un toward the sea, are marked by
impressions on their sides, which make them appear as a succession of
conic hills, with their tops very rugged. The higher ones that run
across, are more uniform in their appearance."

"In the forenoon of the 1st of August, after we had anchored in the
road, I went on shore to one of these valleys, with an intention to
reach the top of the remoter hills, which seemed covered with wood; but
time would not allow me to get farther than their foot. After walking
about three miles, I found no alteration in the appearance of the lower
hills, which produce great quantities of the _euphorbia Canariensis_. It
is surprising that this large succulent plant should thrive on so
burnt-up a soil. When broken which is easily done, the quantity of juice
is very great; and it might be supposed that, when dried, it would
shrivel to nothing; yet it is a pretty tough, though soft and light
wood. The people here believe its juice to be so caustic as to erode the
skin;[72] but I convinced them, though with much difficulty, to the
contrary, by thrusting my finger into the plant full of it, without
afterward wiping it off. They break down the bushes of _euphorbia_, and,
suffering them to dry, carry them home for fuel. I met with nothing else
growing there, but two or three small shrubs, and a few fig-trees near
the bottom of the valley."

[Footnote 72: Glas, p. 231, speaking of this plant, says, "that he
cannot imagine why the natives of the Canaries do not extract the juice,
and use it instead of pitch, for the bottoms of their boats." We now
learn from Mr Anderson their reason for not using it,--D].

"The basis of the hills is a heavy, compact, bluish stone, mixed with
some shining particles; and, on the surface, large masses of red friable
earth, or stone, are scattered about. I also often found the same
substance disposed in thick strata; and the little earth, strewed here
and there, was a blackish mould. There were likewise some pieces of
slag; one of which, from its weight and smooth surface, seemed almost
wholly metalline."

"The mouldering state of these hills is, doubtless, owing to the
perpetual action of the sun, which calcines their surface. This
mouldered part being afterward washed away by the heavy rains, perhaps
is the cause of their sides being so uneven. For, as the different
substances of which they are composed, are more or less easily affected
by the sun's heat, they will be carried away