Great Britain is almost exactly under the same latitude as Labrador, a
region of ice and snow. Apparently, the chief cause of the remarkable
difference between the two climates arises from the action of the great
oceanic Gulf-Stream, whereby this country is kept constantly encircled
with waters warmed by a West-Indian sun.
Were it not for this unceasing current from tropical seas, London,
instead of its present moderate average winter temperature of
6° above the freezing-point, might for many months annually be
ice-bound by a settled cold of 10° to 30° below that point, and
have its pleasant summer months replaced by a season so short
as not to allow corn to ripen, or only an alpine vegetation to
flourish.
Nor are we without evidence afforded by animal life of a greater
cold having prevailed in this country at a late geological period.
One case in particular occurs within eighty miles of London, at the
village of Chillesford, near Woodbridge, where, in a bed of clayey
sand of an age but little (geologically speaking) anterior to the
London gravel, Mr. Prestwich has found a group of fossil shells
in greater part identical with species now living in the seas of
Greenland and of similar latitudes, and which must evidently, from
their perfect condition and natural position, have existed in the
place where they are now met with.--_Lectures on the Geology of
Clapham, &c. by Joseph Prestwich, A.R.S., F.G.S._