600 INLAND DUNES. 
Inland Dunes. 
Vast deposits of sand, both in the form of dunes and of 
plains, are found far in the interior of continents, in the Old 
World and inthe New. The deserts of Gobi, of Arabia, and 
of Africa have been rendered familiar by the narratives of 
travellers, but the sandy wildernesses of America, and even of 
Europe, have not yet been generally recognized as important 
elements in the geography of the regions where they occur. 
‘here are immense wastes of drifting sands in Poland and 
other interior parts of Europe, in Peru, and in the less known 
regions of our own Western territory, where their extent is 
greater than that of all the coast dunes together which have 
hitherto been described by European and American geogra- 
phers.* 
The inland sand-hills of both hemispheres are composed of 
substantially the same material and aggregated by the action 
of the same natural forces as the dunes of the coast. There 
is, therefore, a general resemblance between them, but they 
appear, nevertheless, to be distinguished by certain differences 
which a more attentive study may perhaps enable geologists 
to recognize in the sandstone formed by them. The sand of 
which they are composed comes in both principally from the 
bed of the sea being brought to the surface in one case by the 
action of the wind and the waves, in the other by geological 
upheaval.t The sand of the coast dunes is rendered, to a 
* On the Niobrara river alone, the dunes cover a surface of twenty thousand 
square miles.—HAYDEN, Report on Geological Survey of Wyoming, 1870, p. 108. 
{+ American observers do not agree in their descriptions of the form and 
character of the sand-grains which compose the interior dunes of the North 
American desert. C. C. Parry, geologist to the Mexican Boundary Com- 
mission, in describing the dunes near the station at a spring thirty-two miles 
west from the Rio Grande at El Paso, says: ‘‘ The separate grains of the sand 
composing the sand-hills are seen under a lens to be angular, and not rounded, 
as would be the case in regular beach deposits.”—U. S. Mexican Boundary 
Survey, Report of, vol. i., Geological Report of C. C. Parry, p. 10. 
In the general description of the country traversed, same volume, p. 47, 
