History of Earth The fundamental principle of geology The present is the key to the past is known as Uniformitarianism Rules of relative dating superposition crosscutting relationships inclusion original horizontality be able to decipher relative ages of a section Unconformities are breaks in the rock record Know types angular unconformity disconformity nonconformity Be able to identify in Grand Canyon sequence Correlation of rock ages relies upon fossils Know types of fossilization principle of faunal succession and use of index fossils Geologic time 4500 million years of Earth history Precambrian Eons from first rocks until abundant fossil organisms Phanerozoic Eon divided up into three eras Paleozoic old life trilobites fishes Mesozoic Era middle life age of dinosaurs Cenozoic recent life age of mammals Eras are divided into periods Actual age dates determined by crosscutting relationships with igneous rocks that can be dated radiometrically Atomic Structure Radioactivity Atom smallest particle that retains properties of element Composed of subatomic particles electrons protons and neutrons Electrons orbit the nucleus of protons and electrons Nucleus made of neutrons and protons proton number is atomic number number of protons determines the element Isotopes have the same number of protons but different numbers of neutrons Nearly all of mass in nucleus Proton electron neutron Radioactive decay of unstable isotopes gives off several forms of radiation Alpha decay is release of two protons and two neutrons Beta decay is release of electron Gamma rays are photons released from nucleus to reach rest state Know the effect of types of decay on the atomic mass and atomic number of the parent isotope Be able to determine new element created by decay Half life is the amount of time for one half of a radioactive substance to decay from parent atoms to daughter products Be able to calculate amounts of material ages of substances or length of half life from information about the radioactive decay of isotopes in materials Chemistry Have a general knowledge of what the periodic table can tell you columns are groups of elements with similar physical properties arranged by the number of valence electrons Be able to draw a Bohr diagram of electron orbits Be able to balance chemical equations Molecular formulas cannot be changed reactants or products cannot be introduced or removed only ratios of them can be changed Molecular formulas of methane propane oxygen gas water carbon dioxide hydrogen gas nitrogen gas Know the chemical formulas for the combustion of methane coal propane Determine molecular weight of molecules from known atomic weights Determine molar quantities from known weights of substances Fuels Combustion of hydrocarbons in oxygen releases heat Coal is formed from incompletely decayed plants Petroleum formed from incompletely decayed diatoms and other floating sea organisms Petroleum deposits need source cooking reservoir and trap Reservoirs must be porous and permeable Most traps of petroleum are stratigraphic or structural Be able to distinguish among them Early oil fields in the United States names locations Natural gas is mostly methane Energy Photosynthesis converts Sun s energy to chemical energy Energy is conserved Changes from one form to another never lost Chemical reactions that release heat energy are exothermic ones that consume heat energy are endothermic Weathering Disintegration and decomposition of rock material at surface conditions Mechanical weathering is the physical reduction in size of particles frost wedging ice wedging frost action is the most important of mechanical weathering processes Unloading and biologic acitivity are two and three on the list Chemical weathering alters internal structure of mineral by adding or removing elements to form new minerals Water is necessary for most chemical weathering processes Often an increase of volume due to added elements Sedimentary Rocks Clastic rocks composed of weathered particles of other rocks Lithified by compaction and cementation Cement commonly calcite silica or iron oxide Classified by particle size conglomerate sandstone siltstone shale Know most common type of sedimentary rock Chemical rocks formed by precipitation from solution Includes limestone made of calcite chert silica rock salt and gypsum Some limestone precipitated by organisms made of fossils Know most common chemical rock Features of sedimentary rocks include bedding porosity permeability fossils Alternative Energy Direct use of solar energy as heat conversion to electricity by photovoltaics Disadvantages Biomass types burning plant tissues pressing seeds for oil converting plant material to alcohol or methane Disadvantages Water power turns turbines to generate electricity river dam tidal barrage tidal lagoon Grand Coulee dam facts Disadvantages Wind power make electricity U S locations potential utilization amount Utilization amount in other areas Geothermal present uses include space heating aquaculture other heating electrical generation Present U S and other area utilization amount Advantages disadvantages Other hydrocarbons oil shale tar sands potential locations drawbacks of these Other alternative energy sources coal gasification hydrogen fuel cells
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