Geology

Basaltic Lava Flows

type of lava flow; mafic, low viscosity, extremely hot, flows very quickly.

Geologic Hazards

natural processes that adversely affect people

Catastrophism

theory that states that natural disasters such as floods and volcanic eruptions shaped Earth's landforms and caused extinction of some species

Uniformitarianism

the physical,chemical, and biologic laws thatoperate today have operatedthroughout the geologic past

Earth System Science

Aims to study Earth as a system composed of numerous interacting parts, or subsystems.

4.6 Ga

Earth's age

Nebula

A large cloud of dust and gas in space

Supernova

A gigantic explosion in which a massive star collapses and throws its outer layers into space

seismic waves

vibrations that travel through Earth carrying the energy released during an earthquake

lithosphere

A rigid layer made up of the uppermost part of the mantle and the crust.

asthenosphere

The soft layer of the mantle on which the lithosphere floats.

differentiation

Denser material (mostly iron) sank to core and lighter material remained in outer shell during \___

Continental crust

is 35 - 70 km thick and composed primarily of silica-rich rock

Oceanic crust

~ 7 - 10 km thick and composed of basalt (Fe and Mg rich rock)

Lower mantle

The lowest portion of mantle, a zone of rigid rock

Outer core

A layer of molten iron and nickel that surrounds the inner core of Earth

Inner core

A dense sphere of solid iron and nickel at the center of Earth

Chemical Layers

continental and oceanic crust, mantle, core

Physical Layers

lithosphere(rigid), asthenosphere(flows), lowermantle(flows less), outer core(liquid), inner core(solid)

body waves

seismic waves that travel through the Earth's interior

surface waves

seismic waves that travel along the Earth's surface

glacial rebound

the process by which the surface of a continent rises back up after an overlying continental ice sheet melts away and the weight of the ice is removed

mountain belt

a larger unit of mountain ranges and mountain systems in a long, connected chain

Cratons

a large, stable block of the earth's crust forming the nucleus of a continent.

shields

a large, relatively flat expanse of ancient metamorphic rock within the stable continental interior

stable platforms

portions of cratons covered with a thin veneer of sedimentary rocks

Continental Margins

Where land meets the ocean. Margins near plate boundaries are active, and margins far from plate boundaries are passive.

deep ocean basin

the part of the ocean floor that is under deep water beyond the continent margin and that is composed of oceanic crust and a thin layer of sediment

Oceanic ridges

Underwater mountain ranges where the crust is spreading apart creating new ocean floor.

Marie Tharp

A geologist and an oceanographer who mapped the ocean floor and proved plate tectonics

Continental Drift

The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations

sea-floor spreading

The process by which molten material adds new oceanic crust to the ocean floor

Magnetic anomalies

Magnetic bands in the sea floor that run parallel to the mid-ocean ridge

Paleomagnetism

The study of the alignment of magnetic minerals in rock,specifically as it relates to the reversal of Earth's magnetic poles; also the magnetic properties that rock requires during formation

magnetic declination

the angle between geographic north and the north to which a compass needle points

Active margins

associated with lithospheric plate boundaries and are marked by a high degree of tectonic activity

Passive margins

a continental margin that is not a plate boundary

divergent boundary

A plate boundary where two plates move away from each other.

convergent boundary

A plate boundary where two plates move toward each other.

transform boundary

A plate boundary where two plates move past each other in opposite directions

continental rift

A linear belt along which continental lithosphere stretches and pulls apart

gabbro

A mafic, coarse-grained igneous rock composed predominantly of ferromagnesian minerals and with lesser amounts of calcium-rich plagioclase feldspar.

Basalt

A dark, dense, igneous rock with a fine texture, found in oceanic crust

subduction zone

The region where oceanic plates sink down into the asthenosphere.

volcanic arc

a curved line of volcanoes that forms parallel to a plate boundary

Wadati-Benioff zone

A sloping band of seismicity defined by intermediate- and deep-focus earthquakes that occur in the downgoing slab of a convergent plate boundary.

