Exam 1 Cheat Sheet
Uniformitarianism:The present is the key to the past.Gradual changes over time have big events.If assumptions wrong,conclusions based on them are also wrong.Ibn Sina/ Avicenna: First use Stratigraphic principles. concerns order/relative position of strata and their relationship to the geological time scale. Index Fossil:fossil that existed for a short period of time, abundant in fossil record (generally marine invertebrates). Radioactive Decay:Using the constant decay of radioactive isotopes as a clock.Half-life: time takes for a quantity to reduce half original value.Decay constant:probability that a particular nucleus will decay. Parent nucleus decays into a progeny nucleus. Assumptions:No progeny when start,Nothing adds/removes parent/progeny other than decay,Decay constant is constant.Sedimen- tation Rates rate sediment forms layers.Age of the universe:13.799 ±0.021Ga(billion years).Events After Big Bang: Hydrogen and helium atoms created,Galaxy forms(10 Ga), Heavy elements synthesized by supernova explosions,Solar nebula begins to contract (4.7 Ga),As material collects to form the protosun rotation flattens nebula.Origin of Solar System:Giant spinning ball of gas and dust(energy/mass from big bang/super- nova), Flattens into disk shape(most mass in center), Material sticks together or collided to form clumps (planetesima- ls),Clips eventually become planets:process planetary accretion. Composition of Universe:Solar nebula contained 99% hydrogen and helium<1% Silicon,Carbon,Iron,other important elements for life.Age of Earth:4.55 Ga.Moon form: Impact between earth and smaller planete- simal(size of Mars) to form moon.Planetary Differentiation:Separation of planet into basic layers.Formation of Earth’s Primitive Atmosphere:Began by degassing of Planet’s interior(Composition:H20 vapor,CO2,SO2) Ocean: Atmosphere cooled,H20 vapor condensed to liquid.Rain filled basins forming primitive oceans(primordial soup)First Pollu- tion Crisis:Cyanobacterial photosyn- thetic waste rose the atmospheric oxygen which is poison to organisms.Snowball Earth:Glaci- ation events late in Proterozoic(720-635 Ma) Evolutionary stress rose multicell organ- isms,Volcanic CO2 piled up to warm Earth. Cambrian Explosion(541-485 Ma)Flourish- ing of life,rise in oxygen levels,Origin of life and Cambrian explosion is estimated to be around 3.5 to 4 billion years,(Cambrian explosion and earliest hominins,who lived around 6 million years ago, is much shorter, estimated to be around 535 million years) Giant Insects:Paleozoic(360-252 Ma)
High O2, harmful to larvae–grows bigger. Quaternary glaciation:Tectonic activity, orbital variations, atmospheric composition changes, and ice-albedo feedback. These factors led to the formation of extensive ice sheets in polar regions and influenced global climate patterns for millions of years.Major extinction (P/T;K/P) events:Similarities
(Global events resulting in significant species loss, caused by environmental factors like climate change, volcanic activity, and asteroids)Differences:P/T(Occurred 252 million years ago, primarily due to global warming,low ocean oxygen levels,massive volcanic eruptions,impacting marine species) K/P:Occurred 66 million years ago, triggered by asteroid impact,caused global cooling, wildfires,tsunamis that affected both marine + terrestrial organisms,resulting in the extinct- ion of all non-avian dinosaurs.Plate tectonics, weathering obscures the planetary impacts. Earth Density/Structure:Radius:r=6371km, Volume:V=1.083*10^2 km^3,Mass: m= 5.97 * 10^24kg.Made of concentric shells where the center pressure,temperature,density all increase:Use of Seismology:Probe Earth’s Interior,Seismic radiation travels through different speeds through different materials. Surface waves:like the ocean.Body Waves: P-Waves: compressional waves,travel through solid and liquids,S-Waves:shear waves,travel through solids but not liquids. Composition Earth:Atmosphere:Nitrogen,Oxygen,Argon, etc,~1 kg per cubic meter,Gas+liquid,Meso/ Strato/Troposphere.Crust:Silica rich rocks: silicon,oxygen,aluminum,potassium,calcium, ~2700-3000kg per cubic meter,temp:1000 -30C,minerals quartz+feldspar.Continental crust:granite,30-70 km,less dense.Oceanic crust:6m,more dense,basalt,less buoyant. Mantle:leftover after core and crust formed, silica poor rocks:silicon,oxygen,iron,magne- sium,calcium,~4000 kg per cubic meter,temp 1000-3000C.Upper(30-410km)Transition(410-660 km)Lower(660-2900 km),peridotite Outer Core: Molten (liquid) iron.~11000 kg per cubic meter,temp: 4000-6000.Inner Core: Solid iron.12500kg per cubic meter.Pressure (P = density*gravity*depth)Forced distri- buted over given area, caused by weight of materials above.Upper atmosphere pressure is basically zero,surface 100 kPa, center 350 billion Pascals (50 million psi.Geothermal gradient:Change in temperature as a function of a depth in Earth (temp goes up as you go down)Mantle convection:Hot weak,cold strong.Mantle heated by core,heat circulates as deep as mantle boundary.On 100 million year timescale,drives plate tectonics as heat rises up.Lithosphere:50-200km thick, includes crust and part of upper mantle,rigid
