A descriptive term used for rocks and other earth materials that have an abundance of calcium carbonate (CaCO3). For example, a calcareous sandstone has up to 50% calcium carbonate.
A soil layer at least 15 cm thick that has been enriched with calcium carbonate (CaCO3).
Mineral made of calcium carbonate
(CaCO3). Generally white, easily scratched with knife. Most seashells
are made of calcite or related minerals. This is the lime of limestone.
Large, generally circular, fault-bounded depression caused by the withdrawal of magma from below a volcano or volcanoes. Commonly, the magma erupts explosively as from a giant volcano and, falling back to Earth as volcanic ash, fills the caldera so formed.
A sedimentary rock made mainly of calcium carbonate (CaCO3). Limestone and dolomite are common carbonate sedimentary rocks.
A mild acid formed when water and carbon dioxide chemically combine in the atmosphere and soil.This acid is a very important component in the development of cave decorations (speleothems).
A natural opening in the
ground extending beyond the zone of light and large enough to permit
the entry of an average human.
A cave or caves having a
complex network of interconnected chambers and passages that constitute
an underground drainage system.
A combination of chemical and mechanical weathering processes act on rock surfaces to produce hollows and caverns. This is also called honeycomb weathering.
One of the processes that work together to turn sediment into sedimentary rock (lithification). Mineral-laden water percolates through sediment with open pore spaces. The spaces are gradually filled by minerals precipitating from the water, binding the grains together.
The time span between 66.4
million years ago to the present.
Sedimentary rock composed of minerals that were precipitated from water. This process begins when water traveling through rock dissolves some of the minerals, carrying them away from their source. Eventually these minerals are redeposited, or precipitated, when the water evaporates away or when the water becomes over-saturated.
The process that changes
the chemical makeup of a rock or mineral at or near the Earth’s
surface. Chemical weathering alters the internal structure of minerals
by the removing and/or adding elements. Compare with mechanical weathering.
A very fine-grained sedimentary rock made of quartz. Usually made of millions of globular siliceous skeletons of tiny marine plankton called radiolarians. Black chert is called flint.
Family of platy silicate minerals containing various amounts of magnesium, iron, aluminum, water, and small amounts of other elements. Some mineralogists include chorites in the mica family because the crystals form small flakes. Commonly green.
A bubbly (vesicular) volcanic
rock fragment that forms when molten, gas-filled lava is thrown into
the air, then solidifies as it falls.
A volcanic cone built almost
entirely of loose volcanic fragments, ash, and pumice (pyroclastics
A fragment of a pre-existing
rock or fossil embedded within another rock.
A sedimentary rock composed of fragments (clasts) of pre-existing rock or fossils. (=Detrital sedimentary rocks)
A family of platy silicate
minerals that commonly form as a product of rock weathering. Also, any
particle smaller than 1/256 of a millimeter in diameter.
The tendency of a mineral to break along weak planes.
Loose particles of rock or
mineral (sediment) that range in size from 64 - 256 millimeters in diameter.
Cobbles are a size of gravel larger than pebbles, but smaller than boulders.
Occurs when the weight of overlying material compresses more deeply buried sediment. Along with cementation, this process converts sediments to solid rock.
Rock layers that were deposited in sequence without episodes of erosion between deposition of layers. .
A sedimentary rock rock made
of rounded rock fragments, such as pebbles, cobbles, and boulders, in
a finer-grained matrix. To call the rock a conglomerate, some of the
consituent pebbles must be at least 2 mm (about 1/13th of an inch) across.
Metamorphism caused by heat from an igneous intrusion.
Convergence of two continental
plates. Such a convergence between the Indian and Eurasian plates is
responsible for producing the Himalayas.
The rigid, outer layer of relatively low density rock that makes up the continents.
A hypothesis proposed by
Alfred Wegener suggesting that the continents are not stationary, but
have 'drifted' through time. Plate tectonics is the name for the theory
that provided the evidence necessary to support Wegener’s hypothesis.
Ice cap that grew in western North America during the Pleistocene Epoch. It began growing first in Canada, eventually covering much of British Columbia, Alaska, the northern U.S., and parts of several western states.
convergent plate boundary
A boundary in which two plates
collide. The collision can be between two continents (continental collision),
an relatively dense oceanic plate and a more buoyant continental plate
(subduction zone) or two oceanic plates (subduction zone).
The innermost layer of the
Earth, made up of mostly of iron and nickel. The core is divided into
a liquid outer core and a solid inner core. The core is the most dense
of the Earth’s layers.
The depression produced by a meteorite impact or at the summit of a volcano.
The relatively stable nucleus
of a continent. Cratons are made up of a shield-like core of Precambrian
Rock and a buried extension of the shield.
The rocky, relatively low
density, outermost layer of the Earth.
Growth of minerals (crystalline solids) from a liquid or gas.
A set of words, numbers, locations, or other data put into a computer program. Data bases are set up so that related pieces of information can be easily retrieved and compiled.
An isotope produced
by decay of a radioactive element.
A type of landslide made up of a mixture of water-saturated rock debris and soil with a consistency similar to wet cement. Debris flows move rapidly downslope under the influence of gravity. Sometimes referred to as earth flows or mud flows.
Removal of loose material by wind.
General term for folding, faulting, and other processes resulting from shear, compression, and extension of rocks.
A fan-shaped deposit that forms where a stream enters a lake or ocean and drops its load of sediment.
The weight per unit volume of a material.
A region with an average annual rainfall of 10 inches or less.
Any accumulation of sediment.
surface layer of coarse pebbles and gravel.
To dry out, usually by evaporation of water.
A group of processes that cause physical and chemical changes in sediment after it has been deposited and buried under another layer of sediment. Diagenesis may culminate in lithification of sediment, turning it into solid rock.
Forceful, upward intrusion of a rock mass into overlying rock. In the case of an igneous diapir, the intruding rock may be magma or a crystal-rich mush, either of which is less dense than the surrounding rock.
or tabular-shaped igneous intrusion that cuts across the sedimentary layering,
metamorphic foliation, or other texture of a pre-existing rock.
Intrusive igneous rock made of plagioclase feldspar and amphibole and/or pyroxene. Similar to gabbro only not as so dark, and containing less iron and magnesium.
A measure of the angle between the flat horizon and the slope of a sedimentary layer, fault plane, metamorphic foliation, or other geologic structure.
In karst areas, streams often disappear into the ground usually at a sinkhole.
The amount of water issuing from a spring or in a stream that passes a specific point in a given period of time.
The process of chemical weathering of bedrock in which the combination of water and acid slowly removes mineral compounds from solid bedrock and carries them away in liquid solution. Also called chemical solution.
A boundary in
which two tectonic plates move apart.
Any channel that carries water.
The land area drained by a stream.
A magnesium-rich carbonate sedimentary rock. Also, a magnesium-rich carbonate mineral (CaMgCO3)
A usually asymmetrical
hill of wind-deposited sand.
An outer rind or crust formed on a rock. Durable crusts form when rock chemically reacts with water and possibly atmospheric dust, producing a hard outer surface that resists weathering.