Building the Appalachian Mountains How did the Appalachians
Building the Appalachian Mountains
How did the Appalachian’s form? : Step 1: The Crustal Rocks Form • The crustal rocks of the Appalachian Mountains are more than 1 Billion years old. • These rocks formed when there was a single continent surrounded by ocean. • But then the supercontinent pulled apart. . .
How did the Appalachian’s form? : Step 2: Continental Drift • At first the pieces of the supercontinent drifted apart. – Copper, zinc, iron and sulfur were deposited on the sea floor. • Then, 470 Million years ago the motion--the continents began to move toward each other. – Volcanoes were frequent. – Some of the sea floor was pushed onto the continents.
How did the Appalachian’s form? : Step 3: Continental Collision • About 270 million years ago, the North American and African plates collided. • This is a convergent continental-continental boundary.
How did the Appalachian’s form? : Step 3 : Continental Collision (continued) • Since the plates have the same densities, they pushed most of the crustal rocks upward. • Some rocks were trapped below ground and were transformed into granite, quartz, emeralds, slate, and shale.
How did the Appalachian’s form? : Step 4: Effects of Continental Collision • Earthquakes were common. – Happens as crustal rocks slide along a fault. • Atlantic Ocean begins to form.
Changing the Appalachian Mountains: Erosion • Erosion via wind, water, and ice have affected the shape of the peaks – Originally high, steep, sharp – Now lower, gently sloped, and rounded
Changing the Appalachian Mountains: Glaciers • Glaciers have moved into the area 4 times during the past 2 -3 million years: – Induced climate change – Carved into the mountains – Deposited sediment
Today’s North Carolina • Continued erosion of the peaks – Eroded material moves down the mountains into the Piedmont region but then stops. • The fall line is where the material stops. – This line separates the Piedmont and Coastal Plains regions.
Today’s North Carolina • Earthquakes – Very few occur – Less than 4. 0 on the Richter scale • Gold – Once produced the most of any state – Changed with the California Gold Rush • Emeralds – Still being mined – Many of the world’s largest emeralds
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