The Formation of North America
At a spritely age of just 200 million years old, North America is one of the younger continents on planet Earth. Actually, 200 million years ago is just when North America first resembled its current shape. The actual continental crust that makes up the land mass has been around for much longer. Let's take a look at the evolution of the North American continent.
At a spritely age of just 200 million years old, North America is one of the younger continents on planet Earth. Actually, 200 million years ago is just when North America first resembled its current shape. The actual continental crust that makes up the land mass has been around for much longer. Let's take a look at the evolution of the North American continent.
The oldest part of North America is the Craton. The Craton makes up most of the North Eastern and Midwest regions of The United States as well as most of Canada and Greenland. The rock that comprises the Craton is about 2 billion years old, however it is very rarely visible at the surface in North America, as thick layers of sediment have settled over the bedrock and formed sedimentary rocks over the years. Geologists have given the name "Laurentia" to the first continent of which the Craton was a part. About 750 million years ago, Laurentia was part of an ancient supercontinent called "Rodinia" (In Images: How North America Grew as a Continent).
After being the dominant landmass on Earth for at least 350 million years, Rodinia began to break apart (Dance of the Giant Continents). Above is an image of what the world looked like approximately 542 million years ago. Laurentia is the yellow land mass in the middle that is surrounded by ocean (In Images: How North America Grew as a Continent).
During the Ordovician period, an island chain collided with the east coast of Laurentia. This collision resulted in the rise of the Appalachian Mountains. Although these mountains today are mostly just rolling hills, at their biggest they were the size of today's Himalaya and stretched from Greenland to Mississippi. Around 370 million years ago, there was a similar collision in the southwestern part of Laurentia. This raised mountains in what we now call Utah and Nevada (In Images: How North America Grew as a Continent).
About 300 million years ago, another supercontinent formed. This one was called Pangaea. The collisions that took place during the formation of Pangaea added to mountain building done during the Ordovician period (In Images: How North America Grew as a Continent).
The breakup of Pangaea is what brought Earth's continents to their current positions. 200 million years ago, the Atlantic Ocean opened up, and caused Laurentia to rift westward and away from Pangaea. As this happened, Laurentia got the name North America (In Images: How North America Grew as a Continent).
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Click here to watch a short animation complete with poorly produced Garageband soundtrack!
All images on this page are from: http://www.livescience.com/31910-north-america-geology-through-time.html unless otherwise specified.