Hidden beneath the surface

Image of Crawford Lake by Bonnie Jo Mount/The Post

Hidden beneath the surface
Alternate Title: “In this lake, scientists found a spot like no other — and a record that could redefine our history of Earth”
The Washington Post, June 20, 2023
By Sarah Kapla, Simon Ducroquet, Bonnie Jo Mount, Frank Hulley-Jones and Emily Wright

“Digging deep into a humble lake in Canada, scientists found a spot on Earth like no other — and a record that could redefine our history of the planet”


This summer, researchers will determine whether Crawford Lake should be named the official starting point for this geologic chapter [, The Anthropocene], with pollution-laden sediments from the 1950s marking the transition from the dependable environment of the past to the uncertain new reality humans have created.


In just seven decades, the scientists say, humans have brought about greater changes than they did in more than seven millennia. Never in Earth’s history has the world changed this much, this fast. Never has a single species had the capacity to wreak so much damage — or the chance to prevent so much harm.


“It’s a line in the sand,” said Francine McCarthy, a professor of Earth sciences at Brock University in Ontario, who has led research on Crawford Lake. “The Earth itself is playing by a different rule book. And it’s because of us.”

Seeking the golden spike

Every new phase of Earth’s history begins with a “golden spike” — a spot in the geologic record where proof of a global transformation is perfectly preserved.


An exposed Tunisian cliff face bearing traces of an ancient asteroid impact marks the transition from the age of the dinosaurs to the Cenozoic era. Hydrogen molecules uncovered in Greenland’s ice denote the start of the Holocene — the 11,700-year stretch of stable temperatures that encompasses all of human civilization, up to and including the present day.


These spikes are like exclamation points in the story of the planet, punctuating a tale of shifting continents, evolving species and temperatures that rose and fell as carbon levels fluctuated in the atmosphere. They mark the starts of epochs — small segments of geologic time. And they have helped scientists interpret the forces that shaped Earth’s past climates, which in turn allows them to forecast the effects of modern warming.


In 2009, the International Commission on Stratigraphy — an obscure scientific body responsible for defining the phases of Earth’s past — created a new working group to investigate the evidence for the Anthropocene. The group’s mission: to identify a potential “golden spike” site that might convince fellow scientists of the new epoch’s validity.


Their search spanned from mountain summits to the depths of the ocean, from the Antarctic ice sheet to tropical coral reefs. And, in 2018, it led them to McCarthy’s office door.


Before that moment, few beyond her field knew of McCarthy’s research studying lake sediments for signs of past climate change. Her outreach work was meaningful, but largely local: advocating for conservation of the Great Lakes, teaching geology to students at her midsize public university.


Crawford Lake was similarly modest — just a pretty little pool at a park in the Toronto suburbs. Schoolchildren liked to visit its reconstructed Indigenous longhouses. Locals treasured it as a quaint spot to have a picnic and watch for birds.


Yet McCarthy’s colleague Martin Head, a geologist at Brock who had been involved with the Anthropocene Working Group, was intrigued by the rare chemistry uncovered at Crawford.

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About the Authors:

Sarah Kaplan is a climate reporter covering humanity’s response to a warming world. She previously reported on Earth science and the universe.

Simon Ducroquet is a Climate graphics reporter for The Washington Post. Before joining The Post, Simon worked on the graphics desk for the Brazilian publications O Globo, Folha de S.Paulo and Nexo Jornal.

Bonnie Jo Mount is a is a Pulitzer Prize-winning photojournalist at The Washington Post. She fell in love with photography after learning to print black and white photographs when she was ten years old. She has lived in a variety of places, working as an editor, educator and photojournalist. She joined the Post in 2008.

Frank Hulley-Jones is a designer and developer for The Washington Post. He produces interactive pieces to help audiences engage with complex and important news stories.

Emily Wright is a designer and art director working on digital and print projects for The Washington Post.

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