Theory
Knowledge widely accepted as true by the scientific community
Heliocentric
The sun is at the center of the universe; accepted during the Renaissance; Earth and planets orbit the sun
Geocentric
The Earth is at the center of the universe; the moon, planets, and stars circle the motionless Earth
Rotate
To spin on a fixed axis
Revolve
To circle an object around an orbit
Nebular Theory (Nebulae)
After the Big Bang, atoms began to bond; atoms and H2 molecules coalesced into a nebulae; gravity caused the nebulae to collapse; the collapse resulted in increases in temperature, density, and rate of rotation; the more massive region of the mass in the
Waves, frequency, wavelength
Sound waves compress or relax with relative motion; compressed: shorter wavelength, higher frequency; relaxed: longer wavelength, lower frequency
Doppler Effect
An object moving toward you has a higher pitch and is blue-shifted. An object moving away from you has a lower pitch and is red-shifted.
Volatile
Material that turns into gas at the surface; released from volcanic eruptions
Density
Mass per unit volume
Geothermal Gradient
The rate of increasing temperature with respect to increasing depth in the Earth's interior
Earth's magnetic field; paleomagnetism
Similar to a giant dipole bar magnet; has north and south ends, with the field being weaker the greater distance from the ends; the North Pole of the bar is near earth's geographic South Pole; N on the compass points to magnet S because opposites attract;
Crust
The outermost "skin" of the earth; two kinds: continental and oceanic; mostly oxygen
Mantle
Solid rock; 82% of the earth's volume; ultra-magic rock periodite; convection below 100 km mixes mantle; moves plates
Outer Core
Liquid iron alloy; 2255 km thick; liquid flows
Inner Core
Solid iron-nickel alloy; radius of 1220 km; greater pressure keeps solid
Lithosphere
The outermost 100-150 km of earth; non flowing material (rigid); crust and upper mantle; makes up tectonic plates
Asthenosphere
Upper mantle below the lithosphere; flows as a soft solid; shallow under oceans; deep under continents
Moho
the border between the crust and the upper mantle
Plate tectonics
The explanation of "how Earth works"; earth's outer shell is broken into rigid plates that move; plate motion describes three types of plate boundaries; explains earthquakes, volcanoes, changes in positions of continents and oceans, origins of mountains,
Isostasy
The state of gravitational equilibrium between earth's crust and the mantle such that the crust "floats" at an elevation that depends on its thickness and density of underlying roots of the low density of the mountain
Wegener
German meteorologist and polar explorer; wrote "the origins of continents and oceans" in 1915; hypothesized Pangaea; suggested continental drift of plates
Pangaea
One big supercontinent
Sea-floor Spreading
Earthquakes at mid-oceans ridges indicate cracking; cracked crust splits apart; high heat flow from molten rock rises into the cracked crust; new ocean floor forms
Mid-ocean ridges
Linear mountain range in earth's ocean basins; ex. The Mid-Atlantic Ridge
Trench
Location where the sea floor sinks back into the mantle
Divergent plate boundary
Plates move apart
Convergent plate boundary
Plates move together
Transform plate boundary
Plates slide sideways
Continental Margins
Where land meets the ocean; active: near plate boundaries; passive: far from plate boundaries
Subduction
Old oceanic lithosphere is more dense than the mantle; a flat-lying oceanic plate doesn't subduction easily; plate edge bends down and slips under mantle, then the leading edge sinks downward into the mantle at trenches
Triple Junction
Point where three plate boundaries intersect; multiple boundary combinations occur
Minerals
Make up all rocks and sediments on earth; important to humans; naturally occurring; formed geologically; solid; crystalline structure; definite chemical composition; inorganic
Euhedral Crystals
Grown in an open cavity; good crystal faces
Anhedral Crystals
Grown in a tight space; no crystal faces
Igneous Rocks
Form from the cooling and solidification of magma
Metamorphic Rocks
a rock that has changed due to extreme heat and pressure
Sedimentary Rocks
Form from pieces of other sediment
