34 
Colorado Experiment Station 
ditions, will appear as an incrustation. This does not take place unless the 
water plane is at less distance from the surface than that through which 
capillarity can raise the water in the particular soil”. 
This is all true, but does not preclude the continuance of the for¬ 
mation of these salts at the present time at a sufficiently rapid rate to 
produce all of the salt with which we have to deal. It is simply a ques¬ 
tion of judging from the conditions which is the more probable source 
of these particular alkalis. If we have a heavily irrigated, high coun¬ 
try, such as many of our mesas, underlaid by shales rich in alkali, and 
we find the lower-lying adjacent land wet and strongly alkalied, we are 
justified in speaking of the shale as the source of the alkali without 
reference to the manner, place, or time of its original formation. The 
facts that we find, rightly interpreted, indicate that alkali is of recent 
origin. The wet land, with its abundance of alkali, shows that the 
shales let the water run through them and carry out the alkali. In 
short, it is washing them out. The long time and the water necessary 
to cut these mesas into their present shape would have done just what 
the irrigating waters are now doing. It is just as possible that the 
artesian water mentioned above carried the sodic sulfate into the sand¬ 
stone with it as that it dissolved it out of the sandstone. If we had no 
districts abounding in alkali, except within the Cretaceous shales, we 
might be justified in leaving the impression that our alkali questions 
are intimately connected with the occurrence of these shales and that 
otherwise we have no alkali questions. This is not true, for these 
shales have nothing to do with our most serious alkali questions, for 
the very simple reason that there are none of these shales in the coun¬ 
try where these questions arise, and yet we have square miles of this 
country whitened by these alkalis. Furthermore, we know the char¬ 
acter of the water that is discharged into this country and it does not 
contain these alkalis. The alkalis that I refer to as whitening the coun¬ 
try for many square miles at some seasons of the year are not confined 
to’ cultivated land; the most of it has never been irrigated since it was 
laid down. These alkalis are identical in every way with those referred 
to as coming from the shales. They consist of the same sulfates and 
other compounds and have without doubt been formed where we find 
them. While there has been moisture enough to bring about their forma¬ 
tion there has not been enough to wash them out of the soil, not even to 
wash them so deep into the soil as to remove them permanently from the 
surface, but they are at times washed into the soil only to come to the 
surface again. This is the accepted explanation, and what I have said 
regarding the shales does not in any way contradict it. In the region 
referred to we are dealing with a primary source and in the case of the 
shales with a mediate or secondary source. The salts present in the 
shales may have been in part formed within the shales and in part 
