|The geologic formation that is “the Postpile” is a great example of columnar basalt. The columns of hardened lava, with geometric shapes and four to seven sides, make a sort of honeycomb pattern. The columns formed when a basaltic lava flow shrank while cooling and solidifying. It shrank around many centers, much like mud drying up in a lake bottom. Cracks formed on the surface and ideal conditions allowed them to propagate inwards. Columnar basalts exist in many places, but few are as sharply outlined and well preserved as these at Devil's Postile. The basalts at Devil's Postpile are less than 100,000 years old.
|Dexter Perkins. 2001-05-22.
|431 KB. Outcrop.