Texas State - Physical Geology - GEOL 1410 - Wernette - Exam 2 (Chapters 4 - 8)

deposition

when sediment is released from transportation and finds its final resting point

composite volcano (stratovolcano)

"classic volcano" - conical shape with a steep summit area and gradually sloping flanks product of silica-rich magma having an andesitic composition alternating layers of ash/pyroclastic material and andesitic lava flows (steep sided layers built up by flows) intermediate composition explosive common at subduction zones: - continental volcanic arcs (ocean-continent convergence) - driven by water induced melting associated with the ring of fire forms mountains anatomy: conduit: - pipeline opening by which magma moves toward earth's surface vent: - opening to the surface volcanic cone: - cone-shaped structure created by successive events crater: - funnel shaped depression at the top of the cone fumarole: - vent in a volcanic area from which fumes or gases escape

cooling rates & crystal size

(nearly) instantaneously freeze - results in glass - obsidian cool quickly (not instantaneously) - results in many, small crystals cool slowly - results in fewer, larger crystals - granite cool very slowly: - results in massive crystals

where do we find volcanoes?

1. subduction zones: - convergent plate boundaries - ocean-ocean & ocean-continent - water-induced melting - more than 60% of the world's volcanoes are on the ring of fire - volcanic island arcs & continental island arcs 2. divergent plate boundaries: - decompression melting - active lava extrusions to form new crust (boundaries) - where the greatest volume of magma erupts along - spreading centers decompression melting: - melting that occurs as rock ascends due to a drop in confining pressure - hot, solid mantle rock ascends and moves into regions of lower pressure - ascending mantel plumes reach the uppermost mantle 3. hot spots: - oceanic & continental - mantle plumes bringing heat - intraplate volcanism

volcanic hazards: gases

50-80% water vapor carbon dioxide, sulfuric gases, some nitrogen may cause significant fatalities if higher in toxic gases fumarole: volcanic vent that lets gas escape (degassing can help delay an eruption)

igneous textures (grain size)*

3 factors influence the textures of igneous rocks: - rate at which the molten rock cools (dominant) - amount of silica in the magma - amount of dissolved gasses in the magma pegmatitic: (intrusive) - crystals larger than 1cm (may be much larger) - coarse - formed in deep earth - pegmatitic granite, pegmatitic diorite, pegmatitic gabbro phaneritic: (intrusive) - crystals consistently visible (less than 1cm) - crystals are roughly equal in size - granite, diorite, gabbro, peridiotite porphyritic: (intrusive & extrusive) - visible phenocrysts (large, visible crystals in an igneous rock) set in fine-grained groundmass (fine-grained crystals around a phenocryst, matrix) - formed in the magma chamber then erupted - porphyritic rhyolite, porphyritic andesite, porphyritic basalt aphanitic: (extrusive) - crystals very small (fine-grained) - crystals are not visible to the naked eye - formed at the surface - rhyolite, andesite, basalt glassy: (extrusive) - no crystals - formed at the surface quickly - smooth - obsidian vesicular: (extrusive) - contains air bubbles left from gas bubbles - contain many small cavities (vesicles) - formed at the surface - pumice, scoria, vesicular basalt pyroclastic: (extrusive) - made of broken rock fragments - formed at the surface during eruptions - volcanic breccia (fragments >2mm) - volcanic tuff (fragments <2mm) - felsic explosion

soil horizons

5 horizons (O, A, E, B, and C) differ in texture, composition, structure, and color soil profile: how well the different horizons are developed for that area topsoil: horizons O & A subsoil: horizon B true soil (solum): horizons O, A, E, and B

soil horizon: horizon B*

B = subsouil zone of accumulation: all the clay and chemical components leached/eluviated from E horizon few organisms and little organic matter hardpans: impermeable clay layers O + A + E + B = true soil (solum) solum: living roots and other plant and animal life are largely confined to this zone

soil evolution

O horizon is always the uppermost few cm of loose organics as new sediment enters the system: - the A and O layers migrate upward - the bottom part of A is leached/eluviated (becomes E with mostly sandy quartz left) B grows as it accumulates more clay and soluble chemicals leached/eluviated from above C grows increasingly slowly as the underlying material is weathered (grows downward) as soil accumulates on top, it will shield the parent material, slowing weathering

viscosity

a fluid's resistance to flow depends on: - temperature - silica content high: thick & sticky: felsic - steeper slopes (stratovolcano) - more ash & pyroclastic material - more violent/explosive eruptions (super volcanoes) - yellowstone - more dangerous - conical & piled up low: thin & runny: mafic - faster lava flow - greater lava flow area (flood basalts & shield volcano) - hawaii - low, rounded, gentle slope eruption type/shape is determined by viscosity silicate structure: - well-connected (high, felsic) - less connected (low, mafic) temperature: - cold (high, felsic) - hot (low, mafic) gas content (water vapor and carbon dioxide): - high (high, felsic) - low (low, mafic)

effusive eruption

a quiescent eruption that produces mainly outpourings of fluid lava mafic magmas hawaii

regolith

all the sediment, residue, and other material left in place after weathering ex. sand dunes add decomposing organic matter (humus) → soil

rounding

abrasion reduces the size of the particle by rounding off sharp corners and edges during transport degree of rounding indicates the distance or time involved in transportation of sediment angular vs. rounded

magma migration: stoping

absorbs surrounding brittle rock rock surrounding magma chamber is cracked up and falls in goes through surrounding rock without melting country rock may persist as xenoliths (bits of unmelted country rock)

soil & soil types

accumulation of weathered material, water, air, & humus that can support vegetation regolith + humus + air + water forms in layers (horizons) with different compositions residual soil: - forms when parent material weathers in place - bedrock transplanted soil: - develops when weathered material was eroded and transported to a new location - common around rivers - clay and organic rich (agriculture) - unconsolidated sediment

volcano classification: activity level

active: has erupted recently and is likely to do so again (past 10,000 years) dormant: has not erupted recently but might do so again extinct: is not likely to erupt again indicators: - frequency/recency of past eruptions - geophysical indications of ongoing activity

melt a rock (3) change the composition

adding water induces melting - results in a compositional change subduction zones (convergent boundaries) - water in the subducting plate goes into the mantle with the plate - escaping water induces melting and changes the composition of the mantle

fossils

any evidence of prehistoric life body fossils: - remains of the organism - bones, shells, and other body materials that have been fossilized - sometimes these are washed in/not representative of the environment trace fossils: - indication of the organism's activity - tracks/burrows, fossilized poop, bite marks - more informative - burrows (bioturbation) - footprints (lived/moved through that location)

sedimentary structures

any feature in a sedimentary rock that formed at or shortly after the time of deposition not specific to any specific environment informative about the physical processes occurring when the sediment was deposited - strata/beds - cross-bedding - ripple marks - graded bedding - mud cracks

