Challenge: Iain and Ellen to find water in one of the
driest places on Earth. Kathy and Mike to purify the
water; Jonathan to build a Mars Rover.
Owens Lake is one of hundreds of dry lakes, or playas,
that the American West is home to. It is a legacy of
a glacial past when enormous lakes, filled to brimming
at the height of the last ice age, began to shrink as
the climate sharply dried 10,000 years ago. More extreme
drying over the last few thousand years continued the
shrinkage, but the lake began to dry up in earnest in
1913 when local mountain streams and the Owens River
that used to flow into it were siphoned off to water
Los Angeles. This is where our search for water begins.
Surrounding our salt lake are stranded beaches, former
lake shorelines that - like rings on a bathtub - are
tell-tale geological evidence for the gradual disappearance
of a large body of water. Our first stop of the day
is at one of these high ‘fossil’ shorelines.
Its well rounded beach pebbles showed clearly the signs
of water action, as did the smoothed walls of a nearby
outcrop of limestone. But the water was gone, and the
ravines and gullies that had fed the lake were equally
dry. Most of these dry stream channels were also carved
out during the lake’s wetter glacial past, today
carrying water only during the occasional rainstorms.
So instead our plan is to track up one of these dry
stream beds to look for water higher up in the hills.