Ch 7: Sedimentary Rocks Flashcards
Alluvial fan
A fan-shaped deposit of sediment formed when a stream’s slope is abruptly reduced.
Anthracite
A hard metamorphic form of coal that burns cleanly and hot.
Arkose
A feldspar-rich sandstone.
Atmosphere
The gaseous portion of a planet, the planet’s envelope of air. One of the traditional subdivisions of Earth’s physical environment.
Bar
Common term for sand and gravel deposits in a stream channel.
Beach
An accumulation of sediment found along the landward margin of the ocean or a lake.
Bed
See Strata
Bedding plane
A nearly flat surface that separates two beds of sedimentary rock. Each bedding plane marks the end of one deposit and the beginning of another having different characteristics.
Biochemical
A type of chemical sediment that forms when material dissolved in water is precipitated by water-dwelling organisms. Shells are common examples.
Biomass
Organic material that is renewable energy derived from trees, crops, and waste. Examples include biofuels such as ethanol and biodiesel, as well as biogas, which is methane recovered from landfills.
Biosphere
The totality of life-forms on Earth.
Bituminous coal
The most common form of coal, often called soft, black coal.
Breccia
A sedimentary rock composed of angular fragments that were lithified.
Carbon cycle
An Earth system in which carbon moves through the atmosphere, hydrosphere, biosphere, and geosphere, in different directions.
Cementation
One way in which sedimentary rocks are lithified. As material precipitates from water that percolates through the sediment, open spaces are filled and particles are joined into a solid mass.
Chemical sedimentary rock
Sedimentary rock consisting of material that was precipitated from water by either inorganic or organic means.
Chemical weathering
The processes by which the internal structure of a mineral is altered by the removal and/or addition of elements.
Chert
A durable sedimentary rock formed of microcrystalline quartz.
Clastic texture
A sedimentary rock texture consisting of broken fragments of preexisting rock.
Color
A phenomenon of light by which otherwise identical objects may be differentiated.
Compaction
A type of lithification in which the weight of overlying material compresses more deeply buried sediment. It is most important in the finegrained sedimentary rocks such as shale.
Compound
A substance formed by the chemical combination of two or more elements in definite proportions and usually having properties different from those of its constituent elements.
Conglomerate
A sedimentary rock composed of rounded, gravel-size particles.
Continental shelf
The gently sloping submerged portion of the continental margin, extending from the shoreline to the continental slope.
Cross-bedding
A structure in which relatively thin layers are inclined at an angle to the main bedding. Cross-bedding is formed by currents of wind or water.
Crystal
Any natural solid with an ordered, repetitive atomic structure.
Crystalline
Crystal
Crystalline texture
See Nonclastic texture.
Desert
One of the two types of dry climate; the driest of the dry climates.
Detrital sedimentary rocks
Rocks that form from the accumulation of materials that originate and are transported as solid particles derived from both mechanical and chemical weathering.
Dolostone
A chemical sedimentary rock formed from dolomite, a calcium-magnesium carbonate mineral.
Dune
A hill or ridge of wind-deposited sand.
Environment of deposition
A geographic setting where sediment accumulates. Each site is characterized by a particular combination of geologic processes and environmental conditions.
Evaporite
A sedimentary rock formed of material deposited from solution by evaporation of the water.
Facies
A portion of a rock unit that possesses a distinctive set of characteristics that distinguishes it from other parts of the same unit.
Fine-grained
See Aphanitic texture.
Fissility
The property of splitting easily into thin layers along closely spaced, parallel surfaces, such as bedding planes in shale.
Fossil
The remains or traces of organisms preserved from the geologic past.
Fossil fuel
General term for any hydrocarbon that may be used as a fuel, including coal, oil, natural gas, bitumen from tar sands, and shale oil.
Geosphere
The solid Earth; one of Earth’s four basic spheres.
Glacier
A thick mass of ice originating on land from the compaction and recrystallization of snow that shows evidence of past or present flow.