magma

any mass of molten rock generated within earth that has not breached the surface formed by partial melting at various levels within the crust and upper mantle partial melting of ultramafic rocks tends to yield mafic (basaltic) magmas partial melting of mafic rocks generally yields intermediate (andesitic) magmas partial melting of intermediate rocks can generate felsic (granitic) magmas generated by: - decompression melting (caused by a decrease in pressure as magma rises) - introduction of water (lowers the melting temperature of hot mantle rock) - heating of crustal rocks above their melting temperature magma bodies rises toward the surface because it is less dense than the surrounding rocks 3 components: - liquid component - solid component - gaseous component mantle: mostly solid with just pockets of magma magma from melting the crust: - aluminium (continental) - potassium (continental) - sodium (continental) - calcium (oceanic) - iron (oceanic) magma from melting the upper mantle: - iron - magnesium - some olivine origins: - almost all magma originates in the mantle (mantle plumes, subduction, & decompression melting) mantle: ultramafic oceanic crust: mafic continental crust: felsic

special soils

aridisol: - soil formed in arid regions - little organic matter - slow soil development pedocals: - carbonate-rich soils - chemical weathering is less intense - develops into caliche caliche: - made from leached limestone that develops in the B/C horizon - hardened sedimentary rock of cemented by calcium carbonate - formed in arid regions

detrital sedimentary rocks: shale

as silt and clay accumulate, they tend to form thin layers (laminae) clay and silt particles take on a nearly parallel alignment and become tightly packed shales are weak (poorly cemented and not well lithified) forms barriers to the subsurface movement of water and petroleum

fractional crystallization

as the magma starts to cool, mafic minerals crystallize out leaving the magma more felsic olivine: - first to crystallize (ultramafic) quartz: - last to crystallize (felsic) ultramafic to mafic (1st) - mantle mafic to intermediate (2nd) - rising toward the crust intermediate to felsic (3rd) - moves through continental crust happens at: - mid-ocean ridges (mafic magma cools to form mid-ocean crust) moho: boundary between ultramafic mantle (peridotite) and mafic oceanic crust (gabbro) the longer a magma chamber has to sit and cool, the more fractional crystallization will make it felsic

volcanic hazards: volcanic blocks and bombs

because of their size and weight, bombs and blocks usually fall near the vent volcanic blocks: - large pieces of exploded material - made of hardened lava volcanic bombs: - bits of lava that cool into rocks while in the air (football shaped)

nonoliated rocks: anthracite

black (or grayish) very shiny, lightweight rock with brittle fracture low-grade metamorphism of bituminous coal purer than other forms of coal (more carbon and less toxic volatiles)

caldera (super volcano)

bowl-shaped very felsic (thick) massive magma chambers extremely violent: - blows off top, cracks, collapses - pyroclastic material covers wide distances forms craters (wide valleys) rather than raised forms continental hot spots - yellowstone crater lake-type caldera: - collapse of the summit of a large composite volcano following an explosive eruption of silica-rich pumice and ash fragments hawaiian-type caldera: - collapse of the top of a shield volcano caused by subterranean drainage from a central magma chamber yellowstone-type caldera: - collapse of a large area, caused by the discharge of colossal volumes of silica-rich pumice and ash along ring fractures

physical weathering: ice/frost wedging

breakage of rock (clean, large breaks) water caught in rock cracks will expand when frozen: puts pressure against the rock takes repeated freezing and thawing to break open rock will be most aggressive in wet climates with strong temperature fluctuations

burial & subduction metamorphism

burial: - slow burial of sedimentary layers pushes lower layers into the earth - enough heat and pressure to trigger metamorphosis - sedimentary basins subduction: - subducting oceanic crust - high pressure, low temperature involves other metamorphic processes: - contact: around magma chamber - burial: subducting oceanic crust - hydrothermal: fluids release from the oceanic slab

transportation: gravity

can transport any sized sediment but only a short distance without another medium high movement (not much transported) helped by rain and/or earthquakes assists other transportation methods

transportation: ice (glaciers)

can transport very large sediments that get caught in the glacier

carbon cycle

carbon atoms are cycled between the biosphere, atmosphere, hydrosphere, and geosphere carbon reservoirs: - places that can trap carbon for a long time - limestone - coal/fossil fuels - forests (short time) the more carbon is trapped in a carbon reservoir, the less carbon dioxide is available for the atmosphere cultivating forests for agriculture = less carbon dioxide trapped carbon in reservoirs is released through burning & used in cement as limestone) - released back into the atmosphere - absorbed back into the ocean volcanoes - naturally cycle carbon dioxide between the atmosphere & geosphere - self-regulating (trap amount = release amount)

chemical rocks: carbonates

carbonate minerals - calcium carbonate: calcium + carbon dioxide - chalk - coquina - travertine - fossiliferous limestone made of chemicals produced by organisms or from accumulation of plant/animal debris parent rock: - calcium ions come from pyroxene, amphibole, & calcium-rich feldspar in intermediate & mafic rocks coquina: loosely cemented shell hash (broken shells) fossiliferous limestone: calcite cemented shells chalk: microscopic shells and clay ions are derived from ocean water (previously derived from weathering intermediate & mafic rocks) metamorphic alterations: - marble limestone - mineral component: - calcium carbonate & calcite - always react with acid - chemical (evaporate) - biochemical (produced by organisms) - bioclastic (make from seashell/coral remains) dolostone - mineral component: - reacts with acid when powdered - formed by secondary alteration of limestone infiltrated by magnesium-rich groundwater

chemical rocks: oolitic limestone

carbonate rock little grains of sand, shell, or other particles get coated in layers of calcite sand-sized spheres (ooids) oolitic limestone: ooids cemented together by calcite

chemical rocks: travertine

carbonate rock underground springs rich in calcium and carbonates surface and changes in pressure and/or temperature may cause limestone to precipitate ribboned, bubbly appearance: - light-colored and lacy texture formed in flowing water (not in oceans like most limestones)

chemical weathering

chemical reactions can only take place at the surface: - relies on physical weathering to start the process increasing surface area increases reaction rate - increased by physical weathering water: the most important agent of chemical weathering

metamorphism: fluid activity

chemically active fluids carry dissolved ions and are warm upper crust: water occurs as ground water depth: hot water is released into the surrounding rocks when a magma body cools and solidifies some minerals take in water as part of the chemical reaction hot water provides thermal energy which helps promote the reactions olivine + water = serpentine & magnesium oxide source of fluids: - pore fluids trapped in pore spaces (limestone, sandstone, coal, released by heat/pressure) - volatile fluid (steam/nonliquid fluid trapped in magma escapes and enters surrounding rock) - hydrous minerals (gypsum and some clays naturally contain water that can be released into liquid form during metamorphism)

volcanic hazards: lahars

common for andesitic/rhyolitic volcanoes (felsic - intermediate) violent mudflow from gas and steam (very hot, boiling) results when unstable layers of ash and debris become saturated and flow downslope (following stream channels) volcanic debris becomes saturated with water and rapidly moves down steep volcanic slopes moves fast sediment heavy rivers can be triggered before an eruption

