he interior just as does the Gulf of Mexico, and each continent is
nearly cut in two where the canals of Suez and Panama respectively have
been trenched. Finally in the southern continents a long swing eastward
in America balances a similar swing westward in Africa. Thus Cape Saint
Roque and Cape Verde are separated by scarcely 16 degrees of longitude,
although the extreme points of the Gulf of Mexico and the Black Sea are
140 degrees apart. Finally to the south of the equator the continents
swing away from one another once more, preserving everywhere the same
curious inverse relationship.

Even more striking than the inverse resemblance of the New World to the
Old is the direct similarity of North and South America. In physical
form the two continents are astonishingly alike. Not only does each have
the typical triangular form which would naturally arise from tetrahedral
shrinking of the globe, but there are four other cardinal points of
resemblance. First, in the northeast each possesses an area of extremely
ancient rocks, the Laurentian highlands of Quebec and Labrador in North
America and the highlands of Guiana in South America. Second, in the
southeast lie highlands of old but not the most ancient rocks stretching
from northeast to southwest in the Appalachian region of North America,
and in the Brazilian mountains of the southern continent. Third, along
the western side of each continent recent crustal movements supplemented
by volcanic action on a magnificent scale have given rise to a complex
series of younger mountains, the two great cordilleras. Finally, the
spaces between the three mountain masses are occupied by a series of
vast confluent plains which in each case extend from the northern ocean
to the southern and bend around the southeastern highlands. These plains
are the newest part of America, for many of them have emerged from the
sea only in recent geological times. Taken as a whole the resemblance
between the two continents is striking.

If these four physiographic provinces of North and South America lay in
similar latitudes in the respective continents we might expect each pair
to have a closely similar effect on life. In fauna, flora, and even in
human history they would present broad and important resemblances. As a
matter of fact, however, they are as different as can well be imagined.
Where North America, is bathed by icy waters full of seals and floating
ice South America is bathed by warm sea