Devils Postpile, California

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, Universityof Wisconsin - Green Bay

This very small national monument contains some very regular basalt columnstruncated by beautiful glacial polish. I find it still something of a mysterywhy this site is a national monument, since there are far larger tracts ofcolumns in the Columbia Plateau that are not protected at all.

	The road to Devils Postpile is narrow and winding and parking is very limited, so shuttle buses run from Mammoth ski resort.
	Left and below: views from the overlook at the ridge crest at Minaret Summit. This is the farthest you can get by car.
This is actually the southernmost road that crosses the Sierra drainage divide, if only by a few miles. At one time there were mining and logging roads that connected to the Central Valley, making this the southernmost crossing of the Sierra Nevada.

	View of the Minarets
	Left: the Ranger Station. Below: these are the views of Devils Postpile you see in all the textbooks.


	Left and below: these are the views you don't see in the textbooks, but they are actually very typical of columnar jointing. One hypothesis is that fanning or flaring joints are initiated when water suddenly cools the lava or creates a steam explosion.

	This view shows how the flaring joints pass smoothly into perfectly regular columns.
	Small outcrop at the base of the columns showing columnar jointing.
	The trail to the top of the columns stats at the south end of the palisade
	Left and below: Devils Postpile is famous for its glacially polished and striated pavement that dramatically accents the polygonal columns.


	Left and below: pumice lapilli blanket the area near the Ranger Station as well as slopes leading to Mammoth. This pumice was erupted by the Mono Craters only a few hundred years ago.