Texas State - Physical Geology - GEOL 1410 - Wernette - Exam 1 (Chapters 1 - 3)

plates & plate boundaries

earthquakes outline otherwise calm regions into distinct plates plates are assumed to be rigid with activity only happening on the edges plates: areas of the crust that are rigid with plate tectonics activity 7 major lithospheric plates: - north american - south american - pacific (largest) - african - eurasian - australian-indian - antarctic some are mostly continental (some are all oceanic) the amount of oceanic crust affixed to each plate changes through time (continents are relatively stable)

cleavage (physical property)

flat planes made by a mineral breaking tendency of a mineral to break (cleave) along planes of weak bonding notable: micas (one direction - cleaves to form thin, flat sheets) described by the number of planes and angles between them lots of surfaces all in the same direction count as 1 plane cleavage (breakage pattern) vs. crystal form (growth shape) breaks weak ionic bonds and leaves covalent characterized in terms of: - quality: excellent (micas), poor, good - direction - angle of intersection stair steps = cleavage

polar wander

further evidence for continental drift came when a pole-wandering path was constructed for north america paths for north america and europe were found to be similar in direction but separated by 5000 kilometers explanation for the curves: north america and europe were joined until the Mesozoic (when the atlantic began to open) when north america and europe are moved back to their pre-drift positions, the paths of polar wandering coincide

scientific method

goal: disprove that which is wrong, not prove what we think is right 1. make an abundance of observations 2. ask a question 3. make a falsifiable/testable hypothesis (falsifiable: could be proven false) 4. conduct an experiment / test whether predictions are reliable 5. analyse results 6. reject / reformulate hypothesis or test more of the hypothesis' predictions 7. after the hypothesis has been tested repeatedly, it can be considered a theory

earth's formation 4) planets form

gravity causes space debris to clump up clumps smash into each other forming even bigger clumps until there are planets (some protoplanets got smashed and/or merged in the process) left as the dust settled: - the Sun - 8 Planets (4 inner rocky & 4 outer gassy) - dwarf Planets (like Pluto) - >101 moons/natural satellites (most around outer planets) - asteroids - comets and meteorites

sulfur

gun powder matches health spas skin treatments

crust differentiation: oceanic vs continental plates

hadean-archaean transition: ~4Ga (4 billion years ago) continental crust: - granitic - old (3.9-2 ga) - very difficult to destroy - thick (10-70km) - low density (granite, 2.7g/cm3) - silica, potassium, and sodium - forms the core (craton) of continents with thick units of newer rocks surrounding it - roots (average 30km and mountain belts reach 60km) oceanic crust: - basaltic - young-ish (up to jurassic, 200 ma) - getting destroyed all the time - thin (5-10km) - thinnest at mid-ocean ridges - high density (basalt, 2.9g/cm3) - iron & magnesium - forms the bottom the oceans with a thin covering of younger rock on top of it

convergent boundaries

plates are colliding towards each other destructive margin: crust is destroyed trenches, mountains, arcs ocean-continent - ocean plate subducts - ocean trench - continental volcanic arc (created on a continental plate) ocean-ocean: - older plate subducts - deep ocean trench - oceanic island arc (volcanic island arc, created on a ocean plate) continent-continent: - no subduction - mountain building subduction: - old crust is recycled back into the mantle at subduction zones

earth's formation 5) earth's layers form

~4.6ga: earth formed as an independent planet that had out-competed other rocky chunks in its sector of the solar system (stabilized and started differentiating) gasses formed the atmosphere: atmosphere helped burn up the meteorites that were still bombarding earth back in the hadean very heavy elements (especially iron) sank to form the core less heavy elements (iron and magnesium) stayed in the middle to form the mantle light elements (silicon, aluminum, oxygen, etc.) formed the crust

kaolinite

clay facial products medical powders paint thickener food additive

borax

cleaner

carbonates (mineral class)

...CO32- covalent bonds 1 carbon + 3 oxygens covalently bonded in triangles (don't link with each other) CaCO3 (calcite) & CaMg(CO3)2 (dolomite) triangles arranged in sheets with cations in between many react (fizz) with acid

sulfates (mineral class)

