The Devil's Postpile National Monument

We visited this monument, located along the San Joaquin River just outside Mammoth Lakes, in the late afternoon after we'd arrived and checked into our motel. These "postpiles" are columnar basalt, literally created from fire and ice.

Fewer than 100,000 years ago, a volcano two miles upstream of the postpile erupted and basalt lava poured out. As the lava cooled, it contracted and cracked. Then, between 20,000 and 12,000 years ago, a glacier flowed down the San Joaquin River overriding the fractured lava. The moving ice carved away one side of the postpile, exposing a sheer wall of columns 60 feet high.

Erosion and earthquakes later felled many columns that now lie fragmented on the slope below.

Unlike its violent origins, this area is now peaceful and quiet -- a wonderful place for an afternoon walk after a long day on the road.

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