What, a couple millimeters? So, Earth surface 510M km2, 70% water that's some 350M km2. Everest 8km by, say, way too generously 10x20 km2, that's 1600 km3 wor

What, a couple millimeters? So, Earth surface 510M km2, 70% water that's some 350M km2. Everest 8km by, say, way too generously 10x20 km2, that's 1600 km3 worth of rock prism. 1.6k km3 / 350M km2 = 4.5 micro km = 4.5 millimeters. (Yeah, a couple mm.)