Basalts from the Uinkaret volcanic field flow into the Grand Canyon from its North Rim. On the right is Lava Falls, with Vulcan's Throne at the top, half visible along the right-hand edge of the photo. Vulcan's Throne is about 73,000 years old.[1] These are among the most recent features of the Grand Canyon. The topmost layers over which the lava flowed, the Kaibab Limestone, was deposited in Early Permian time, around 290 million years ago.Vulcan's Throne (top right) and Lava Falls, 2008 aerial photo
Lava flows from the Uinkaret volcanic field that have cascaded down into the Grand Canyon, damming the Colorado River, have been used to date the canyon's carving.[3] One of these cascades is today's Lava Falls. Lava Falls Rapid, below Lava Falls on the Colorado River, is "at all water levels, the most severe rapid in Grand Canyon."[4]
The Colorado River was dammed by lava flows multiple times from 725,000 to 100,000 years ago.[5] While some believe that these lava dams were stable, lasting up to 20,000 years and forming large reservoirs,[6] others think they failed quickly and catastrophically as massive floods.[7] Lava flows traveled downriver 76 miles (121 km) from river mile 178 to 254.[citation needed]
^Karlstrom, K., Crow, R., Peters, L., McIntosh, W., Raucci, J., Crossey, L., and Umhoefer, P., 2007, 40Ar/39Ar and field studies of Quaternary basalts in Grand Canyon and model for carving Grand Canyon: Quantifying the interaction of river incision and normal faulting across the western edge of the Colorado Plateau: GSA Bulletin, v. 119, no. 11/12, pp. 1283–1312.
^Hamblin, W.K., 1994, Late Cenozoic lava dams in the western Grand Canyon: Geological Society of America Memoir 183, 139 p.
^Fenton, C.R., Poreda, R.J., Nash, B.P., Webb, R.H., and Cerling, T.E., 2004, Geochemical discrimination of five Pleistocene lava-dam outburst-flood deposits, western Grand Canyon, Arizona: The Journal of Geology, v. 112, pp. 91–110, doi:10.1086/379694.