Polymorph

Two different mineralsthat have the same composition butdifferent crystal structures

Euhedral

a mineral with well-formed crystal faces

Anhedral

mineral without well-formed faces; their shape does not reflect their crystal structure

crystal habit

the general shape of a crystal or cluster of crystals that grew unimpeded

crystal cleavage

the way or shape the crystal fractures

conchoidal fracture

A curved fracture surface; looks like the inside of a clam shell

specific gravity

ratio of a mineral's weight compared with the weight of an equal volume of water

silicate minerals

minerals that contain a combination of silicon and oxygen

Silica tetrahedra

molecule composed of one silica atom and four oxygen atoms in a tetrahedral arragement

decompression melting

melting due to a drop in confining pressure that occurs as rock rises

Volitiles

Gases in magma

heat transfer

melting that results from the transfer of heat from a hotter magma to a cooler rock

single chain silicates

form a chain by sharing oxygen atoms

double chain silicates

form when two single chains of tetrahedra link to each other by sharing oxygen atoms

sheet silicates

each tetrahedron shares three oxygen atoms with other tetrahedra

framework silicates

form when each tetrahedron is bonded to four other tetrahedra

ferromagnesian silicates

Contain iron and/or magnesium. Typically dark and relatively heavy

non-ferromagnesian silicates

silicate minerals that contain sodium, aluminum, and/or potassium

Granite

A usually light colored igneous rock that is found in continental crust

Igneous

a type of rock that forms from the cooling of molten rock at or below the surface

Sedimentary

A type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together

Metamorphic

A type of rock that forms from an existing rock that is changed by heat, pressure, or chemical reactions.

Magma

A molten mixture of rock-forming substances, gases, and water from the mantle

Lava

Magma that reaches Earth's surface

extrusive igneous

rock that forms from the cooling and solidification of lava at Earth's surface

intrusive igneous

rock formed from the cooling and solidification of magma beneath Earth's surface

flux melting

melting due to addition of volatiles

Bowen's Reaction Series

the simplified pattern that illustrates the order in which minerals crystallize from cooling magma according to their chemical composition and melting point

fractional crystallization

process in which different minerals crystallize from magma at different temperatures, removing elements from magma

magma mixing

the process of altering the composition of a magma through the mixing of material from another magma body

ultra mafic

are composed almost entirely of olivine and pyroxine, with no feldspar. The ultramafic are thought to originate within the upper mantle of the earth, and are very rare at the surface.

Mafic

gabbro, basalt. describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color

intermediate

diorite and andesite

Felsic

granite, rhyolite. Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.

First to melt

Felsic, last to crystalize

last to melt

mafic, first to crystalize

Phaneritic

Form in intrusive environments. coarse-grained, crystals are large enough to be seen w/out a microscope, formed by slow cooling (intrusive)

Assimilation

Changing a magma's composition by the incorporation of foreign matter (surrounding rockbodies) into a magma

Aphanitic

Form in extrusive environments. Rapid cooling at earth's surface results in tiny mineral crystals that can only be seen under a microscope.

plutonic rocks

igneous rocks that form at depth

Porphyritic

describing an igneous rock composed of both large and small crystals

granite

A usually light colored igneous rock that is found in continental crust

Rhyolite

A light-brown to gray, fine-grained extrusive igneous rock with a felsic composition. The extrusive equivalent of granite.

Obsidian

volcanic glass

Pumice

a very light and porous volcanic rock formed when a gas-rich froth of glassy lava solidifies rapidly.

Andesite

An intermediate colored rock, generally gray greenish-gray, also classed as an aphanite because of the small crystal or grain size.

Diorite

Coarse-grained igneous rock of intermediate composition. Up to half of the rock is plagioclase feldspar and the rest is ferromagnesian minerals.

Gabbro

A mafic, coarse-grained igneous rock composed predominantly of ferromagnesian minerals and with lesser amounts of calcium-rich plagioclase feldspar.

Periodotite

Composes the upper mantle and is olivine-rich, igeneous rocks

Komatiite

the fine-grained, extrusive equivalent of peridotite; very rare (Earth not hot enough to form)

sills and dikes

products of intrusive volcanism

chilled margin

Where the igneous rock has cooled rapidly so it has fine crystals

Laccoliths

igneous intrusion that has been injected between two layers of sedimentary rock.

Lopoliths

vast, saucer-shaped, and layered intrusions of basic rocks. typically of gabbro type composition.