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115 Cards in this Set

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Mixture of gas and pyroclastic debris that is so dence that it hugs the ground
Pyroclastic flow
A fluids resistence to flow
viscosity
Opening through which lava erupts
vent
Small, steeply sloped, composed of pyroclatic fragments ejected from a central vent
cinder cones
Very fluid (basalts), dose not build cone or volcano, large in volume, andcreates lava plateaus
flood eruptions
Layers of basalt flows that have built up to a great thickness
plateau basalts
Volcanic glass
obsidian
Intermediate composition volcanic rock
andesite
Basinlike depresin over a vent at the summit of the cone
crater
Moderately to steeply sloped, composed prodomenty of andesites, most common at convergence plate boundaries
composite volcanos
Nearly always basalt, mid-ocean ridge eruptions, pilow basalts
submarine eruptions
Type of mudflow composed of pyroclastic material and water that flows down from a volcano
lahar
Rapidly cooled rock fragments
pyroclasts
Gental slopes formed due to low viscosity of lava. commly associated with sheild volcanos
mafic magma
Volcaic depreion much larger then original crater, having a diameter of at least 1km
caldera
Hill or mountain formed by the extrusion of lava or ejection of rock fragments from a vent
volcano
Broad and gently sloping due to low viscosity of lava, contain lava tubes
shield volcanos
Steep-sided, dome, or spine-shaped masses of volcanic rock (viscous lava) that solidifies in or immediately above a volcanic vent or crater
volcanic dome
Frothy volcanic glass that floats in water
pumice
spewed 6 cubic miles of rock
Krakatoa
35,000 people killed
Krakatoa
high silica; light color
Rhyolite
low silica; dark color
Basalt
glass without mineral crystals
Glassy
most crystals < 1 mm
Fine-grained
larger crystals in a matrix of much finer crystals or glass
Porphyritic
originally created from gases released by magmas
Atmosphere
produced by condensation of volcanic water vapor
Hydrosphere
group of destructive processes that change physical and chemical character of rocks at or near Earth’s surface
weathering
Mechanic effect of freezing (and expanding) water on rocks
frost action
Decomposition of rock from exposure to atmospheric gases
chemical weathering
Highly leached and unproductive soils
laterites
physical picking up of rock particles by water, ice, or wind
erosion
Removal of overlying rock allowing for expansion and fracturing
pressure release
Chemically active oxygen from atmosphere cuases
oxidation
any layer of firm detrital matter, as of clay, underlying soft soil
hardpan
the movement of eroded particles by water, ice, or wind
transportation
granite subsequently erodes in concentric layers (similar to the way an onion peels) forming rounded masses
exfoliation domes
Hydrogen cations replace others in minerals
acid dissolution
Frost action, pressure-release fracturing, plant growth, burrowing animals, salt wedging, thermal cycling
mechanical weathering
Large temperature changes fracture rocks by repeated expansion and contraction
thermal cycling
a layer of weathered, unconsolidated material on top of bedrock
soil
weathering of underlying rock
Residual soil
brought in from elsewhere
Transported soil
rocks produced from rock fragments
detrital rocks
produced by precipitation of dissolved ions in water
chemical rocks
produced by accumulation of biological debris, such as in swamps or bogs
organic rocks
features found wihin sedimentary rock
sedimentary structures
loose, solid particles
sediment
shift to a tighter packing, with a resulting decrease in pore space
compaction
composed of rounded gravel cemented together
conglomerate
Slightly coarser-grained than shales
siltstone
occurs due to abrasion during transport
rounding
Chemical precipitates of material in the space between sediment grains, binding the grains together into a hard rock
cementation
Medium-grained clastic sedimentary rock
sandstone
Predominantly clay-sized grains; non-fissile
claystone
Silt- and clay-sized grains; massive/blocky
mudstone
Fine-grained clastic sedimentary rock
Splits into thin layers (fissile)
Silt- and clay-sized grains
shale
Hard, compact, fine-grained, formed almost entirely of silica
chert
occurs as sediment is separated according to grain size by transport agents, especially running water
sorting
open space between grains
pore space
the location in which deposition occurs
environment of deposition
composed of coarse, angular rock fragments cemented together
sedimentary breccia
