lerably perfect.
"Their presence," says Captain Cautley, "is easily accounted for, as a
great number of these and other animals are constantly lost in galloping
over the jungles and among the high grass by falling into deserted
wells."[1056]

Above the village of Selside, near Ingleborough in Yorkshire, a chasm of
enormous but unknown depth occurs in the scar-limestone, a member of the
carboniferous series. "The chasm," says Professor Sedgwick, "is
surrounded by grassy shelving banks, and many animals, tempted towards
its brink, have fallen down and perished in it. The approach of cattle
is now prevented by a strong lofty wall; but there can be no doubt that,
during the last two or three thousand years, great masses of bony
breccia must have accumulated in the lower parts of the great fissure,
which probably descends through the whole thickness of the
scar-limestone, to the depth of perhaps five or six hundred feet."[1057]

When any of these natural pit-falls happen to communicate with lines of
subterranean caverns, the bones, earth, and breccia, may sink by their
own weight, or be washed into the vaults below.

At the north extremity of the rock of Gibraltar are perpendicular
fissures, on the ledges of which a number of hawks nestle and rear their
young in the breeding season. They throw down from their nests the bones
of small birds, mice, and other animals, on which they feed, and these
are gradually united into a breccia of angular fragments of the
decomposing limestone with a cement of red earth.

At the pass of Escrinet in France, on the northern escarpment of the
Coiron hills, near Aubenas, I have seen a breccia in the act of forming.
Small pieces of disintegrating limestone are transported, during heavy
rains, by a streamlet, to the foot of the declivity, where land shells
are very abundant. The shells and pieces of stone soon become cemented
together by stalagmite into a compact mass, and the talus thus formed is
in one place fifty feet deep, and five hundred yards wide. So firmly is
the lowest portion consolidated, that it is quarried for mill-stones.

_Recent, stalagmitic limestone of Cuba._--One of the most singular
examples of the recent growth of stalagmitic limestone in caves and
fissures is that described by Mr. R. C. Taylor, as observable on the
north-east part of the island of Cuba.[1058] The country there is
composed of a white marble, in which are numerous cavities, partially
filled with a calca