is means, in spite of prohibitory laws, many harbors, in
various parts of the world, have been blocked up. We rarely transport
heavy materials to higher levels, and our pyramids and cities are
chiefly constructed of stone brought down from more elevated situations.
By ploughing up thousands of square miles, and exposing a surface for
part of the year to the action of the elements, we assist the abrading
force of rain, and diminish the conservative effects of vegetation.

CHAPTER XLV.

INCLOSING OF FOSSILS IN PEAT, BROWN SAND, AND VOLCANIC EJECTIONS.

Division of the subject--Imbedding of organic remains in deposits on
emerged land--Growth of peat--Site of ancient forests in Europe now
occupied by peat--Bog iron-ore--Preservation of animal substances in
peat--Miring of quadrupeds--Bursting of the Solway moss--Great
Dismal Swamp--Imbedding of organic bodies and human remains in blown
sand--Moving sands of African deserts--De Luc on their recent
origin--Buried temple of Ipsambul--Dried carcases in the
sands--Towns overwhelmed by sand-floods--Imbedding of organic and
other remains in volcanic formations on the land.

_Division of the subject._--The next subject of inquiry is the mode in
which the remains of animals and plants become fossil, or are buried in
the earth by natural causes. M. Constant Prevost has observed, that the
effects of geological causes are divisible into two great classes; those
produced during the submersion of land beneath the waters, and those
which take place after its emersion. Agreeably to this classification, I
shall consider, first, in what manner animal and vegetable remains
become included and preserved in deposits on emerged land, or that part
of the surface which is not _permanently_ covered by water, whether of
seas or lakes; secondly, the manner in which organic remains become
imbedded in subaqueous deposits.

Under the first division, I shall treat of the following topics:--1st,
the growth of peat, and the preservation of vegetable and animal remains
therein;--2dly, the burying of organic remains in blown sand;--3dly, of
the same in the ejections and alluviums of volcanoes;--4thly, in
alluviums generally, and in the ruins of landslips;--5thly, in the mud
and stalagmite of caves and fissures.

_Growth of Peat, and Preservation of Vegetable and Animal Remains
therein._

The generation of peat, when not completely under water, is confined