Miocene, and Pliocene formations. In answer to this
inquiry, it may certainly be affirmed, that an oscillation of climate
has occurred in times immediately antecedent to the peopling of the
earth by man; but proof of the intercalation of a less genial climate at
an era when nearly all the marine and terrestrial testacea had already
become specifically the same as those now living, by no means rebuts the
conclusion previously drawn, in favor of a warmer condition of the
globe, during the ages which elapsed while the tertiary strata were
deposited. In some of the most superficial patches of sand, gravel, and
loam, scattered very generally over Europe, and containing recent
shells, the remains of extinct species of land quadrupeds have been
found, especially in places where the alluvial matter appears to have
been washed into small lakes, or into depressions in the plains
bordering ancient rivers. Similar deposits have also been lodged in
rents and caverns of rocks, where they may have been swept in by land
floods, or introduced by engulphed rivers during changes in the physical
geography of these countries. The various circumstances under which the
bones of animals have been thus preserved, will be more fully considered
hereafter;[127] I shall only state here, that among the extinct mammalia
thus entombed, we find species of the elephant, rhinoceros,
hippopotamus, bear, hyaena, lion, tiger, monkey (macacus[128]), and many
others; consisting partly of genera now confined to warmer regions.

It is certainly probable that when some of these quadrupeds abounded in
Europe, the climate was milder than that now experienced. The
hippopotamus, for example, is now only met with where the temperature of
the water is warm and nearly uniform throughout the year, and where the
rivers are never frozen over. Yet when the great fossil species
(_Hippopotamus major_, Cuv.) inhabited England, the testacea of our
country were nearly the same as those now existing, and the climate
cannot be supposed to have been very hot. The bones of this animal have
lately been found by Mr. Strickland, together with those of a bear and
other mammalia, at Cropthorn, near Evesham, in Worcestershire, in
alluvial sand, together with twenty-three species of terrestrial and
freshwater shells, all, with two exceptions, of British species. The bed
of sand, containing the shells and bones, reposes on lias, and is
covered with alternating strata of gravel, sand, and l