Maankuori

Maankuori is the Finnish term for the Earth's crust, the outermost solid shell of the planet. It constitutes the uppermost part of the lithosphere and lies above the mantle. The crust is divided into two major types based on composition and where it occurs: continental crust and oceanic crust.

Continental crust is thicker and less dense, composed mainly of granitic and granodioritic rocks, with thickness typically 25–70 kilometers (average around 35 kilometers). Oceanic crust is thinner and more dense, dominated by basaltic rocks, with thickness about 5–10 kilometers. The crust sits above the mantle and is underlain by the Mohorovičić discontinuity, or Moho, which marks the crust–mantle boundary. Depth to the Moho is roughly 30–50 kilometers beneath continents and about 5–10 kilometers beneath the oceans.

Geologically, crust formation and evolution are governed by plate tectonics. Oceanic crust is continually created at mid-ocean ridges through basaltic magmatism and is recycled back into the mantle at subduction zones. Continental crust forms through a combination of magmatism, accretion of crustal blocks, and long-term remodeling, leading to a complex and heterogeneous structure. The crust's composition and thickness influence surface geology, mineral resources, soils, and land use, and it plays a key role in the biosphere’s habitability.

In summary, maankuori refers to the Earth's outer shell, comprising continental and oceanic crust, each with distinct compositions, thicknesses, and geologic histories that together drive the dynamics of the planet’s surface.