GeoSnaps - Image of the Day
Geologic snapshots capturing Arizona’s geologic setting and mining history with a picture of the day from 1 January through 31 December 2013.
Check out previous GeoSnaps/Images of the Day.

The Colorado River in Grand Canyon has experienced basaltic volcanism in the last 830,000 years. On at least thirteen occasions, flows were voluminous enough to completely block the river, causing it to carve a new channel. Here a lava plus is clearly visible in the center of the picture where dark basalt fills a cream-colored channel cut into the Cambrian Muav Limestone. The rivers current channel is now to the left (south) of this fill. (Photo by Wayne Ranney)