posed in great
part of sand, shingle, and boulders, the only fossils observed being the
vertebrae of a crocodile, shell of a trionyx, and fragments of wood very
little altered, and similar to that buried in beds far above. These
gravelly beds constituted the bottom of the section at the depth of 481
feet, when the operations were discontinued, in consequence of an
accident which happened to the auger.

The occurrence of pebbles at the depths of 120 and 400 feet implies an
important change in the geographical condition of the region around or
near Calcutta. The fall of the river, or the general slope of the
alluvial plain may have been formerly greater; or, before a general and
perhaps unequal subsidence, hills once nearer the present base of the
delta may have risen several hundred feet, forming islands in the bay,
which may have sunk gradually, and become buried under fluviatile
sediment.

_Antiquity of the delta._--It would be a matter of no small scientific
interest, if experiments were made to enable us to determine, with some
degree of accuracy, the mean quantity of earthy matter discharged
annually into the sea by the united waters of the Ganges and
Brahmapootra. The Rev. Mr. Everest instituted, in 1831-2, a series of
observations on the earthy matter brought down by the Ganges, at
Ghazepoor, 500 miles from the sea. He found that, in 1831, the number of
cubic feet of water discharged by the river per second at that place
was, during the

Rains (4 months) 494,208
Winter (5 months) 71,200
Hot weather (3 months) 36,330

so that we may state in round numbers that 500,000 cubic feet per second
flow down during the four months of the flood season, from June to
September, and less than 60,000 per second during the remaining eight
months.

The average quantity of solid matter suspended in the water during the
rains was, by weight, 1/428th part; but as the water is about one-half
the specific gravity of the dried mud, the solid matter discharged is
1/856th part in bulk, or 577 cubic feet per second. This gives a total
of 6,082,041,600 cubic feet for the discharge in the 122 days of the
rain. The proportion of sediment in the waters at other seasons was
comparatively insignificant, the total amount during the five winter
months being only 247,881,600 cubic feet, and during the three months of
hot weather 38,154,240 cubic feet. The total annual discharge, then,
would be 6,368,077,440 cubic f