One day back in the 1980s, when I was working in the Smithsonian Institution’s
Department of Paleobiology, I pulled open the drawer of an old wooden specimen
cabinet. There, among the dust and fossil bones, was a yellowed slip of paper.
I forgot long ago what was written on the paper; what I remember is the tingle
I felt holding it in my hand. The note dated from the late 1800s. The person
who wrote it had collected the fossils nearly 100 years before.
I had to laugh at myself for being so easily impressed. To a geologist, 100
years is pretty small potatoes. The fossils, which I only glanced at, were more
than 3 million times older than that. But 300 million years is a lot for the
human mind to fathom — even if the mind belongs to a geologist.
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Without
the
enormous span of time revealed by geology, much of modern science would make no sense at all. |
Some years later, when I decided to write a book about geology for general
readers, there was no question that a central theme would be geological time.
“Deep time,” as the writer John McPhee calls it, is geology’s
great intellectual gift to the world. Without the enormous span of time revealed
by geology, much of modern science would make no sense at all — not evolution
or the Big Bang, and certainly not plate tectonics.
But if deep time is geology’s greatest gift, it is also geology’s
greatest puzzle. I knew from experience how difficult it can be for someone
to appreciate the vastness of the geological past. Charles Darwin knew how hard
it was to visualize the great swaths of time that his theory of evolution implied.
“A man must for years examine for himself great piles of superimposed strata,”
he wrote, “and watch the sea at work grinding down old rock and making
fresh sediment, before he can hope to comprehend anything of the lapse of time,
the monuments of which we see around us.”
My book, I hoped, would give readers a shortcut to understanding. I intended
to demystify the science of so-called geochronology and lay out the overwhelming
evidence of Earth’s great age. Drafting my outline, I piled fact upon fact.
It soon became clear, however, that the tome I planned would convey a feeling
of deep time in one sense only: An hour of reading would seem like a million
years.
Obviously, if I wanted to open my readers’ minds to geologic time, I needed
to take a different approach. In talking to nongeologist friends about my “time”
book, I found myself recounting the tale of my own mental disconnect at the
Smithsonian years before. That story of a little scrap of old paper drew a bigger
reaction than explanations of half-lives and index fossils.
So I decided to write a different book. It would be about the human struggle
to grasp geologic time, not time itself. The story would largely stay within
the narrow slice of time known as human history. E.B. White once advised, “Don’t
write about man, write about a man.” So I chose a man: Nicolaus Steno,
the 17th-century scientist whose stratigraphic principles laid the foundations
for historical geology.
I was lucky. In the wake of Dava Sobel’s surprise bestseller Longitude,
publishers were scrambling for stories about obscure scientific geniuses. And
Steno’s story had a unique twist: This scientific revolutionary and founder
of geology was also an inspirational religious figure, living a life of sacrifice
for which he was beatified by the Catholic Church in 1988. If a man like this
studied kumquats, readers would want to learn about kumquats.
Since the book came out, I’ve been invited to give talks and readings not
only in bookstores and geology classes, but also churches. I have no illusions
that my book will open the minds of zealots hostile to evolution, geology or
the rest of modern science, nor do I have illusions it will do much to help
people truly grasp deep time. Darwin was right: It’s the rocks, not words,
that convey the real message.
But the questions I get from these audiences are always thoughtful, and it is
clear that Steno’s story means something to them. Their curiosity has been
aroused. The age of Earth is not a cold, technical fact, but an idea woven through
science and through modern culture. It’s also an idea that people will
always struggle to accept.
Scientists and teachers rely on the strength of their data and the rigor of
their logic to persuade and enlighten — and rightly so, as that’s
what science is all about. But communicators to the public can’t afford
to ignore the power of the human connection. That day in the fossil collections,
what jolted my awareness of the elapsed years was not the date written on the
page. It was the hand that wrote it.
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