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SUMMER 2002 - This month from Architects
of Eternity
The father, the son and the sleeping
hills of Umbria, Lat 43.25N, Long, 12.32E. Sometime in the
early 1980's
The hills above Gubbio slept as they always
have. The occasional chirp of a cricket the only noise to
invade the silence of the long road that winds between steepening
cliffs of limestone. The Bottaccione Gorge is a very different
place though to the Contessa Highway - a mile to the east
over the mountain. There the roads vibrate to the rattle
of huge lorries transporting limestone from the quarries
on the west side of the valley. And the Bottaccione does
not have anything like the snake pit that the Contessa has.
A deep, uninviting little gully that smells of cat pee and
digs deep into the succession just to the north of the K-T
boundary. And so Walter Alvarez and his new team from the
Renaissance Geology Group at Berkeley are grinding their
way up the hill out of Gubbio along the Bottaccione Gorge
to where the bar is. It's closed. No surprises there: the
bar at the bend in the Bottaccione always seems to be closed
these days. Perhaps the owner's retired on the profits of
geotourism? In fact a beer would have been nice, if only
to break the journey before they introduce the old man to
the clay layer. His father is in the passenger seat but
he seems cool: Luis Alvarez is winding down, his volatility
cooling with the passage of the years, like an old volcano
as the magma vents close up. As a young man he was incandescence
personified among the firebrand glitterati, nothing less
than a physicist on the Manhattan project. And then he went
on to the work for which he won his Nobel in 1968, the discovery
of several subatomic particles. But that was all behind
him now. He's here to celebrate his swan-song, his final
if perhaps not his greatest achievement. A piece of good
solid, geological research that he would never have got
into if his boy had not decided all those years ago to become
a geologist.
The jeep grinds further up the road, the cliffs
of red and white limestone slashed at regular intervals
of a metre or less by narrow fibres of brown clay, technically
known as marl. Eventually the road curves gently into a
bend and there Walter pulls off, climbs out, stretches and
look around. He spreads out the map on the bonnet of the
car. The silence is absolute, deep, eerie, punctuated only
by the click of cooling metal. They aren't the first people
to have been here. The gorge has been well known since the
Italian geological survey mapped it in the aftermath of
the second world war. Then, in the 60s a young micropalaeontologist
from Milan logged the succession of microfossils along it
and discovered an enigmatic clay band about half-way along
the length of the gorge.
In the 1970s the gorge was host to the attentions
of two of the brightest geologists of their generation -
Pete Scholle and Mike Arthur - who showed that the particular
era boundary exposed in these rocks is associated with a
major upset in the carbon cycling of the oceans. But it
is since 1980 that this place has become the most famous
shrine to geological science in the world.
Walter remembers that for him this all started
with something far more prosaic, even if it was a 'solid'
piece of science. He had originally been interested in the
palaeomagnetism of the area but then became interested in
measuring sedimentation rates - the speed with which particles
of sediment float down from the surface of the ocean especially
in the interval represented by the clay layer. This was
the K-T boundary, the division between the Mesozoic and
the Cenozoic. Sedimentation rates have historically always
been a difficult thing to measure. Fundamentally it boils
down to only two things - knowing where undisputed time
markers are in the sequence of (often otherwise undistinctive)
strata, and then knowing the thickness of the sediment between
these two time lines. By calculating the difference you
get the sedimentation rate. As Walter leans back against
the jeep and stares down the hill towards the bend it occurs
to him again that this is nothing less than the history
of stratigraphy. To know time and thickness of rock is to
know the nature of time itself - the fundamental essence
of palaeontology.
But the way that they tackled the problem
of trying to measure the sedimentation rate in a clay layer
only a few centimetres thick - the one place in the Bottaccione
Gorge sequence where there were no forams to date the sequence
- now that stemmed from the fertile, restless brain of his
father. Luis' hypothesis had been: what if there were an
independent measure of the rate at which sediments accumulated?
Suppose, for example, that it was not necessary to know
where the time horizons in a rock sequence were. Suppose
instead that your measure of time came from somewhere else
entirely.
It was a physicist's solution. Unencumbered
by a formal geological education Luis had a fundamentally
different approach to the problem - a different 'take' if
you will - and consequently saw things from a more flexible
perspective.
Walter realises that now, realises that by
inviting his dad to get involved with his own work, he has
been responsible for a seismic shift in the history of palaeontology.
Probably the biggest one since Harold Urey unlocked the
key to fossil climate research three decades before. Palaeontology
has come out of the closet. Palaeontology now talks to other
disciplines on an equal footing.
Luis is out of the jeep know, walking toward
him. Walter leads him down the hill. The limestone ribs
are interrupted here by a great trench dug in the cliff.
This part of the succession used to be level with the rest.
The trench is the result of the legion of geologists who
have descended on this place since the mid-1970s. They excavated
it so deep that you now have to lean far into the rock to
find what you came for.
The rock around this area looks too as though
it's been in a war. Everywhere it is pocked by perfectly
circular holes an inch across. Legacy of the palaeomagnetists
and the pestilential rock-drills they use to collect their
samples. So many palaeomag samples have been taken that
in only five years this once pristine outcrop has been converted
into something that looks disconcertingly like either a
gruyere cheese, or maybe that car that Bonnie and Clyde
met their maker in at the end of Peckinpah's film.
And then Luis leans in close and peers into
the bottom of the trench. It's hard to locate in the high
sunlight of the middle of the day but Walter points it out
and eventually he sees it. There at the very bottom is a
narrow band - only a couple of centimetres wide - of reddish
brown clay. It comes up out of the ground at his feet, extends
through the trench and continues on up the cliff face out
of reach. The cause of all the excitement - the Cretaceous-Tertiary
boundary clay. The famous outcrop of the K-T boundary in
the Bottaccione Gorge where Luis and Walter Alvarez discovered
the iridium anomaly which led to the asteroid impact theory
of the extinction that killed the dinosaurs.
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Extracted
from Architects of Eternity by Richard Corfield. Published
by Hodder Headline, ISBN 0-7472-7179-8.
Buy Architects of Eternity at www.amazon.co.uk
Or visit the Headline Website at www.madaboutbooks.com
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SUMMER
2002
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