THE giant canyons on Mars were carved not by water but by an icy equivalent
of the rivers of ash that helped to destroy Pompeii, claims an Australian
geologist.
If he’s right, this would mean that Mars has been cold and dry—and
probably lifeless—for the past 3.5 billion years, far longer than most
scientists believe. “Mars has always been a place of people’s imaginations,”
says Nick Hoffman of La Trobe University in Melbourne. “People want Mars to be
an abode for Earth-like life forms.”
Hoffman thinks “density flows”, similar to the so-called pyroclastic flows of
gas, ash and…
