Devils Postpile

 formation, cliff, geography, interesting place, draw only border

Devils Postpile is a dark cliff of columnar basalt near Mammoth Mountain in eastern California. The postpile was created by a lava flow sometime between less than 100,000 years ago (according to current potassium-argon dating) to 700,000 years ago (according to other dating methods). The source of the lava is thought to have been somewhere near Upper Soda Springs campground at the north end of Pumice Flat on the floor of the Middle Fork of the San Joaquin River, from where it flowed to the site of the Postpile, was impounded by a moraine, and reached a thickness of 400 feet (newer estimate) to 600 feet (older estimate). In any event, the lava that now makes up the Postpile was near the bottom of this mass.

www.topoquest.com/map.php?lat=37.62438&lon=-119.08180&d...