Dust and the American West

Images of deserts in the United States show dusty, barren landscapes, but the land may not always have been this way. Ever since settlers moved west across the US there have been dust-clouds of it everywhere. It was part of the landscape, or so it seemed to them. But there were no records of the landscape of the West until the settlers arrived. Now evidence is starting to emerge, which suggests that before the settlers, there was very little dust.

The evidence comes from the San Juan mountains of southwest Colorado, downwind of Arizona and New Mexico. There Jason Neff, a geochemist from the University of Colorado, has been analyzing sediments, the sand, stones and mud, laid down over the past 5000 years. Atmospheric dust was minimal throughout those five millennia until the mid-19th century, he says, but then, ‘from about 1860 to 1900, dust deposition rates shot up.’

This is surprising because usually dry means dusty, and the American West has almost always been dry-often drier than today. There was a near-permanent drought between 900 and 1300 which was so intense that it destroyed a series of native American civilizations, including the Anasazi, whose cliff homes are now national treasures. Yet the evidence from the San Juan lakes is that it was not dusty. Even as their civilization was collapsing, the Anasazi seem to have protected their soils from erosion.

This was not the case with the European settlers once they brought their cows. The landscape the cattle were introduced to was remarkably ill-equipped to cope with grazing animals, says Neff. ‘Unlike most other parts of the US, there were few grazers in the American Southwest until the Europeans came. No bison and few antelope or deer.’

In the Great Plains to the east and north, bison roamed in vast herds. Their regular grazing had created tough grass, while the herds manured the soil. In the Southwest, the land had few defenses against a sudden invasion of millions of livestock, whose teeth stripped the grass and whose hooves punctured the hard crust of desert soils that protected them from the wind. The invasion was sudden, funded by a bubble of speculative investment, much of it from Britain. The money went into railroads, and herds of cattle and sheep that rode the rails to the wide open pastures. By 1900, when sedimentation rates peaked, there were 20 million cattle and 25 million sheep in the West.

One of the biggest ranches was owned by the Aztec Land and Cattle Company, which owned a million acres of land by 1884. Each acre had cost the company a mere 50 cents, and like many other speculators, it was only interested in quick profits and had little incentive to protect the land from overgrazing. By the time Aztec sold the ranch in 1901, it was an ecological disaster. The land was stripped bare, and wind erosion had taken hold on a massive scale. This pattern was repeated across the region.

The consequences were severe. The Dust Bowl of the 1930s, which devastated the Great Plains, was partly a product of this earlier degradation combined with drought and poor farming practices. The legacy of dust continues to affect the region today, influencing air quality, soil fertility, and water availability. Modern conservation efforts aim to restore damaged grasslands and implement sustainable grazing practices, but the evidence from the San Juan sediments serves as a stark reminder of how quickly human activity can transform a landscape and create an environmental legacy that lasts for centuries.

Questions 1-5

Complete the summary below. Choose NO MORE THAN TWO WORDS AND/OR A NUMBER from the passage for each answer.

Research in the …… mountains shows that dust levels were low for 5000 years until the mid-19th century. This is surprising because the region experienced a severe …… from 900 to 1300, yet remained relatively dust-free. The increase in dust is linked to the arrival of …… settlers and their livestock. Unlike the …… that had grazed the Great Plains, the Southwestern landscape was not adapted to heavy grazing. By 1900, there were millions of cattle and sheep, funded largely by …… investment.