fossil fuels

coal, oil, natural gas, bitumen from tar sands, and shale oil source rock: - organic-rich sediments in which hydrocarbons form - shales - marine, lacustrine (lake), or deltaic source rock → reservoir rock reservoir rock: - rock into which hydrocarbons migrate and collect - needs good porosity (pore space) and permeability (easy to flow through) - sandstones cap rock: overlying impermeable layer that prevents hydrocarbons from escaping to the surface - gas (least dense) - oil - water trap: structural feature of the rocks that forces hydrocarbons to collect against the impermeable cap rock anticline trap: - folds in a layer (dome) - rising oil and gas collect at the top of the fold (natural gas collects above the oil) fault trap: - sealed off by a nonporous layer (bend) - strata are displaced so that a dripping reservoir rock abuts as an impermeable bed oil shales: hydrocarbons are trapped in impermeable source rocks called tight formations hydraulic fracturing (fracking): - opening up pore spaces in impermeable rocks, permitting natural gas and oil to flow out into wells - horizontally drill through the layer

volcanic hazards: pyroclastic flows

common for andesitic/rhyolitic volcanoes (felsic - intermediate) heated steam, gas, ash, and rocks (hot gasses infused with incandescent ash and larger lava fragments) burning, melting, asphyxiating, entrapment moves fast most deadly volcanic hazard & most destructive forces of nature

volcanic hazards: dome/sector collapse

common for andesitic/rhyolitic volcanoes (felsic - intermediate) - steep & explosive portion of volcano collapses under force of eruption large landslide moves fast happens near ocean = tsunami

volcanic hazards: lava flows

common for mafic volcanoes - basalt (common) - andesite (less common) - rhyolite (rare) dangers: melting & burning moves slow basaltic lava types: - pahoehoe lava (hot, ropy, folds on itself, flowy) - aa lava (thick, cooler, rocky, sharp, jagged) basaltic lava formations: pillow basalt: - the result of very fast outer cooling around a very hot center - indicates that the lava flow formed below the surface of a water body columnar basalt (forms in sills): - the result of contraction along joints while cooling (breaks along straight planes) lava tubes: - solid rock forming on the outside with a liquid flowing center - insulated pathways that allow lava to flow great distances from its source

nonoliated rocks: hornfels

common, non-descript fine-grained rock composition depends on the original rock clay-rich rocks (shale and mudstone) are intruded by a hot magma body wide variety of parent rocks (shale common)

intermediate (andesitic) magma

composition between felsic and mafic composite cones

marine deposition: continental shelf

continental crust flooded by water shallow, low to moderate energy (some wave action) warm water (near equator) evaporation: - rock salt & rock gypsum carbonate factory: - warm waters produce limestone - takes carbon dioxide out of the atmosphere and locks it in the geosphere - ocean traps carbonate in limestone, helping slow the rise of carbon dioxide in the atmosphere & hydrosphere - too much carbonic acid = acidic waters (disturbs carbonate production) diverse life forms (coral reefs) characteristics: - shale (clays from delta), fossiliferous limestone, micritic (chemical) limestone, oolitic limestone - bioturbation (trace fossils in limestone - burrows) - marine fossils (clams, oysters, corals, shells)

chemical rocks: evaporites

crystalline limestone: - crystallization of calcite - nonclastic: fine to coarse crystalline - produced in warm, shallow seas rock gypsum: - crystallization of gypsum (68%) - nonclastic: fine to coarse crystalline - parent rock: calcium ions come from pyroxene, amphibole, & calcium-rich feldspar in intermediate & mafic rocks - sulfates produced from sulfur released from volcanoes (or burning coal) into the atmosphere rock salt: - crystallization of halite (88%) - nonclastic: fine to coarse crystalline water evaporates (causes dissolved ions to link up and form rocks) ion-rich water evaporates and ions concentrate/link up requires a warm, evaporating environment - desert & ocean maintains all the properties of the mineral component

lithification: cementation

crystals or other materials precipitate around grains and lock them together lithifies sand and gravel ions from water latch onto the side of mineral grains common cements: - quartz or microcrystalline silica (makes hard rocks - chert) - hematite (makes the rock red) - calcite (makes the rock react with acid) chemical sediment may also precipitate as a chemical sedimentary rock - pure cement (calcite rock)

soil horizon: horizon O*

dark humus/organic rich layer at the top of the profile first place organic matter lands (ex. leaves) critical for bringing nutrients to plants enhances moisture retention (absorption rates) few centimeters thick teeming with microscopic life (bacteria, fungi, algae, and insects) O for organic

foliated rocks: amphibolite

dark rock primarily composed of hornblende (amphibole) and plagioclase elongated minerals get rearranged slightly foliated texture (elongate amphibole) intermediate-high grade metamorphism of basalt/gabbro

sources of heat

deep burial: brings rocks closer to heat lava: brings heat to the surface magma: intrudes into surrounding rocks (heats country rock) subduction: moves cold ocean slabs to hot areas (water induced melting) friction: meteorites (quick transfer of kinetic to thermal energy) or convergence (boundaries and fault planes)

composition sorting

dense iron-based minerals/rocks fall out of transportation unstable minerals continue to weather away until only quartz is left after very long transport different minerals have different densities: - high = fall out fast (dense) - low = weather out (turn into clays)

metamorphic grades

describe the extent of alteration and reflects increasing heat & pressure classifies how intensely metamorphic something is high grade: - high temperature & high pressure - masses may be deformed (by folding) low grade: - low temperature & low pressure - shale becomes the more compact metamorphic rock slate - transition is gradual and change is subtle

volcanoes in space

different materials can be volcanic: sulfur & water olympus mons: largest shield volcano in the solar system moon, venus, mars, io, enceladus

metamorphic index minerals

different minerals form under different grades can be used to interpret the metamorphic grade of the rock in which it occurs used to distinguish different zones of regional metamorphism chlorite (1st): low-grade muscovite: low/intermediate-grade biotite: intermediate-grade garnet: intermediate/high-grade staurolite: intermediate/high-grade) sillimanite: high-grade

intermediate igneous rocks

diorite, andesite, scoria plagioclase feldspar & amphibole: - some pyroxene and biotite gray or salt & pepper (even composition of each) andesite (extrusive): - aphanitic or porphyritic - andes mountains diorite (intrusive): - phaneritic or pegmatitic - plagioclase feldspar and amphibole - intrusive equivalent of andesite scoria (extrusive): - vesicular - product of basaltic magma occur in: - ocean-continent subduction zones (andes) - newly forming continental divergent zones (scoria) source material: - melted mantle + felsic/continental material (magma) via partial melting - granite, sandstone, shale, gneiss (silica-rich rocks) weathering products: - sand/gravel (feldspar and amphibole) - clays (from silicate hydrolysis, abundant) - ions (potassium, sodium, aluminum, calcium, magnesium, and iron: abundant) ions + clays: form chemical sedimentary rocks metamorphic alterations: - gneiss (rarely schist)

effects of weathering

dull surfaces & loss of features color changes structural disintegration (rocks break up - chemical) weathering rinds (product of weathering) spheroidal weathering (rounding)

bowen's reaction series*

each mineral melts or crystallizes in a specific order - except plagioclase feldspar olivine: - ultramafic - last to melt - first to crystallize pyroxene (augite): - mafic amphibole (hornblende): - intermediate - mafic biotite mica: - intermediate plagioclase feldspar: - variable - white with striations potassium feldspar: - felsic - pink with lamella muscovite mica: - felsic quartz: - felsic - first to melt - last to crystallize ultramafic: green - oceanic crust mafic: black - green intermediate: gray (black & white) felsic: white - pink - red - continental crust

