GEO Ch. 12

yes because new seafloor is being made

is the Atlantic ocean growing?

lower mantle

layer of Earth that's less dense and hot; made of more elements; plastic

asthenosphere

layer of the outer Earth that lies within the mantle from about 70 km to 250 km in depth; hottest region of the mantle, about 10% is uneven patters

contact metamorphism

metamorphisis that occurs when magma rising within the crust "cooks" adjacent rock; occurs adjacent to igneous intrusions and results from heat alone

conduction, convection

methods of heat transfer the Earth uses from core to crust

silicates

mineral family that makes up roughly 95% of Earth's crust

carbonates

minerals in which carbon compounds combine with oxygen and other elements such as calcium, magnesium, and potassium

calcium carbonate

most common cement in lithification

radiometric dating

numerical age determined by this which uses a rate of decay for different unstable isotopes to provide a steady time clock to pinpoint the ages of Earth materials

regional metamorphism

occurs when a large areal extent of rock is subject to metamorphism; can occur when sediments collect in broad depressions in the Earth's crust and create enough pressure in the bottommost layers to transform he sediments into metamorphic rock

more dense

oceanic plates are ____ _____ compared to continential

Greenland, Western Australia, and northern Quebec, Canada

oldest known rocks surfaced here

8-10

plates on the planet

dikes

plutons that cross layers of the rock they invade

bouyancy

principle that something less dense, such as wood, floats in something denser, such as water

isostasy

principle; the balance between the buoyancy and gravitational forces; explains the elevations of continents and the depths of ocean floors as determined by vertical movements of the Earth's crust

rapid succession

process by which the life on Mt. St. Helens was able to grow back in a few years because of deer mice walking around, breaking up the soil and allowing pollen to be transported and planted; Lupine and deer grew

seafloor spreading

process that builds ocean ridges and drives continental movement; proposed by Harry H. Hess

exogenic system

processes operating at Earth's surface, driven by solar energy and the movement of air, water, and ice

endogenic system

processes operating in Earth's interior, driven by heat and radioactive decay

metamorphic

rock type altered by heat and pressure; generally more compact than the original rock and therefor are harder and more resistant to weathering and erosion

igneous

rock type formed from molten material; solidifies and crystallizes from a molten state; form from magma; make about 90% of the Earth's crust

relative age

the age of one feature with respect to another within a sequence of events and is deduced from the relative positions of rock strata above or below each other

oxygen

the most reactive gas in the lower atmosphere; 46% of the crust

higher

the speed of the waves varies as it passes through different materials; cooler, more rigid areas transmit seismic waves as a ______ velocity than hotter, more fluid areas

seismic waves, borehole, kimberlites

three things that allow us to study Earth's internal structure

converging, diverging, transform

three types of plate boundaries

grind past each other Ex. San Andreas fault

transform boundaries do not diverge or converge but rather they

conduction

type of energy transfer in the crust

plume reached the stratosphere forming sulfuric acid that blocks solar radiation causing lower global temperatures

1991 Mt. Pinatubo eruption

inner core, outer core, lower mantle, upper mantle, crust

5 layers of Earth's internal structure

at least 90%

Earth's outer core generates _____ of Earth's magnetic field

crust

Earth's outer layer; makes up only a fraction of Earth's overall mass; makes up a small portion of the overall distance from Earth's center; just eight natural elements make it up; rocky, cold, brittle, least dense

Laurasia; North America, Europe

Pangaean continent that progressively evolved into what today is ________ and ____________

