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couldn't shake off the feeling that these outcrops held some important secret. He felt he was big-game
hunting, but for what?
Then something began to nag at him.
Everywhere Paul went in Namibia, he spotted signs of ancient ice. He would be hiking up a gully
and suddenly he would see a huge white boulder embedded in the grey siltstone. Siltstone is formed
from an ancient seabed. Over time in the ocean, a fine rain of sediment lands gently on the seafloor
and is gradually converted to rock. But a boulder had to be brought in separately from the shore. So-
mething must have carried it out into the ocean and then flung it overboard. There were no ships in the
Precambrian, and certainly no creatures capable of flinging anything. The culprit had to be icebergs.
The boulder, a “dropstone”, must have fallen from a melting berg up on the sea surface.
That wasn't all. As Paul looked more closely, he would see a medley of rocks appearing in the
siltstone. Not a single boulder now, but countless pebbles and stones, all shapes, sizes and colours;
fractured and rounded; pink, brown, tan, white and grey; granite basement, quartzite and carbonate.
This mad jumble had somehow become bound up in the fine grey silt. Like the boulder, these rocks
were interlopers. Something had gathered them up from mountains and gullies throughout Namibia.
Something had bulldozed them down to the shore and on into the silty sea. The mix of multicoloured
rocks stretched in every direction for hundreds of miles. Only one agent was capable of transporting
so many different kinds of rock over such large distances: ice.
Paul recognized these ice-signs immediately. His mother's fireplace in her Canadian cabin was
held up with two great chunks of pale stone packed with ice-borne pebbles. Paul had seen them every
weekend and throughout the summer as a child.
He had also known for years that rocks like these show up all over the world. They can be found in
the Americas, Asia, Europe—in fact on every single continent. And they all date from one particular
point in time: the mysterious end of the Precambrian, just before the first real fossils appeared, just
before life went complex and the Earth changed for ever. Paul had known all this even when he was
working in Canada, but he had never really thought much about it. His mind had been fully occupied
with his work on the shifting of continents.
Now, though, faced on all sides with the Namibian ice rocks, Paul started to wonder just why they
were there. Why they were
everywhere
. You expect to see ice at the North and South Poles. But to
find signs of ice on every continent seemed extraordinary. And the ice rocks in Namibia came with an
extra mystery. They appeared in the middle of rocks that had clearly been formed in warm, tropical
waters. What was ice doing in the tropics? And why did it appear there at that crucial moment in the
history of life? Was it a coincidence? As he probed and pondered over the Namibian ice rocks, Paul
grew more and more intrigued. He was haunted still by the sense that Namibia held some extraordin-
ary story, just waiting to be told. Could these strange rocks be the key? Forget the motions of ancient
continents. Now all he wanted to know about was ice.
What Paul didn't know yet was that the ice rocks brought nothing but trouble. For decades they
had been grabbing the imagination of geologists without revealing their secrets. There was always
some reason why ice in many of these places simply had to be impossible. Until now, everyone who
had tried to explain the ice rocks had faltered. On the way, though, they uncovered clues that would
prove vital for the Snowball story.