erosion

erosion: movement of sediment away from the source area requires external forces: - wind - rainwater - water flow (stream/river) - ice (glacier) - gravity increases rates: - more exposure to the elements - faster flow (wind or water) - steeper slopes

texture: foliated vs nonfoliated

foliated: - rock has notable foliation/banding (layers) - results from differential pressure (one direction) - pressed elongated (platy) minerals into orientation - schist nonfoliated: - rock lacks foliation/banding - results from confining or lithospheric pressure (or compositional homogeneity of spherical grains) - quartzite

continental deposition: deserts

experience temperature extremes (hot or cold) 2 primary desert environments: - sand dunes (dune deposition) - interdune playas (flat areas between dunes or other places in the desert) ephemeral lakes: - forms after a flood event - dry out fast - mud cracks and evaporates (rock salt) characteristics: - well sorted, rounded (quartz) sandstone - scarce fossils - cross-bedded/ripples - mudstone & claystone - mud cracks

metamorphic facies*

facies: groupings of metamorphic rock based on a prescribed range of pressure & temperature conditions each facies is named after a characteristic mineral eclogite: moderate temperature + high pressure blueschist (subduction zones): low temperature + high pressure granulite: high temperature + moderate pressure hornfels (contact metamorphism): high temperature + low pressure different protoliths may produce different metamorphic rocks under the same facies - limestone (amphibolite facies) = calcite - sandstone (amphibolite facies) = garnet the same protolith may produce different metamorphic rocks under different facies - shale (hornfels facies) = slate - shale (amphibolite facies) = garnet porphyroblast: - larger crystal within a finer grained metamorphic groundmass - schists

size sorting

far from source: - very well sorted - beach sand close to source: - very poorly sorted - alluvial fan well sorted: all the grains in a sample of sandstone are about the same size poorly sorted: - contains mixed large and small particles - result when particles are transported for a short time and then rapidly deposited improves with: - distance of transport - energy variation of transport

dome volcano

felsic - intermediate - rhyolite (extrusive felsic) - andesite (extrusive intermediate) produced when thick lava is slowly squeezed from the vent steeper sided version of a shield volcano small felsic lava flows are thicker and pile up more "plug" vents inside larger volcanoes forms mountains Collapsing lava domes produce powerful pyroclastic flows

igneous compositions

felsic: white/pink/red - light-colored silicates - solidifies to form granite (granitic composition) intermediate: gray - contains at least 25% dark silicate minerals - solidifies to form andesite (andesitic composition) mafic: black - dark-colored silicates - solidifies to form basalt (basaltic composition) ultramafic: green - contains olivine and pyroxene - main constituent of the upper mantle

magma migration: void filling

fills rifts, cracks, and fissures magma moves into cracks and fills voids divergent boundaries

magma migration: forceful injection

fills thin sheets (sheets/dikes) pressurized magma pushes itself into cracks and weak points causes major uplift of overriding strata (laccoliths)

shield volcano

form on oceanic crust - begin on the ocean floor as seamounts hawaiian Islands - mauna loa: earth's largest shield volcano - kilauea: hawaii's most active volcano low, broad, and round very runny basalt flows (mafic) - mostly lava flows - very little ejection besides lava accumulation of fluid basaltic lavas hotspots forms mountains

fault metamorphism

friction on fault zones (heat and pressure) loosely coherent rock (fault breccia) composed of broken and crushed rock fragments forms thin layers of metamorphic minerals

magma migration: assimilation

full melt of surrounding material country rock heated to melting point: - surrounding rock becomes part of magma (incorporated in which increases the rate of partial melting) promotes composition change through partial melting melting causes heat loss, advancing fractional crystallization plutons and batholiths

nonoliated rocks: quartzite

fused grains from quartz sandstone very hard (scratches glass) & hard to break due to fused quartz crystals waxy and flecked appearance from where it has been struck moderate- to high-grade metamorphism sedimentary features (cross-bedding) are preserved and creates a banded appearance iron oxide may produce reddish or pinkish stains

mafic igneous rocks

gabbro & basalt gabbro (intrusive): - phaneritic or pegmatitic - significant percentage of oceanic crust basalt (extrusive): - aphanitic or porphyritic - most common extrusive igneous rock pyroxene, plagioclase, and olivine: - some amphibole dark & crystalline (shiny) occur in: - lower oceanic crust (gabbro) - upper oceanic crust (basalt) - oceanic hotspots - ocean-ocean subduction zones source material: - melted mantle + oceanic crust - basalt and gabbro (as well as serpentinite & mafic metamorphic rocks) weathering products: - sand/gravel: minor component (plagioclase feldspar & amphibole; locally olivine & pyroxene) - clays (from silicate hydrolysis, abundant) - ions (magnesium, iron, some calcium: abundant) sand/gravel: little amount because mafic minerals are unstable and don't stick around as physical particles metamorphic alterations: - schist and some gneiss

felsic igneous rocks

granite, rhyolite, obsidian, and pumice quartz & potassium feldspar: - some muscovite, biotite, amphibole & plagioclase feldspar white, light gray, or pink granite (intrusive): - phaneritic or pegmatitic - quartz, potassium feldspar, some biotite, amphibole, and muscovite - abundant in the continental crust rhyolite (extrusive): - aphanitic or porphyritic - light-colored silicates - contains glass fragments and voids (cooled rapidly at the surface) obsidian (extrusive): - volcanic glass - glassy - felsic (dark color caused by impurities) - high silica content - conchoidal fracture pumice (extrusive): - glassy vesicular rock with granitic composition - floats in water - granitic composition occur in: - continental hotspots - continental convergence (intrusive only) source material: - melted felsic/continental material (magma) via partial melting - granite, sandstone, shale, gneiss (silica-rich rocks) weathering products: - sand/gravel (quartz and feldspar) - clays (from silicate hydrolysis of micas and feldspar) - ions (potassium, sodium - rock aalt, aluminum) ions + clays: deposited in the ocean (shale) metamorphic alterations: - gneiss (rarely schist) - burial + pressure (continental convergence)

nonoliated rocks: serpentine (greenstone)

green/dark colored from chlorite, epidote, and amphibole product of mafic rocks low grade metamorphism

metamorphism: magmatic & lava heat

heat: - most important driving factor of metamorphism - provides energy needed to produce the chemical reactions that result in the recrystallization of existing minerals heat is highest close to the magma chamber and decreases with distance further from heat = less metamorphism (less heat) closer to heat = more metamorphism (more heat)

shock metamorphism

high pressure and temperature from meteorite impacts (happens quickly) energy of the once rapidly moving meteorite is transformed into heat energy and shock waves that pass through the surrounding rocks

regional metamorphism

high pressures over broad areas at convergent boundaries associated with large-scale mountain building continents come together and compress together sediments and crustal rocks that form the margins of the colliding continents are folded and faulted deep burial of large quantities of rock as one crustal block is thrusted beneath another deeply buried rocks become heated beyond their melting points (producing magma) shale: produces slate, phyllite, schist, and gneiss quartz sandstone: produces quartzite limestone: produced marble