Laurentia, Godwana

Pangaean continents where life evolved independently from each other

lithosphere, asthenosphere

Two layers of the outer Earth

geyser

a hot spring characterized by intermittent discharge of water and steam

igneous, sedimentary, and metamorphic

a rock cycle produces three classes of rocks

geology

a science that studies all aspects of Earth- its history, composition and internal structure, surface features, and the processes acting on them

radiogenic dating

absolute dating method based on the half-life of an element present and how much has decayed; allowing geologists to backtrack

rock

an assemblage of minerals bound together or a mass composed of a single material or of undifferentiated material; or even solid organic material

pluton

an intrusive body that cools slowly in the crust

magnetic declination

angular distance in degrees between the direction of the compass needle and line of longitude at a given location

dehydration

another way to unite particles by heat

342 W/m^2

average incoming solar radiation at the top of the atmosphere

500,000 years

average period of a magnetic reversal

seismic waves

best way to study Earth's internal structure; imagery that allows us to observe changes in density because they are faster the closer to the core

chemosynthesis

biological conversion of one or more carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic molecules (e.g. hydrogen gas, hydrogen sulfide) or methane as a source of energy, rather than sunlight; creatures in the deep ocean and by hydrothermal vents use this

drastic changes in density between two layers on the mantle

both Moho and Gutenberg discontinuities characterized by:

Gutenberg

boundary between the lower mantle and outer core

mud pots

bubbling pools that are highly acidic with limited water supply, and thus produce mainly gases that are broken down by microorganisms to release sulfuric acid, which in turn breaks down rock into clays that form mud

mineral

building blocks of rocks; an inorganic, natural solid compound having a specific chemical formula and usually possessing a crystalline structure; each one has its own characteristic color, texture, crystal shape, and density, among other unique properties

5730 year

carbon-14 half-life

clastic, biochemical, organic, chemical

categories of sedimentary rocks

evaporites

chemical sedimentary rocks formed when salt deposits precipitate as water evaporates

hydrothermal deposits

consist of metallic minerals accumulated by chemical precipitation from hot water, often are found near vents in the ocean floor- often along mid-ocean ridges created by spreading of the seafloor

core

contains a third of the Earth's entire mass, but only a sixth of its volume

few cm/year

continents and oceans creep at a rate of ______

oceanic crust

crust that is most dense; composed of basalt; granular and high in silica, magnesium, and iron; sometimes called sima

continential crust

crust that's relatively low in density, composed mainly of granite; crystalline and high in silica, aluminum, potassium, calcium, and sodium; aka sial

oceanic

crust with basalt as its main rock

continential

crust with density of 2.7-2.8 g/cm^3

oceanic

crust with density of 2.8-3.0 g/cm^3

continential

crust with main rock type of granite

continential

crust with thickness 10-200 km

oceanic

crust with thickness 5-10 km

hydrologic, rock, tectonic

cycles that form geologic cycle

tectonic cycle

cyclic system that drives rock cycle below and within the Earth's surface; powered by internal heat; drive the endogenic processes

hydrologic cycle

cyclic system that drives the rock cycle at and above the Earth's surface; fueled by solar energy; drives the exogenic processees

numerical age

determined most often by using isotopic dating techniques

Moho

discontinuity that is the boundary between the upper mantle and the crust above

Atlantic because seafloor is not being subducted as quickly

do you expect to find older seafloor in the Atlantic or Pacific

inner core

earth core; formed first; solid iron that is well above the melting temperature of iron (about 4000 degrees C) at the surface but remains solid due to tremendous pressure

outer core

earth core; in a liquid state due to high temperatures and the flow of material generates Earth's magnetic field; separated from the mantle by a transition zone several hundred kilometers wide at an average depth of about 2900 km; made of mostly iron and nickel

transform fault

fault characterized by the movement along one side of the fault line opposite to movement along the other side

basalt

finer-grained igneous rock formed from the faster cooling of lava; most common extrusive rock

heat must flow from hotter to colder parts until equilibrium is reached

first law of thermodynamics states

volcanic arcs

form along convergence zone of a continental and oceanic plate

island arcs

form when two oceanic plates converge

chemical precipitation

formation of a separate solid substance from a solution, such as warm water evaporates and leaves behind a residue of salts

crater

forms from the last hotspot eruption; rejuvination phase; circular surface depression; usually found at or near the surface

mountain range Ex. Himalayans

forms from two continental plates colliding

caldera

forms when magma empties from an active volcano and collapses; large, basin-shaped depression that forms when summit material on a volcanic mountain collapses after an eruption or other loss of magma

