Specifically, they are composed of the Navajo Sandstone, a massive, cross-bedded sandstone formation that was deposited in a vast desert environment around 180 million years ago.
Here's why it's important to note:
* Sandstone: This type of rock is formed from cemented grains of sand, which in the case of Monument Valley were primarily quartz.
* Navajo Sandstone: This particular formation is known for its red color, due to the presence of iron oxides. It's also notable for its well-developed cross-bedding, which you see as the layered patterns in the buttes and mesas.
The erosion of the Navajo Sandstone over millions of years, carved by wind and water, has shaped the dramatic landscape of Monument Valley that we see today.
