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UA GEO 101 - Exam 1 Study Guide

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GEO 101 1st EditionExam # 1 Study Guide- What is geology?o Geology, or geoscience, is the study of the earth- Scientific Inquiryo Observations lead to hypotheses which lead to theories which lead to laws- Origin of the solar system and universe (big bang, nebular hypothesis, types of planets in our solar system)o The Big Bang  Big Bang Theory – a cataclysmic explosion that scientists suggest represents the formation of the Universe; before this event, all matter and all energy were packed into one volumeless spot- First instant – universe was so small, dense, and hot- Within seconds – hydrogen atoms could begin to form - 3 minutes --- temp has fallen below 1 billion degrees, diameter had grown to about 53 million km (35 million miles); hydrogen atoms could fuse together to form helium atoms - Formation of new nuclei in first few minutes of time is called Big Bang nucleosynthesis because it happened before any stars existed - Eventually universe became cool enough for chemical bonds to bind atoms of certain elements together in molecules - Nebulae – a cloud of gas or dust in spaceo The Nebular Theory for Forming the Solar System  Nebular Theory (v) – explanation for the origins of planets, moons, asteroids, and comments- According to nebular theory, these objects formed from the material in the flattened out part of the disk, the material that did not become part of the star, this outer part is called the protoplanetary disk (v) o Protoplanetery disk contained all 92 elements, some as isolated atoms and some bonded to others in molecules o Materials divided into two classes  Volatile materials (v) Refractory materials (v) o Inner part of disk – refractory dusto Outer part of disk – volatile materials and iceo Material of surrounding rungs began to clump and mind together due to gravity and electrical attraction - Planetestimals (v)  protoplanet (v)  full fledged planet - Planets may have grown from planetestimals in 10-200 million years- Inner orbits where protoplanetary disk consisted mostly of dust, small terrestrial planets composed of rock and metal formed - Outer part of solar system, where significant amounts of ice existed, protoplanets latched on to cast amounts of ice and gas and evolved into the giant planets - Solar system formed about 9 billion years after Big Bang - Origin of the earth & age of the eartho Differentiation of the Earth and Formation of the Moon  When planetestimal planets started to form – homogeneous distribution  Then they became to heat up because: - Heat produced during collisions- Heat produced when matter is squeezed into a smaller volume - Heat produced from the decay of radioactive elements  Internal melting lead  denser iron alloy separated out and sank to the center of the body, where lighter rocky materials remained in shell surrounding center  That was called differentiation (v) Central ball of iron alloy  core  Outer shell  mantle  Early days of solar system  planets bombarded by meteorites (v)  Left surfaces with huge craters, bombardment also contributed to heating the planets  Creation of our moon - 4.53 GA  mars sized protoplanet slammed into newborn earth - Colliding body disintegrated and melted along with large part of Earth’s mantle - Ring of debris formed around earth and quickly coalesced to form the moon - Not all moons are formed this way, some may have been independent protoplanets or comets that were captured by larger planet’s gravity- Formation of the layered structure of the earth o SEE ABOVE- Understand the physical stratification and attributes of the crust, mantle, core: defined by compositiono A layered Earth  We live on the thin outer skin of Earth Early perceptions about earth’s interior were wrong- Open caverns filled with magma, water, and air - Furnaces and flames We now know that Earth is comprised of layers - The crust- The mantle - The core o Outer core o Inner coreo Earth’s Interior Layers  Crust- Continental - Oceanic  Mantle - Upper - Lower  Core - Outer – liquid - Inner – sold  Moho separates crust and mantle o The Crust  Base of cruse – Moho (v); shallow depth (7-70km)  Crust is very think, about .1-1.0% of earth’s radius  Crust consists of a variety of rocks that differ in composition (chemical makeup) from mantle rock  Oceanic Crust - Underlies sea color - 7-10 km thick - Top – blanket of sediment generally less than 1km thick composed of clay and tiny shells - Beneath that the oceanic crush consists of a layer of basalt and below that a layer of gabbro  Continental crust - Most 35-40km thick (4-5 times the thickness of oceanic crust) - Contains variety of rock types ranging from mafic o felsic, on average upper continental crust is less mafic than oceanic crust – it has felsic (granite-like) to intermediate composition  Oxygen is most abundant element in crust o The Mantle 2,885 km thick layer surrounding core In terms of volume – largest part of earth  Consists entirely of an ultramafic (dark and dense) rock called peridotite (rare onsurface bust most abundant rock in our planet) Upper mantle (v) – down to depth of 660 km Lower mantle (v) – 660 km down to 4,900 km  Transition zone (v) – 400 km and 660 km  Almost all is solid rock, but so hot its soft enough to flow (but slowly at rate of less than 15 cm a year) Temperature increases with depth; warmer regions are less dense while cooler regions are denser  Warmer mantle is relatively buoyant and gradually flows upward, while cooler, denser mantle sinks o The Core  Iron alloy (iron mixed with tiny amounts of other elements)  Two parts - Outer core o Btw 2,900 and 5,155 km deep) o Liquid iron alloy o Temp so high that even pressures can’t keep it solid- Inner core o From 5,155 to earth’s center at 6,371 km o Radius – 1,220 kmo Solid iron alloy o Temps over 4,700 but stays solid because its deeper and subjected to even greater pressure - Lithosphere, asthenosphere, mesosphere and attributes: defined by physical propertieso The Lithosphere and the Asthenosphere Earthquake waves travel at different velocities through these layers Rigid materials – cannot flow but bend and break  Plastic materials – flow without breaking  Lithosphere – The relatively rigid, nonflowable, outer 100 to 150 km thick layer of the earth, constituting the crust and the top part


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