Kolob Canyon provides spectacular examples of large sandstone cliffs of the Colorado Plateau. The Kolob Canyon section of Zion National Park is located just off Interstate 15 at exit 40. Due to its proximity to the freeway, many cross country travelers take an hour or two to stop and admire these spectacular cliffs, and scenery. To accommodate this cross country traffic, the canyon has a reduce entrance fee.
If you are traveling through Utah, but do not have time to do a more extensive exploration of the region, I strongly recommend stopping at Kolob Canyon. However, if you have several days on your vacation, I would recommend concentrating your Zion vacation on the main Zion Canyon.
The large cliffs in Kolob Canyon are of Navajo Sandstone. This sandstone was deposited by sand dunes 190 to 136 million years ago in the Jurassic period. The Temple Cap formation sits on top of the Navajo Sandstone. This harder layer is composed of ironoxide rich muds.
The Navajo sandstone sits atop the Kayenta Formation which is 200 to 600 feet deep in this area. The Kayenta layer is composed of distinct alternating layers of sand and silt deposited by stream beds. The Kayenta layer is stronger than the Navajo Sandstone.
When one first sees the towering Navajo Sandstone cliffs, they would think that the Navajo Sandstone must be stronger than the other layers. It is actually the other way around. The deep canyons occur because the temple cap formation protects the top of the Navajo Sandstone. When the Temple Cap formation is washed away, water will quickly erode through the Navajo Sandstone down to the harder Kayenta Layer.
The other key element to creating spectacular cliffs is the composition of the layers. Navajo Sandstone was deposited by dunes. That means you have an extremely thick layer of sand that is relatively consistent. The Kayenta Layer was deposited by stream beds with distinctive layers of silt and sand. This Kayenta Layer ends up eroding in a chunky fashion. The Kayenta layer will erode from underneath the Navajo Sandstone. When the Kayenta Layer erodes from underneath the Navajo Sandstone, large slabs of the Navajo Sandstone will slice off the mountain, break up and erode away. The result is long lines of beautiful cliffs.
Here is a full list of formations found in the Kolob Canyon region, starting from the top. Geology buffs will notice the lack of a Wingate Sandstone.