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62 Cards in this Set
- Front
- Back
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Mechanical Weathering
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The physical disintegration of rock, resulting in smaller fragments.
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Chemical Weathering
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The processes by which the internal structure of a mineral is altered by the removal and/or addition of elements.
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Spheroidal Weathering
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Any weathering process that tends to produce a spherical process that tends to produce a spherical shape from an initially blocky shape.
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Differential Weathering
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Weathering varies, like a volcanic neck, or rough uneven surfaces on marble.
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Frost Wedging
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The mechanical break-up of rock caused by the expansion of freezing water in cracks and crevices.
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Sheeting
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A mechanical weathering process characterized by the spitting off of slab-like sheets of rock.
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Exfoliation Dome
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Large, dome-shaped structure, usually composed of granite, formed by sheeting.
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Regolith
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The layer of rock and mineral fragments that nearly everywhere covers Earth's land surface.
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Soil
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A combination of mineral and organic matter, water, and air; that portion of the regolith that supports plant growth.
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Soil Profile
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A vertical section through a soil showing its succession of horizons and the underlying parent material.
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Zone of Leaching
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The depletion of soluble materials from the upper soil by downward-percolating water.
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Accumulation Zone
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The part of a glacier characterized by snow accumulation and ice formation. The outer limit of this zone is the snow line.
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Detrital Sedimentary Rock
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Rocks that form from the accumulation of materials that originate and are transported as solid particles derived from both mechanical and chemical weathering.
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Chemical Sedimentary Rock
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Sedimentary rock consisting of material that was precipitated from water by either inorganic or organic means.
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Organic Sedimentary Rock
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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.
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Sedimentary Environment
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Geographical setting where sediments are collecting.
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Clastic Texture
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Sedimentary rock texture consisting of broken fragments of preexisting rock.
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Sorting
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The degree of similarity in particle size in sediment or sedimentary rock.
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Evaporite
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A sedimentary rock formed of material deposited from solution by evaporation of water.
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Lithification
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The process, generally by cementation and/or compaction, of converting sediments to solid rock.
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Cementation
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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.
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Compaction
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A type of lithification in which the weight of overlying material compresses more deeply buried sediment. It is most important in fine-grained sedimentary rocks such as shale.
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Strata (Beds)
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Parallel layers of sedimentary rock.
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Cross-Bedding
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Structure in which relatively thin layers are inclined at an angle to the main bedding. Formed by currents of wind or water.
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Graded Bed
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A sediment layer characterized by a decrease in sediment size from bottom to top.
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Ripple Mark
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Small waves of sand that develop on the surface of a sediment layer by the action of moving water or air.
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Mud Crack
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A feature in some sedimentary rocks that forms when wet mud dries out, shrinks, and cracks.
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Contact Metamorphism
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Changes in rock caused by the heat of a nearby magma body.
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Regional Metamorphism
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Metamorphism associated with large-scale mountain building.
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Fault-Zone Metamorphism
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Breccia is a common example. Read In Book For Better Understanding.
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Confining Pressure
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Force is applied equally in all directions, and force gets stronger the deeper you go.
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Differential Stress
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Forces acting on a rock in different directions, for example a convergent plate boundary.
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Foliation
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A term for a linear arrangement of textural features often exhibited by metamorphic rocks.
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Slaty Cleavage
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The type of foliation characteristics of slates in which there is a parallel arrangement of fine-grained metamorphic minerals.
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Schistosity
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A type of foliation characteristic of coarser-grained metamorphic rocks. Such rocks have a parallel arrangement of platy minerals such as the micas.
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Gneissic Texture
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The texture displayed by the metamorphic rock gneiss in which dark and light silicate minerals have separated, giving the rock a banded appearance.
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Porphyroblastic Texture
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A texture of metamorphic rocks in which particularly large grains (porphyroblasts) are surrounded by a fine-grained matrix of other minerals.
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Metasomatism
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A significant change in the chemical composition of a rock, usually by the addition or removal of ions in solution.
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Aureole
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A zone or halo of contact metamorphism found in the host rock surrounding an igneous intrusion.
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Index Mineral
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A mineral that is a good indicator of the metamorphic environment in which it formed. Used to distinguish different zones of regional metamorphism.
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Migmatite
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A rock exhibiting both igneous and metamorphic rock characteristics. Such rocks may form when light-colored silicate minerals melt and then crystallize, while the dark silicate minerals remain solid.
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Relative Dating
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Rocks are placed in their proper sequence or order. Only the chronological order of events is determined.
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Radiometric Dating
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The procedure of calculating the absolute ages of rocks and minerals containing certain radioactive isotopes.
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Original Horizontality
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Layers of sediment are generally deposited in a horizontal or nearly horizontal positions.
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Law of Superposition
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In any undeformed sequence of sedimentary rocks or surface-depositied igneous materials, each layer is older than the one above it and younger than the one below.
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Cross-Cutting Relationships
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The theory that intruding faults and dikes must be younger than the rocks they intrude.
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Correlation
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Establishing the equivalence or rocks of similar age in different areas.
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Unconformity
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A surface that represents a break in the rock record; caused by erosion or non-deposition.
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Angular Unconformity
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An unconformity in which the older strata dip at an angle different from that of the younger beds.
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Disconformity
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A type of unconformity in which the beds above and below are parallel.
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Nonconformity
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An unconformity in which older metamorphic or intrusive igneous rocks are overlain by younger sedimentary strata.
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Fossil Succession
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Fossil organisms succeed one another in a definite and determinable order, and any time period can be recognized by its fossil content.
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Index Fossil
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A fossil that is associated with a particular span of geologic time.
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Geologic Time Scale
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Geologic time history broken into varying magnitudes.
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Half-Life
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The time required for one half of the atoms of a radioactive substance to decay.
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Paleozoic Era
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A time span on the geologic time scale between the Proterozoic and Mesozoic eras- from about 542 million to 251 million years ago.
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Mesozoic Era
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A time span on the geologic time scale between the Paleozoic and Cenozoic eras- from about 215 million to 65.5 million years ago.
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Cenozoic Era
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A time span on the geologic time scale beginning about 65.5 million years ago following the Mesozoic era.
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Precambrian
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All geologic time prior to the Paleozoic era.
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Effects of Mechanical Weathering Figure 5.3
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Chemical weathering can occur only to those portions of a rock that are exposed to the elements. Mechanical weathering breaks rock into smaller and smaller pieces, thereby increasing increasing the surface area available for chemical attack.
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Products of Weathering Table 5.1
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Quartz-Quartz
Feldspars-Clay-K,Na,Ca Amphibole-Clay-Ca,Mg Olivine-Limonite-Mg They all leave Silica |
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Soil Horizons Figure 5.18
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O-loose decayed matter
A-matter mixed with humus E-zone of leaching B-accumulation of clay C-partially alter parent mat. Unweathered Parent Material |
