Mantle Waves
By Thomas Gernon, Sascha Brune
A hidden geological process reframes our understanding of how diamonds erupt and continents evolve.
This Article From Issue
March-April 2026
Volume 114, Number 2
Page 112
"Tell us where the diamonds are,” said Wynand Kleingeld, a larger-than-life South African employee of De Beers, as he reclined in a leather swivel chair and gently stroked a dachshund sleeping on his lap. It was 20 years ago, and we were in Wells, a quiet city in the English countryside where Kleingeld led a small, elite think tank of geoscientists and statisticians. Forthright if a touch eccentric, Kleingeld was no James Bond villain—merely a visionary who recognized that rigorous science must guide the search for the world’s most valuable and elusive resources.
QUICK TAKE
- Aspects of diamond formation have long puzzled geologists, including why magmas that become diamond-rich rocks called kimberlites erupt far inland from tectonic boundaries.
- Throughout the geologic record, peaks in kimberlite eruptions occur 26 million years after supercontinent breakups, suggesting an unknown global mechanism in the mantle.
- The mantle wave hypothesis explains this process and has far-reaching implications for volcanism, landscape evolution, mantle structure, and mysterious continental earthquakes.
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