Geologic map of the Lower Grand Wash cliffs and vicinity, Mohave County, Northwestern Arizona: pamphlet to accompany miscellaneous field studies map MF-2427

Billingsley, George; Beard, L.; Priest, Susan; Wellmeyer, Jessica; Block, Debra

This summary describes the geology of the lower Grand Wash Cliffs. The geologic setting and map units are described... INTRODUCTION This geologic map is a product of a cooperative project between the U.S. Geological Survey, the National Park Service, and the Bureau of Land Management designed to provide geologic information for part of Grand Canyon National Park, Lake Mead National Recreation Area, and Grand Canyon Parashant National Monument, Arizona. The map area is mostly in the Grand Wash trough of the Basin and Range Province and partly in the Grand Wash Cliffs and the Grand Gulch Bench (Sanup Plateau on large-scale maps) of the Colorado Plateaus Province (herein the Colorado Plateau), all in northwestern Arizona. Grand Wash is the principal drainage for the Grand Wash trough, which is bounded by the Grand Wash Cliffs on the east, the Virgin Mountains on the north (not in map area), the South Virgin Mountains on the west (not in map area), and Lake Mead on the south (southwest edge of map). Grand Wash drains southward toward the Colorado River that is now covered by Lake Mead. The map area is one of the few remaining areas where uniform scale geologic mapping was needed to complete the Mount Trumbull 30' x 60' quadrangle of Arizona (Billingsley and Wellmeyer, 2003). The geologic information in this report may be useful for federal, state, and private land resource managers who develop land management programs such as range management, biological studies, and flood control. The geologic data will also contribute to future geologic investigations and related scientific studies of this unique area. The map area is in a remote region known as the Arizona Strip in northwestern Arizona about 20 mi north of Meadview, Arizona, the nearest settlement. Elevations range from about 6,748 ft on the Grand Gulch Bench (east-central edge of map area) to about 1,200 ft at Grand Wash (southwest corner of map area). Primary vehicle access is by dirt road and unimproved jeep trails that traverse various parts of the map area, except within the Grand Wash Wilderness Area of the Grand Gulch Bench (northeast corner of map area). Maps, extra fuel, two spare tires, and extra food and water are highly recommended when traveling in this remote region along with local U.S. Geological Survey 7.5′ topographic quadrangle maps (Grand Gulch Bench, Gyp Hills, Olaf Knolls, and Pakoon Springs) to accompany this map.

Geologic map of the Lower Grand Wash cliffs and vicinity, Mohave County, Northwestern Arizona: pamphlet to accompany miscellaneous field studies map MF-2427

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