DUDE, where’s the Grand Canyon?

Ya’ll, I am a certified Junior Ranger of the Grand Canyon National Forest.

Apparently, there’s a nifty little program called Junior Rangers, in most National Forests, Parks, and Monuments. Sure, it’s made for kids. But every ranger I’ve met (I’m now 5 levels of certified Jr.Rangerness) seemed more than happy to officiate my certification.

As for the title of this post… No, I’m not going Ashton Kutcher on you.

 Our lovely park ranger, giving the DUDE talk. 

DUDE is actually the acronym to explain how the Grand Canyon was formed.

Deposition. Uplift. Down cutting. Erosion. BAM. You now have a Grand Canyon.

Deposition

Deposition is the (duh) depositing of layers of sediment. There are three types of rock in the canyon: Sandstone, Limestone, and Shale. Determining where each type of rock sits in the formation of the canyon can identify what type of environment was present at that time.

Limestone is made up of calcium carbonate, which comes from the remains of organisms (meaning plants, microscopic animals, etc.). This indicates that the area was underwater as the limestone was formed – shells, particles, etc. all fell to the ocean floor and compressed into limestone.

Shale is what is formed after the ocean (which formed the limestone) recedes. It comes from swampy, muddy, beachy environments.

Sandstone is basically solidified sand, so these layers came about when the water had fully receded.

 See the flat horizon? Uplifted almost 2 miles, during a plate shift.

Uplift

I think one of the most striking features about the Grand Canyon is that, for the most part, it’s fairly level at the rim. You see the massive canyon below, and the completely flat horizon.

In actuality, the North Rim is a good 2,000ft higher in elevation than the South Rim.

So where does uplift come in? If anyone else was an arts major, and therefore took the easiest science courses possible to fulfill your minimum requirements, you’ll certainly know about plate tectonics.

At some point in history (I’m just a Jr. Ranger, don’t know specifics), a plate shift occurred, uplifting the Colorado Plateau that the Grand Canyon rests on.

Remember that the plate shift isn’t quite level on the two rims – this comes into play later!

 Grading my extremely tough Jr. Ranger handbook. 

Down cut

So we’ve got the layers of rock, and the elevation covered, but what about the actual canyon part of the Grand Canyon? That comes from down cutting, from the Colorado River.

The Colorado is a fast and forceful river, mainly due to the massive change in elevation it experiences through its course.  It actually has an elevation loss of about 7 feet per mile! Compare that with the Mississippi, which is closer to 1.5 feet per mile.

The river tumbles all different types of sediment – from small sand particles to large boulders – all of which cut down, little by little, to form the Grand Canyon.

Now we have dams in place to control the flow of the river. It’s estimated that the downcutting each year is only equivalent to the thickness of a sheet of paper. So, in 500 years, you would see the equivalent of a ream of paper cut into the canyon!  Not that significant. Actually, because of the damming of the river, some sediment is settling – meaning that the Grand Canyon is (very very incrementally and not really noticeably at all) filling back up! 🙂

  Discussing official ranger information. 

Erosion

What makes the Grand Canyon so pretty, in my opinion, is the hundreds of ridges and “side canyons” that stem out from the Colorado River. How did this canyon, which can be up to 18 miles wide, develop from a river with an average width of 300 feet? These are all due to erosion.

You can see that the North Rim is a little more eroded than the South Rim – more interesting crags and canyons are on that side! This is because of the plate shift I mentioned earlier. With the higher altitude, the North Rim experiences more rain, and more runoff. Water flow into the canyon is greater on the north side, as well.

 After two young kids in our tour group were certified, several “adults” wanted to join in!

And now it’s official! 

Hope you enjoyed my little seminar on the creation of the Grand Canyon! Pretty helpful acronym to know!