a little eastward of the gorge. When I endeavoured to follow these streams
over the stony level plain, which is almost destitute of soil and
vegetation, I was much surprised to find, that although composed of hard
basaltic matter, and not having been exposed to marine denudation, all
distant traces of them soon became utterly lost. But I have since observed
at the Galapagos Archipelago, that it is often impossible to follow even
great deluges of quite recent lava across older streams, except by the size
of the bushes growing on them, or by the comparative states of glossiness
of their surfaces,--characters which a short lapse of time would be
sufficient quite to obscure. I may remark, that in a level country, with a
dry climate, and with the wind blowing always in one direction (as at the
Cape de Verde Archipelago), the effects of atmospheric degradation are
probably much greater than would at first be expected; for soil in this
case accumulates only in a few protected hollows, and being blown in one
direction, it is always travelling towards the sea in the form of the
finest dust, leaving the surface of the rocks bare, and exposed to the full
effects of renewed meteoric action.

INLAND HILLS OF MORE ANCIENT VOLCANIC ROCKS.

These hills are laid down by eye, and marked as A, B, C, etc., in Map 1.
They are related in mineralogical composition, and are probably directly
continuous with the lowest rocks exposed on the coast. These hills, viewed
from a distance, appear as if they had once formed part of an irregular
tableland, and from their corresponding structure and composition this
probably has been the case. They have flat, slightly inclined summits, and
are, on an average, about six hundred feet in height; they present their
steepest slope towards the interior of the island, from which point they
radiate outwards, and are separated from each other by broad and deep
valleys, through which the great streams of lava, forming the coast-plains,