Geology Word/Term of the Day!
Law and Order Week continues!
Law of Superposition - A general law upon which all geologic chronology is based: In any sequence of sedimentary strata (or of extrusive igneous rocks) that has not been overturned, the youngest stratum is at the top…1/2
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Geology Word/Term O’ the Day!
Law and Order Week continues…
Law of Original Horizontality - A general law of geology: Water-laid sediments are deposited in strata that are horizontal or nearly horizontal, and parallel or nearly parallel to the Earth’s surface.
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Geology Word of the Day!
Tsunami - A gravitational sea wave produced by any large-scale, short-duration disturbance of the ocean floor, principally by a shallow submarine earthquake, but also by submarine earth movement, subsidence, or volcanic eruption. 1/3
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Geology Word/Term of the Day…Law and Order Week!!
Law of Original Continuity - A general law of geology: A water-laid stratum, at the time it was formed, must continue laterally in all directions until it thins out as a result of nondeposition…1/2
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Geology Word/Term of the Day!
Punctuated Equilibria - That evolutionary pattern exhibited by successive species in an evolving lineage, in which rapid and substantial morphologic change is concentrated within geologically short moments… 1/2
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Geology Word/Term of the Day!
Bimodal Sediment - A sediment whose particle-size distribution shows two maxima; for example many coarse alluvial gravels.
From the 2nd Edition of AGI’s Glossary of Geology
[This distribution may indicate variable sources or transport mechanisms.] 1/3
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Geology Word/Term of the Day!
Backshore - The upper or inner, usually dry and narrow, zone of the shore or beach, lying between the high-water line of mean spring tides and the upper limit of shore-zone processes; 1/2
From the 2nd Edition of AGI’s Glossary of Geology
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Geology Word/Term of the Day!
Gilgai - The micro-relief of heavy clay soils with high coefficients of expansion and contraction according to changes in moisture. Gilgai is typical of vertisols.
(A new one for me!)
From the 2nd Edition of AGI’s Glossary of Geology
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Geology Word/Term of the Day!
Halocline- A steep downward increase in salinity of seawater.
From the 2nd Edition of AGI’s Glossary of Geology
Note: A surprisingly short definition from The Glossary for such a complex and widely varying condition.
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Geology Word/Term of the Day!
Ejecta - Glass, shock-metamorphosed rock fragments, and other materials (including pyroclastic or phreatomagmatic rock) thrown out of an explosion or impact crater during formation.
From the 2nd Edition of AGI’s Glossary of Geology (modified)
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Geology Word/Term of the Day!
Cone of Depression - A depression in the potentiometric surface of a body ground water that has the shape of an inverted cone and develops around a well from which water is being withdrawn. It defines the area of influence of a well.
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2/2 Well Graded - Good representation of all particle sizes from largest to smallest.
US DOI/BOR Earth Manual 2nd Edition
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The mechanical agent is usually alluvial but can also be marine, eolian,lacustrine, or glacial, and the mineral is usually a heavy metal such as gold.
From the AGI Dictionary of Geologic Terms
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Geology Word of the Day!
Placer Deposit - A surficial mineral deposit formed by mechanical concentration of mineral particles from weathered debris. 1/2
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Geology Word (and bonus word) of the Day!
Hydroclast - A rock fragment that is transported and deposited in an aqueous environment.
BTW - Had not heard this term and yet it typifies why I love our jargon heavy study. There is literally a word for everything!
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Geology Term of the Day!
Rootless Pluton - A pluton that formed exogenously and was emplaced onto a continental mass through accretion…apart from its source of magma.
My own definition…because in vacation mode from the eastern margin of the rootless Mt. Ashland pluton.
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Geology Words of the Day!
Bicarbonate - A salt containing a cation and the radical HCO3, e.g., NaHCO3 (sodium bicarbonate).
Spring - A place where without the agency of man(kind), water flows from rock or soil upon the surface of the land or into a body of surface water.
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Blueschist - A schistose metamorphic rock with with a blue color owing to the presence of sodic amphobole, glaucophane or crossite, and commonly mottled bluish-gray lawsonite.
3/3
From the 2nd Edition of AGI’s Glossary of Geology
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2/2 Some schlieren are modified inclusions, others may be segregation of minerals.
Etymology: German for a flaw in glass due to a zone of abnormal composition.
From the 2nd Edition of AGI’s Glossary of Geology
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Geology Word of the Day!
Schlieren - Tabular bodies, generally a few inches to tens of feet long, that occur in plutonic rocks. They have the same general mineralogy, but because of differences in mineral ratios they are darker or lighter; the boundaries tend to be transitional. 1/2
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Its temperature may exceed 54 °C (129 °F) and the relative humidity may fall below 10%.
Source: Wikipedia as this is more a meteorological word than a Geology term!
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Bonus word…
Liquefaction - In cohesion less soil, the transformation from a solid to a liquid state as a result of increased pore pressure and reduced effective stress.
From the 2nd Edition of AGI’s Glossary of Geology
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Geology Word of the Day!
Tsunami - A gravitational sea wave produced by any large-scale, short-duration disturbance of the sea floor, principally by a shallow submarine earthquake, but also by submarine earth movement, subsidence, or volcanic eruption.
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From the 2nd Edition of AGI’s Glossary of Geology
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Geology Word of the Day!
Prospect - (A) An area that is a potential site of mineral deposits based on preliminary exploration; (B) Sometimes an area that has been explored in a preliminary way but has not given evidence of economic value; 1/2
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2/2
Etymology: Pliny the Younger, AD 79.
From the 2nd Edition of AGI’s Glossary of Geology
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B) Pertaining to clastic rocks, the fragments of which have been produced by the fracture of pre-existing rocks by Earth stress, eg crush breccia. 2/2
From the 2nd Edition of AGI’s Glossary of Geology
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Geology Word(s) of the Day!
Magmatic Evolution - The continuing change in composition of a magma as a result of magmatic differentiation, assimilation, or mixing of magmas.
1/2
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Geology Word of the Day!
Maar - A low relief, broad volcanic crater formed by multiple shallow explosive eruptions. It’s surrounded by a crater ring, and may be filled by water. Type occurrence is in the Eifel area of Germany.
From the 2nd Edition of AGI’s Glossary of Geology
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Geology Word of the Day!
Mylonite - Chertlike rock without cleavage, but with a streaky or banded structure, produced by the extreme granulation and shearing of rocks that have been pulverized and rolled during overthrusting or intense dynamic metamorphism. 1/2
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