Digging into the Past
The Earth's landscape is shaped by tectonic
During the Silurian-Devonian periods, much of North America lay under a tropical
The sea retreated by the Carboniferous period, allowing land
Insects led animal colonization of land, followed by amphibians and other
in the Permian period.
The Permian period was followed by the Triassic, beginning the age of
Global climate began to cool during the Tertiary
Continued cooling triggered a series of Ice
in the Quaternary period.
The North American prairies evolved during the current
Jun 19, 2012