When Curiosity came burning through Mars' atmosphere two-and-a-half years ago, it marked the planet with its landing, and the impact of shedding its sky crane, heat shield, backshell, and parachute. But the planet is recovering, obscuring the scars with unending wind and dust.
Rocks are not eternal. Even the tallest mountain will eventually dissolve and disintegrate. Geologists call this process "weathering." It sounds harmless enough, but weathering is one of the most destructive forces on the face of the planet.
Twain Harte rock in California is in a period of active exfoliation, sloughing sheets of granite in creaking, cracking, rock-flaking, dust-shedding, exhilarating glory.