Devils Postpile

Etymology
The monument was established in 1911 as "Devil Postpile National Monument" (no possessive) but is widely referred to as "Devils Postpile National Monument", and has been officially styled as plural without the apostrophe since the 1930s. An alternate historic name was.

Proper noun

 * 1) An unusual rock formation of columnar basalt near Mammoth Mountain in Eastern California, United States, the site of a national monument.