Along the picturesque Middle Fork of the San Joaquin River at 2,300
meters (7,600 feet) on the western slopes of the Sierra Nevada lies
Devils Postpile National Monument. The 324-hectare (800-acre) monument
near the resort community of Mammoth Lakes includes one dominant
feature: a formation of columnar basalt known as Devils Postpile.
Another important feature in the area is Rainbow Falls. Pumice is the
dominant rock-type encountered, but basalt, andesite, rhyodacite, and
granite lie just under the surface and crop out in many places. Plants
and animals are typical of lodgepole pine and red fir forests. To see
the features of the monument one must walk.