NEBRASKA’s famed Sand Hills region – a vast area of undulating grass-covered dunes, punctuated by river canyons and waterfalls – was a dust-bowl a thousand years ago. It turns out that shifting winds plunged the region into a severe drought and created what is today the largest formation of sand dunes in the US.
Tree rings and archaeological measurements show that a severe drought gripped the western side of what is now the US between AD 1000 and 1200. To determine what caused the drought, Venkataramana Sridhar of the University of Nebraska in Lincoln and colleagues studied the Sand Hills. These long,…