heating, pressure, heating and pressure together, and compression and shear

four processes that can cause metamorphism

Earth's internal heat, solar energy from space

fuels geologic cycle

Alfred Wegener

geologist that first concluded all continents formed Pangaea; father of plate tectonics

uniformitarianism

guiding principle of Earth science that presupposes that the same physical processes now active in the environment were operating throughout Earth's history; the natural laws that govern geologic processes have not changed throughout geologic time even though the rate at which these processes operate is variable; present is the key to the past

rift

happens at divergent plate boundaries; continental crust splitting into the ocean basin

400 W/m^2

heat flow can reach _____ at volcanoes and mid-ocean ridges

0.08 W/m^2

heat flow to the surface averages ______ and is very uneven

geothermal energy

heat from the Earth's interior

deduction of gravity allowed him to calculate Earth's density; the inside of the Earth was more dense than the outside

how Newton's law of universal gravitation has anything to do with the discovery of Earth's internal structure

radiation, conduction, convection

how energy (heat) can be transferred

texture and composition

how scientists classify igneous rocks

circulation in the outer core converts thermal and gravitational energy into magnetic enery

hypothesis that explains the production of magnetic field

mafic

igneous rocks that are derived from magnesium an iron; lower in silica and higher in magnesium and iron and have high melting points; darker in color and of greater density than those from felsic minerals

felsic

igneous rocks that are high in silicate minerals, such as feldspar and silica; generally lighter in color, have low melting points, and less dense than those from mafic minerals

upper mantle

layer of Earth that thinner, cooler, lighter, mostly rigid with a few molten parts

lithosphere

layer of the outer Earth that includes the crust and uppermost mantle, to about 70 km in depth, and forms the rigid, cooler layer at Earth's surface; floats on the denser layers beneath

1. submarine volcano creating pillow basalt 2. volcano emerges and island forms 3. volcano matures and declines as it moves farther from the hotspot 4. possible rejuvination with last eruption 5. atoll- eroded volcano

life process of a hotspot

hot spots

localized source of high energy; fixed in the mantle an volcanoes are from it don't erupt

lava

magma that emerges to the surface

borehole

man made hole to study Earth's core; helps determine rock type; farthest gone is almost 12 km

limestone

most common chemical sedimentary rock; formed from a chemical process in with calcium carbonate in solution is chemically precipitated out of groundwater that has seeped to the surface

rock cycle

name for the continuous alteration of Earth's materials from one rock type to another

lithification

occurs as loose sediment is hardened into solid rock; involves compaction of buried sediments as the weight of overlying material squeezes out the water and air between clasts and cementration by minerals, which fill any remaining spaces and fuse the clasts into a coherent mass

transportation

part of formation of clastic sedimentary rocks in which gravity, water, wind, and ice carries sediment across landscapes; occurs from "higher energy" sites to "lower energy"

deposition

part of formation of clastic sedimentary rocks whereby sediment settles out of the transporting medium and results in material dropped along river channels, on beaches, and on ocean bottoms, where it is eventually buried

divergent

plate boundaries that occur in areas of seafloor spreading, where upwelling material from the mantle forms new seafloor and lithospheric plates spread apart in a constructional process

transform

plate boundaries that occur where plates slide past one another, usually at right angles to a seafloor spreading center; form a fault

convergent

plate boundary occurring in areas of crustal collision and subduction; crust is compressed and lost in a destructional process as it moves downward toward the mantle

sills

plutons that form parallel to layers of sedimentary rock

weathering, erosion, transportation, deposition

processes that contribute to the formation of clastic rocks by disintegrating and dissolving them

mantle

represents 80% of Earth's total volume; rich in iron and magnesium oxides and in silicates, which are dense and tightly packed at depth, grading to lesser densities toward the surface; temperatures are highest at depth and decrease toward the surface; materials are thicker at depth, with higher viscosity, due to increased pressure

kimberlites

rock formed in the mantle that is pushed up quickly; between 150-400 km; main carrier of diamonds

