The crust is the thin, solid outer layer of a rocky body like Earth, the Moon, or some planets, sitting above deeper, hotter layers such as the mantle and core.

Basic idea

  • In planetary science, crust means the rigid, outermost shell made of solid rock or ice that forms the “skin” of a planet or moon.
  • On Earth, the crust lies above the mantle and is broken into tectonic plates that move slowly over geological time.

Types of Earth’s crust

  • Continental crust : Thicker, less dense crust that makes up the continents; it is mostly composed of lighter, silica‑rich rocks like granite.
  • Oceanic crust : Thinner, denser crust beneath the oceans; it is mainly made of darker, basaltic rocks formed at mid‑ocean ridges.

How it fits in Earth’s structure

  • Earth is commonly divided into crust, mantle, outer core, and inner core, with the crust being the smallest and outermost layer.
  • Despite being thin relative to Earth’s radius, the crust contains all familiar surface features such as mountains, oceans, and plains where life and human activity occur.

Other uses of “crust”

  • In everyday language, crust can also mean the hardened outer layer of foods like bread or pizza, or any hard surface “skin” on a material such as snow or soil.
  • Some moons and icy bodies have a crust made of frozen materials like nitrogen or water ice instead of rock.

Information gathered from public forums or data available on the internet and portrayed here.