The Grand Canyon in Arizona got carved by water over millions of years of slow but steady erosion. Two similarly-sized canyons on the moon got carved by flying rocks in about ten minutes.

That’s because these two canyons formed in the wake of an asteroid or comet smashing into the moon, a crash that sent streaks of rocky debris flying at incredible speeds, according to a new analysis in the journal Nature Communications.

“This was a dramatic impact that was followed by a series of smaller impact events that excavated these canyons in, you know, roughly 10 minutes,” says David Kring with the USRA Lunar and Planetary Institute in Houston.