Soil Layers and Life on Earth

GeographySoils, Biosphere & EnvironmentAges 11–12

On the left, a soil profile forms over time: click Run to see the litter, humus and accumulation layers thicken above the parent rock; change the climate, parent rock and slope to see why steep mountain soils stay thin while alluvial and basaltic soils grow thick and fertile. On the right, a vegetation column by latitude (tropical rainforest, savanna, desert, broadleaf forest, taiga, tundra) and a mountain show that vegetation also changes with altitude, just as it does from the Equator to the poles. Drag the latitude arrow or click a soil layer to read an explanation.