level which the oysters, and marine shells, found 800 miles inland
in the blue mountains of America, would seem to indicate ; for the
deposit (extending about three-quarters of a mile in each direction)
is boundèd by hills and small peaks, rising several hundred
feet above it, composed of the same tufa on which the sand and
. shells are deposited, and in the soil of which this small forest must
have been growing, thus ; which peaks and elevations present
no traces of sand on their surface, or elsewhere, 'above the highest
level of that in the flat, i. e., above 250 feet or thereabouts. Seeking
for that explanation; which rests on the fewest? arid 1 the
simplest causes, it occurred to me, when I first reached this bed of
sand, (which was on the southern side, where it is level with thè
water’s edge) that there might have been nò irruption or elevation
of the level of the sea; but a subsiderice- of the tufa strata (like
that of the shores'of Alexandria,1 rthich, according to' DOlomieu are
a foot lower than they were in the time of the Ptolemies), the
natural consequence of gravity, or one of those slips so frequently
evident along the coast, which led to a deposit of calcareous sand
on! the border of the sea,—which sand, from its extremely fine
grain, was readily dispersed by the winds, until it reached the
north side of the island (for it is barely three-quarters of a mile
broad on this part), where the drift line of the sand, with the tufa
on which it rests, is about fifty feet above the sea. But then,
should we find the marine shells in such heaps at the height of
250 feet ?-—Wóiild the sand have been so firmly agglutinated, as it
is in the indurated sheaths which ètìvèlòpe the trunks and'bran-
ches of the trees?—and could there be a regular, or dip line
descending S. 30.E.? I cannot help thinking, that there must have
been an irruption of the sea’from the northward, covering both this
small flat, and that already described in Porto Santo, (where a
marine shell,: an ampullina“, is also intermixed with the helices)
and depositing the bed of sand on both. However, I have
performed the most important part of my duty by particularizing
the, fact as well as I am able, and will therefore sayt no more. The
high cliffs on the- north side of: this part of the island, behind
Canifal, are broken off abruptly in their whole depth towards the
sea, and present; numerous dip lines of strata, deeply inclined to
the southward, from these broken faces ;- thus, as if a considerable
part of the island had been broken off or worn away on that side,
which would also sëerii to have been formed from a crater now
lost in the ocean, to the'northward.
I took leave of the worthy vicar (yitfr some regret, his reception’
had been so cordial, and, his mariners were so frank, and his,
hospitality so cheerful. It is painfrilj after being surprised by
meeting ari agreeable or éstiriiable character in a barren and almost
uninhabited corner of the world, to leave him without sonie proof
of respect, and without the smallest chance of future intercourse.
He had been twenty-three years in this miserable spot, without
preferment, or recompense beyond his own coriscierice, and still
remained without the hope, or' prospect of either.
“In addition to the fossil shells, which I found in the limestone at Baxo, I have
now to mention the mould of a> spondylus} and the upper valve of a lima.