Rock formations are truly a thing of beauty if you take the time to admire them. Too often people take them for granted, including the incredible processes and forces of nature that had to occur in order to make them what they are today.

Some of the most awe striking rock formations are located right here in the United States of America, more specifically in the Southwestern US. From Monument Valley to the Grand Canyon there are some seriously epic rock formations.

Monument Valley

Monument Valley

How did these formations get here? They aren’t man made structures so how exactly could that form? To get the answer, let’s start with the formation of rocks.

Formation of Rocks

Rocks typically form in one of three ways; sedimentary, igneous, and metamorphic.

Sedimentary rocks are aptly named because of their formation through the accumulation of sediments. You can start with something like sand or mud. Then that layer gets covered. As the original layer of sediment gets buried, it begins to compact becoming so dense that it forms a rock.

Igneous rocks are formed through crystallization of melt or magma. This magma is actually made up of pre-existing rocks which have been melted from the Earth’s mantle. It ends up passing upwards through cooler rock, forming rock types as it moves. These are typically found near coastlines and volcanic areas.

Metamorphic rocks were once our sedimentary or igneous friends but have been subjected to heat and pressure from the Earth’s crust. This heat and pressure can actually change the composition of the rock. These are often found in mountains.

Understanding the formation of rocks is important because we can understand how the rock itself got there. For example in the Southwestern US, sediments have built over time to form the initial structures of the formations we see today. However, they still needed to undergo another process in order for us to see the beautiful formations that stand before us today.

Erosion

Erosion is a naturally occurring process in which elements such as water flow or wind, remove soil and rock from the Earth’s crust and displace them elsewhere. There are multiple types of erosion that can lead to some pretty incredible sites.

To start, there are a few types of erosion that can lead to rock formations, but unlikely were the causes of rock formations such as the Grand Canyon or Monument Valley.

The first of those is considered Coastal Erosion. All of the gorgeous cliffs that you can find in coastlines such as Hawaii, Malibu, Ireland, Michigan, and more are all due in part to coastal erosion. The waves crashing into the sides of existing rock formations over centuries causes new formations to take place. This is known as wave pounding. Other types of coastal erosions such as hydraulic action, abrasion, and corrosion can also play part in eroding rock formations along the coast. However, obviously not the case the Southwestern U.S.

Another source of erosion but not the erosion in the area we are looking at, is glacial erosion. Glaciers can cause scouring, plucking, and thrusting. When glaciers move they can scour the rock formations they move against, polishing or cracking them.

Mass movement is a form of erosion that can play a part in areas such as the Southwestern U.S. Mass movement is basically gravity doing its job. Particles of the rock formation will break off due to gravitational forces and move downward and outward on a sloped surface.

However, the main sources of erosion you’ll see in the Grand Canyon and Monument Valley are water and wind related. The Grand Canyon has the Colorado River snaking through the base of it. This river was once much deeper and played a part in eroding the canyon walls. Additionally, rainfall and ice melt paved the way for other areas of erosion.

Grand Canyon

Grand Canyon

Now you might discount the strength of wind, but it actually plays a pivotal role in erosion. Wind erosion played a role in the Grand Canyon formation and a probably the primary role in forming the monuments of Monument Valley. Two main types of wind erosion exist including deflation and abrasion. Deflation is nature’s vacuum, picking up and carrying away loose particles. Abrasion occurs when the wind causes airborne particles to strike and wear down surfaces.

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