2 BULLETIN 54, U. S. DEPARTMENT OF AGRICULTURE, 
of the deposit if any exists. It can not be said that any one of these 
questions is more important than the others, since the solution of all 
will be essential to a full understanding of the greater problem. Itis 
fair to say, however, that the question first named must first besolved. 
It takes precedence, perhaps, not logically, but chronologically. It 
is obviously useless to spend time in study of the conditions which 
may have controlled segregation in a basin to which no pe has 
been supplied or from which it has escaped. — 
The problem, then, is first of all that of locating those areas in which 
potash reasonably may be expected to have accumulated and from 
which it apparently has not been withdrawn. This is not a matter of 
simple observation. There are only very few of the basins in which 
deposits of soluble salts are exposed on the surface and may be exam- 
ined directly. Nearly everywhere the salt bodies indicated on sub- 
stantial though theoretical grounds have been more or less deeply 
buried by later deposits. Their character, even their presence or 
absence, must be inferred from general geological evidences, appar- 
ently somewhat remote from the point at issue. 
_ Direct evidence being thus lacking and not easily obtainable, the 
first question (that of accumulation) becomes essentially one of topo- 
graphy and of areal geology. It is reasonable to expect that potash 
will have accumulated in largest quantity in that place where the 
greatest drainage has been concentrated for the longest time and 
where the rocks from which that drainage is derived are such as 
may reasonably be expected to yield potash most largely, easily, and 
rapidly. The matter may be reduced to three formal criteria: (1) 
The drainage area of the basin (past as well as present) ; (2) the exist- 
ence or possibility of a present or past overflow (which might have 
- removed the potash) ;. (3) the nature of the rocks and soils exposed to 
the drainage. 
Of these criteria the first two are the most important and both are 
essentially topographic. It is seldom that the rocks of an area are 
either entirely potash bearing or entirely the reverse. The study 
of the areal geology is not only seldom conclusive, but is always 
laborious and is obviously never necessary unless topographic con- 
ditions are known to be favorable. The first step of the inquiry is, 
therefore, the study of the topography of the undrained regions, and 
it is this step only which is taken in the present report. The writer 
here sets out to answer the question “In what basins has potash 
probably accumulated and been. retained in significant amount?” 
With the no less important matters of segregation and position (es- 
pecially depth) he is not here concerned. 
The topographic data upon which the report is based_have been 
gathered from many and various sources. Chief and most important 
are the topographic sheets of the United States Geological Survey, 
