struct&materials

struct&materials - Earth Struct & Materials Page 1...

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This page last updated on 16-Jan-2006 EENS 204 Natural Disasters Tulane University Prof. Stephen A. Nelson Earth Structure, Materials, Systems, and Cycles The Earth in the Solar System The Solar System z The Earth is one of nine planets in the solar system z In addition to the planets, many smaller bodies called asteroids, comets, meteoroids are present. z All objects in the solar system orbit around the Sun. z The four planets closest to the Sun (Mercury, Venus, Earth, and Mars) have high densities because they are mostly composed of rock, and are called the Terrestrial Planets. z The five planets outside the orbit of Mars (Jupiter, Saturn, Uranus, Neptune, and Pluto) have low densities because they mostly composed of gases, and are called the Jovian Planets. Origin of the Solar System z Original Solar Nebula z Condensation of the Sun about 6 billion years ago z Condensation of the Planets about 4.5 billion years ago. z Process is continuing today, although at a much slower rate. Page 1 of 17 1/16/2006
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The Planet Earth Interior Structure of Earth z The Earth has a radius of about 6371 km, although it is about 22 km larger at equator than at poles. z Density, (mass/volume), Temperature, and Pressure increase with depth in the Earth. z The Earth has a layered structure. This layering can be viewed in two different ways (1) Layers of different chemical composition and (2) Layers of differing physical properties. { Compositional Layering ± Crust - variable thickness and composition z Continental 10 - 70 km thick z Oceanic 8 - 10 km thick ± Mantle - 3488 km thick, made up of a rock called peridotite. ± Core - 2883 km radius, made up of Iron (Fe) with some Nickel (Ni) { Layers of Differing Physical Properties ± Lithosphere - about 100 km thick (up to 200 km thick beneath continents), very brittle, easily fractures at low temperature. ± Asthenosphere - about 250 km thick - solid rock, but soft and flows easily (ductile). ± Mesosphere - about 2500 km thick, solid rock, but still capable of flowing. ± Outer Core - 2250 km thick, Fe and Ni, liquid ± Inner core - 1230 km radius, Fe and Ni, solid All of the above is known from the way seismic waves (earthquake waves) pass through the Earth. Page 2 of 17 1/16/2006
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Before we can begin to understand the causes and effects of natural hazards and disasters we need to have some understanding of the materials that make up the Earth, the processes that act on these materials, and the energy that controls the processes. We start with the basic building blocks of rocks - Minerals. Minerals The Earth is composed of rocks. Rocks are aggregates of minerals. Minerals are composed of atoms. In order to understand rocks, we must first have an understanding of minerals. We'll start with the definition of a Mineral. A
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struct&materials - Earth Struct & Materials Page 1...

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