Felsic Rocks
Made up of a high concentration of silicon; light in color; ex. Feldspar and silica
Mafic Rocks
Made up of a low concentration of silicon; dark in color; ex. Magnesium and iron
Magma
Melted rock below the surface
Lava
Melted rock that has reached the surface
Intrusive Igneous Rock
Rock that cooled underground; high volume; slower cooling rate
Extrusive Igneous Rock
Rock that cooled at the surface; quick cooling rock
Viscosity
Thickness/ability to flow
Oceanic Rift
Plates spread, which leads to decompression melting; basaltic magma wells up and fills magma chambers; solidifies as gabbro at depth; moves upwards to form dikes or extrude as pillow basalt
Continental Rift
Places where continental lithosphere is being stretched; ex. East African Rift
Mantle Hot Spots
Independent tectonic plate boundaries; about 50-100 exist; may erupt through oceanic or continental crust; burn a volcano chain through overriding plate
Shield Volcano
Broad, dome-shaped volcano; lateral flow of low viscosity basaltic lava; have a low slope and cover large geographic areas; ex. Mauna Loa
Scoria Volcano
Cinder cone volcanoes; conical piles of tephra; smallest type; guilt of ejected lapilli and blocks piled up at a vent; often symmetrical with a deep summit crater; typically from a single eruption event
Stratovolcanoes
Composite volcanoes; large, cone-shaped; steep slopes; made of alternating layers of lava, tephra, and debris; ex. Mt. Fuji, Rainier, Vesuvius
Tuff
Lithification ash; may or may not contain lapilli; air-fall tuff: accumulations of ash that fall like snow; ignimbrite: tuff deposited while hot that welds together
Crater
A bowl-shaped depression atop a volcano; up to 500 m across and 200 m deep; form as erupted lava piles up around the vent; summit eruptions: located within the summit crater; flank eruption: located along the side of the volcano
Caldera
Gigantic volcanic depressions; much larger than a crater (one to tens of km across); usually exhibits steep sidewalls and flat floors; a magma chamber empties and the volcano collapses in
Weathering
Generation of detritus via rock disintegration
Erosion
Removal of sediment grains from parent rock
Soil
The mixture of minerals, organic matter, gases, liquids, and the countless organisms that together support life on earth
Clastic Sedimentary Rock
Loose rock fragments (class) cemented together; ex. Sandstone
Biochemical Sedimentary Rock
Cemented shells of organisms; ex. chalk
Organic Sedimentary Rock
Carbon-rich remains of once-living organisms; ex. Coal
Chemical Sedimentary Rock
Minerals that crystallize directly from water; ex. Calcium carbonate
Terrestrial environment of depoition
Glaciers, mountain streams, alluvial fans, sand dunes, rivers, lakes, deltas
Marine environment of deposition
Deltas, coastal beach sands, shallow marine clastic deposits, shallow water carbonate environments, deep marine deposits
Diagenesis
Physical, chemical, and biological changes to sediment
Subsidence
Sinking of land during sedimentation
Transgression
Flooding due to sea-level rise; sediment belts shift landward; strata "deepen" upward
Regression
Exposure due to sea level fall; depositional belts shift seaward; strata "shallow" upward; tied to erosion; less likely to be preserved
Foliated Metamorphic Rock
Parallel surfaces or layers; ex. Slate, phylite, schist, metaconglomerate, gneiss, migmatite
Nonfoliated Metamorphic Rock
No planar fabric evident; ex. Hornfels, quartzite, marble
Low grade metamorphic rock
Weaker metamorphism; ex. Shale protolith
Intermediate grade metamorphic rock
Moderate metamorphism; ex. Schist
High grade metamorphic rock
Intense metamorphism; ex. Micah, gneiss
Protolith
Pre-existing rock
Rock cyle
Dynamic process of rocks changing form over time
Thermal/contact Metamorphism
Heating by a plutonic intrusion
Burial Metamorphism
Increases in pressure and temperature by deep burial in a basin
Dynamic Metamorphism
Shearing in a fault zone
Regional Metamorphism
Pressure and temperature alteration due to orogenesis
Hydrothermal Metamorphism
Alteration by hot water leaching
Subduction Metamorphism
High pressure, low temperature alteration in subduction zones
Shock Metamorphism
Extreme high pressure resulting from a bolide impact (meteor)