North and South Menan Buttes are two of the world's largest tuff cones. Their volumes are 0.16 cubic miles (0.70 cubic km) and 0.07 cubic miles (0.30 cubic km), respectively. Diamond Head. a better known tuff cone, has a volume of 0.15 cubic miles (0.6 cubic km). Photo by Mike Lovas, NASA-Ames, 1969. Figure 5-67 in Greeley, 1977.
The deposits that make the cones are fairly uniform and without structures or with thin beds. The tuff is lapilli-size particles made of volcanic glass that has been altered by the addition of water. Photo by Steve Mattox, 1988.
Some layers preserve bomb sags, indentations made by larger pyroclasts that landed on the soft layers of tuff. Photo by Steve Mattox, 1988.
Vertical aerial view of the Menan Buttes. The crater of North Menan Butte is about 3,000 feet (900 m) in diameter and the cone is about 6,000 feet (1,800 m) in diameter. U.S. Department of Agriculture photographs CXS-6AA-50 and 51, July 1960. Figure 5-66 from in Greeley, 1977.
Cross-section of North Menan Butte. From Hamilton and Myers (1963).
The Menan Buttes formed when a dike intruded into a shallow aquifer. The water turned to steam and explosively fragmented the basaltic magma. The cones are late Pleistocene in age.
View towards North Menan Butte. The cones rise about 800 feet (250 m) above the surrounding plain. Photo by Steve Mattox, 1988.
Sources of Information:
Creighton, D.N., 1987, Menan Buttes, southeastern Idaho, in Beus, S.S., ed., Centennial Field Guide Volume 2 Rocky Mountain Section of the Geological Society of America, p. 109-111.
Greeley, R., 1977, 5. Aerial guide to the geology of the central and eastern Snake River Plain, in Greeley, R., and King, J.S., eds., Volcanism of the eastern Snake River Plain, Idaho: A comparative planetary geology guidebook: NASA, Washington, D.C., p. 59-112.
Hackett, W.R., and Morgan, L.A., 1988, Explosive basaltic and rhyolitic volcanism of the eastern Snake River Plain, in Link, P.K., and Hackett, W.R., eds., Guidebook to the Geology of Central and Southern Idaho: Idaho Geological Survey Bulletin 27, p. 283-301.
Hamilton, W., and Myers, W.B., 1963, Menan Buttes, cones of glassy basalt tuff in the Snake River Plain, Idaho: U.S. Geological Survey Professional paper 450E, p. E114-E118.
Stearns, H.T., Crandall, L., and Steward, W.G., 1938, Geology and ground-water resources of the Snake River Plain in Southeastern Idaho: U.S. Geological Survey Water-Supply Paper 774, 268 p.