CREATION - Snowball Earth - page 96

granite. Disembowelled sea urchins lie where they were dropped on the rocks and then eviscerated by
seagulls or yellow-headed gannets.
The fossil surfaces extend out sideways from the cliffside like a toppled stack of topics. We climb
down on to one of them, and huddle miserably in the wind, praying for a gap in the clouds. The rock
is dull in the flat grey light, and the surface appears blank. Though we are crouched some twenty feet
above the sea, occasional waves crash over the edges of the rock layer and people leap out of the way,
squealing. Everyone has reverted to geology talk; they are speaking of clasts and volcanic bombs,
gravity flows and forearc basins. Someone is talking about Paul Hoffman, though he isn't on the field
trip. Bragging about him. “Paul worked for me once. He was my junior assistant in the field.” “Did
you hear that?” my companion says. “Everyone wants to claim a piece of Paul.”
The afternoon is drawing on, but it seems the rain may be easing. Now the wind is a blessing, as
it dries off the rock surface. And then suddenly, miraculously, slanting rays of sunlight appear through
the clouds. Fossil light! The surface of the rock is suddenly crammed with strange shapes: fronds and
spindles and discs and branches. “Look at that!” Jim Gehling whoops. “Someone switched on a pro-
jector in the sky!”
Despite the damp rocks, everybody immediately takes off their boots. These fossil forms may have
survived thousands of years of pounding by wind and waves, but nobody wants to risk scratching
them. As geologists pad over the rock surface in their thick hiking socks, the scene seems oddly bib-
lical. And yes, there's even a “burning bush” fossil, the size of a spread hand, with fronds curling up-
wards like tongues of flame. Jim is standing to one side, staring raptly at the shapes that have appeared
in the rocks. “Just imagine if you could have this as the floor of your house,” he says. “Imagine if you
could walk on it every day.”
The fossils of Mistaken Point are different in many ways from those at Ediacara or the White Sea.
These creatures were nowhere near a sandy shore when they died. Instead they rested on the deep,
dark floor of an underwater canyon. And they were overwhelmed not by sand, but by ash.
Northwest of here, a range of volcanoes once poked through land that would later become parts of
Central America and Brazil. Now and then, there would be a rumble, a roar, and an explosive erup-
tion that sent dark clouds of ash flying through the air and into the ocean. The Ediacarans had no ears
to hear any warning sounds. A thick, swirling cloud would simply have appeared from nowhere and
filled their world, blanketing the canyon floor and everything that lived there.
The ancient Roman town of Pompeii was smothered by just such an ash cloud when Vesuvius
erupted in 79 A.D. Fleeing, crouching or writhing, the bodies of Pompeii's residents were preserved in
death by the same ash that ended their lives. First this ash smothered them, then it hardened around
their rotting corpses. Centuries later, the bodies themselves had disappeared. But archaeologists injec-
ted plaster into the voids left behind, and re-created the shapes of the dying residents in extraordinary,
sometimes horrible, detail.
In just the same way, volcanic ash hardened over the rotting bodies of the Ediacarans. Then, like
the plaster at Pompeii, mud from the former seafloor forced its way up into the hollows they left be-
hind, making faithful images that turned slowly into rock.
Preservation by ash is unusual. Most Ediacaran fossils were smothered by sand, and their images
are preserved only as indented death masks in an overhead layer of sandstone. But in Newfoundland
the image comes from the underlying mud. The ash layers have mostly weathered away, and solid
casts of the Ediacarans stick up from the rock surface. Mudstone on mudstone, they are still only vis-
ible when the sun is low enough to outline them with their own shadows. But then they are revealed