...SO42- covalent bonds 1 sulfur + 4 oxygen covalently bonded in a tetrahedron CaSO4 • 2H2O (gypsum) anhydrite (dry wall) when dehydrated

silicates (mineral class)

...SiO44- most abundant minerals in the crust covalent bonds include: potassium, sodium, aluminum, iron, and/or magnesium iron & magnesium-rich: - ferromagnesian (dark) silicates - oceanic crust - heavier & dark black or green - olivine (found in basalt), pyroxene (augite), hornblende (amphibole) sodium, potassium, and aluminum-rich: - non-ferromagnesian (light) silicates - continental crust - less dense & lighter color - quartz, muscovite, potassium feldspar silicate tetrahedron: - silicon & 4 oxygen bonded covalently (SiO44-) - tetrahedron (-4 net charge) bonds ionically with cations - building block of all silicate minerals subdivisions: when silicates break or dissolve, the surrounding bonds (not the tetrahedra) break and results in a unique set of properties for each silicate subclass 1. nesosilicates (isolated tetrahedra): olivine - covalent bonds (tetrahedra) - ionic bonds (break easily) - 4 oxygen ions for every silicon ion 2. inosilicates (single-chain): pyroxene - silicates are bonded (share oxygen) - oxygen-to-silicon ratio is 3:1 3. inosilicate (double-chain): amphibole - share up to 3 oxygens - every 2 chains connect at oxygen 4. phyllosilicate (sheet): mica/clay/talc - infinite 2D image - 3 of the 4 oxygen atoms being shared by adjacent tetrahedrons 5. tectosilicate (framework): feldspar/quartz - infinite 3D image - covalent bonds in 3 directions (stronger) - oxygen-to-silicon. ratio is 2:1

halides (mineral class)

...group 7 ionic bonds cation(s) ionically bonded with group 7 anion(s) NaCl (halite) & CaF2 (fluorite)

minerals

1. inorganic - does not contain organic molecules 2. naturally occurring 3. solid 4. orderly crystalline structure - made up of atoms (or ions) that are arranged in an orderly, repetitive manner 5. definable (definite) chemical composition that allows for some variation can be described by chemical formula: - SiO2 = quartz - Fe2O3 = hematite substitutions are allowed: - cations (+ve charge) have similar size/charge - anion (-ve charge) substitutions: new mineral (Mg,Fe)2SiO4 = olivine K(Mg,Fe)3(AlSi3O10)(OH,F)2 = biotite polymorphs: two minerals may have the same chemical formula - CaCO3: calcite & aragonite - C: diamond & graphite usually made of a combination of ionic and covalent bonds (olivine)

convergent boundary (continent-continent)

1. no subduction: buoyancy of continental material inhibits it from being subducted 2. mountain building: formation of a new mountain belt composed of deformed sedimentary and metamorphic rocks that contain slivers of oceanic lithosphere

(plate-mantle convection) layer cake model

2 zones of convection: - thin, dynamic layer in the upper mantle - thick, larger, sluggish layer located below downward convective flow is also driven by the subduction of cold, dense oceanic lithosphere upper layer: contains recycled oceanic lithosphere of various ages lower mantle: sluggish and does not provide material to support volcanism at the surface

native gold, silver, copper

coins, jewelry, wiring

anhydrite

dehydrated gypsum drywall

specific gravity (physical property)

density heavier or lighter than you expected for its size most common minerals have a specific gravity between 2 and 4 galena (7.5): extremely dense magnetite & pyrite: pretty dense (iron-based)

elements

all atoms with the same number of protons have the same chemical and physical properties over 100 elements are known (92 naturally occurring) vertical columns: similar size/charge atomic number: how many protons are in the atom (unique for each element) atomic weight: - about the number of protons + neutrons - changes depending on the number of neutrons - different isotopes have different atomic weights

