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Titanium isotopic evidence for felsic crust and plate tectonics 3.5 billion years ago.

One type of magma, called felsic or rhyolitic, is about 65 percent to 75 percent silicon dioxide; its temperature is roughly 1,112 to 1,472 degrees Fahrenheit.

Molten rock that glows red is probably in the felsic temperature range.

Should a volcano erupt, for example, the newly released lava will push down on mafic rocks until they become so deeply buried that they melt under the high subterranean pressures and temperatures, transforming into felsic rocks.

Given that light-colored felsic rocks were abundant billions of years ago, plate tectonics had likely already kicked into action.