The researchers found that in the first 1.5 billion years or so of the Earth’s history, the average net rate at which new continental crust formed remained high, at about 0.7 cubic miles (3 cubic kilometers) annually, enough to establish about 65 percent of the present-day volume of the crust by 3 billion years ago. However, after that, average net new crust growth slowed greatly to about a third of its prior rate as the proportion of crust that formed after being recycled through the mantle rose sharply.