ta, the character of
rivers entering an inland sea; the movements of the ocean being then
subordinate to the force of the rivers, and only slightly disturbing
their operations. The great gain of the delta in height and area takes
place during the inundations; and, during other seasons of the year, the
ocean makes reprisals, scouring out the channels, and sometimes
devouring rich alluvial plains.

_Islands formed and destroyed._--Major R. H. Colebrooke, in his account
of the course of the Ganges, relates examples of the rapid filling up of
some of its branches, and the excavation of new channels, where the
number of square miles of soil removed in a short time (the column of
earth being 114 feet high) was truly astonishing. Forty square miles, or
25,600 acres, are mentioned as having been carried away, in one place,
in the course of a few years.[370] The immense transportation of earthy
matter by the Ganges and Brahmapootra is proved by the great magnitude
of the islands formed in their channels during a period far short of
that of a man's life. Some of these, many miles in extent, have
originated in large sand-banks thrown up round the points at the angular
turning of the rivers, and afterwards insulated by breaches of the
streams. Others, formed in the main channel, are caused by some
obstruction at the bottom. A large tree, or a sunken boat, is sometimes
sufficient to check the current, and cause a deposit of sand, which
accumulates till it usurps a considerable portion of the channel. The
river then undermines its banks on each side, to supply the deficiency
in its bed, and the island is afterwards raised by fresh deposits during
every flood. In the great gulf below Luckipour, formed by the united
waters of the Ganges and Megna, some of the islands, says Rennell, rival
in size and fertility the Isle of Wight. While the river is forming new
islands in one part, it is sweeping away old ones in others. Those newly
formed are soon overrun with reeds, long grass, the Tamarix Indica, and
other shrubs, forming impenetrable thickets, where the tiger, the
rhinoceros, the buffalo, deer, and other wild animals, take shelter. It
is easy, therefore, to perceive, that both animal and vegetable remains
may occasionally be precipitated into the flood, and become imbedded in
the sediment which subsides in the delta.

Three or four species of crocodile, of two distinct sub-genera, abound
in the Ganges, and its tributary and contiguou