ionic bonds

all or nothing weaker dissolve in water (halite) atom will give up electrons or steal them from others to complete its shell atoms with usually give or take 1-2 electrons ion: atom with unequal numbers of protons and electrons (charged) positively and negatively charged ions attract each other in order to balance the charge an atom that only has a couple of electrons in its outer shell will give them up (cation) cation + : positively charged (more protons than electrons) atom that is close to having a full outer shell will take electrons from others (anion) anion - : negatively charged (more electrons than protons ex. NaCl - Na: cation (gave 1) - Cl: anion (took 1) charge strength: bigger charge = stronger attraction - NaCl: weaker (+1/-1) - CaCO3: stronger (+2/-2) bond strength decreases with atom's size - small atoms = stronger attraction - negative ion: large - positive ion: small bond strength increases with packing efficiency - tighter packing = stronger attraction

native elements (mineral class)

any single element metallic or covalent bonds metals: - Au (gold) - Ag (silver) - As (arsenic) - Cu (copper) non-metals: - S (sulfur) - C (graphite) - C (diamond)

magnetic reversals

as lava cools, iron-rich grains become magnetized and align themselves in the direction of the existing magnetic lines of force paleomagnetism: the natural remnant magnetism in rock bodies earth's magnetic field reverses itself somewhat regularly over time (hundreds-thousands of years) causing magnetic north to become south and vice versa normal polarity (black): when rocks exhibit the same magnetism as the present magnetic field reverse polarity (white): when rocks exhibit the opposite magnetism as the present magnetic field as magma solidifies at the crest of an oceanic ridge, it is magnetized with the polarity of Earth's magnetic field at the time when earth's magnetic field reverses polarity, any newly formed seafloor having the opposite polarity would form in the middle of the old strip (two halves of the old strip are carried in opposite directions - symmetry) rocks can be dated based on amount of time between polarity reversals (like tree rings)

scientific law

basic principle that describes a particular behavior of nature that is generally narrow in scope and can be stated briefly (often as a simple mathematical equation) tend to be observations rather than explanations

(plate-mantle convection) whole-mantle convection

cold oceanic lithosphere sinks to great depths and stirs the entire mantle ultimate burial ground for subducting lithospheric slabs is the core- mantle boundary downward flow of subducting slabs is balanced by buoyantly rising mantle plumes that transport hot mantle rock toward the surface heat for both narrow plumes and the mega-plumes is thought to arise mainly from Earth's core narrow tube-like plumes: long, narrow plumes originate from the core-mantle boundary and produce hot- spot volcanism (hawaiian Islands) giant upwellings, mega-plumes: occur beneath the pacific basins and southern africa

streak (physical property)

color of a mineral in powered form much more reliable than regular color diagnostic for some minerals no streak = harder than streak plate hematite - metallic (red streak) metallic luster: dense, dark streak nonmetallic luster: light-colored streak

quartz

consists entirely of silicon and oxygen 3D framework conchoidal fracture colored by inclusions of various ions (impurities) jewelry microchips abrasives (sandpaper) glass making (foundation) electronic insulation

forces that drive plate motion

convection: - the transfer of heat by the mass movement or circulation of a substance (heating causes materials to become less dense and float to the surface, which cools, increases in density and sinks to the bottom: restarting the process) - driving force of plate movement slab drag: convection in the asthenosphere (whole mantle) drags overriding plates with the convection currents (arthur holmes, 1920s) ridge push: - magma extruding from mid ocean ridge pushes plates apart - elevated position of the oceanic ridge causes slabs of lithosphere to "slide" down the flanks of the ridge - contributes far less to plate motions than slab pull slab pull: - plate "falling down" at subduction zone pulls mid ocean ridge open after it - cool, dense oceanic crust sinks into the mantle and "pulls" the trailing lithosphere along - major contribution to plate movement trench/slab suction: overlying plate at subduction zone is pulled towards subducting plate, causing spreading further away from the trench subduction is some combination of these factors

earth's compositional layers (chemical)

crust: - aluminum silicates - oxygen, silicon, aluminum - some sodium and potassium - formation rates vary by ridge (1.8-15cm per year) - atlantic is very slow: ~2.5 cm/yr - pacific is very fast: up to 16 cm/yr continental crust: - 10-70km - less dense, thicker, rides high - rocks are older and lighter oceanic crust: - 5-7km - more iron, magnesium - denser, thinner, rides low - rocks are younger and denser mantle: - ferromagnesian silicates - iron, magnesium, silicon - dominate rock type in the uppermost mantle is peridotite core: - 3500km - iron, nickel - inner core mostly iron

