At the Grand Canyon of the Yellowstone visitors are awed by the beauty of erosion. The Yellowstone River has carved a canyon 20 miles long and it plunges over two waterfalls in the first mile. The North and South Rim drives and trails offer overlooks where you can see the stunningly bright yellow colors of the canyon walls and glimpse the green river below.

The canyon walls are a volcanic rhyolite rock that has been altered chemically by hydrothermal features. The normally gray rhyolite has been cooked, altering the colors with iron oxides adding pinks and reds. Not only did the heat and chemical action cause the brilliant coloration, but it also softened the rocks, weakening them, which allows the river to carve the canyon more easily.

In fact, the two big waterfalls here occur where unaltered rhyolite, which is hard and erosion-resistant, meets up with the softer altered rhyolite. The Upper Falls is 109 feet high and the Lower Falls (sometimes called Yellowstone Falls) plunge 308 feet. At the top of both falls there are platforms where one can stand at the brink and really feel (and hear) the power and force of the water. It is an amazing experience!

The trail to the brink of the Lower Falls is much longer and more strenuous than the brink of the Upper Falls but the canyon is much deeper and more brightly colored downstream of the Lower Falls. So it’s worth the journey if you have the stamina. From the South Rim, the adventurous can descend a stairway into the canyon to get a closer look at the Lower Falls. It’s called Uncle Tom’s Trail and with over 300 metal mesh stairs, it can be quite a challenge to come back up! But at least today’s visitors have a staircase rather than ropes and ladders like Uncle Tom Richardson’s original trek.

For easy viewing of the Lower Falls try Lookout Point on the North Rim or Artist Point on the South Rim. No matter how you view the canyon—from the scenic overlooks or trails—be sure to watch your footing! The altered rhyolite rock is quite soft and crumbly and has caused those who venture too close to the edge of the canyon to slide in. The canyon averages 1000 feet deep. It is dangerous and unlawful to leave the trails, go beyond rock barriers and walls, or climb in the canyon.

The Grand Canyon of the Yellowstone is a popular spot among park visitors and its beauty helped convince Congress to set this area aside as the world’s first national park.