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Mysteries of Terra Firma: The age and evolution of the Earth by James
Lawrence Powell, The Free Press, $25, ISBN 068487282X

GEOLOGY today is so vastly different from its first incarnation—the
accumulation of beautiful and intriguing samples by gentlemen of
leisure—that it can be hard to appreciate the revolution which has taken
place over the past century. James Lawrence Powell has decided to give us a
hand.

In Mysteries of Terra Firma he tracks this upheaval of ideas by examining
three themes: the measurement of time, continental drift and plate tectonics,
and the importance of planetary and meteorite impacts. He gives this historical
scientific debate a freshness, guiding us through the ideas and characters. He
often gives us the arguments in their original form. Even better, these
quotations are not always familiar, and reach into disciplines outside
traditional geology. This gives the stories of progress towards the radiometric
timescale, for example, a novelty that is very engaging.

Powell’s treatment sets this analysis of geological thinking firmly in the
context of the modern multidisciplinary approach. It’s a gentle introduction for
those new to the subject—the bonus is that it’s also a concise study of
scientific method in the 20th century. And anyone familiar with the outline of
these debates will enjoy the Powell’s lucid analysis of how theories that were
once rejected as outright nonsense became the foundations of the modern
geological establishment.