Earth Science: Plate Tectonics Present to Cambrian

These global maps are ordered from the present back to late precambrian times, but much of the text reads better "forwards." Summary statements are in blue. In all but the first map, red lines indicate divergent plate boundaries, and blue lines indicate subduction zones. "Ma" stands for "millions of years ago".

From the late Cretaceous to the present, rifts separated Africa from South America and then India, Australia, and Antarctica. North America rifted away from Europe. Then the rifted masses of old Gondwana, Africa, India, and Australia, moved northward towards Eurasia, closing the Tethys Ocean and forming the great Alpine-Himalayan mountains. As the process continues, a new super continent appears to be in the near geologic future, centered about the North Pole.

Southwestern North America intercepts the East Pacific Rise and a great extensional event, the Basin and Range orogeny begins. Orogeny continues in the Mediterranean region and India nears its junction with southern Asia.

The Atlantic lengthens and widens, the Sevier orogeny continues, and the Caribbean arc is formed.

During the middle Mesozoic, Pangaea began to rotate, but the different components of the huge mass rotated at different rates and then in different directions -- rifts began to form. The first of these was a southwestward tear on the mouth. It opened as the southern part of the North Atlantic Ocean and continued westward into the Gulf of Mexico. The Cordilleran arc was now firmly established along the Pacific margin of North and South America.

The Atlantic continues to expand as Pangaea breaks up. The Cimmerian orogeny continues. Arcs and micro continents slam into western North America and the Sevier orogeny begins.

The great supercontinent begins to fracture and the central Atlantic and Gulf of Mexico are born. A great arc is built on western North America and the Nevadan orogeny begins. Cimmeria begins its collision with Laurasia to form the Cimmerian orogeny.

During the latest Paleozoic into the early Mesozoic, Pangaea lay extant, across the equator. Several slices were removed from the northeastern margin of Gondwana and drifted across the Tethys Ocean to collide with Asia. Most notable were the Cimmerian blocks that included Turkey, Iran, Afghanistan, Tibet, and Malaysia. The western fringe of Pangaea was adjacent to a long subduction zone that formed the eastern margin of the Pacific "ring of fire".

Arc collision along western N. A. forms the Sonoman orogeny. As the Tethys Ocean expands, Cimmeria (Turkey, Iran, and Afghanistan) move northward towards Laurasia.

The supercontinent Pangaea dominates the Permian Earth. A new arc approaches western N. America. A new spreading center forms as Cimmeria rifts from Gondwana and marks the opening of the Tethyian Ocean.

During the middle and late Paleozoic, about a third of the Rodinian mass was torn apart and moved to equatorial regions. Most of these blocks were assembled by a series of plate collisions into the super continents of Laurussia [the Old Red continent] by the Devonian and Laurasia by the Pennsylvanian. Meanwhile the remains of Rodinia, Gondwana, rotated clockwise and moved northward to collide with Laurasia -- the result was the super continent Pangaea [all land]. Pangaea was shaped like a huge "pack man", mouth agape and facing eastward across the equator. The large,open mouth was the Tethys Ocean.

Laurussia and Siberia collide to form Laurasia; meanwhile Gondwana collides from the south. The resulting Appalachian, Ouachita, Marathon, Ural, Variscan, and Hercynian orogenies formed some of the largest mountains of all time. The Ancestral Rockies formed in west-central N. A.

The Antler arc collides with western North America creating the Antler orogeny. Gondwana, with a large, developing glacier, nears southern Laurussia.

The Caledonian-Acadian orogeny marks the assemblage of the macro continent Laurussia, sometimes called the "Old Red continent". Meanwhile, Gondwana closes in from the south. An arc approaches western North America from the west.

Baltica and the attached micro continent Avalonia begin colliding with North America in scissors fashion [north to south] to form the Caledonian-Acadian orogeny.

In the latest Precambrian and early Paleozoic, the supercontinent Rodinia, centered about the south pole, broke apart as blocks drifted northward. Most notable of these blocks were the large continents North America [Laurentia], Baltica, and Siberia.

Numerous plates and continental blocks approach North America from the south and east. The Taconic arc has just collided forming the Taconic orogeny.

North America lay isolated, stretched across the Cambrian equator. An arc approached from the south [east today] and Baltica and Siberia approached from the SE.

The supercontinent Rodinia lies about the south pole.
Last modified: Tue Mar 23 22:51:01 CST 1999