314 '^Ji<^ Atnerican Geologist. May, i9oo 
large and deep lakes may also for some time have received 
sediments from inflowing rivers and from shore erosion; but 
the view here presented by Davis, that fluviatile deposition 
accounts for the far greater part of these -Tertiary beds, 
seems most acceptable. 
Extending a similar revision to the explanation of for- 
mations on the Atlantic slope in the eastern United States, 
a region not considered by Davis, we may equally question 
the assumed marine sedimentation of the Lafayette and 
Columbia formations, which seem b)- their physical features 
and their fossil contents to be mainh' or wholly attributable 
to river deposition on land areas, from erosion of the Ap- 
palachian mountain belt, at times when that region has un- 
dergone epeirogenic uplifts. 
In the Old World the great efficienc)' of fluvial action for 
the formation of very extensive and thick deposits is grand- 
ly illustrated by the plains of the Hwang-ho, the Ganges 
and Indus, and the Po, and by the more ancient river beds 
now upturned and deeply eroded in the Siwalik hills. Dur- 
ing the Tertiary era the Rocky mountain belt and its in- 
closed basins and adjacent great plains appear, under the 
view taken by Davis, to have been even more remarkable 
for their river flood-plain formations. Until the problem of 
their origin shall be further studied and decided, it is ad- 
vised that Penck's term, continental, be applied to these for- 
mations, leaving the questions open, for investigation in 
every district, as to the interrelations and proportional 
shares of lacustrine, fluviatile, and seolian action, in the 
transportation and deposition of the sediments forming our 
western plains and intermontane parks. 
\v. u. 
