MONUMENT VALLEY

Today, Monument Valley sits at an elevation of 5,000 to 6,000 feet. But long ago, it was buried beneath an additional one to two miles of sedimentary rock. Back then, no "monuments" existed — only a flat, quiet basin.

     Between 270 and 160 million years ago, rivers, seas, and deserts took turns shaping this region, layering it with sand, silt, and clay. Yes, what is now Monument Valley was once the bottom of an ancient sea!

     Over millions of years, those sediments were compressed into rock — mainly sandstone, but also shale and limestone — each layer reflecting a different ancient environment. Then, tectonic uplift raised the region, and nature began carving.

     Wind, water, and freeze-thaw cycles gradually wore down the softer rock layers, leaving only the most resistant sandstone behind. That's how the iconic landforms of Monument Valley came to be:

• Mesas – vast, flat-topped formations with steep sides
• Buttes – narrower cousins of mesas
• Spires – slender, towering columns of stone

     The deep red color? That's iron oxide — rust — staining the surface of the sandstone.

     All told, erosion has stripped away nearly 10,000 feet of rock. Today's towering monuments are the exposed bones of an ancient world. And just as erosion pulverized that ancient rock, today's towering monuments, too, will one day crumble.

     So take it in. You're looking at a fleeting chapter in Earth's long, slow story.