DAVIS: THE PLATEAU PROVINCE OF UTAH AND ARIZONA. 43 
Johnson, Merriam, and Calkins, the lacustrine theory has been definitely 
replaced by theories of fluviatile or eolian agencies, and at present there. 
is evidently a strong tide of opinion turning from the unqualifiedly 
lacustrine origin of the various fresh-water Tertiaries; but in just what 
manner the unqualified lacustrine theory shall be amended or replaced 
is not yet apparent in all cases. Indeed, this aspect of the problem can 
be settled only by extended and detailed study in the field of each for- 
mation. It is essential in the prosecution of such study that a critical 
attention should be given to the deposits now accumulating in and 
around the basins of large and small, deep and shallow lakes, as well as 
on the flood-plains of large and small rivers; for at present one of the 
chief difficulties of the problem comes from a lack of knowledge regard- 
ing the characteristic minute structures of such deposits. Truly the 
day is passing when coarse conglomerates and cross-bedded sandstones 
can be described as of lacustrine origin without leaving some doubt in 
the mind of the geologist who reads so undiscriminating a description ; 
but the day has not yet come when even-bedded, fine-textured strata 
are habitually and critically examined to learn whether they are of lake- 
bottom or of flood-plain origin. 
It is confidently believed that one of the best aids towards the solution 
of the class of problems here considered that an observer can carry with 
him into the field is a careful analysis of the many possible conditions 
under which continental deposits may accumulate. It is in particular 
important to recognize on the one hand the very fine and uniform de- 
posits that should characterize the central area, and the coarse deposits 
that should accumulate around the marginal area of Jong-enduring lakes 
of large area and considerable depth, with their shores close against the 
base of encircling mountains; and on the other hand the very variable 
deposits that should characterize short-lived, fluctuating lakes of small 
area and slight depth, with ill-defined shores on gently sloping fluviatile 
plains of piedmont waste. With such an analysis in mind, the observer 
is likely to find it difficult to reconcile the theoretical conditions sug- 
gested by such phrases as a “lake of vast dimensions” and ‘ the great 
Eocene lake” with the variable deposits that prevail in many of the 
Tertiary basins. 
Eocene oF THE HicH Prateaus or Utag. — Our route to the head 
of Sevier river, south of Panguitch, and thence over the low divides to 
the headwaters of the Virgin river and of Upper Kanab creek and to the 
Pink cliffs of the Paunsagunt, led us past many excellent exposures of 
the Eocene, described by Howelland Dutton. The refreshed faces of the 
