National Geographic : 1957 Nov
family, has crinkly leaves like the true holly. When it has water, the plant is gray-green and succulent. Dry, its leaves wear a nat ural varnish that reflects lamplight with a silvery sheen. A few feet above Mr. Rooke's desert ranch a prominent beach line, the so-called traver tine rocks, runs along the Santa Rosa Moun tains. Formed when the Colorado River emp tied into this basin, vanished Lake Cahuilla left its indelible signature 40 feet above the ocean level and 275 feet above Cahuilla's shrunken survivor, the Salton Sea. Above this line the rocks are plainly of granite; below it water has coated them with a coral like calcium carbonate. Mr. Rooke led me up the rocks to places where long-vanished Indians had carved pic ture writing. A modern "Betty and John," like Kilroy, had added their names. Salton: America's Dead Sea From these rocks we could glimpse the 40 mile-long Salton Sea shimmering between Coa chella and Imperial Valleys. This desert bowl, 235 feet below sea level, is the deep est depression in North America after Death Valley, a minus-282-foot dry sink 210 miles to the north. Water, fed by the Colorado River, escapes only by evaporation, leaving a briny solution the consistency of ocean water (page 712). In recent years Salton Sea has been rising and flooding its shores. Helen Burns, owner of a Salton Sea resort, has had to move her beach house three times. One April afternoon Mrs. Burns and I sat by the edge of the sea and watched as a dust storm rolled in until we could see scarcely 200 feet. 708 Imperial Dam Across the Colorado Makes Deserts Bloom in Two States Stretching 3,475 feet and raising the river level 23 feet, the dam gives birth to California's All American Canal (foreground) and Arizona's Gila Main Canal (below intake gates at upper right). Three desilting basins in the center remove mud picked up by the river on its 300-mile journey from Hoover Dam and flush it into channels at right. Dams and basins save farmers and the Imperial Irri gation District about $1,400,000 in desilting costs a year. Life line of the Imperial Valley, the All American Canal flows entirely through U. S. soil (page 718). Before engineers rerouted it in 1940, part of the big artery ran through Mexico. Twenty feet deep and a maximum 232 feet broad, the canal can divert 15,000 cubic feet of water a second. A branch canal waters Coachella Valley.