From Earth Science Picture Of The Day; January 15, 2014:
Dike and Hoodoos Along the Upper Missouri River in Montana
Photographer and Summary Author: Kathleen Kiefer
The photo above was snapped while paddling the Wild and Scenic Upper Missouri River in west-central Montana. At center is a remnant of an igneous dike — a cooled and hardened lava flow. Note that this ancient flow made a path to the draw below. Hot magma was flowing here, forced upwards from deep within the Earth, some 55 million years ago, at a time when this area was covered by thousands of feet of overlaying rock layers. Eroded sandstone pedestals on the left side of the large, rectangular rock formation, at right center, are known as hoodoos. Yucca plants are in the foreground. Photo taken on September 27, 2013.