hardness (physical property)

hard things can scratch soft things most useful diagnostic property mohs scale - relative only - based on strength & arrangement of bonds - more ionic bonds = softer (weak bonds) - more covalent bonds = harder (strong bonds) talc, 1 gypsum, 2 *fingernail: 2.5 calcite, 3 *copper penny: 3.5 fluorite, 4 *wire nail, 4.5 apatite, 5 *piece of glass: 5.5 orthoclase feldspar, 6 *streak plate, 6.5 quartz, 7 topaz, 8 corundum, 9 diamond, 10 fingernail: 2.5 copper penny: 3.5 piece of glass: 5.5 two (talc, 1) girls (gypsum, 2) - coming (calcite, 3) from (fluorite, 4) alaska (apatite, 5) on (orthoclase feldspar, 6) quick (quartz, 7) trains (topaz, 8) carrying (corundum, 9) diamonds (diamond, 10)

diamond

harder tools high pressure experiments

seafloor spreading

harry hess, 1960s: new oceanic crust is produced at the crests of mid-ocean ridges (sites of divergence) new magma pushes up from the mantle at mid-ocean ridges, creating new crust as new crust is created the old crust spreads apart explains: - earthquakes (grinding movement) - valleys between ridges - new crust in the middle of ridges - magnetic reversals (flipped polarity has symmetry)

luster (physical property)

how light reflects/refracts on a surface nonmetallic (descriptions are qualitative and subjective): - dull/earthy - waxy - pearly/satiny - adamantine (transparent & refracts light - fluorite) - resinous (dull shine) - greasy (shiny/oily - graphite) - vitreous/glassy (quartz, halite, calcite) metallic - most are shiny like a metal - some are duller metal looking like horseshoes, rebar, or cast iron *graphite: light weight, nonmetallic mineral that looks very shiny metallic

earth's spheres

interacting, interdependent components of the earth system biosphere: - all life - primitive life first appeared in the oceans about 4 billion years ago atmosphere: all the gasses from earth's surface until the vacuum of outer space hydrosphere: - all water on and beneath earth's surface - cryosphere: solid, icy parts - includes freshwater found underground, and in streams, lakes, and glaciers geosphere: - the solid, earth from the earth's surface to the planet's center - largest of earth's 4 spheres and extends from surface to the center of the planet

subduction (convergent boundaries)

isostasy: denser plate rides lower in the asthenosphere plates collide: denser plate slips under the less dense one denser plate now has the force of even more material above it (pushing it deeper into the asthenosphere) angle at which oceanic lithosphere subducts depends on its: - age and density (young and buoyant subducting lithosphere results in a low angle of descent) rules: continents don't subduct: - both are shortened and thickened (mountains) oceanic crust always subducts below continental older (denser) ocean always slips under younger deep earthquakes: - earthquakes only occur in the lithosphere - as the lithosphere subducts, earthquakes occur at increasing depths - at some depth, the lithosphere is heated enough that earthquakes can no longer occur - very large earthquakes (megathrust) at shallow to intermediate depths

diamond, corundum, beryl, topaz

jewelry

earth's mechanical layers (physical)

lithosphere: - 10-200km - strong, rigid solid (breaks) - crust + uppermost mantle - rocks get hotter and weaker with depth - mechanically detached from asthenosphere due to a small about of melting in the upper asthenosphere (able to move independently from the asthenosphere) oceanic lithosphere: - 100 kilometers thick in the deep-ocean - thinner along the crest of the oceanic ridge system - composed of basalt (rich iron and magnesium) - older (cooler) is gets, the greater its thickness continental lithosphere: - 150 kilometers thick (may extend to depths of 200 kilometers+ beneath the interiors of continents) - composed of less dense granitic rocks asthenosphere: - weak, plastic solid - upper mantle - convection - weak solid mesosphere: - stiffer plastic solid - mantle outer core: - liquid - movement of metallic iron within this zone generates Earth's magnetic field inner core: - solid due to immense pressures in the center of the planet outer + inner core = geodynamo

