Download !GLG 101-Illustrated Vocabulary-Chapter 16 !Structure of the Earth

!GLG 101-Illustrated Vocabulary-Chapter 16
!Structure of the Earth
copyright 2003-Roger Weller
!asthenosphere
*a semi-plastic layer in the structure of the Earth which is beneath the lithosphere and is
variable in thickness.
!atmosphere
*the outermost spherical structure comprising a planet; the gases that cover the planet.
!continental crust
*a portion of the Earth's crust that is thicker and less dense than oceanic crust.
Consequently, this type of crust floats at a higher elevation and protrudes above sea level
to form continents.
!core
*the innermost spherical structure of a planet; it is the densest material, probably
consisting mostly of iron and nickel, similar to the composition of iron meteorites. The
outer portion is liquid and the inner portion is solid.
!crust
*the upper most solid layer of the earth's structure; often divided into oceanic crust
(thinner) and continental crust (thicker)
!density
*a measurement of the mass of an object compared to its volume; often expressed in
terms of grams per cubic centimeter.
!gravitational magmatic segregation
*under the influence of gravity crystals that form as as a magma cools either settle to the
bottom of the magma chamber (dense compounds) or rise to the roof of the magma
chamber (low density compounds).
!hydrosphere
*the layer of water that covers the crust of a planet.
!isotasy
*is tied into the concept that the crust of the planet floats on top of a denser, semi-plastic
mantle. Mountain ranges, made mostly of granite, stick up higher than surrounding
plains because the crust beneath the mountains is thicker, allowing the mountains to float
higher.
!mantle
*the layer of the Earth located between the lithosphere and the core
!mantle plume
*hot, low density molten (or semi-molten) material rises from the mantle and comes up
underneath the crust.
!oceanic crust
*the crust of the Earth beneath the oceans; typically only 2 to three miles thick.
!thermal convection
*within the mantle of a planet, hot fluid material rises because of its lower density, while
cold material sinks because of its higher density