Earth layer formation:As earth cooled, dense materials sank(aka planet differen- tiation)macroscopic structure:Crust,mantle, cores.chemical composition:Iron,oxygen, silicon,magnesium,etc.physical state:Crust+ upper mantle(solid),lower mantle(partially molten),core(liquid+solid)Plate tectonics: Theory that movement of lithosphere in response to mantle convection.Wegener’s Continental Drift:Continents were joined together called Pangaea, evidence(coastline matching shapes,fossils found on different continents)Mid-ocean ridges:chains under- water mountains,forming where tectonic plates diverging from other.Can melt from high temp,low pressure,and the presence of water from the mantle,resulting magma rises to the surface and cools to form new oceanic crust.Magnetism:Research shows symme- trical magnetic fields across ridge.Earth’s rotation causes spiral flow in liquid outer core which aligns spin axis,electrically charges spiral flow generates magnetic field. Age of the seafloor:New crust created at mid-ocean ridges,convective flow of mantle pushes plate outwards,old plates recycled into mantle (AKA subduction).Continental rifting: Buoyant upwelling leads to doming of crust, breaks and produces rift valley(like E African Rift Valley)Seafloor spreading:Continuous continental rifting produces a linear sea which develops into ocean(like Hawaiian Islands) Accretion:Progressive addition of material (teranes:a 3D unit with geologic history distinct from the material borders) to the continental crust.Orogenesis:Processes of accretion,volcanism, uplift that produces large continental mountain ranges(like Himalayas). Isostasy:Balance of buoyancy forces exists between the lithosphere + underlying astheno- sphere,explaining how former lays on the latter.Convergent boundaries:Andes MT. Divergent boundaries:Mid- Atlantic Ridge
Transform boundaries:San Andreas Fault.Rocks deform:must apply stress,Brittle Deformation(rocks break along discrete surfaces i.e. fractures or faults, insensitive to temp, increases with pressure, dominates shallow crust)Ductile(Rocks changes shape like a fluid,strength decreases with temp, insensitive to pressure, dominates deep crust and mantle)Folds:bends in layers caused by compressive forces,creating ridges.Faults: normal:div plate.reverse(thrust):conv plate, strike-slip:transform plate.Seismic moment: Estimates energy released earthquake based on:stiffness,size of area,amount of slip, quantified in moment magnitude.Mercalli intensity:1-10 scale on earthquake effects. Earthquake early warning systems:tsunami warning,volcano monitoring. Geospatial science:Uses geographic info+tech to answer questions to space/time.Remote sensing: making measurements+obtaining data from a distance using instruments that detect emitted or reflected electromagnetic energy.Geodesy: measuring+representing Earth’s size,shape, potential grav/ magnetic fields, to study properties vary in space/time.Cartography: measuring position,elevation,perimeters,areas to define position info to make maps or communicate geospatial infoGeoinformatics: combination of tech to analyze and produce geographic info.Precision/Accuracy:More precise makes it less general,but could be less accurateMinerals:Any naturally occurring inorganic solid, orderly crystalline structure+ well-defined chemical comp(In granite,has quartz, hornblende,feldspar)Used for construction,electronics, agriculture,medicine. Bonding Behavior:Influenced by valence electrons and ionic radius.Abundance of elements in Earth:Earth(Iron,oxygen,silicon, magnesium)Crust(more silicon+aluminum), Mantle(less silicon,more magnesium).Types silicates:Independent tetrahedra, single chain, double chain,sheet structure,3D frame- work.Affects weathering/erosion,volcanism, earthquakes(lots bc of relative availability of silicon and oxygen).Minerals crust+mantle: Feldspar,quartz,pyroxene,olivine,amphibole. Lava:liquid form exposed to surface.Magma: liquid form contained.Intrusive igneous: Formed by cooling magma in Earth’s interior. Extrusive igneous:Formed by cooling lava at surface Decompression melting:decrease in pressure as rock rises towards surface.Flux melting:addition to volatiles(like water,CO2, Sulfur) that lower melting temp of rock. Solidus:melting curve where below, rock is solid.Liquidus:melting curve where below, rock is liquid.Partial melting:only portion of rock melts.Happens when temp of rock rises above melting point to only some minerals. Composition:igneous:Felsic(granite,rhyolite)Intermediate(diorite,andesite)Mafic(GabbroBasalt)Ultramafic(Peridotite,Komatiite)Magma chamber composition:Assimilation of host rock to magma mixing.Crust by melting mantle:Partial melting of upper produces mafic magma, rises up to lithosphere,pools at base of crust,differentiation magma chamber produces intermediate melts,evolved melts travel upwards/fill chambers at shallow, forming granite+felsic volcanism.Comp/ properties:magma/lava:Low(silica,explosive,viscosity),High(“”)Explosivity of volcanoes: weak->strong(Basaltic,Andesitic,Rhyolitic), increases(SiO2,viscosity midterm difficulty for gas to escape from magma),decrease in temperature.Shield:broad,gently sloping mountains with fluid+low viscosity lava flow (Hawaii)Flood basalt:large,flat formed by eruption of highly fluid+low viscosity lava over a wide area(Columbia)Cinder(scoria) cones:small,cone-shaped made of loose volcanic fragments(aka cinders)Strato- volcanoes:aka composite,tall+steep-sided cones built up from alternating layers of lava and ash(Mount Shasta)Calderas:large, circular depression that partially/completely collapses(Crater Lake)