geologic time

ma (my): million years ga: billion years earth: its age is about 4.6 billion years old (~4.6ga)

variably occurring mineral properties

magnetism - magnetite (can be picked up with a magnet) acid reactivity - carbonates (calcite & dolomite) lamellae - potassium feldspar - inside minerals striations - plagioclase & pyrite - physical grooves taste - halite (salty) smell - sulfur (rotten eggs) twinning - habit feel - graphite (greasy) - talc (soapy) elasticity flexibility - muscovite malleability - copper fluorescence - fluorite, halite (some), apatite

hematite & magnetite

magnets iron (ore) hematite jewelry

mantle plumes and hot spots

mantle plume: - a mass of hotter-than- typical mantle material that ascends toward the surface - surface manifestation of this activity is a hot spot hot spot: - concentration of heat in the mantle, capable of producing magma that extrudes onto Earth's surface - hawaiian islands

convergent boundary (ocean-continent)

melting is triggered within the wedge of hot asthenosphere that lies above it ("wet" rock in a high-pressure environment melts at substantially lower temperatures than does "dry" rock of the same composition) 1. ocean plate subducts: old oceanic lithosphere is more dense than the underlying asthenosphere, causing it to sink 2. ocean trench: produced where oceanic lithosphere bends as it descends into the mantle along subduction zones 3. continental volcanic arc: mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent (andes)

muscovite

member of the mica family breaks into single planes (excellent cleavage) glitter window glass (replaced by quartz)

oxides (mineral class)

metal + O (oxygen) ionic bonds Fe2O3 (hematite)

sulfides (mineral class)

metal or H (hydrogen) + S2- ionic bonds PbS (galena)

metallic bonds

metallic elements can pack together as cations, sharing electrons freely among themselves free electron sharing bond that holds them together results from each atom contributing its valence electrons to a common pool of electrons that move freely throughout the entire metallic structure gives electrical/thermal properties to metallic minerals (conductors) iron, gold, silver, etc.

tenacity (physical property)

minerals resistance to breaking, bending, cutting, or other forms of deformation nonmetallic minerals (quartz) and minerals that are ionically bonded (fluorite & halite) tend to be brittle and fracture or exhibit cleavage when struck malleable: native metals (copper and gold) can be hammered without breaking sectile: minerals that can be cut into thin shavings (gypsum & talc) micas: elastic and bend and snap back to their original shape after stress is released

rock

naturally occurring, solid aggregate of mineral or mineral-like matter aggregates of several different minerals some rocks are composed almost entirely of one mineral (limestone - calcite) some rocks are composed of nonmineral matter - obsidian & pumice (volcanic rock) - coal (solid organic debris)

do all volcanic arcs indicate plate boundaries?

no: hotspot arcs form in the middle of a plate as the plate moves and cuts the volcano off from the mantle plume, the plate develops a tail of increasingly younger volcanoes hot-spot track: chain of volcanic structures produced as lithospheric plate moves over a mantle plume (age of each volcano indicates how much time has elapsed since it was situated over the mantle plume)

opacity/transparency (physical property)

opaque: - blocks all light - metallic minerals - pearly, waxy, resinous translucent: - allows some light - waxy, resinous transparent: - allows most light and detail - vitreous

fracture (physical property)

opposite of cleavage: all bonds are equal chemical bonds that are equally (or nearly equally) strong in all directions framework silicate: conchoidal fracture (bowl-shaped & found in silica-based minerals, quartz)

continental growth

original formation of cratons 3ga (billion) - cratons: part of the continental crust that has attained stability continental extension/thinning (nevada) accretion of islands & sediments during subduction magmatic addition: continental volcanic arcs & hotspots exotic terranes broken off during rifting (plymouth rock)

earth's formation 3) solar system forms

our sector of the Milky Way had a star go supernova only supernovas form elements heavier than iron supernova's leftover dust/gas form a spinning cloud (nebula) that collapses into a disk central burning gasses turn into the sun heavy, rocky materials stay in the inner disk light gasses spin off toward the rim

