The solid Earth forms distinct layers. The rocky lithosphere comprises continental crust 30–40 km thick (but 80 km thick beneath Tibet) and is composed mainly of up to 1 km sediments, 1–30 km granite and granodiorite, beneath that gabbro, and oceanic crust a total 7 km thick, comprising up to 0.5 km sediments, 0.5–1 km basalt, and beneath that gabbro. The somewhat plastic asthenosphere lies beneath the lithosphere and extends to a depth of about 200 km. The upper mantle extends to a depth of about 670 km and the lower mantle to about 2885 km. The liquid outer core extends to a depth of about 5150 km, and the solid inner core to the centre of the Earth, at a depth of 6360 km.
Earth rheological layering
- bitumen
- bituminous coal
- bituminous sand
- biuret test
- bivalence, principle of
- bivalent
- bivalent((in genetics))
- bivalves
- Bivalvia
- bivariate
- bivariate data
- bivariate distribution
- bivariate normal distribution
- bivariate probability distribution
- biweight function
- Bjerknes, Jacob Aall Bonnevie
- Bjerknes, Vilhelm Friman Koren
- Bjerknes, Vilhelm Frimann Koren (1862–1951)
- BJT
- Black-and-Tans
- Black Arrow rocket
- black bear
- BlackBerry
- blackbird
- blackboard system