sedimentary

rock type formed from compaction or chemical processes in which loose clasts (grains or fragments) are cemented together

foliated rock

rock with a bounded or layered appearance, demonstrating their alignment of minerals, which may appear as wavy striations in the new rock

nonfoliated rock

rocks that do not exhibit mineral alignment

seismic tomography

science that studies seismic waves; able to identify the boundaries between different layers within Earth by measuring the depths of changes in seismic wave velocity and direction

magma rises from hot areas in the upper mantle and asthenosphere and perhaps from the deeper lower mantle causing new seafloor to move outward from the ridge as plates pull apart and new crust is formed

seafloor spreading proess

chemical

sedimentary rock that is formed from shells of organisms that contain calcium carbonate or from dissolved minerals that precipitate out of water solutions and build up to form roc

fumaroles

steam vents that emit gases that may contain sulfur dioxide, hydrogen chloride, or hydrogen sulfide

geomorphology

study of Earth's surface landforms, specifically their origin, evolution, form, and spatial distribution

Pangeae

supercontinent

magnetosphere

surrounds and protects Earth from solar wind and cosmic radiation

paleomagnetism

the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials. Certain minerals in rocks lock-in a record of the direction and intensity of the magnetic field when they form

plate tectonics

theory that the lithosphere is divided into a number of plates that float independently over the mantle and along whose boundaries occur the formation of new crust, the building of mountains, and the seismic activity that causes earthquakes; describes the motion of Earth's lithosphere; hot mantle rises at the mid-ocean ridge and the cool slabs sink and get carried back into the mantle in the sea floor

granite

type of coarse-grained igneous rock formed from the slower cooling of magma beneath the surface

conduction from inner to outer; convection in outer

type of energy transfers in the core

convection of magma

type of energy transfers in the mantle

mid-ocean ridges

underwater mountain systems formed when the mantle rises to the surface, forming new sea floor; longest mountain chain at 65,000 km; where the youngest rocks can be found

isostatic rebound Ex. ice sheets, mountain chains

uplift of the lithosphere after removal of surface load

tephrochronology

using ash layer as a marker of time due to the specific chemical makeup of the ash

geologic cycle

vast give-and-take at the Earth-atmosphere-ocean interface

Mt. St. Helens

volcano where 1980 eruption occurred following earthquakes; caused landslides, most plants/animals wiped out

rocks melt, creating volcanism

what happens as the oceanic crust sinks below a tectonic plate

crust + upper mantle

what layers of Earth make the lithosphere

lower mantle

what makes the asthenosphere

2 cm/year

what's the mean SFS rate; doesn't vary much

200 Ma

when Pangaea started breaking down

subduction

when one portion of the lithosphere descends beneath another and dives downward into the mantle

geomagnetic reversal

when the magnetic field has faded to zero and then returned to full strength with the polarity reversed; the field diminishes slowly to low intensity then rapidly regains full power

primordial heat, radioactive decay, crystallization of iron

where Earth's internal heat comes from

slowly plunging beneath continential lithosphere along Earth's deep-ocean trenches

where the old seafloor goes once new ones are made

farthest from the ridge

where the oldest sample of the mid-ocean ridge lies

the small magnetic particles in the material align according to the orientation of the magnetic poles at that time

why magnetic reversals are key tool in understanding evolution of landmasses and movements of continents; as rocks cool and solidify from molten material what happens?

convection currents in the asthenosphere and upper mantle provide upwelling and downwelling that push and pull portions of the lithosphere

why we say continents are adrift

discontinuity

a place where physical differences occur between adjoining regions in Earth's interior

plastic zones

absorb seismic waves

hyrdothermal vents

cracks in molten rock through which seawater sinks deep and collects minerals and expels in black smoke because it's heated by magma

60 Ma

creation of Panama allowing life to migrate between Laurentia and Godwana

black smoke

expelled in hydrothermal vents

location and rate of cooling

factors that determine the crystalline texture of a rock. whether it is made of coarser or finer materials