Some 225 million years ago all the
world's land masses were joined together
into one supercontinent, Pangaea, surrounded by a single universal sea,
Through the upheavals that we have since come to know as plate tectonics,
the shifting of the Earth's crust slowly tore the supercontinent asunder
about the middle of the Mesozoic period (approximately 180 million years
B.P.) and large bodies of land drifted across the surface of the Earth
to ultimately become our present-day continents.
This process is known as continental drift.
The theory of continental drift was first proposed by German meteorologist
Alfred Wegener in 1912. It was not until the 1960s, however, when geologist
Harry H. Hess and oceanographer Robert S. Dietz developed the theory of
seafloor spreading that Wegener's postulate gained acceptance.
Taken together, they led to the theory of plate tectonics, or global tectonics.
It is now believed that the several moving plates of the Earth's crust
are formed by volcanic activity at the oceanic ridges and destroyed in
great seafloor trenches at the margins of the continents, accounting for
the massive redefinition of the Earth's surface over millenia.
Certain species of terrestrial mammals became isolated, as a result, in
Antarctica, South America, Africa and Australia. It would be thousands
of years before volcanic eruption would reunite South America with the
North American continent again in a land bridge.
Pangaea Gazette with Illustrations
Gazette Template PDF file