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Fire may seem as inherent to this planet as earth, wind, and water. But while writing Strata, I learned that flames were all but absent here for more than 90 percent of Earth’s existence.
I had this revelation while researching the rise of oxygen in the atmosphere some 2.4 billion years ago—roughly halfway through Earth’s 4.54-billion-year history. I was interested in the arrival of this gas mostly for the ways it influenced life, and how it made possible all of the biological complexity we live amongst today (including, of course, ourselves).
Humans have only understood the origins of the landscapes we inhabit for the past six decades.
Only once I began trying to place myself in the geologic moment of oxygen’s early rise, and imagine what pre-oxygen days may have looked and felt like, did I realize that an oxygen-free Earth must have also been free of flames. I began digging into the geologic history of fire and connected with Ian Glasspool, a paleobotanist at Colby College who studies the oldest evidence of wildfire on Earth. He confirmed that fire would have been all but absent here until enough oxygen accumulated in the atmosphere to support combustion, and enough kindling sprouted on continents to sustain a flame. This would not have taken place until plants first began growing widespread on land, some 458 million years ago. Lightning strikes may have ignited a microbial mat here or there before this time, but those early flames would have been small and short-lived.
When conditions finally shifted to support sustained wildfires, this new planetary element licked its way through the carbon cycle and became inextricably linked with global climate. Glasspool looks to the rock record to try to understand how past periods of climate change influenced ancient wildfire patterns, in hopes of better informing predictions of future fire patterns in a warming world.
I grew up in the 1990s, at a time when scientists had a basic understanding of how mountains form, why volcanoes erupt where they do, and how tectonic plates shape these fundamental features of our planet. For most of my life, I have considered all of this to be rudimentary knowledge that must date back many generations. But while writing Strata, I realized that my own parents—both born in the mid 1950s—were not raised in a world with this same understanding of Earth. Scientists did not agree on the theory of plate tectonics until well into the 1960s. It was only then that they could begin to comprehend the inner and outer workings of Earth, and make sense of the basic building blocks of mountains, volcanoes, and all the other physical features that comprise the world we live in.
Immersing myself in deep time has transformed the most mundane daily activities.
Humans have existed for some 300,000 years but have only understood the origins of the landscapes we inhabit for the past six decades.
Any field of science can spark awe and wonder, but I have found that Earth history can go a step further by offering a deep source of solace and grounding. This comfort that I find in the rock record inspired me to write Strata, but I was surprised to find that it did not flatline or become stale over the years of writing the book; it only became deeper and more profound. When I brought this up with the researchers I interviewed, I often found that they felt similarly, and were drawn to their work for this very reason—for the way it changed how they see and experience their day-to-day lives.
Immersing myself in deep time and seeing the world through a geologic lens has transformed the way I experience even my most mundane daily activities. When I’m weeding my garden or taking my dog for a walk, I’ll recall in a flash that grass and trees did not grow on Earth for most of this planet’s existence. I’ll remember how new all of this is—the paws trotting down a road, the nose sniffing branches, the hearts beating. I’ll remember all that had to happen to make any of this possible—the emergence of oxygen in the atmosphere, the much later evolution of plants and animals—and I’ll have a renewed sense of awe and gratitude that we get to be here at all. 
Read an excerpt from Laura Poppick’s new book, Strata: Stories from Deep Time, here.
Lead image: Ad Gr / Shutterstock
