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Unformatted text preview: CHAPTER 1: BUILDING A PLANET &#2; Introduction Geology: the science that studies earth n how it was born n how it evolved n how it works n how we can help preserve its habitats for life Geologists concept of time n Earth is 4.5 billion years old n More than 3 billion years ago living cells developed on earth n Humans only few million years old n The Scientific method Goal of all science explain how universe works Scientific Method: all scientists rely on this general research plan based on methodical observations and experiments Hypothesis: tentative explanation based on data collected through observations and experiments n Theory: a hypotheses that has survived repeated challenges and accumulated a substantial body of experimental support n A theory can never be considered finally proved n Essence of science no explanation, no matter how believable or appealing, is closed to questioning Model: a representation of some aspect of nature based on a set of hypotheses (usually including some established theories) Code of ethics among scientists n Must acknowledge the contributions of all others on whose work they have drawn n Not fabricate or falsify data n Or other wise be deceitful in their work n Must accept responsibility for training next generation n The Modern Theory and Practice of Geology outdoor science grounded in observations and experiments conducted in the field and collected by remote sensing devices Compare direct observation of processes that occur in modern world w/ what they infer from Geological Record: the information preserved in rocks formed at various times through Earths long history Principle of Uniformitarianism: e James Hutton, Scottish physician n Summary the present is the key to the past n The geologic processes we see in action today have worked in much the same way throughout geological time n Does not mean all geologic phenomena are slow n Bollide: a large meteoroid that impacts earth and causes a crater n Does not imply that only significant geological phenomena are the ones we see occurring today n The Origin of our System of Planets Big Bang Theory n Universe began 13-14 bya w/ a cosmic explosion n Before explosion all matter compacted into single, inconceivably dense point n Since then, the universe has expanded and thinned out to form galaxies and stars n Last 4.5 by time during which our solar system formed 1 CHAPTER 1: BUILDING A PLANET The Nebular Hypothesis n German philosopher, Immanuel Kant, suggested origin of solar system could be traced to rotating cloud of fine dust and gas n Nebular Hypothesis: the idea that the solar system originated from a diffuse, slowly rotating cloud of gas and fine dust ( a nebula) that contracted under the force of gravity and eventually evolved into the sun and plants n Gases hydrogen and helium n Dust-sized particles similar to those found on earth n Slowly rotating cloud contracted under force of gravity (the attraction btw pieces of matter...
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- Fall '05