in the high southern latitudes.

Why there should be a slow increase of cold on this portion of the
globe is because of the independent circulation of the waters of the
Southern Ocean. The strong westerly winds of the southern latitudes
are constantly blowing the surface waters of the sea from west to east
around the globe. This causes an effectual barrier, which the warm
tropical currents cannot penetrate to any great extent. For instance,
the tropical waters of the high ocean levels, which lie abreast Brazil
in the Atlantic and the east coast of Africa in the Indian Ocean, are
not attracted far into the southern sea, because the surface waters of
the latter sea are blown by the westerly winds from west to east
around the globe. Consequently the tropical waters moving southward
are turned away by the prevailing winds and currents from entering the
Southern Ocean. Thus the ice is accumulating on its lands, and the
temperature of its waters slowly falling through their contact with
the increasing ice; and such conditions will continue until the lands
of the high southern latitudes are again covered with glaciers, and a
southern ice period perfected. But while this gathering of ice is
being brought about, the antarctic continent, now nearly covered with
an ice sheet, will, through the extension of glaciers out into its
shallow waters, cover a larger area than now; for where the waters are
shoal the growing glaciers, resting on a firm bottom, will advance
into the sea, and this advancement will continue wherever the shallow
waters extend. Especially will this be the case where the snowfall is
great.

Under such conditions, it appears that the only extensive body of
shallow water extending from the ice-clad southern continent is the
shoal channel which separates the South Shetlands from Cape Horn,
which is a region of great snowfall. Therefore, should the antarctic
ice gain sufficient thickness to rest on the bottom of this shallow
sea, it would move into the Cape Horn channel, and eventually close
it. The ice growth would not be entirely from the southern continent,
but also from lands in the region of Cape Horn. Thus the antarctic
continent and South America would be connected by an isthmus of ice,
and consequently the independent circulation of the Southern Ocean
arrested. Hence it will be seen that the westerly winds, instead of
blowing the surface waters of the Southern Ocean constantly around the
globe, as they are