The relations of these rocks are shown in the views and in the following cross sections: Fig. A.— Section across Grand Canyon from El Tovar Hotel through Buddha Temple to Kaibab Plateau. Fig. B.— Section across Grand Canyon near El Tovar, looking west.
The top limestone, Kaibab, caps the plateaus on both sides and the highest buttes. The out cropping edge of the Coconino sandstone is marked by a distinct band of light gray all along the canyon walls and capping some buttes 700 to 800 feet below the top. The red beds of the Supai formation everywhere constitute the middle slopes and many buttes, usually pre senting a series of relatively small terrace-like steps. The conspicuous cliff below these, and stained red by their wash, is the hard massive Redwall limestone. It projects in many flat topped spurs, buttresses and outliers isolated by erosion. The Tonto group, i next below, form ing slopes and a platform, s recognized by its greenish color.
For many miles the shelf of this sandstone of the Tonto group is cut through by a steep inner gorge which descends to the river 800 to 1,000 feet below, and exposes granite and gneiss of the original earth crust. At certain localities
Algonkian rocks lie between the Tonto and the granite and they occupy a wide area northeast of Grandview. They consist of 42,000 feet of limestone, sandstone, red shale and lava, known as Unkar and Chuar group. These beds dip at moderate angles and on their irregular sur face, which was land in earlier Cambrian time, lies the shale of the Tonto Group.
The first white men to see the Grand Canyon were Cardenas and his 12 companions, who were guided to the rim by Hopi Indians in ' 1541. Nearly 330 years later the first trip ever made down the river was accomplished by Maj. J. W. Powell. He left Green River, Wyo., 24 May 1869, in small boats and had a perilous and exciting but entirely successful passage. A memorial to Major Powell has been erected lby the government on the rim at Sentinel Point. Since his pioneer effort this hazardous journey has been made by a few others, among them a ,party surveying for a proposed railroad, a proj