hydrothermal metamorphism

high temperatures and hydrothermal fluids fluids are headed by local heat sources hot, ion-rich water circulates through fractures (pore spaces) in rock swap out ions & undergo chemical reactions with rock enhances the recrystallization of existing minerals common at: - mid-ocean ridges (seawater percolating through the young, hot oceanic crust is heated and chemically reacts with the newly formed basaltic rocks) - sources of heat with fluids greenstone and greenschist

contact (thermal) metamorphism

high temperatures around igneous intrusions occurs in the earth's upper crust (low pressure) when rocks immediately surrounding a molten igneous body are "baked" (high temperature) contact with heat source (lava/magma chamber) aureole: - metamorphosed region surrounding an intrusion - consist of distinct zones of metamorphism close to the magma body, high-temperature minerals form (garnet) further away, low-grade metamorphism minerals form (chlorite)

transitional deposition: beaches

high transport energy well sorted sediment (mostly quartz) home to abundant life forms green/black hawaiian beaches: - olivine/pyroxene/basalt weathered from the island's rock - mafic islands and ocean-ocean subduction zones characteristics: - quartz rich sandstones; coquina - calcite cement - shells, bones, etc. - symmetrical ripples (differs from deltas)

chemical weathering: silicate hydrolysis

hydrolysis (water-losen): chemical reaction with acidic water alters a substance cations (potassium, sodium, aluminum): replaced with hydrogen in acidic water after reacting with carbonic acid breaks down silicates: turns silicates into clay and releases ions

rock cycle

igneous: melting sedimentary: weathering metamorphic: heat & pressure

nonoliated rocks: marble

interlocked crystals of calcite from limestone (sometimes dolomite from dolostone) consists of intergrown calcite crystals that lack banding reacts with acid susceptible to chemical weathering fine-grained "sugary" look to coarsely granular

volcanic neck (volcanic plug)

isolated, steep-sided, erosional remnant consisting of lava that once occupied the vent of a volcano

fissure eruption

lava flows out gently through long cracks in the crust emit fuild basaltic lavas that blanket wide areas mid-ocean ridges (fissure at boundary & flows out) flood basalts (mafic) pyroclastic deposits & ash flows (felsic) basalt plateau: - broad and extensive accumulation of lava from a succession of flows emanating from fissure eruptions flood basalt: - flow of basaltic lava that issues from numerous cracks or fissures and commonly covers extensive areas to thickness of hundreds of meters - deccan plateau

sedimentary structures: cross-bedding

layers form at an angle to the primary bed surface points downward in the direction the sediment was being transported requires wind/water currents in 1 direction (unidirectional) sand dunes, river deltas, and certain stream channel deposits results when sediment does not accumulate in horizontal beds

melt a rock (2) reduce the pressure

less pressure on rocks divergent boundaries: - continental thinning - mid-ocean ridges

ultramafic magma

less than 45% silica (least) mostly olivine mantle

mafic (basaltic) magma

less than 52% silica (least) gas content (least) eruption temperature (highest) low viscosity pyroclastics (few) shield volcanoes, basalt plateaus, cinder cones calcium, iron, magnesium - ferromagnesian (produce heavy, green and/or black rocks) oceanic crust darker in color

felsic (granitic) magma

less than 70% silica (most) gas content (most) eruption temperature (lowest) high viscosity pyroclastics (lots) pyroclastic flow deposits, lava domes rhyolite: extrusive equivalent of granite

soil horizon: horizon E*

lighter colored layer with little organic matter zone of eluviation & leaching eluviation: "washing out" fine particles (clay & silt) leaching: dissolution and removal of "soluble materials (ions and unstable chemicals) water flowing through O and A picks up carbonic acid as it washes downward: making for effective dissolution/hydrolysis in E sand and gravel left E for eluviation

physical weathering: thermal expansion & contraction

melted materials expand & cooled materials contract rapid cooling causes fractures differences in temperature between night and day pore water may help accelerate the process

chemical sedimentary rocks

made of minerals dissolved in water and precipitated out in a mineral or mineraloid (microcrystalline) form biochemical: chemical sediment that forms when material dissolved in water is precipitates by water-dwelling organisms (shells) types: - evaporites - carbonates - chert

detrital sedimentary rocks

made of solid particles of gravel, sand, silt, or clay/mud lithified through compaction/cementation main constituents: - clay minerals and quartz - other minerals are feldspars and micas magma produced (by melting): - felsic parent rock: any other rock conglomerate - grain size: gravel - rounded grains - parent rock: anything - metamorphic: metaconglomerate breccia - grain size: gravel - angular grains - parent rock: anything - metamorphic: metaconglomerate quartz sandstone - grain size: sand - mostly quartz - parent rock: granite, gneiss, quartzite - metamorphic: quartzite arkosic sandstone - grain size: sand - mostly feldspar - parent rock: granite, gneiss, diorite - metamorphic: schist/gneiss siltstone - grain size: mud/silt - breaks into blocks claystone - grain size: silt/mud/clay - crumbles and breaks into blocks shale - grain size: silt/mud/clay - fissile (splits easily) - parent rock: clays of silicates (any silicate except quartz) - metamorphic: slate, phyllite, schist, gneiss fissile: describes a rock that splits into well developed closely spaced planes

lava

magma that reaches earth's surface (exposed to air)

migmatite: a "mixed rock"

melted felsic minerals + metamorphosed mafic minerals temperature high enough to melt felsic minerals bands of granite & gneiss, amphibolite, or other mafic metamorphic rock

foliated rocks: gneiss

metamorphosed rock with gneissic banding gneissic banding: alternating bands of light (felsic) and dark (mafic) minerals many different parent rocks possible (shale, granite, and diorite) high-grade metamorphic rock

foliated rocks: schist

metamorphosed rock with schistose foliation schistose foliation: texture with more than 50% elongated/platy minerals (visible micas) schistosity: - type of foliation that is characteristic in coarser-grained metamorphic rocks - platy minerals and deformed quartz and feldspar crystals appear flattened or lens shapes many different parent rocks possible (shale - common) subcategorized by primary mineralogy - chlorite schist - biotite schist - garnet schist (garnet) porphyroblasts intermediate grade metamorphism

foliated rocks: phyllite

metamorphosed shale with glossy/lustrous sheen but no visible minerals phyllitic cleavage: coarser than slate splits into layers (shiny wrinkled/wavy surface) low grade metamorphism: grades into slate and schist green = chlorite

foliated rocks: slate

metamorphosed shale with slatey cleavage slaty cleavage: - fine-grained (not visible) texture that breaks on flat surfaces - parallel arrangement of fine-grained metamorphic minerals excellent rock cleavage (tendency to break into flat slabs) lowest grade metamorphism - least metamorphosed foliated rock well consolidated & feels harder than shale (also brittle) chalkboards & roofing tiles

silicate weathering resistance

minerals with the lowest crystallization/melting temperatures are the most stable at the surface olivine: least stable & lease resistant quartz: most stable & most resistant decomposed granite: mostly quartz and feldspar

