Colorado River Raft Tour - remnants of massive lava flows

~ Mile 178.5: Looking downstream at remnants of massive lava flows that poured into the Grand Canyon in Quaternary time. The volcanic flows and intrusions are part of the Uinkaret volcanic field located on the north rim of the Grand Canyon in the Grand Canyon National Park. Dates on the volcanic rocks range from about 1.2 million years old to about 12,500 years old (Nash, 1990; Hamblin, 1990).