Boulder in The Abyss...Grand Canyon

Boulder in The Abyss...Grand Canyon

Looking into the bowels of 'The Abyss' I saw a huge white chunk of rock lying among the red rock of the surroundings. From its size relative to surrounding vegetation, I judged it to be about the size (and shape) of a railroad freight car. It is slightly below center in this photo, looking like an alien intruder.

Erosion from the harder layers of rock at the Grand Canyon takes the form of undercutting by erosion of softer layers beneath the hard layer, and then collapse of a portion of the undercut hard layer. This collapse releases huge boulders which can remain intact and tumble and bound far down into the canyon. The huge boulder seen here could have come from either the upper Kaibab limestone layer, or the Coconino sandstone layer.

Location: 'The Abyss' overlook, Hermit Road, South Rim, Grand Canyon NP, Arizona, USA