Laurentia

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Laurentia is the North American craton in this image.

Laurentia is the original form of the North American continent, which existed between 3 billion years ago, and still does today in its more common name, North America. However, it also included Scotland, and it lacked Florida and most of Central America. Laurentia was named after St. Lawrence of Rome.

Tectonic Plates[edit]

Laurentia associates with many tectonic plates. The main North American Plate not only includes the continent, but also Russia east of Magadan, Sakhalin, and Japan north of Tokyo. However, they are sometimes considered part of their own individual plate, called the Okhotsk plate. The second plate is the Juan de Fuca plate, located off the coast of Vancouver. However, the Juan de Fuca plate's southern fraction, located off the coast of California, is sometimes also considered separate and is called the Gorda plate. The third is the Cocos Plate, located off the coast of Mexico. The Juan de Fuca and Cocos Plates were remnants of the Farallon Plate, a tectonic plate that collided with and subducted under North America in the Cretaceous period. By today, almost all of the Farallon Plate had been subducted under the North American plate, with only a few chunks of it remaining.

Geological History[edit]

  • 700 million years ago, Laurentia was part of the major supercontinent Rodinia.
  • 650 million years ago, Australia broke away from Laurentia's western coast, opening the Pacific Ocean
  • Around 600 million years ago, Laurentia was part of the major supercontinent Pannotia.
  • In the Cambrian (540 million years ago), Laurentia was an independent continent.
  • In the Devonian (420 million years ago), Laurentia collided against Baltica, forming the minor supercontinent Laurussia.
  • In the Permian (250 million years ago), all major continents, including Laurentia, collide against each other for forming the major supercontinent Pangaea.
  • In the Jurassic (150 million years ago), Africa's tectonic plate separated from Laurentia opening parts of the Atlantic Ocean.
  • In the Cretaceous (120 million years ago), the Farallon plate collided with and subducted under Laurentia, which was an independent continent called North America.
  • In the Neogene (45 million years ago), Europe's tectonic plate separated from Laurentia, opening the North Atlantic Ocean.
  • Today, Laurentia is an independent continent called North America, after Italian navigator Amerigo Vespucci.
  • 200 million years from now, Laurentia, alias North America, will have collided with either Africa, forming the supercontinent Pangaea Ultima, or Asia, forming the supercontinent Novopangaea, which was depicted in the documentary The Future is Wild.

Test[edit]

By now, you should have a good idea of the history of the continent of North America. See if you can correctly answer the following test:

1

at what rate is the San Andreas Fault moving per year?

33mm
5 cm
10 cm
25 mm

2

In order for the Colorado River to carve the deep Grand Canyon, what must happen first?

Uplift of the Colorado plateau
Breakup of a supercontinent
Collision with another continent
Volcanic activity

3

The Yellowstone supervolcano has developed as a result of:

Subduction of the Farallon plate under North America
Movement along the San Andreas fault
Extension across the basin and range province
Upwelling of magma from the mantle (i.e. a hotspot)

4

Shallow subduction of the Farallon plate and subsequent uplift of the Rocky Mountains (i.e., Laramide orogeny) occurred:

200 million years ago
650 million years ago
85 million years ago
15 million years ago