massive in form and 
crystalline in structure. It is probable they represent the oldest 
parts of the earth which is exposed to view anywhere upon its 
surface. Itis likewise probable there was a time in the early history 
of the earth when the ocean waters entirely covered the whole 
surface of the sphere. Subsequent irregularities of the surface were 
produced by a contraction of the volume of the earth and portions 
of the ocean bottoms were lifted into dry land. No sooner was 
this accomplished than the ordinary agents of destruction and de- 
cay everywhere present in the atmosphere began acting upon these 
freshly exposed surfaces and resulted in wearing vast quantities 
of them away and carrying them back into the ocean by the drain- 
age which resulted from the rainfall. In this way sedimentary 
material was produced which, added to the various forms of sedi- 