graphite

pencil led

divergent boundaries

plates are spreading apart from each other constructive margin: new crust is created upwelling of material from the mantle to create new seafloor ridges & rifts tensional stress = lithospheric thinning (continental or oceanic) and new oceanic crust thinned lithosphere = decompression melting of mantle melting = rising magma, lava flows, and spreading plates

transform boundaries

plates slide past each other without creation or destruction of crust byproduct of convergent and divergent faults acting on a spherical earth shearing tectonics: - side-to-side motion (friction = earthquakes) can be found on the ocean floor where they offset segments of the oceanic ridge system (step pattern) fracture zone: linear zone of irregular topography on the deep-ocean floor that follows transform faults and their inactive extensions most transform fault boundaries are located within the ocean basins (few cut through continent - san andreas fault) aligned parallel to the direction of spreading and measurements of transform faults reveal the direction of plate movement

eons and eras

precambrian (eon, 4.6 billion years ago - beginning) - proterozoic: proto/almost animals - archaean: really old - hadean: early, molten Earth phanerozoic: big/visible animals (eon: 540 million years ago) - paleozoic: old life (era: 540 million years ago) - mesozoic: middle life (era: 250 million years ago) - cenozoic: modern life (era: 65 million years ago)

wilson cycle

process by which ocean basins open and close "supercontinent" cycle convergent and divergent plate boundaries combine oceanic crust opens and closes over time bringing continents together and apart 1. rifting within a continent splits the continent... 2. ...leading to the opening of a new ocean basin and creation of new oceanic crust, starting the cycle 3. as seafloor spreading continues and an ocean opens, passive margin cooling occurs and sediment accumulates 4. convergence begins; oceanic crust is subducted beneath a continent, creating a volcanic mountain belt at the active margin 5. terrane accretion (from the sedimentary accretionary wedge carried by the subducting plate) welds material to the continent 6. as continents collide, the crust thickens and builds mountain, forming a new supercontinent 7. the continent erodes, thinning the crust (eventually the process may begin again)

wegener's hypothesis of continental drift

proposed in 1912 after wegener started noticing the fit of continents (suggested that all present continents once existed as a single supercontinent) hypothesis: continents have separated slowly over time from a single continent (pangea, "all lands") to their current positions (beginning 200 million years ago) proposed that gravitational forces of the moon and sun that produce Earth's tides were also capable of gradually moving the continents across the globe 4 lines of evidence: 1. jigsaw fit of continents - similarity between the coastlines on opposite sides of the Atlantic Ocean 2. distribution of fossils across oceans - mesosaurus (eastern south america and southwestern africa) - glossopteris (africa, australia, india, and south america, and antartica) 3. distribution of equivalent rock units across oceans - igneous rocks in brazil resembled similar rocks of the same age in africa 4. paleoclimate (ancient climate) records - discovery of evidence for a glacial period dating to the late paleozoic era in southern africa, south america, australia, and india (ice sheets form near the equator?) hypothesized mechanism: continents crash through oceanic crust, crumpling it up and pushing it out of the way (incorrectly suggested larger/sturdier continents broke through thinner oceanic crust) rejected: 1. the mechanism was highly implausible 2. gross overestimation of the rate of continental movement supported by arthur holmes (magma convects, dragging crust with it)

Resources

renewable: a resource that is virtually inexhaustible or can be replenished over short time spans nonrenewable: a resource that forms or accumulates over such long time spans, it must be considered as fixed in total quantity mineral resource: all discovered and undiscovered deposits of a useful mineral that can be extracted now or at some time in the future ore deposit: a useful metallic mineral that can be mined at a profit

geology

science that deals with the earth's (or other planets') physical structure and substance, its history, and the processes that act on it examines earth, its form and composition, and the changes it has undergone and is undergoing geo = earth logos = discourse physical geology: examines the materials composing earth and seeks to understand the processes operating within Earth and on its surface historical geology: examines the origin and evolution of earth and its inhabitants through time (continents, oceans, atmosphere and life through time)

covalent bonds

sharing is caring stronger resistant to water & other materials (diamond) atoms that are neither close to finishing nor losing a shell share electrons so both atoms have a full set carbon bonds with itself infinitely

