STRATA

Looking at what lies beneath.

This book about Earth’s endless stacks of rock and sediment begins with a quote from famed environmentalist Rachel Carson. “The sediments are a sort of epic poem of the earth. When we are wise enough, perhaps we can read in them all of past history.” Author Poppick, a science journalist, methodically, yet gracefully, brings the reader through much of that now-understood past. As she writes, “Beyond an accrual of knowledge, I have found that my own understanding of strata has given me a deeper and still deepening love of Earth in all its layered complexity.” Since Carson’s death, in 1964, Poppick notes, we have found that oxygen appeared only halfway through Earth’s existence, when cyanobacteria, the “greatest environmental engineers in the planet’s history,” began using solar energy to “turn sunshine into sugar” by splitting water into hydrogen and oxygen. The following eruptions of oxygen, when aided by the rise of “solar panels” of protective manganese, let cyanobacteria rewrite “the chemical composition of the Earth from the seafloor to stratosphere,” ultimately generating literal oceans of multicellular life. Turgid but relentless glacier invasions then dislodged and stirred that life to “explode and diversify.” And the mud that oozed out of rewarming oceans finally expelled life onto land. Understanding how the Earth reacts to change wasn’t always considered central. Now, in the era of climate change, it is viewed as vital. For the ancient past has taught us that ecosystems can adapt to change at a slow rate. “But,” Poppick concludes, quoting a farsighted geologist, “the minute you start ramping the rates up, that’s when we start seeing extinctions.”

A lyrical book that will appeal to science and literature buffs alike.