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Glossary abrade
to grind a rock surface by the friction of rock particles carried by
water
amphibolite
a metamorphic rock that is formed when basalt is subjected to
heat and pressure to alter the mineral components; characterized by large dark
colored crystals accrete
to grow by addition, to include a new portion, to fuse a new part to an
older one adit
an entrance to a mine, usually a horizontal entrance rather than a
vertical one aggregate
a mixture of rock
fragments, concrete is a cemented aggregate alluvial
a deposit of unconsolidated sediment that has been transported by a
stream anticline
an elongated fold in sedimentary rock that resembles an arch in which
rock layers slope downwards in opposite directions from the central axis (the
apex of the fold) arkose
a sandstone that is rich in unweathered or slightly weathered feldspar basalt
a dark, fine grained igneous rock that has a composition that is low in
silica; basaltic is to have the properties of a basalt bedding
layering in sedimentary rock; the surface of a bed is time specific
bentonite
a rock layer that results from volcanic ash falls useful in time
correlations berm
the shoulder of the canal opposite the tow path, generally an elevated
slope bioherm
an accumulation of organic remains and debris formed under conditions of
prolific life, for example, a coral reef fits the definition of a bioherm calcareous
like or containing calcium carbonate, generally to a significant degree carbonaceous
consisting of or containing a significant carbon content; example, coal clastic
broken fragments of pre-existing rocks; sandstones are clastic rocks
conglomerate
a rock composed of fragments of varying sizes embedded in a much finer
grained matrix, or cemented chemically as the case of a limestone conglomerate detrital
a rock formed from the accumulation of solid fragments transported from
a source area to a site of deposition (beach, basin, stream channel, lake, etc.)
diabase
a dark, fine grained igneous rock that generally forms dikes or
irregular bodies dislocations
separations from the normal state as offsets of rock layers along a
fault dolomite
a common rock-forming mineral, calcium magnesium carbonate; also used to
identify a rock that is principally composed of the mineral dolomite erosion
the incorporation and transportation of rock material by an agent such
as water fault
a break in a rock mass along which movement has occurred flexure
a fold where a layer of rock, once horizontal, has been bent (not
broken) fracture
a break in the rock along which there has been little or no movement
granite
a light colored, often coarse grained igneous rock of high silica
composition granodiorite
a light colored igneous rock similar to granite but with slightly
different composition/mineral content graywacke
a rock similar to sandstone but with a significant content of mud/silt;
graywackes exhibits poor sorting and bedding, characteristic of minor
water action greenstone
a metamorphosed volcanic rock in which green minerals impart the color hematite
a red colored ore mineral of iron (iron2oxygen3), often found in layers
Igneous
the primary rock that is formed by the cooling of molten magma karst
a land surface underlain by carbonate rocks that contains numerous
sinkholes lamprophyre
an igneous rock composed mainly of mica and feldspar; occurs as dikes limonite
called brown hematite; a hydrated ore mineral of iron with a
variable composition (iron2oxygen3hydroxyl) that causes a range of color
(brown/yellow/orange) lithified
the state of having been cemented or compacted so as to form solid rock magnetite
the magnetic ore mineral of iron, black in color (iron3oxygen4) metamorphosed
changed in form or nature, a metamorphic rock is created by heat and
pressure such that the minerals, fabric, color are changed, but not the
composition migmatite
a highly metamorphosed rock that was formed by being subjected to
sufficiently elevated heat and pressure that the original rock is nearly or
partly melted molusk
generally meaning a shelled marine invertebrate animal orogeny
the process of forming mountains through structural disturbance of the
earths crust by folding and/or faulting permeable
a rock property relating to its ability to transmit water; pore
connectivity phyllite
a metamorphosed rock formed from silstones and mudstones in which
surfaces exhibit a lustrous sheen caused by newly formed small crystals of mica
and chlorite plunge
descends steeply, thrust downward as a fold whose axis is not horizontal
but at an angle to the horizontal precipitate
separates out from a liquid, a substance that was once soluble but
becomes a solid due to changes in concentration or by chemical reaction prism
the geometric shape of a cross section through the canal rectilinear
a pattern (cracks in rock) of intersecting lines meeting a right angles quartzite
a rock composed of quartz grains cemented with silica regressive
retreating from a given line or boundary as a shoreline moving seaward rhyolite
the volcanic rock equivalent of granite, coarse grained crystals in a
fine matrix rifting
a breaking apart, divergence of continents along a common boundary sandstone
a sedimentary rock composed of grains of minerals of a common size;
composition is not implied, in a quartz sandstone the grains are quartz schist
a metamorphosed rock, generally the original rock was fine grained as
silt/mud sedimentary
a rock that is formed by the deposition of sediments, fragment size is
not implied nor is composition; examples, limestone, sandstone, siltstone,
conglomerate siltstone
a very fine grained sedimentary rock, sometimes referred to as a shale subaerial
located or occurring on or near the surface of the earth syncline
an elongated fold in sedimentary rock that resembles a trench, rock
layers slope upwards in opposite directions from the central axis tectonic
large scale process that deforms the earths crust; for example, plate
tectonics, earth crust deformations caused by the movement of continental
masses, a.k.a. plates terrane
a crustal block bounded by faults whose geologic history differs from
the histories of adjoining crustal blocks; often exotic in not being native to
its current locale topography
the natural configuration of the surface of the earth, changing
elevations transgressive
advancing beyond a boundary as a shoreline moving landward turbidity
muddy or cloudy state caused by the stirring action of sediments FOSSILS OF INVERTEBRATE ANIMALS brachiopods
sedentary marine with uneven sized upper and lower valves for shells cephalopods
mobile marine with or without shells; have distinct head with beak-like
jaws and tentacles; includes the squid, octopus, chambered nautilus, ammonite conodonts
fossil remains of unidentified life forms, perhaps fragments of early
forms crinoids
sedentary marine exhibiting a mostly cup shaped body with featherly arms
attached to the sea floor by a long jointed stalk Cyrtospirifer
disjunctus a brachiopod that is associated with a specific span of time gastropods
mobile marine/non-marine with a univalve shell often spirally coiled
with a single internal chamber;
includes snails, slugs, whelks ostracods
small mobile marine with right and left valves for shells and an
indistinctly segmented body; widely used in time/rock layer correlations over
moderate distances pelecypods
burrowing mobile marine with compressed bodies enclosed in hinged
bivalve shells; includes clams, oysters, mussels Skolithos
early life that is represented by burrows; presumed to be early worms
trilobites extinct mobile marine with a body divided by two furrows into three parts; crayfish-like, related to millipedes, scorpions, sea spiders; important early fossil |
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