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In theory, smectite seemed like a solid connection between tectonics and ice ages.

MIT geologists have found that a clay mineral on the seafloor, called smectite, has a surprisingly powerful ability to sequester carbon over millions of years.

Ideally, researchers should confirm this by finding smectite in ancient rock layers dating back to each global cooling period.

Now, the MIT team has shown that the carbon-trapping clays are a product of plate tectonics: When oceanic crust crushes against a continental plate, it can bring rocks to the surface that, over time, can weather into minerals including smectite.

Over millions of years, smectite can have a global effect, helping to cool the entire planet.