Tracing the evolution of a landscape
From above, parts of California’s Southern Coast Ranges appear startlingly uniform: The landscape is composed of ridges and valleys that form a pattern of parallel lines as evenly spaced as teeth on a comb. “When you see such a regular pattern, it’s like the landscape is screaming at you to figure out what’s making it do that,” says Taylor Perron, an associate professor of geology in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). The pattern is not unique to the California Coast Ranges; many landscapes around the world have evenly spaced valleys. In 2006, as a graduate student at the University of California at Berkeley, Perron hit upon a physical process to explain this striking feature of Earth’s topography: The even spacing of valleys arose from competing forces of rivers eroding valleys and soil creeping downhill and filling them in. One force balances the other, keeping adjacent valleys from getting...