The Birth of the Appalachian Mountains
The rocks at the core of the Appalachian Mountains formed more than a billion years ago. At that time, all of the continents were joined together in a single supercontinent surrounded by a single ocean. Remnants of the supercontinent make up much of the North American core and contain minerals that are more than a billion years old. We can see fragments of the billion-year-old supercontinent (shown in red in the figure) at the surface in many places in the Appalachian Mountains. Examples include Blowing Rock in northern North Carolina and Red Top Mountain in northern Georgia.
In this section, we will start at the beginning of the history recorded in the rocks and look at the major stages in the development of the mountains and landscape.
- The Supercontinent Breaks Up: About 750 million years ago, the supercontinent began to thin and rocks at depth pulled apart like warm taffy.
- Continental Collision: About 470 million years ago, the motion of the crustal plates changed and the continents began to move toward each other.
- Another Continental Breakup: After the continental collision that formed the Appalachian Mountains about 240 million years ago, the continental mass began to pull apart again.
- Carving the Mountains: For the last 100 million years, erosion has carved away the mountains, leaving only their cores standing on the ridges of today.
- What Next? Today, the age old geologic processes continue. Change is constant. Alist of suggested reading is made available for those wishing to further explore the changing geological landscape of the Appalachian Mountains
- Another Continental Break Up : The present-day margin of North America is the result of a reversal in crustal plate movement. After the continents collided, the continental mass began to pull apart.
- Carving the Mountains : While the Atlantic Ocean was still in its infancy, the Appalachians were already being attacked by erosion. At the time they formed, the Appalachians were much higher than they are now, more like the present-day Rocky Mountains.
- What Next
- The Supercontinent Breaks Up : About 750 million years ago, the supercontinent began to thin and pull apart like warm taffy because of expansion of the continental crust. Then, about 540 million years ago, the continental crust split into pieces that drifted away from each other.
- Continental Collision : How did rocks that formed on sea floors and islands become the mountains and valleys of today? About 470 million years ago, the motion of the crustal plates changed, and the continents began to move toward each other.
Encyclopedia ID: p1544
