Dust to Dust
from the book, "Petrified Lightning"
Dust to Dust
During a late afternoon in June 1962 a geologist mapping an area called the 111 Ranch Beds near Safford, Arizona, took a break. As he sat admiring the desert scenery, he observed a high wall of dust—the front of a violent sandstorm about a mile to the south. In a few seconds he jumped to his feet and yelled, "Holy smoke, it's coming this way!"
He reached camp, which consisted of a field vehicle, just as the storm hit with great impact. His partner was not present, and he worried enough to tie a hundred—foot rope around his waist with the other end attached to the door handle. Wearing wind goggles he crawled on his knees into the storm trying to find his friend. Reaching the end of the rope he started back to the truck, taking a slightly different path, and ran smack into his partner, who had tied a rope around himself and was looking for partner number one. With visibility almost at zero, they followed the ropes back to their vehicle and sat out the storm, which lasted for at least an hour. Both men, badly sandblasted in the face and arms, had to return to Tucson for medical care.
As climatic historian Paul Sears said in Deserts on the March, "Dust is nothing new. . . . Like the circle, it is a symbol of eternal time." For millions of years atmospheric winds have picked up dust and carried it elsewhere. Throughout the world are vast deposits of fine sediment often hundreds of feet thick. Geologists refer to these thick deposits of dust as loess. In other places sandstone layers with sloping bedding planes attest to wide expanses of desert throughout hundreds of million of years of time, even in places where today the climates are humid and tropical.
Extremely violent sandstorms have always occurred in the deserts of the world. In 1923 a U.S. expedition team was busily excavating a dinosaur nest in the Gobi Desert. To the scientists' amazement they uncovered the skeleton of a four—foot—long toothless dinosaur lying about three inches above a clutch of eggs. Later named Oviraptor (egg seizer) the animal probably lived by feeding on dinosaur eggs. This unlucky specimen was in the act of digging up the nest when it was overcome by a violent sandstorm and buried alive on top of the very eggs it had come to steal. This prehistoric drama occurred over 100 million years ago.
Some of the earliest journals of civilization call attention to dust clouds—if only for purposes of reverence, even religion. On the Thracian plain of Greece, Dicaeus the Athenian and Demaratus the Lacedaemonian once chanced to be standing where a great cloud of dust advanced toward them, not unlike the dust cloud observed by the Arizona geologist thousands of years later. To these two ancient Greeks it was like a cloud of dust raised by 30,000 men marching, and they wondered who the men might be. Suddenly they heard the sound of voices, very likely the howling of the wind—but to them it was voices singing the mystic hymn of Bacchus. As they watched, the dust became a cloud and rose into the air to sail away to Salamis, an almost sure prediction of ill for their enemies and good for themselves. No doubt the enemy had a reverse opinion.
Both Homer and Virgil mention dust storms. Early legends tell of shifting sands burying entire caravans and marching columns. Violent sandstorms and dust storms are not uncommon in the great Sahara Desert, but people born into this environment have learned to cope with them as normal events. Sahara storms can be much more severe than those in Arizona and will last much longer, sometimes for days. Some of the most violent storms have been known to drive people mad or, at times, bury them alive as it did the dinosaur 100 million years earlier.
Sand and dust are almost always on the move; they are picked up, blown a short distance, and dropped to earth again. But at times great amounts of dust are carried thousands of miles to settle in foreign lands. Some Sahara dust storms have become exceptionally widespread: in 1901 a mass of dust estimated to weigh nearly four million tons was spread in a thin mantle across North Africa and Europe. An estimated 10 million tons fell on England in two days in 1903, and it is not uncommon for ships at sea to be brushed with dust from the Sahara.
Dust on the move can produce some rather unusual effects. Red rains and red snows, comparatively frequent in some places, are the result of reddish Sahara dust encountering humid air and condensing to douse broad areas with reddish sediment. Some of the millions of tons of Sahara dust sailing along at high elevations to moist climates is precipitated widely, as occurred in Germany in 1959. Over 15,600 square miles were blanketed with deep reddish snow. Dust seems to prefer that area; in 1980, ski resorts advertised the thrill of skiing on red snow. Business zoomed!
The wind current that flows off the Sahara Desert is known as a sirocco. It is responsible for delivering the unusual precipitation as it carries million of tons of reddish—colored sand over Europe. However, such events can have negative results. In a.d. 582 a deep "shower of blood" fell on Paris. The red rain caused great fright; many Parisians tore at their "bloodstained" clothing while vigorously repenting their sins. The local churches were filled to capacity that day.
Windstorms can have a comical side. In 1901 an engineer examined a prospective placer diamond property in what was then German East Africa. He found the sand rich in very fine diamonds and began negotiating for a deal with the owner. When a fierce windstorm suddenly descended on the area, they retreated into the owner's shack. Both watched with mouths agape as the wind picked up the sand, stripping the area down to bedrock, and carried sand, dust, and diamonds to other properties farther down the valley. The deal was off.