GLACIAL DEPOSITS OF THE CONTINENTAL TYPE 205 
Mendenhall, no striated pebbles were found, but other clays with 
striated pebbles have been observed. 
Sand dunes.—Overlying the outwash and till, in places, are 
dunes, and the. thickness of the sand is over 20 feet in one case. 
The cross-bedded sand, in other localities beneath till, gravel, and 
clay suggests either older sand dunes or cross-bedded outwash, 
but whether in pro-glacial deposits or in recessional deposits of an 
earlier oscillation is uncertain. The dunes observed are at the very 
edges of bluffs and the wind-blown material was derived from the 
modern outwash plains. Dune sand has been described by 
Schrader and Spencer,’ and by Mendenhall? and the authors 
have observed the same phenomena near the junction of the Copper, 
Chitina, and Kotsina rivers. 
Finer wind-blown material than the dune sand has not pre- 
viously been observed to our knowledge, except by Schrader and 
Spencer in 1900. They noted that ‘besides wind-blown deposits 
in the forms of dunes, the surface soil is frequently composed of 
fine sand, doubtless of similar origin, and careful investigation 
would probably show that eolian deposits are rather generally 
distributed over the Copper Basin.” 
THE LOESS OR EOLIAN SILT4 OF THE COPPER RIVER BASIN 
Localities —The localities where we have observed loess soil 
or eolian silt are (a) at Chitina near the southern edge of the Copper 
River basin just north of the Chugach Mountains; (6) at a number 
of localities along the military trail between Chitina and the 
Delta River pass across the Alaska Range, scattered throughout 
a distance of over 160 miles; and (c) near the junction of the 
«F.C. Schrader and A. C. Spencer, House Doc. 546, 56th Cong., 2d sess., 1901, 
p. 61. 
2W.C. Mendenhall, Prof. Paper 41, U.S. Geol. Survey (1905), pp. 64-65, 72. 
3 Op. cit., p. 61. 
4 Professor T. C. Chamberlin has suggested that this coarse wind-blown deposit 
from Alaska be called by some such name as Eolian silt or Loess soil, because of the 
desirability of retaining the term Loess as a structural term rather than one that is 
purely genetic, especially as a hard-and-fast genetic classification could not be justi- 
fied historically and presents insuperable difficulty in such a region as China, the great 
home of the loess, where fluvial Joess and eolian loess are most intimately intermingled. 
