# Example Question 2 what is the approximate rate of Colorado River downcutting (incision) at this loc

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Example Question 2
what is the approximate rate of Colorado River downcutting (incision) at this location (Latitude: : 36.0135 Longitude: -111.911) in meters per million years?

Step 1: Fast Travel to these coordinates Latitude: 36.0135 Longitude: -111.911

Step 2: Write down the elevation that is on the rim of the Grand Canyon: 2181 m

Step 3: Jump down to the bottom of the Grand Canyon. You can see the avatar way below hanging out in this screenshot, and look at the elevation of the Colorado River: 780 m

Step 4: Determine how deep the Grand Canyon is at this spot? 2181-780 = 1401 m NOTE: DO NOT WORRY ABOUT EXACTLY WHERE IS "THE RIGHT" SPOT TO MEASURE THE ELEVATION. THE CHOICES WILL BE FAR ENOUGH APART SUCH THAT WHERE YOU DECIDE TO HOP THE AVATAR DOWN TO THE BOTTOM WILL NOT MAKE A DIFFERENCE.

Step 5: Divide the Depth (1401 m) by the amount of time it took the Colorado River to reach its current position (4,800,000 - 1,200,000 or 3.6 million years. The unit of the answer should be in meters per million years (m/Ma). The answer would thus be 389 m/Ma. THE INCORRECT CHOICES WOULD BE FAR ENOUGH AWAY SUCH THAT THE EXACT ELEVATION OF THE AVATAR WILL NOT MATTER. CLOSE IS GOOD ENOUGH. JUST WALK DOWN BELOW THE STARTING POINT TO THE BOTTOM OF THE RIVER.

WHAT DOES THIS MEAN? You probably noticed that the rate of incision is a lot higher here in the heart of the Grand Canyon. The reason is that the elevation of the top edge is a lot higher. Thus, the river had to incise into a lot more rock material.

NOTE 1 The questions you will receive from canvas will not be all of the same. They will be randomly delivered to you from three "pools" of questions from the eastern end of the Grand Canyon, Heart of the Grand Canyon, and western end of the game study area.

NOTE 2: The answers are far apart numerically. Thus, even if you find that your answer is a bit different, please pick the CLOSEST to what you calculate.

Note 3: The wording of the question will be the same for all questions, where the X and Y are replaced by pool questions. You will get three questions, one from the eastern, one from the heart, and one from the western end of the Grand Canyon

Question 5

What is the rate of downcutting of Tater Stream (the major tributary in the area of Latitude: 36.446 Longitude: -112.0231)? Select the best answer.

STEP 1: Teleport to Latitude: 36.446 Longitude: -112.0231 I changed the camera to up high and have a west-looking view to see the major canyon that has eroded and exposed the monocline. This is the view that shows your study area, with the arrow showing the location of the avatar

STEP 2: Walk your avatar or fast travel to about this location. It's the base of Tater Canyon and determine its elevation Latitude: 36.4364 Longitude: -112.053

STEP 3: Walk your avatar up to the top of the Kaibab Limestone.look at the compass and hop up in the northwestern direction. You should be somewhere around these coordinates ( 36.4473, -112.0685). Determine the elevation. This elevation is an approximation of the surface before Tater Canyon started to develop about 20 million years ago.

STEP 4: Question: what is the rate of downcutting of Tater Stream, or the main stream in this study area, using the elevations you measured and the timescale of its development. Just use the same thinking that you used in Stage 4 of this lab.