Early settlers responsible for dusty west
A study of sediment cores collected in Colorado in the western USA has
shown that dust levels in the region rose sharply after the arrival of
early settlers at the start of the 1800s.
A team from the University of Colorado at Boulder studied sediment cores extracted from two lakes in Colorado’s San Juan mountains and found atmospheric dust levels in the area jumped 500 per cent during the past 200 years – higher than at any other time during the previous 5,000 years.
‘From about 1860 to 1900, the dust deposition rates shot up so high that we initially thought there was a mistake in our data,’ said geological scientist and lead author of the study Jason Neff.
‘But the evidence clearly shows the western USA had its own dust bowl beginning in the 1800s when the railroads went in and cattle and sheep were introduced into the rangelands.’
At the turn of the century, some 40 million head of livestock were grazed on the western rangeland, causing severe degradation. The 1934 Taylor Grazing Act imposed restrictions on grazing and led to a decrease in dust accumulation rates, which can be seen in the cores.
‘There seems to be a perception that dusty conditions in the west are just the nature of the region,’ said Neff. ‘We’ve shown here that the increase in dust since the 1800s is a direct result of human activity and not part of a natural system.’
A team from the University of Colorado at Boulder studied sediment cores extracted from two lakes in Colorado’s San Juan mountains and found atmospheric dust levels in the area jumped 500 per cent during the past 200 years – higher than at any other time during the previous 5,000 years.
‘From about 1860 to 1900, the dust deposition rates shot up so high that we initially thought there was a mistake in our data,’ said geological scientist and lead author of the study Jason Neff.
‘But the evidence clearly shows the western USA had its own dust bowl beginning in the 1800s when the railroads went in and cattle and sheep were introduced into the rangelands.’
At the turn of the century, some 40 million head of livestock were grazed on the western rangeland, causing severe degradation. The 1934 Taylor Grazing Act imposed restrictions on grazing and led to a decrease in dust accumulation rates, which can be seen in the cores.
‘There seems to be a perception that dusty conditions in the west are just the nature of the region,’ said Neff. ‘We’ve shown here that the increase in dust since the 1800s is a direct result of human activity and not part of a natural system.’
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