struck me as curious. On approaching, among the
sand-hills, an open level space, covered thickly over with water-rolled
pebbles and gravel, I was surprised to see that, dry and hot as the day
was elsewhere, the little open space seemed to have been subjected to a
weighty dew or smart shower. The pebbles glistened bright in the sun,
and bore the darkened hue of recent wet. On examination, however, I
found that the rays were reflected, not from wetted, but from polished
surfaces. The light grains of sand, dashed against the pebbles by the
winds during a long series of years--grain after grain repeating its
minute blow, where, mayhap, millions of grains had struck before--had at
length given a resinous-looking, uneven polish to all their exposed
portions, while the portions covered up retained the dull unglossy coat
given them of old by the agencies of friction and water. I have not
heard the peculiarity described as a characteristic of the arenaceous
deserts; but though it seems to have escaped notice, it will, I doubt
not, be found to obtain wherever there are sands for the winds to waft
along, and hard pebbles against which the grains may be propelled. In
examining, many years after, a few specimens of silicified wood brought
from the Egyptian desert, I at once recognised on their flinty surfaces
the resinous-like gloss of the pebbles of Culbin; nor can I doubt that,
if geology has its sub-aerial formations of consolidated sand, they
will be found characterized by their polished pebbles. I marked several
other peculiarities of the formation. In some of the abrupter sections
laid open by the winds, tufts of the bent-grass (_Arundo
arenaria_--common here, as in all sandy wastes) that had been buried up
where they grew, might be distinctly traced, each upright in itself, but
rising tuft above tuft in the steep angle of the hillock which they had
originally covered. And though, from their dark colour, relieved against
the lighter hue of the sand, they reminded me of the carbonaceous
markings of sandstone of the Coal Measures, I recognised at least _their
arrangement_ as unique. It seems to be such an arrangement--sloping in
the general line, but upright in each of the tufts--as could take place
in only a sub-aerial formation. I observed further, that in frequent
instances there occurred on the surface of the sand, around decaying
tufts of the bent-grass, deeply-marked circles, as if drawn by a pair of
compasses or a trainer--