Geoscience Reference
In-Depth Information
erosion of mountains, whose pulverized rocks spilled into nearby valleys to create new layers of geo-
logical history. And, crucially, the Earth cycled through these processes. What had once been an ocean
floor could be thrust upwards to become a mountain, then be eroded into a valley, and eventually be
flooded to become an ocean once again. The Earth's surface was continually created and eroded away
and re-created again, in a process which Hutton famously said had “no vestige of a beginning—no
prospect of an end”. Through his insights, Hutton had laid the foundations of the notion of deep, un-
fathomable geological time. His dear friend, the professional mathematician and amateur geologist
John Playfair, described the vision of geological eternity thus: “The mind seemed to grow giddy by
looking so far into the abyss of time.”
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Of the perception that the Earth had existed for dizzying eons,
the late Stephen Jay Gould said that “all geologists know in their bones that nothing else from our
profession has ever mattered so much.”
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But even the rational Hutton obtained his inspiration from religious convictions. In his farming
days, Hutton noted that soil was created when old rocks were eroded away, with the debris carried
ultimately off to sea. If this were the only process allowed, all of Earth's land would ultimately erode
away and there would be nowhere left for mankind to live. Since Hutton believed that a kind and lov-
ing God had created the world expressly for the benefit of its human occupants, he reasoned that there
had to be another process that rebuilt the Earth's surface and kept it comfortably habitable. That's how
he developed the idea that seafloors could become mountains, and that volcanoes could create new
land to replace the land that had washed into the oceans.
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Hutton's arguments about God's motivations would hold no weight in modern geology, but they
show that science is muddier than it seems, and that scientists' ideas and inspirations can come from
unexpected sources. What distinguishes science from pseudoscience is not whether your theory ori-
ginated with some particular conviction about how the world works, or whether you feel an emotional
attachment to it. What matters is the evidence you find to support it, and whether you are ultimately
prepared to accept that it could be wrong. Perhaps it's appropriate, then, that students of geology flock
to the site of Hutton's original inspiration with a most irrational reverence. They go for the sheer pleas-
ure of witnessing first-hand the rocks that inspired it all.
It must have been obvious to everyone on the field trip that Pip's rock was sacred to Paul. And
Nick was exasperated. This outcrop wasn't informative so much as photogenic. That, Nick felt, was
why Paul was revering it. It was just showmanship. Nick marched up to the rock face and looked for
some fault to find.
He found something almost immediately, in the stones that Paul claimed had been dropped on to
the ancient seafloor from icebergs floating overhead. You can tell when a stone has come from an
iceberg because it deforms the soft mud that it lands in. Instead of lying flat, the layers of mud imme-
diately beneath the dropstone are squashed downwards.
But this should only happen to the sediment
below
the stone. If you peer at the cliff face and see
lines of sediment deformed above as well as below the boulder, that's a warning sign that the stone
may never have been dropped at all. Instead, it probably rolled down a subterranean slope. And then
when the soft sediments were squeezed around the hard boulder they bent around it, top and bottom.
Crudely put, distortion below an embedded boulder implies a dropstone, while distortion both above
and below implies something else. That's what Nick was looking for at Pip's rock. He moved along the
rock face peering at the boulders until he found one to be suspicious of. Look! he shouted in triumph
to anyone who would listen. There's deformation above this one as well as below. That's compaction!
Look. That shows that some of the boulders didn't come from ice.
