Final answer:
Density stratification explains the composition of the Earth through a process called differentiation, which sorts materials by density, allowing heavier metals to form a core and lighter materials to form a crust.
Step-by-step explanation:
How does density stratification explain the composition of the Earth? Density stratification is the result of a process known as differentiation, which sorted the Earth's major components by density. Early in Earth's history, the planet was hot enough for its interior to melt, allowing heavy metals to sink and form a dense core, while lighter materials floated to form the crust. This concept is evinced when we contrast the planet's average density (5.5 g/cm³) with that of surface materials (3 g/cm³), indicating the presence of much denser materials in the Earth's core.
Over time, as the Earth cooled, these layers became solid, preserving the stratified structure comprising the core, mantle, and crust. Such density differences can also be observed in volcanic activities where lava rises, or in the buoyancy of mountain ranges on the higher-density crust and mantle. Thus, density stratification not only provides a qualitative understanding of the composition of the Earth but also offers insights into the geological and dynamic processes that shape our planet's surface.