The Grand Canyon is perhaps the most famous natural feature in the United States. Although some sources mistakenly refer to it as the largest canyon in the world, the Grand Canyon is still quite large, with a length of 277 miles and depths of over a mile. There is no official volume of the Grand Canyon and getting a precise calculation would be extremely difficult, given the natural and changing inconsistencies in its dimensions. However, with a few figures it is possible to obtain an estimate of the volume and get an idea of how large it is.
To get a rough working estimate of the volume of the Grand Canyon is a simple task. The Grand Canyon is 277 miles long and has an average depth of 5000 feet, according to the National Park Service. The average width is widely cited as 10 miles. Converting to feet, we have Length at 1,462,560 feet, Depth at 5000 feet. and Width at 52800 feet. A simple volume calculation (L x W x D) brings us to 386,115,840,000,000 cubic feet. In other words over 386 trillion cubic feet. Converting back to miles we get 2623.1 cubic miles. Important to note, this is a very rough estimate of the actual volume, but it gives a good indicator of just how large the Grand Canyon is.
What makes it difficult to calculate the volume of the Grand Canyon is its very formation. In simple volume calculation, you'd be looking at a cube, sphere or other congruent object with defined dimensions. Taking one look at the Grand Canyon, you can tell that such defined dimensions do not exist. The width and depth of the Grand Canyon vary along its great length, and rough, incongruent structure of rock also alters the dimensions. To actually calculate an accurate volume would require painstakingly calculating the volume of many tiny individual segments and adding together. Given the enormous size of the Grand Canyon this would be extremely time-consuming and difficult.
Even if one were able to get an accurate volume, it would quickly be rendered obsolete due to the erosion that takes place at the Grand Canyon. The canyon was created by this process, when the Colorado River eroded the rock over millions of years and created the massive canyon we see today, and the river continues its work. Wind, rain, snow and other weather elements also play a role in eroding the rock of the Grand Canyon. Erosion causes sizeable changes of the dimensions of the Grand Canyon, meaning that the volume is always shifting.
The National Geographic Visitors Center's website has the average depth of the Grand Canyon listed at 4000 feet. In this case, the volume would be 308,892,672,000,000 cubic feet or 2098.5 cubic miles.
Although the volume of the Grand Canyon is an interesting statistic to consider, it is not a largely cited figure. Most figures on the Grand Canyon include dimensions like length, width and depth, but don't cover volume, probably due to the lack of an accurate figure.