atoms

smallest unit of an element that retains the characteristics of that element combine in chemical reactions to form molecules nucleus: - center - mostly immutable portion of the atom inhabited by protons and neutrons proton: - positive charge - number of protons gives the element its identity - inside the nucleus neutron: - neutral charge - controls radioactive stability and some chemical signatures - inside the nucleus electron: - negative charge - outside the nucleus - controls how the atom bonds with others - occupy shells/levels - each shell can hold a certain number of electrons - innermost shells are filled first - outermost shell is left incomplete (except noble gasses) - atoms want to have a complete outer shell balanced atom: #protons = #electrons valence electrons: electrons involved in the bonding process

fluorite

soft abrasive toothpaste

earth system science

system: group of interacting or interdependent parts forming a complex whole earth system: matter and energy are exchanged between biological components, rocks, oceans, the atmosphere, etc. earth is an open system because energy and matter also are exchanged with outer space (powered by the sun and earth's interior)

halite

table salt

principle of uniformitarianism

the present is the key to the past physical, chemical, and biological laws that operate today also operated in the geologic past

habit (physical property)

the shape a mineral grows into some minerals have diagnostic habits one mineral can have multiple habits massive: no clear habit (magnetite) common habits: dipyramidal prismatic rhombohedral cubic botryoidal fibrous bladed dodecahedral crystal form: - geometric habits - every mineral has 1+ crystal form at the microscopic size - expresses underlying molecular crystal structure - some minerals display their crystal form at larger sizes cube: pyrite, halite, fluorite dodecahedron: garnet pyritohedron: pyrite octahedron: sagnetite, magnetite, some fluorite (usually cleavage, not habit) prism/dipyramid: quartz many factors can cause minerals to take a different habit or fail to show one at all: - cramped conditions (calcite vein) - fast cooling/growth (bismuth) - growth within sediment (garnet)

earth's formation 2) expansion/ordering

the universe grew energy started to drop and convert to subatomic particles which became hydrogen atoms that collected into galaxies in which dense pockets of gas collected into stars through nuclear fusion, stars converted hydrogen to heavier elements (iron)

earth's formation 1) the big bang

the universe was in a hot dense state, and nearly 14 billion years ago, expansion started big bang: theory explaining the evolution of the universe tiny loss of energy caused expansion that propelled itself forward as energy cooled and converted to matter

geodynamo

the whole core is iron: magnetic the outer core is liquid: convection the earth is spinning: causes the iron to become magnetized, generating a long-lasting magnetic field around earth the magnetic field protects earth from harmful solar radiation that destroys the atmosphere

science

tool used to learn about the world by developing hypotheses and then subjecting them to scrutiny through observation and experiment systematic study of the structure and behavior of the physical and natural world through observation and experiment

subduction zones (convergent boundaries)

trench: - the valley formed as the plate going down bends - oceanic lithosphere bends as it descends into the mantle accretionary prism/wedge: the wedge of sediments scraped off the subducting plate and onto the overriding plate volcanic arc: subducted water causes the overlying plate to melt (volcanic arc on the overriding plate)

plate tectonics: a paradigm shift

unifying theory of geology: theory of plate tectonics connects every observation, law, and principle of geology, physical/bio geography, climatology, and oceanography the lithosphere is divided into plates that move across earth's surface as new oceanic crust is created at mid-ocean ridges and old oceanic crust is destroyed in subducting trenches rules: - plates are rigid (they break, not bend) - tectonic activity only occurs at plate edges - plate motions include rotation (earth is a sphere) - earth stays the same size (equal amounts of material are created and destroyed) - don't say plate tectonic acceptance: widespread accpetance had been reached by the late 1960s (1968)

color (physical property)

unreliable plagioclase feldspar (creme) vs. potassium feldspar (pink) fluorite & quartz: occur in a wide range of colors variations: caused by ion substitutions - change whole element - olivine: iron (green) or magnesium (black) caused by trace elements - add a little of an element - quartz: titanium (pink quartz)

convergent boundary (ocean-ocean)