Graded bed
A sediment layer characterized by a decrease in sediment size from bottom to top.
Groundwater
Water in the zone of saturation.
Hardness
A mineral’s resistance to scratching and abrasion.
Hydrosphere
The water portion of our planet; one of the traditional subdivisions of Earth’s physical environment.
Igneous rock
Rock formed from the crystallization of magma.
Ion
An atom or a molecule that possesses an electrical charge.
Limestone
A chemical sedimentary rock composed chiefly of calcite. Limestone can form by inorganic means or from biochemical processes.
Lithification
The process, generally involving cementation and/or compaction, of converting sediments to solid rock.
Metamorphism
The changes in mineral composition and texture of a rock subjected to high temperatures and pressures within Earth.
Mineral
A naturally occurring, inorganic crystalline material with a unique chemical structure.
Mud crack
A feature in some sedimentary rocks that forms when wet mud dries out, shrinks, and cracks.
Near-shore
The zone of a beach that extends from the low-tide shoreline seaward to where waves break at low tide.
Nonclastic texture
A term for the texture of sedimentary rocks in which the minerals form a pattern of interlocking crystals.
Offshore
The relatively flat submerged zone that extends from the breaker line to the edge of the continental shelf.
Oil shale
A fine-grained sedimentary rock that contains a solid mixture of organic compounds from which liquid hydrocarbons called shale oil can be produced.
Organic sedimentary rock
Sedimentary rock composed of organic carbon from the remains of plants that died and accumulated on the floor of a swamp. Coal is the primary example.
Outcrop
Sites where bedrock is exposed at the surface.
Oxidation
The removal of one or more electrons from an atom or ion. So named because elements commonly combine with oxygen.
Quartz
A common silicate mineral consisting entirely of silicon and oxygen that resists weathering.
Radiocarbon (carbon-14) dating
Dating of events from the very recent geologic past (the past few tens of thousands of years) based on the fact that the radioactive isotope of carbon is produced continuously in the atmosphere.
Recrystallization
The formation of new mineral crystals in a rock that tend to be larger than the original crystals.
Ripple marks
Small waves of sand that develop on the surface of a sediment layer by the action of moving water or air.
Rock
A consolidated mixture of minerals.
Rock cycle
A model that illustrates the origin of the three basic rock types and the interrelatedness of Earth materials and processes.
Salt flat
A white crust on the ground that is produced when water evaporates and leaves behind its dissolved materials.
Sandstone
An abundant, durable sedimentary rock primarily composed of sand-size grains.
Sediment
Unconsolidated particles created by the weathering and erosion of rock by chemical precipitation from solution in water, or from the secretions of organisms, and transported by water, wind, or glaciers.
Sedimentary environment
See Environment of deposition.
Sedimentary rock
Rock formed from the weathered products of preexisting rocks that have been transported, deposited, and lithified.
Shale
The most common sedimentary rock, consisting of silt- and clay-size particles.
Shore
Seaward of the coast, a zone that extends from the highest level of wave action during storms to the lowest tide level.
Sorting
The degree of similarity in particle size in sediment or sedimentary rock.
Strata
Parallel layers of sedimentary rock.
Stream
A general term to denote the flow of water within any natural channel. Thus, a small creek and a large river are both streams.
Texture
The size, shape, and distribution of the particles that collectively constitute a rock.
Travertine
A form of limestone (CaCO3 ) that is deposited by hot springs or as a cave deposit.
Turbidite
A turbidity current deposit characterized by graded bedding.
Turbidity current
A downslope movement of dense, sediment-laden water created when sand and mud on the continental shelf and slope are dislodged and thrown into suspension.
Volatiles
Gaseous components of magma dissolved in the melt. Volatiles will readily vaporize (form a gas) at surface pressures.
Weather
The state of the atmosphere at any given time.
Well
An opening bored into the zone of saturation.