#9: Devils Postpile National Monument (Mammoth Lakes)
Devils Postpile is a rare formation of columnar basalt, with most columns being six-sided and up to 60 feet tall, created by cooling lava over 100,000 years ago. A glacier once scraped across the Postpile, polishing the tops of the columns and leaving behind smooth, striated surfaces. The monument’s other major attraction, Rainbow Falls, gets its name from the vibrant rainbows that form in its mist on sunny days.