sand grains surrounded by dark, fine-grained matrix, often clay-rich
greywacke
composed mainly of calcite
Most are biochemical, but can be inorganic
Often contain easily recognizable fossils
limestone
Sedimentary rock forming from compaction
of partially decayed plant material
coal
Form from evaporating saline waters
Evaporites
Series of visible layers within a rock
Most common sedimentary structure
bedding plane
Series of thin, inclined layers within a horizontal bed of rock
Cross-bedding
Small ridges formed on surface of sediment layer by moving wind or water
Ripple marks
Progressive change in grain size from bottom to top of a bed
Graded bedding
Polygonal cracks formed in drying mud
Mud cracks
Traces of plants or animals preserved in rock
fossils
General term for processes converting loose sediment into sedimentary rock
lithification
solid-state changes to rocks in Earth’s interior
metamorphism
causes flattening perpendicular to stress
compressive stress
prduced when grains of quartz in sandstone are welded together while the rock is subject tohigh tempatures
quartzite
metamorphic rock characterized by coarse-gained minerals oriented approximately parallel
schist
parts of body move or slide relative to one another across a plane
shearing
a very fine-grained, nonfoliated, metamorphic rock whose parent rock is either shale or basalt
hornfels
produced by rapid application of extreme pressure
Shock metamorphism
Metamorphic rocks common in the old, stable cores of continents
craton
Metamorphic rock composed of light and dark layers or lenses
gneiss
Line or rock where the tempature of the rock is the same
isotherm
pre-existing rocks
parent rock
Planar rock texture of aligned minerals produced by differential stress
foliation
Fine-grained rock that splits easily along flat, parallel planes
slate
High temperature is dominant factor
Produces non-foliated rocks
Occurs adjacent to magma bodies intruding cooler country rock
Occurs in narrow zone (~1-100 m wide) known as contact aureole
Rocks may be fine- (e.g., hornfels) or coarse-grained (e.g., marble, quartzite)
contact metamorphism
Partial melting during metamorphism produces
migmatite
Rocks precipitated from or altered by hot water
hydrothermal
Pressure aplied equallyon all surfaces of a body
confining pressure
Coarse-grained rock composed of interlocking calcite crystals
marble
Metamorphic rock in which clay minerals have recrystalized into microscopic micas, giving the rock a silky sheen
phyllite
High pressure is dominant factor
Results in rocks with foliated textures
Prevalent in intensely deformed mountain ranges
May occur over wide temperature range
Higher pressure and temperature will produce increased metamorphic grade
regional metamorphism
Byproduct of shock metamorphism
tektites
same processes operating in past are operating at present
actualism
the age of events or objects, expressed as a number or numbers
numerical(absolute)age
the order of events or objects, from first (oldest) to last (youngest)
Relative age
beds of sediment
deposited in water are initially formed as
horizontal or nearly horizontal layers
original horizontality
within an
undisturbed sequence of sedimentary
or volcanic rocks, layers get younger
from bottom to top
superposition
original horizontal layer extends
laterally until it tapers or thins at its edges
lateral continuity
a disrupted pattern is older than the cause of the disruption
cross-cutting relationship
a surface (or contact) that
represents a gap in the geologic record
unconformity
an unconformity in which the
contact representing missing rock layers
separates beds that are parallel to each other
disconformity
an unconformity in which
the contact separates overlying younger layers from
eroded tilted or folder layers
angular unconformity
an unconformity in which an erosion surface on plutonic or metamorphic rock has been covered by younger sedimentary or volcanic rock
nonconformity
determining the time-equivalency of rock units
correlation
Fossil species succeed one another through the layers in a predictable order
faunal succession
Fossil from which a very short-lived, geographically widespred species known to exist during a specific period of geologic time
index fossil
groups of different fossil species
fossil assemblage
Determining the age of a rock through its radioactive elements
isotopic dating
Spontaneous nuclear change of isotopes wth unstable nuclei
radioactive decay
time it takes for a given amount of radioactive isotope to be reduced by half
half-life
Youngest eon/current eon
Phanerozoic
Eon where life first appered
Proterozoic