This area, known as both Tuweep and Toroweap, is on the northwest rim of the Grand Canyon in the remote Arizona Strip. The Kanab Plateau rises sharply to the east, while the volcanic Pine/Uinkaret Mountains form the western margin of Toroweap Valley.
The view from Toroweap Overlook, 3000 vertical feet above the Colorado River, is breathtaking; the sheer drop, dramatic! Equally impressive are the volcanic features, cinder cones and lava flows, which make this viewpoint unique in Grand Canyon National Park. Renowned Lava Falls Rapid is just downriver and can easily be seen and heard from the overlook. Toroweap, a Paiute term meaning "dry or barren valley," refers to many local features, including the geologic formation and fault, the valley, and the overlook.
Tuweep came into use to describe the local white settlement and later the park district. Tuweep in Paiute refers to "the earth," but this place name may be derived from a longer Paiute word meaning "long valley." A visit to this area can be challenging, but rewarding. Since the National Park Service manages the area for its primitive values, improvements and services are minimal.
GEOLOGY
The geologic history of the Tuweep area is similar to the rest of Grand Canyon, but includes a more recent chapter of volcanism. The Toroweap Fault underlies the valley, crosses the Colorado River, and continues south up Prospect Canyon. Volcanic activity began along this fault around seven million years ago. Over time lava issued from more than 60 vents.
Beginning about 1.2 million years ago some flowed into Toroweap Valley, forming the flat-bottomed valley we see today. Vulcans Throne, Mount Trumbull and the Uinkaret Mountains are other features that are the result of volcanic activity. More than a dozen times, lava spilled over the canyon rim, damming the Colorado River. Remnants of these flows and dams are easily visible just west of the overlook.
Sediments clinging to the canyon walls high above the river indicate the formation of large lakes. The river eroded the lava dams and continued its downward cutting. It is now 50 feet (15 m) deeper than the base of the dams.
Despite its name, Lava Falls Rapid was formed from debris washed down Prospect Canyon, not from remains of the lava flows. It is less than one mile across the canyon to the Hualapai Indian Reservation on the South Rim, making this one of the narrowest and deepest segments of the inner canyon. The colorful redrock of the Hermit Shale and Supai sandstones to the east contrasts with the black, basaltic lava flows to the west, making Toroweap Overlook a memorable, and often-photographed, viewpoint in Grand Canyon.
