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GEO-100 (Cain) Overview of our Planetary Environment Outline

GEO-100 (Cain) Overview of our Planetary Environment...

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Chapter 1 : An Overview of Our Planetary Environment The Planets : - Our sun and its system is a system of circling planets, including the earth are believed to have been formed from a rotating cloud of gas and dust. The formation of our solar system is believed to have been essentially completed over 4 ½ billion years ago. The compositions of planets formed depended largely in how near they were to the hot sun. The planets formed nearest to the sun contained mainly metallic iron and a few minerals with very high melting temperatures, with little water or gas. Somewhat farther out, were temperatures were lower, the developing planets incorporated much larger amounts of lower temperature minerals , including some that contained water locket within their crystal structures. (This development later made it possible for the earth to have liquid water at its surface.) Still farther from the sun, temperatures were so low that nearly all of the materials in the original gas cloud condensed – even materials like methane and ammonia , which are gasses at normal earth surface temperature and pressure. The Earth, Then and Now : - The earth has changed continuously since its formation, undergoing some profound changes early in its history. The early earth lacked modern oceans and atmosphere, having a much different surface than its present one. (Probably resembling more closely the barren cratered surface of the moon.) - The earth was heated by the impact of the colliding dust particles and meteorites as they came together to form the earth, and by the energy release from the decay of several naturally radioactive elements that the earth contains. - These heat sources combined to raise the earth’s internal temperature enough that parts of it, perhaps even most of it, melted (even though it was probably never molten all at once). Dense Materials , like metallic iron , would have tended to sink towards the center of the earth.
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As cooling progressed , lighter, low-density minerals crystallized and floated out toward the surface.
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GEO-100 (Cain) Overview of our Planetary Environment...

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