metamorphism: pressure

more force = more pressure confining pressure: applied uniformly from all directions lithostatic pressure: pressure exerted on rocks by weight of surrounding rocks (burial pressure) directed pressure (differential stress): - force exerted in a particular direction - associated with tectonic activity (convergent zones)

how soil forms: climate*

most important factor in soil formation long-term average of temperature & precipitation hot, wet climate: produces a thin layer of chemically weathered soil cold, dry climate: produces a thin mantle of mechanically weathered debris tropical: - very thick (large B layer, little topsoil - leaches fast) - more rain = more leaching temperate: - moderately thick (more organic-rich material, topsoil) - slow development of soil desert: very thin (usually no O/A layers and grows slowly) polar: very, very thin (little chemical weathering, slow decomposition of organic matter)

chemical rocks: coal

most organic rock (no minerals, only organic matter) carbon-based organic matter partial decomposition of plant remains in an oxygen-poor swamp: peat parent rock: - n/a (purely organic) leaves & wood settle to the ground in oxygen-deprived bogs heat and pressure decompress the water and break down plant material into purer carbon form lignite coal: some original plant matter (most moisture is driven out) bituminous coal: shiny & industrial grade metamorphic alterations: anthracite

continental deposition: alluvial fans

mountains meets flatland rainfall in the mountains makes high energy drainage channels discharge lots of material hits flat areas at the base and drop out heavy materials due to a loss of energy characteristics: - breccia/conglomerate - poorly sorted (coarse) - graded bedding (lakes) - very thick beds (drops a lot at once) - distally may get arkose

transportation: wind (aeolian)

moves mostly only sand and smaller sediments (silt and clay) little to no chemical sediment is moved sand: - requires less energy to be transported - windblown dunes and river deposits, and beaches

continental deposition: glaciers

moving: form of erosion stopped: melts and forms a deposition environment trap sediment in and around the ice deposition: glacier reaches the extent of its growth and starts to melt, leaving behind a pile of sediment characteristics: - leaves behind breccia - poorly sorted - angular - large, coarse grains

how soil forms: time*

need to keep soil in place for it to develop rich nutrients and support vegetation is one reason erosion-control projects are important more time = more soil development the longer a soil has been forming, the thicker it becomes and less it resembles parent material as weathering continues, the influence of parent material on soil is overshadowed by other soil-forming factors (climate)

nonfoliated

no discernable preferred orientation in mineral alignment produced by: - contact or hydrothermal metamorphism - regional or burial metamorphism of rocks with no elongate/platy minerals (limestone & sandstone)

where rocks melt - types of magma

ocean-ocean convergent zone: - mafic magma - water driven melting (subduction) - moves through less crust ocean hot spot: - mafic magma (ocean zone) - hawaii ocean-ocean divergent zone: - mafic magma - lithosphere thinning (mid-ocean ridge) - moves through less crust ocean-continent convergent zone: - intermediate magma - mountains (subduction) - moves through more continental crust continent-continent divergent zone: - mafic magma - thin boundary - begins as intermediate

silicate weathering products

olivine → serpentine pyroxene → clay + ions amphibole → clay + ions biotite → clay + ions feldspar → clay + ions muscovite → clay + ions quartz doesn't change (stable)

redox weathering

oxidation + reduction oxidation: - removal of one or more electrons from an atom or ion - elements combine with oxygen - important in decomposing ferromagnesian minerals redox reactions: way of altering oxide minerals (both need water + oxygen) oxide = metal + oxygen (rusting process) changes iron-rich minerals (oxides) into different states magnetite → hematite combined with hydrolysis & dissolution: 1. iron is loosened up by hydrolysis 2. mixes with oxygen 3. creates different iron states

chemical rocks: chert

parent rock: any silicate (or siliceous organisms) microscopic crystals of silica has most properties of quartz but is opaque and microcrystalline - scratches glass - conchoidal fracture - hardness of 7 purely chemical or biological based grows as: - nodules/concretions within limestone as silica-rich ground water drops silica into vugs/holes - layers of siliceous ooze formed by phytoplankton (skeleton & shells) subgroups: - flint: reserved for the black version of chert (contains organic matter) - jasper: varieties that are red/brown because of hematite metamorphic alterations: - metachert (not one of our rocks)

soil horizon: horizon C*

partially altered parent material residual regolith & fragments grades downward to unaltered parent material

physical weathering: abrasion (water)

particles caught within water currents grind down whatever they flow past most common weathering factor

ultramafic igneous rocks

peridotite (intrusive): - phaneritic olivine - some pyroxene - little plagioclase feldspar usually green with black occurs in: - upper-most mantle (oceanic crust) source material: - mantle weathering products: - sand/gravel: minor component (olivine breaks down very easily) - clays (from silicate hydrolysis) - ions: most important component (magnesium and iron) metamorphic alterations: - serpentinite

deposition environment

place where deposition happens each has a characteristic set of biological (fossils), physical and chemical conditions (type of rock/sea structure) continental/terrestrial (on land): - dominated by clastic sedimentary rocks, largely because of their proximity to the source of the sediments - lakes - deserts - alluvial fans - glaciers - streams transitional (coastal): - anywhere that is directly affected by or periodically covered by marine waters - deltas - beaches - tidal flats - barrier islands - lagoons marine: - places permanently covered by ocean waters - continental shelf - continental slope - deep marine environments with no deposition: - mountains - tops of glaciers low energy = silt & clay high energy = gravel & sand rivers = cross-bedding beaches = symmetrical ripples dunes = cross-bedding

how soil forms: organic activity & organisms*

plants: - control how much organic matter accumulates - alter soil acidity/other chemistry - trees help promote more soil formation - help keep soil in place to build upwards (erosion control) bugs & fungi: - break down organic matter (into nutrients) - contribute to the organic matter - help aerate soil and redistribute nutrients good ecosystem = good soil

lithification: compaction

pressing sediment together (burial) drives out water and locks grains together weight of overlying material compresses more deeply buried sediment reduction in pore space (open space between particles) and water that was trapped in the sediments is driven out lithifies clay/mud (fine-grains)

recrystallization

primary process in metamorphism mineral grains break down into larger grains or new types of minerals reorder and rebind into new larger & new grains mineralogy may not change: sandstone (tiny grains) → quartzite (large grains) mineralogy may change: shale (clays) → schist (mica & garnet)

lithification

process of turning sediment into a rock methods: - compaction - cementation

petroleum & natural gas

product of deposited organic material (hydrocarbons) subjected to low-moderate heat & pressure forms easily in the deep ocean where oxygen can't destroy the organic material

distance from the source

proximal: - sediments found close to the source - poor size sorting - angular - poor composition sorting distal: - sediments found far from the source - well size sorting - rounded - well composition sorting

melt a rock (1) raise the temperature

raising the temperature without raising the pressure results in melting mantle plumes: transfer heat from the core-mantle boundary hot spots: - heat migrates upwards and melts rocks - formed by plumes - as plates move, hot spots stay in one place leaving trail of older volcanoes - oceanic: hawaii - continental: yellowstone

