Rocky Mountains Orogeny

Now that we’ve discovered how the Appalachian Mountains were formed, I did some research to learn about the other major mountain range of America. The Rocky mountains are located in the western part of the country from the northernmost part of British Columbia, in Canada, to New Mexico, in the United States. The Rocky Mountains are taller than the Appalachians today; however, this was not the case millions of years ago. So how did the Rockies get there?

Over Earth’s 4.5 billion years of existence, the landscape has been reshaped many times by the movement of the Earth’s crust; also known as plate tectonics. Oceans and mountains have been formed and erased and reformed again. 2.8-2.4 billion rocks formed underneath where the present day Rockies exist at depths around six miles deep. These rocks were later uplifted during a mountain forming period. The mountains eventually eroded away to leave the “roots” of the Rocky Mountain range. Some of the rock capping in the central Teton Range of the Rockies has been dated to 2.4 million years old. Eventually the mountain forming ceased and the land around the peaks continued to erode. 570 million to 240 million years ago, the western part of the North American plate was continually flooded with seas and this area was mostly under water. During this time, the west coast shoreline ran down through Colorado and Wyoming. Also at this time, the deep sea periods deposited limestone, sandstone, and shale layers on top of the crust. 240-66 million years ago during the Mesozoic period, the land was covered in sand dunes, vast tidal flats, swamps, seas, and plains. The dinosaurs lived on the edge of the Rockies along the shores of a great sea that covered the center of the North American plate. This great shallow sea stretched from present Mississippi River to Texas, Colorado, Utah, and the Dakotas.  The shore area near the Rockies (Wyoming and Western Montana) has become a fossil haven because of the land at the time was ripe for dinosaurs and the fossilization process. The sea left thick deposits of shale and sandstone. But, organic-rich sediments transformed by heat and pressure became coal and oil. During the Cretaceous period, the western North America plate was squeezed and pushed by the Pacific oceanic plate. This is what ultimately built the Rockies. The first named orogeny has been labeled the Sevier Orogeny, which started about 110 million years ago. Huge parts of the land were uplifted into folds or thrust into low-angled faults. 80 million years ago, the Laramide Orogeny period began. This is what later became the Teton mountain Range. The past 66 million years; volcanoes, earthquakes, and glaciers shaped what is today’s Rocky Mountains. The subducted Pacific plate reaked havoc on the North American plate above it. As the oceanic plate dove under the continental plate, the crust melted as it got closer to the mantle.  Some of the melted crust floated back up to the surface and collected silica rich melted rock along the way. This is what caused the explosive volcanoes that formed and shaped the range.



This entry was posted in Uncategorized. Bookmark the permalink.

One Response to Rocky Mountains Orogeny

  1. bw44c says:

    I knew that the Rocky Mountains took up a large land mass, but I did not know that they had such a large affect on the entire west coast. It is also very interesting that dinosaurs thrived through this mountainous terrain.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s