From first to last the civilization of America has been bound up with its physical environment.

Geologists are rapidly becoming convinced that the mammals spread from their central Asian point of origin largely because of great variations in climate.

Curiously enough man's body and his mind appear to differ in their climatic adaptations.

From first to last the civilization of America has been bound up with its physical environment.

In America the most widespread type of forest is the evergreen coniferous woodland of the north.

The buffalo is a surprisingly stupid animal.

America forms the longest and straightest bone in the earth's skeleton.