transportation: water

rivers and waves the faster the flow, the bigger the pieces transported primary method of moving sediment gravels: moved by swiftly flowing rivers, landslides, and glaciers sand: - requires less energy to be transported - windblown dunes and river deposits, and beaches clay: - requires very little energy to be transported - settles very slowly (accumulations are associated quiet waters of lakes, lagoons, swamps, or marine environments) dissolved load: sodium & calcium suspended load: floating (silt/clay) bedload: larger materials saltation: bouncing traction: rolling

transitional deposition: deltas

rivers meet oceans unidirectional currents subcategories: - sands close to the river mouth (deposited 1st) - silts (deposited 2nd) - clays that are the lightest weight and float into ocean (deposited 3rd) characteristics: - quartz-rich sandstones, siltstones, and shales - well sorted and rounded - calcite cement (calcium carbonates) - organic rich = black clays - plant matter, shells, and vertebrate fossils

physical weathering: exhumation & unloading

rock is stable under confining pressure, but as soon as it has room to expand, it does exhumation (unbury) exfoliation: - sheets of rock break off - rocks swell under pressure (outer layers peel back) -parallel to the surface jointing: - cracks and fissures go down into the rock (rocks swell under pressure) - perpendicular to the surface - allows water to penetrate to depth and start the process of weathering long before the rock is exposed sheeting: mechanical weathering process that is characterized by the splitting off of slab-like sheets of rock exfoliation dome: large, dome-shaped structure (usually composed of granite) that is formed by sheeting

physical weathering: abrasion (glaciers & ice)

rocks caught at the base of a glacier scour striations into underlying rock

turning magma into rock

rocks formed directly from magma (inside earth): - intrusive (plutonic) - slow cooling rocks formed directly from lava (outside earth): - extrusive - fast cooling type of rock formed depends on: - magma's composition - speed of cooling (controls crystal size - texture)

metamorphic rocks

rocks formed from chemical/physical alteration of pre-existing rocks, caused by heat (without melting), pressure, and/or ion-rich fluids rocks may look similar to their parent rock (protolith), or they may have an entirely new appearance - similar (quartz sandstone to quartzite) - different (shale to blueschist) most of the crust is metamorphic: - continents: gneiss - oceans: schists produce economically important minerals and building materials requirements: - heat - pressure - chemically active fluids - time identified by: - composition & texture

igneous rocks

rocks produced from melted rocks that originated within the earth and solidify through cooling/crystallizing key: -melting & crystallization

biological weathering

root wedging (physical) lichen (physical) humic acid (chemical): - organic material decomposes and produce acids that contribute to chemical weathering burrowing (physical): - turns up rocks - break down rock by moving fresh material to the surface for physical and chemical processes

physical weathering: salt wedging

salty water gets into rock and evaporates leaving salt crystals behind salt crystals grow and break up more material

resources in sedimentary rocks

sand and gravel: construction industry pure clay deposit (kaolinite): ceramics limestone: manufacture of cement & building materials evaporates: table salt (rock salt) & dry wall (rock gypsum) uranium bearing sedimentary rock: energy bituminous coal, lignite: energy

sediments

sediment: - chemical or physical products of weathering a rock - materials produced by weathering that are then subject to erosion and transportation detrital sediments: - solid particles coming from preexisting rock - clastic or physical - larger than 2mm = gravel - less than 2mm = sand chemical sediments: minerals that precipitate from solutions and are created by organisms to build their shells bioclastic sediments: remains of once living things (shells, plant matter, etc.)

information preserved in sedimentary rocks

sedimentary rocks contain numerous clues to help us interpret past conditions and environments on Earth sedimentary textures: - well sorted (quartz sandstone), well rounded sand-sized sediment may indicate a windblown dune - poorly sorted, large angular fragments may indicate a glacier fossils: any remains or evidence of ancient life including tracks, bones, shells, leaves, etc.

soil deterioration

soils are a non-renewable resource on human time scales (#1 economic resource) soil degradation: any process leading to loss of soil productivity (erosion, chemical pollution, compaction) practices contributing to erosion: - removing natural vegetation - overgrazing - over exploitation by firewood (removes decaying wood so it can't help develop soil) - deforestation

intrusive magma structures*

sill (tabular): - horizontal, thin sheet like intrusion between sedimentary layers (parallel) - concordant: intrusive igneous masses that form parallel to the bedding of the surrounding rock - form when magma exploits weaknesses between sedimentary beds or other rock structures - accumulates magma and increase in thickness laccolith: - sill-like feature that is swollen enough to cause a dome on the surface (shallow, bulging sill) dike (tabular): - sheet like vertical intrusion cutting across sedimentary layers and other magmatic bodies (vertical sill) - discordant: plutons that cut across existing rock structures - transport magma upward - more resistant and weather more slowly than the surrounding rock stock: - vertical intrusion that feeds a volcano (vent, neck, pipe) - portions of larger intrusive bodies that would be classified as batholiths if they were fully exposed pluton: - any large intrusive body that is slow cooling (most intrusive bodies) batholith: - a particularly large intrusive body >100km2 (large pluton) - enchanted rock - formed when magma was emplaced at depth, crystallized, and exposed by erosion - felsic (granitic) and intermediate rock types intrusions: - tabular: an igneous pluton that has two dimensions that are much longer than the third - massive: an igneous pluton that is not tabular (blob shaped) columnar jointing: - pattern of cracks that form during cooling of molten rock to generate columns - igneous rocks cool and develop shrinkage fractures that produce elongated, pillar-like columns

sedimentary structures: graded bedding

single layer that shows a decrease in grain size from bottom to top fluid experiences turbulence while flowing turbulent flow (underwater landslide) current experiences a rapid energy loss: largest particles settle first followed by successively smaller grains

soil horizon: horizon A*

some humus with more "mineral" matter (sand, silt, etc.) intense biological activity: - plant roots (anchor down) - bacteria & fungi - burrowing animals O + A = topsoil no topsoil: hard to grow plants

chemical weathering: carbonate dissolution

some minerals dissolve better in the presence of acid (boosts dissolution) much more effective than just water at dissolving rocks as water percolates, it picks up carbon dioxide carbonic acid - formed when carbon dioxide is dissolved in water - readily decompose many rocks and produce certain products that are water soluble causes marble statues to disintegrate karst topography: the caves and sinkholes associated with limestone dissolution

sedimentary rocks

source of information for what has happened outside the lithosphere throughout earth's history rock formed from the deposition and solidification of physical or chemical sediment any rock composed of physical, chemical, or bioclastic sediment rocks formed when fragments of pre-existing rock, biologically produced matter, or ions dissolved in water lithify at or near earth's surface lithification: process of turning lose material into a cohesive rock using cementation and compaction key: uplift - weathering - erosion - transportation - deposition - lithification clastic: - texture consisting of broken fragments of preexisting rock - detrital rocks (some chemical sedimentary rocks) nonclastic: - texture in which the minerals form a pattern of interlocking crystals - evaporites and some limestone

cinder cone volcano

steep sided (piled up coarse material) small made of scoria, ash (tiny rock fragments), and pyroclastic material - not lava intermediate composition: andesitic (mafic over time) most are produced by a single, short-lived eruptive event forms mountains

