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They used these values to create thermal models of craton formation.

The churning mantle can cause ripples at the craton’s base, setting off eruptions over tens of millions of years, helping explain why many kimberlites seem to migrate toward continental interiors over such a long time.

Jackson, who once helped evaluate lease blocks in a region of Mali several hundred kilometers away from Bourakébougou, believes greenstone belts deep in the West African craton are driving the hydrogen production there.

“At the very edge of the craton we get these carbonatite lavas,” he says.

New York City was on the edge of the craton — imagine Japan with respect to Asia.