270 University of Kansas Geological Survey. 
and those held together more firmly seem to be structureless as 
though the carbonate was deposited under such conditions that a 
crystalline form could not be assumed. 
Origin of the Cement.—The geologic period during which the 
cementing material was deposited is difficult to determine, but if the 
views herein expressed are correct, the accumulation of the cement 
began as soon as the climate became arid, and continues until the 
present time. It may be stated, however, without reserve that the 
cemented masses bear evidence of having been originally deposited 
without the cementing material, and that the latter was deposited 
within them by percolating waters after they were accumulated in 
beds as they are now found. A question of no little importance is 
what water carried the calcium carbonate and what was the source of 
the carbonate. To answer this it is desirable to consider first a few 
subjects which have an important bearing on the question. The 
Tertiary materials as has already been explained are principally 
derived from debris produced by the disintegration of crystalline 
rocks in the mountainous areas to the west. Such debris therefore 
contains a relatively large amount of calcium in one form or an- 
other. In this respect it is similar to the great mass of glacial 
debris scattered over so large a part of northern United States, 
which is generally supposed to have been principally produced by 
the weathering of crystalline rocks lying farther to the north. The 
recent weathering processes of the glacial material produces large 
quantities of calcium carbonate as is abundantly shown from 
the temporary ‘“‘hardness” of almost all the weil water found any- 
where throughout the glacial area. Is it not reasonable to sup- 
pose therefore that by the similar weathering of the Tertiary 
material in Kansas and elsewhere on the plains calcium carbonate 
will likewise be produced which would be changed to acid carbonate 
and dissolved by the surface waters were they existing in sufficient 
quantity ? 
The great mass of glacial material in northern United States at 
present lies in a humid climate. Therefore the rain waters fall upon 
the surface and dissolve the calcium carbonate as fast as it is 
formed, carrying it downward and away through the sub-drainage 
channels. On the great plains, however, the climatic conditions are 