water released from the subducting slab of oceanic lithosphere triggers melting in the hot wedge of mantle rock above volcanoes grow up from the ocean floor rather than upon a continental platform 1. older plate subducts: older plates are more dense then younder plates 2. deep ocean trench: produced where oceanic lithosphere bends as it descends into the mantle along subduction zones 3. oceanic island arc: - volcanic island arc (chain of volcanic islands located a few kilometers from a trench where there is active subduction of one oceanic plate beneath another) - most are in the western Pacific

evidence for plate movement

wegener's evidence: 1. jigsaw fit of continents 2. distribution of fossils across oceans - distribution of fossils matches the jigsaw-fit of the continents 3. distribution of equivalent rock units across oceans - line up across continents 4. paleoclimate (ancient climate) records - remains of glaciers at the equator plus: 1. earthquake distribution - earthquakes perfectly follow ridges 2. gps plate movement - different plates move at different rates and plates can move differently relevant to each other - pacific plate: fast - north american plate: slow 3. discrepancies in polar wander - declination: difference between true North and magnetic North - declination changes over time (within a single polarity stripe) called polar wander 4. mid-ocean ridges & trenches - deep quakes happen at trenches 5. magnetic reversals - zebra stripe pattern of magnetic reversals on the sea floor (symmetrical across mid- ocean ridges) 6. age of oceanic crust - combines paleomagnetic and radiometric dating - young: center of ridges - old: up against trenches (further away) - elevation of the sea floor is controlled by ocean crust cooling with age (causes it to contract, becoming denser and more deeply settled in the mantle) all illustrate the mechanism for pushing plates around: sea floor spreading (convection and upwelling mantle pushes the plates)

scientific theory

well-tested and widely accepted view that explains certain observable facts consistently describes objective facts reliably predicts outcomes of experiments and other tests closely scrutinized and tested repeatedly very high probability of being correct always remains open to tests and revision ex. theory of plate tectonics (provides a framework for understanding the origins of mountains, earthquakes, and volcanic activity and explains the evolution of the continents and the ocean basins through time)

mid-ocean ridges & rifts (divergent boundaries)

where new oceanic crust is formed (constructive) youngest & thinnest part of the lithosphere ridge is pushed up by elevated mantle and is not actually that thick longest mountain chain with the longest valleys on earth (interconnected ridges) fast spreading rate: - east pacific rise - no/very narrow axial rift - few sea mounts - broad ridge - empty of features slow spreading rate: - north atlantic ridge - well-defined axial rift - numerous sea mounts ('volcanoes" on the seafloor) - narrow ridge - full of features life on mid-ocean ridges: - greatest heat flow on the surface of earth - supports rich biological communities rift: linear zone along which continental lithosphere stretches and pulls apart rifting: - begins when plate motions produce tensional forces that pull and stretch the lithosphere - marks the beginning of a new ocean basin

continental margins

where oceanic and continental crust meet passive: - continent crust transitions into ocean crust without a distinct plate boundary - continent and attached oceanic crust form a single, stable plate - have lots of sediments active: - continent and oceanic crust are on different plates (plate boundary) - differential movement and seismic activity between the two - earthquakes, volcanoes, trenches may include: continental shelf: the gently sloping submerged portion of the continental margin that extends form the shoreline to the continental slope continental slope: the steep gradient that leads to the deep-ocean floor and marks the seaward edge of the continental shelf continental rise: the gently sloping surface at the base of the continental slope

wwii + the cold war & geophysics

wwii: - ocean surveys -magnetic fields (to detect submarines) - submarine tracking (detect bombs and enemies) - bathymetry (elevation/typography on the seafloor) - navigation (know what areas to avoid) cold war: - world-wide standardized seismographic network (monitors seismic activity searching for hints of nuclear bomb testing) - satellites & gps - promoted a big push in making sea floor maps submarines could use to navigate wwssn findings: - highly ordered pattern to earthquake distributions, including depth harry hess: - dragged sonar to map bathymetry (sea floor elevation) - mapped north pacific sea floor and found trenches (via patterns reflected by sonar waves) marie tharp: - noticed patterns when making seafloor maps (found a ridge in the atlantic)