Colin Devey launched his deep-dive career on land, studying a 66-million-year-old lava flow __that once covered half of India. But a year later, in 1987, he found himself on a research cruise to Tahiti, joining a bunch of fellow volcanologists and geochemists looking for volcanic rocks on the ocean floor. Though hard to see down there, he found the geology simple. “The continents are complicated because they’ve been around for billions of years and they’re messed up,” Devey says, “like a billboard covered in 150 advertisements. The oceans are like a new billboard.”
For the past three decades, Devey has busied himself at the bottom of the sea, reading those billboards and hauling news of their movement to the surface. In the process, he has altered what we know about plate tectonics and how our continents push away from (and toward) each other.
For years, geologists believed __that the underwater volcanoes that make up the mid-Atlantic ridge (a 37,000-mile chain that goes straight up the ocean’s center) were equally active and therefore pushing North America away from Eurasia with equal force and speed. Devey found a much more asymmetrical process. He discovered patches of extremely active volcanoes that created new ocean crust and pushed the plates (and continents) apart faster than other areas. Because of him, we now know the south is spreading slowly and the north is spreading fast. “Colin has been really involved in characterizing these important differences,” says Lynne Elkins, a marine volcanologist at the University of Nebraska in Lincoln. But it’s not just the volcanoes’ force.
It’s also the mineral deposits that form around the volcanoes and the way the volcanoes constantly circulate chemicals, and magma, through the ocean, that pushes the continents. “The seafloor is where most of our planet’s volcanic activity takes place,” says Devey, a U.K. native whose work for the GEOMAR Helmholtz Centre for Ocean Research Kiel, in Germany, has put that institution on the map. “We want to understand why they are there and what they do.”
Devey has made more than 550 deep-sea dives and led more than 30 expeditions to map and analyze seafloor volcanism around the planet. But one of his most famous finds had nothing to do with volcanoes. In 2015, his research ship, Sonne, accidentally discovered the largest cache of manganese nodules in the Atlantic. Inky black mineral deposits they are a source of rare earth elements for electronics. They littered the seafloor, some as big as bowling balls and 10 million years old. “It’s surprising how many and how big they were,” he says. “It looked rather weird.”
Devey is now focusing on the geochemistry of an even less well-known area of the Atlantic.
His next stop: the volcanically active Reykjanes Ridge, south of Iceland, where he will drop an ROV to study fresh lava for clues to the ridge’s spread rate of about 2.5 centimeters a year. No matter what he finds, his curiosity will be intact. “This planet is fascinating and we know almost nothing about it,” Devey says. And the only way to learn, he says, is “go out there and do it.”
Depth Gauge
1994 Achieves his deepest dive: 11,483 feet, in the Pacific Ocean. During the dive, a squid rockets past his submersible and explodes a cloud of black ink. "I would have jumped out of the submersible if I could, it was so scary."
2004-2006 Co-chairs the InterRidge program, an international co-operative for studying midocean ridges and oceanic spreading
2015 While searching for deep-sea organisms off Brazil, discovers the largest cache of round, black manganese deposits ever found in the Atlantic Ocean, some as big as bowling balls and 10 million years old
2016 Studying new volcanic rock in the South Pacific, found that the magma held recycled Archean sediment that had been stored deep in the earth for over 2.5 billion years before rising to the surface as magma
Read about how other ocean explorers are solving the planet’s mysteries in the rest of our Deep Sea Six feature from the January/February 2017 issue of Popular Science.