In whatever way we may account for the series of geological
changes thus cursorily enumerated, they must have required immense
periods of time; and we have Mr. Babbage’s authority for saying,
that even those formations which are nearest to the surface have
occupied vast periods, probably millions of years.* It is only with
these latest formations, however, that we shall have any immediate
concern.
The D il u v iu m , or drift, as now called, is almost universal in extent
(except within the tropics); and,is marked by deposits of clay and
sand; and erratic blocks or boulders of all sizes, from common
pebbles to masses thousands of tons in weight, occur at all levels up
to the summits of lofty mountains, where no agency now in operation
could have placed them. The drift abounds in fossil remains of
animals; such as the elephant, mastodon, rhinoceros, hippopotamus,
and other large mammalia: genera which, now living only in warm
climates, must have then existed in England, Erance, Germany, and
other northern countries. These animals were destroyed by the same
inundations which left the deposits we call drift: yet the works and
the remains of man have been found among them! These drift-forma-
tions are of immense antiquity, being in this country older than the
basin of the Mississippi; and may be regarded as the last great transition
in the earth’s geological history.
All formations of the drift do not belong to one and the same period;
nor were they produced by the same causes. According to the
glacial theory of Prof. Agassiz, the climate of the northern hemi-
sphere, which had been of tropical warmth, became colder at the
close of the tertiary era. The polar gla,ciers advanced towards the
south, leaving the marks of their, passage in the ground and upon
striated surfaces of rocks and mountains, whilst distributing on every
side the blocks and masses they had entangled in their course: which
last, with the finer detritus, were swept far and wide by torrents
occasioned by the melting of these glaciers.
At other times, a sudden elevation of mountain-chains from
beneath the surface of the sea, produced violent inundations of
surrounding countries, and transported boulders and drift in every
direction. The Alps furnish illustrations in point. They have been
heaved up since the deposition of the tertiary strata; for those strata
are found capping their summits or lying in their mountain-valleys;
while the “ drift” is seen scattered in all directions — on the range
of the Jura, and over the plains of Lombardy. Blocks of granite,
10,000 cubic feet in size, have been found in the Jura mountains,
2000 feet above the Lake of Geneva. The rock in Horeb, from which
* Babbage: Bridgewater Treatise.
the leader in Israel miraculously drew water, is a mass of syenitic
granite, six yards square, lying insulated upon a plain near Mount
Sinai. There are displays of the drift in our own country, on a magnificent
scale, hut as our object does not require, nor our limits allow,
more than a mere reference to this as an interesting stage in the
earth’s antiquity, we pass on.
Last comes the A l l u v ium ; that is, the formation along the margins
of rivers and the deltas at their mouths, and the deposition of those
superficial coverings of soil which have taken place since the earth
assumed its present configuration of sea and land. Of the antiquity
of the- older formations, fossils have afforded unerring information;
each set serving as medals to mark the epoch of their existence. The
alluvium must he judged by comparison, and all we shall attempt
is, to show that the earth, in its present condition, has been the Itabi-
tation of man for many thousand years longer than people* com-
monly suppose.
It appears, from recent observations,* that the hydrographic basin
of the Mile (within the limits of rain), is about 1,550,000 square miles,
and the whole habitable land of Egypt is formed of the alluvial deposits
of the river. The Delta is of a fan-like form, narrow at its
apex below Cairo, and spreading out as it extends towards the sea,
until its outer border is about 120 miles in extent. The same immense
deposits are still carried annually to the sea, yet the Delta has
not perceptibly increased within the limits of history. Tanis, the
Hebrew Zoan, at a very remote period of Egyptian annals, was built
upon a plain at some distance from the sea; and its ruins may still be
seen, within a few miles of the coast. The lapse of more than 3000
years, from the time of Ramses H., has not produced any great increase
in the alluvial plain, nor extended it farther into the Mediterranean.
Cities which stood, in his day, upon the coast, and were even then
referred to the gods Osiris and Horus, may still be traced at the same
localities; and Homer makes Menelaus anchor his fleet at Canopus,
at the mouth of the Egyptus or Mile.f In short, we know that in
the days of the earliest Pharaohs, the Delta, as it now exists, was
covered with ancient cities, and filled with a dense population, whose
civilization must have required a period going back far beyond any
date that has yet been assigned to the Deluge of Moah or even to the
Creation of the world.
The average depth of the Gulf of Mexico, between Cape Florida
* Beke, in Gliddon’s Handbook to the Nile, 1849, p. 29; and, Map of the “ Basin of the
Nile.” .'
■j* Wilkinson: Manners and Customs, i. p. 5—1 1 ; ii. 1 0 5 -1 2 1 : — Gliddon, Chapters, p. 4 2 -3 .