GLGY 209 Lecture Notes - Lecture 2: Star Formation, Solar Wind, Continental Crust
4 Apr 2016
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Describe the difference between continental crust and oceanic crust. The moho is the crust- mantle boundary, first recognized by an abrupt change in seismic- wave velocities. The mantle is mostly made of an ultramafic silicate rock termed peridotite. The core is mostly iron; the inner part is solid, whereas the outer part is liquid. The lithosphere is relatively cool and rigid compared to the hot, soft asthenosphere, which flows more readily. The lithosphere consists of the crust (oceanic basalt and gabbro, or continental granite) plus the uppermost mantle (peridotite) down to a depth of about 100 to 150 km. The asthenosphere is only molten (liquid) in places: the farther a galaxy lies from earth, the greater its red shift. Why? (hint: draw two points that are initially 1 cm apart, and two points that are initially 2 cm apart. Imagine doubling the distance between the points in each pair in a given time. )
