Geology And Geophysics

Explaining Pangaea

Red Dwyer's image for:
"Explaining Pangaea"
Image by: 

Pangaea is a Greek word meaning "all land", which is why scientists chose that name for the single continent on Earth during the Permian Era, 225 million years ago. Pangaea stretched from North Pole to South Pole and was C-shaped. The single universal ocean was Panthalassa.

Over the next 25 million years, Pangaea responded to volcanic activity, earthquakes and the shifting of the molten rock beneath it. At the end of the Triassic Period, Pangaea broke into two "supercontinents", Gondwanaland and Laurasia, respectively south and north of the Tethys Sea.

During the Mesozoic Period, 180 million years ago, Gondwanaland, the southern supercontinent, would break up into South America, Africa, India, Australia and Antarctica. Laurasia, the northern supercontinent, would break into North America, Greenland, and Eurasia. Thousands of years of volcanic activity would eventually reconnect North and South America. Continental drift would unite Eurasia with India and bring them closer to Africa.

The first mention of the possibility of Pangaea is mentioned in 1596, by a Dutch mapmaker, Abraham Ortelius. He theorized that studying the coastlines of the continents, specifically Europe, Africa and the Americas, one could surmise the three connected at one time, but later ripped apart by "earthquakes and floods".

In 1912, Alfred Wegener, a German geologist and meteorologist, propose the theory of continental drift. He theorized the Earth's crust was a series of earthen plates which moved on a bed of molten rock or lava. It would be after 1960 before Wegener's postulate would gain acceptance. Geologist Harry Hess and oceanographer Robert Dietz developed and proved the theory of seafloor separation, which validated Wegener's theory and streamlined the theory of plate tectonics.

Seismology, the study of earthquakes, supports the theory of Pangaea's break up. Seismic activity is noted as most severe on the edges of continental plates. The simple explanation is that earthquakes are most likely when plates collide.

Paleontology, the study of fossils, supports the plate tectonic theory and holds the key to Pangaea's history. Today, we know migration of the animals across Pangaea is documented by fossil remains found in both the northern and southern hemisphere. Fossilized Glossopteris, a tree-like, tropical fern, are found near polar regions. Fossils of Mesosaurus, a marine reptile, are found in deeply southern South America, Antarctica and South Africa, where they could not survive in today's climate.

When Pangaea broke, terrestrial animals were isolated. Some species were further isolated to the continents of Antarctica, Africa Australia and South America. Each species would travel different evolutionary paths based on the changes in the climates on the smaller continents.

Discovery of glacial deposits in arid regions Africa further support the theory of Pangaea. Mismatches in the geological history and current climates attest to the fact today's continents were not always where they are now.

References: _On the Origin of Continents and Oceans_, Wegener 1915; _Thesaurus Geographicus_, Ortelius 1596;;;;

More about this author: Red Dwyer

From Around the Web