1974 Words Aug 11th, 2012 8 Pages
Chapter 12

Earth’s radius is 6,499km

Core: spherical central mass of the earth composed largely of iron and consisting of an outer liquid zone and an interior solid zone. Radius = 3,500km. Core temp. =3,000 degrees -5,000 degrees Celsius.

Mantle: rock layer or shell of the earth beneath the crust and surrounding the core, composed of ultramafic igneous rock of silicate mineral composition. About 2,900km thick. Temp.’s range from 2,800 near the core to 1,800 degrees near crust.

Crust: outermost solid layer of the earth, composed largely of silicate minerals.

Earthquakes produce 3 different types of waves:
P wave: produced by earthquakes, they are the highest velocity of all seismic waves. They can travel through both
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Soft layer b/w hard lithosphere above and strong mantle rock layer below.

Lithospheric plate: segment of lithosphere moving as a unit, in contact with adjacent lithospheric plates along plate boundaries.

Radiometric Dating: establishes the age of certain minerals within rocks using principles of radiometric decay.

3 eras of time past the “Precambrian Time”:
Paleozoic, Mesozoic, Cenozoic

Cenozoic era: important b/c nearly almost all landscape features seen today have been produced in the last 65 million years. Subdivided into 7 epochs (smaller units of time).

Mountain arc: curving section of an alpine chain occurring on a converging boundary b/w 2 crustal plates.

Island arcs: curved lines of volcanic islands associated with active subduction zones along the boundaries of lithospheric plates.

Continental shields: low-lying continental surfaces, beneath which are complex arrangements of ancient igneous and metamorphic rocks. 2 types of shields, exposed and covered.

Exposed shields: include very old rocks, mostly from Precambrian time, and have complex geologic history. Typically regions of low hills and low plateaus. Many thousands of meters of rock have eroded over the past half-billion or more years.

Covered shields: continental shield areas that are covered in younger sedimentary layers, ranging in age from Paleozoic through Cenozoic eras.

Continental margin: narrow zone in

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