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Geology
Glossary
Anticline
Rock layers that have been bent
so that they bow upwards or fold
convex side up.
Aquifer
A rock layer with enough space between
its grains to allow water to flow
relatively freely.
Butte
A hill or very small mountain that
is flat topped and steep sides all
around.
Calcite
A mineral composed of calcium carbonate
commonly found in sedimentary rocks.
It is the main component of limestone.
Conglomerate
A sedimentary rock composed of gravel,
cobbles and boulders mixed in with
sand or mud.
Fault
A fracture in rock layers along
which movement has occurred.
Feldspar
A common mineral occurring in
igneous rocks that sometimes erodes
out and becomes incorporated into
sedimentary rocks. Feldspar is the
most common mineral in the world.
Formation
Layer of rock with distinct characteristics,
such as color, particle size and
composition that can be identified
and mapped over extended distances.
Igneous
rocks
A type of rock formed from molten
magma after it has cooled and solidified.
Joint
A fracture in rock layers along
which no movement has occurred,
usually formed by stresses placed
on the rock, such as uplift and
folding of rock layers.
Limestone
A sedimentary rock formed in aquatic
environments from calcium carbonate.
Often contains fossil remains.
Marine
regression
A drop in sea level resulting in
the exposure of land previously
covered by water.
Marine
transgression
A rise in sea level resulting in
the inundation of land by ocean.
Mesa
A flat topped mountain with at least
one steep side.
Metamorphic
rocks
Sedimentary or igneous rocks heated
and/or compressed until the minerals
in the rock break down and form
new minerals without melting.
Monocline
A bend in rock layers where a steep
dip occurs resulting in one side
being lower than the other.
Pinnacle
A slender isolated column of rock,
often the erosional remnant of a
butte.
Plateau
A large region that is higher than
the surrounding area and relatively
flat.
Quartz
The basic composition of sandstone
and a major component in shales,
conglomerates and some igneous and
metamorphic rocks.
Sandstone
A sedimentary rock composed of sand
grains glued together by silica
or calcium carbonate.
Sedimentary
rocks
Rocks formed by the deposition or
accumulation of pieces of weathered
rocks that later were buried and
cemented, or glued, together.
Shale
A sedimentary rock composed of particles
smaller than sand, such as clay
and mud.
Syncline
Rock layers that have been bent
so that they bow downwards or fold
convex side down.
Unconformity
A break in the rock record where
layers were eroded, never laid down
or are missing.
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