how soil forms: relief*

steeper slope = less soil development length and steepness of slopes significantly affect the amount of erosion and the water content of soil steep slopes: - soils are often poorly developed - due to rapid runoff, the quantity of water soaking in is slight optimum terrain for soil development: - a flat-to-undulating upland surface (good drainage, minimum erosion, and sufficient infiltration of water into the soil) exposure variables: - wind - rain (coast-facing slope receives more rain) - sun (north hemisphere north-facing slopes stay covered in snow longer)

sedimentary structures: strata/beds

strata: layering in sedimentary rock bed: an individual layer of rock that indicates a single depositional event (may be any thickness) top = new | bottom = old change in rock types/characteristics through successive layers of strata record changes shale → limestone → shale: indicates fluctuating ocean depth (glacial cycles of shallow, deep, shallow) sandstone → shale → limestone: indicates rising sea levels sandstone → tuff→ sandstone: records a volcanic eruption (ash on beach after an eruption)

factors enhancing weathering

surface exposure time: - short (less weathering) - long (more weathering) mineral stability: - stable (less weathering) - loose (more weathering) temperature: - more chemical (warm) - variable temperature better for physical amount of water - low (less weathering) - high (more weathering) acidity: - low (less weathering) - high (more weathering) biological activity - low (less weathering) - high (more weathering) slope steepness: - more physical and less chemical - steep: more exposure (less chemical weathering) vegetation: - low (less weathering) - high (more weathering) - slows down erosion rates

partial melting

temperatures between the melting point of quartz and the crystallization of olivine: - partial melting more felsic than the original rock melting order: - felsic, intermediate, mafic, ultramafic the more magma has to migrate through the crust to approach the surface, the more partial melting drives it towards being felsic

geotherm

the average temperature of the crust at any given depth (temperature increases with depth) temperature rises gradually enough that the rising pressure keeps rock solid (equal) melting: - geotherm must enter the melt portion of the diagram - increase temperature, reduce pressure, or change the composition

transportation

the movement of sediment once it has been picked up the bigger the sediment, the more energy is needed to erode and transport methods: - water (rivers and waves) - wind (aeolian) - ice (glaciers) - gravity (assists other transportation methods) effects: - sorting sediment by size and mineralogy - further weathering out unstable minerals - rounding sediment

volcanic hazards: ash falls

tiny shattered fragments of rocks - volcanic glass and very small mineral crystals (fast cooling) common for andesitic/rhyolitic volcanoes (felsic - intermediate) volcanic winters (blocks sunlight) dangers: burning, asphyxiation, entrapment moves slow most far-reaching volcanic hazard dating: radiometric dating can be done on volcanic rocks more accurately than sedimentary (use ash to constrain sedimentary sequences)

differential weathering

variation in the rate and degree of weathering caused by factors such as mineral makeup, degree of jointing, and climate caprock: less weatherable rock protecting softer underlying layers canyons

foliation grades & textures

under differential pressure, platy & elongate minerals get rearranged into layers regional metamorphism micas & amphiboles are easy to rearrange - not quartz & calcite original bedding may still be visible not all parent rocks go through all foliation grades: - granite → gneiss shale (parent rock) goes through all foliation grades: slate → phyllite → schist → gneiss bigger minerals = coarser/higher grade low grade (slate): - no visible crystals - fine layering high grade (gneiss) - visible crystals - coarse layering

marine deposition: continental slope

underwater alluvial fan environment: - downslope movement - underwater mountain cliff steep gradient processes of underwater debris flows characteristics: - carbonate conglomerate - graded bedding - disarticulated fossils & plankton

sedimentary structures: ripple marks

undulating structures in sandstone or siltstone symmetrical: - slope is the same in both directions - formed by waves moving back and forth - beaches - bidirectional waves (2 directions) asymmetrical: - one slope (downstream side) is steeper than the other - associated with small-scale cross-bedding - unidirectional currents (1 direction)

continental deposition: rivers & streams

unidirectional flow (follows a certain path, channelized) stretch from mountains to oceans mountains: - fast moving - high energy - moves large particles oceans: - energy drops - takes quartz into the ocean different subdivisions: - braided stream (upper) - meandering river (lower) deposition: - conglomerate (mountains) - arkose sandstone (close to mountains) - quartz sandstone & mud (end of river) rivers: - accumulate terrestrial fossils - bones and shells get caught and buried on point bars (inside bends of rivers) characteristics: - better sorting downstream - arkose, sandstone, conglomerate - cross-bedding

pegmatites

very coarse-grained igneous rock (granite) commonly found as a dike associated with a large mass of plutonic rock that has smaller crystals crystallization in a water-rich environment results in the large crystals known for its unusually large crystals

marine deposition: deep ocean

very low energy (not affected by waves) washed out clays settle shallow deep ocean: chalk characteristics: - shales, cherts (silica rich) - planar bedding - open ocean fossils

volcanos & volcanism

volcano: a landform formed around a vent from which magma reaches the surface of the earth to become lava - or other materials are ejected due to volcanic activity (underwater or on land) significance: - emitted the earliest surface and atmospheric gasses - produces oceanic crust at spreading ridges - produces new land (oceanic islands) - produces highly fertile soil through weathering in tropical areas - water in the atmosphere (water vapor, gas, and steam) volcanism: process by which magma and associated gases are extruded onto Earth's surface or atmosphere products: - lava - gasses - pyroclastic material (bombs, blocks, ash, and lapilli) warning signs: - seismic activity (earthquakes) - inflation or swelling - increased heat and gas emissions 2 primary factors that determine how magma erupts: - viscosity - gas content

chemical weathering: dissolution

water totally dissolves rock into ion components halite: salt water

how soil forms: parent rock*

weaker rocks develop soil faster (thicker soil develops over a weaker parent rock) parent rock chemistry controls soil chemistry weathering happens at different rates - soft = fast regolith production (shale) = hard = slow regolith production (granite) hot spot volcanoes (hawaii): - iron-rich minerals = iron-rich soils - mafic minerals weather quickly (good soil)

weathering

weathering: the process that breaks rocks into smaller particles or chemical components physical/mechanical weathering: - mechanical breakdown of rocks into smaller pieces (clasts) - not changing chemically chemical weathering: chemical alteration of rock to release chemical components and produce new minerals biological weathering: chemical and physical weathering caused by life forms (plants, animals, etc.) uplift: - all weathering happens at the surface, so deeply buried rocks must come up - rise to the surface via tectonics and erosion

sedimentary structures: mud cracks

wet clay-rich sediment dries and shrinks (cracks) preserved when other sediment fills them in before they get wet again periodically wet but dry for an extended time (deserts) cycles of wet/dry: - wet = swells - dry = dries & cracks

physical weathering: abrasion (wind)

wind blown sand particles grind away at exposed rock weathers them flat or grinding holes in them

metamorphic zones

zones: regions of equal metamorphic intensity/grade temperature & pressure conditions slate: low gneiss: high isograds: lines connecting points of the same grade (boundaries between zones) high-grade metamorphic center is flanked by lower grade metamorphic zones