ts importance
as a metropolis, became a heap of ruins. The rapidity with which the
sun-dried bricks, of which even the most splendid oriental palaces are
often constructed, crumble down when exposed to rain and sun, and are
converted into mounds of ordinary earth and clay, is well known.
According to Captain Dangerfield, trap tuff and columnar basalt
constitute the rocks in the environs of Oujein[1033], and the volcanic
nature of these formations, from which the materials of the bricks were
originally derived, may have led to the idea of the city having been
overwhelmed by a volcanic eruption.

CHAPTER XLVI.

BURYING OF FOSSILS IN ALLUVIAL DEPOSITS AND IN CAVES.

Fossils in alluvium--Effects of sudden inundations--terrestrial
animals most abundantly preserved in alluvium where earthquakes
prevail--Marine alluvium--Buried town--Effects of Landslips--Organic
remains in fissures and caves--Form and dimensions of caverns--their
probable origin--Closed basins and subterranean rivers of the
Morea--Katavothra--Formation of breccias with red cement--Human
remains imbedded in Morea--Intermixture, in caves of South of France
and elsewhere, of human remains and bones of extinct quadrupeds, no
proof of former co-existence of man with those lost species.

_Fossils in alluvium._--The next subject for our consideration,
according to the division before proposed, is the embedding of organic
bodies in alluvium.

The gravel, sand, and mud in the bed of a river does not often contain
any animal or vegetable remains; for the whole mass is so continually
shifting its place, and the attrition of the various parts is so great,
that even the hardest rocks contained in it are, at length, ground down
to powder. But when sand and sediment are suddenly swept by a flood, and
then let fall upon the land, such an alluvium may envelop trees or the
remains of animals, which, in this manner, are often permanently
preserved. In the mud and sand produced by the floods in Scotland, in
1829, the dead and mutilated bodies of hares, rabbits, moles, mice,
partridges, and even the bodies of men, were found partially
buried.[1034] But in these and similar cases one flood usually effaces
the memorials left by another, and there is rarely a sufficient depth of
undisturbed transported matter, in any one spot, to preserve the organic
remains for ages from destruction.

Where earthquakes prevail, and the levels of a