Wendall Duffield (USGS, retired) and his colleagues established the age of Merriam Crater at ca. 20,000 years. There's good reason to believe that basalt lava flows from Merriam Crater temporarily dammed the Little Colorado leading to the formation of Grand Falls several miles to the east. The nearby Sproul (the smaller feature in this image) is a large elliptical spatter cone with low ramparts of spatter, agglutinate, and rootless flows.
Photographer: Dale Nations
Photo Date: circa 1990
Photo Location Accuracy: Known Location
Photo Tags: Merriam Crater, Sproul, basalt, volcanism, Grand Falls, agglutinate, spatter, San Francisco volcanic field, Natural resource, geotourism 
