Category Geology Dictionary

Geological Terms Beginning With "J"
Geology Dictionary

Geological Terms Beginning With "J"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Jade "Jade" is a cultural term used for a translucent gem material consisting of either jadeite or nephrite. The typical color cut into gemstones and used in ornamental work is a bright to deep green.

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Geology Dictionary

Geological Terms Beginning With "J"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Jade "Jade" is a cultural term used for a translucent gem material consisting of either jadeite or nephrite. The typical color cut into gemstones and used in ornamental work is a bright to deep green.
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Geology Dictionary

Geological Terms Beginning With "X"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Xenoblast A crystal that has grown in a rock during the process of metamorphism and which has not developed its characteristic crystal faces because of space limitations. These crystals typically have boundaries that are straight or that conform to the shape of adjacent crystals.
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Geology Dictionary

Geological Terms Beginning With "H"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Habit An external shape displayed by an individual crystal or an aggregate of crystals. A few examples of crystal habits are shown in the photo. Clockwise from top left: prismatic habit; geodic habit; banded habit; pisolitic habit.
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Geology Dictionary

Geological Terms Beginning With "T"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Talus An accumulation of angular rock debris at the base of a cliff or steep slope that was produced by physical weathering. The image shows a portion of the talus apron that surrounds Fajada Butte in Chaco Valley, New Mexico.
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Geology Dictionary

Geological Terms Beginning With "O"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Oblique-Slip Fault A fault that has both horizontal and vertical elements of displacement. Obsidian A glassy igneous rock with a composition similar to granite. The glassy texture is a result of cooling so fast that mineral lattices were not developed.
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Geology Dictionary

Geological Terms Beginning With "Q"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Quadrangle (Quad) In geometry: a four-sided plane figure such as a square or a rectangle. In geology: an area shown on a standard topographic map sheet published by the United States Geological Survey.
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Geology Dictionary

Geological Terms Beginning With "I"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Igneous Rock A rock formed by the crystallization or solidification of molten rock material. They can form underground, on the surface or as ejecta. The rock in the photo is a piece of diorite.
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Geology Dictionary

Geological Terms Beginning With "G"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Gabbro A black, coarse-grained intrusive igneous rock that is the compositional equivalent of basalt. Composed of calcium-rich feldspars, pyroxene, and possibly olivine, but containing little if any quartz.
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Geology Dictionary

Geological Terms Beginning With "B"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Backarc The tectonic region on the landward side of a volcanic arc. Image by USGS. Backwash The seaward rush of water down a beach that occurs with a receding wave. Ball Mill A device used to reduce the particle size of laboratory specimens, dry chemicals, mined ores, and other solid materials.
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Geology Dictionary

Geological Terms Beginning With "E"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Earthflow A type of landslide or mass wasting. A downslope movement of soil and rock debris that is confined to a well-defined "chute" and spreads out over the run-out area in the form of a lobe.
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Geology Dictionary

Geological Terms Beginning With "K"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Kame Surface deposits in the form of mounds, hummocks or ridges that are composed of stratified glacial sediments. These were deposited on, under or within glacial ice and then were left behind as positive relief features when the ice melted.
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Geology Dictionary

Geological Terms Beginning With "V"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Vadose Water Water that exists in the pore spaces of a rock or soil within the vadose zone (between the ground surface and the water table). Valence Electrons Electrons in the outermost shell of an atom.
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Geology Dictionary

Geological Terms Beginning With "N"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Nannofossils A generic term used in reference to very small fossils that are at the limit of resolution by a light microscope. They are therefore studied with electron microscopes. Discoasters and coccoliths are frequently called "nannofossils.
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Geology Dictionary

Geological Terms Beginning With "U"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Ubiquitous Found everywhere, constantly encountered. Some geologists say that the minerals quartz, calcite, and pyrite are ubiquitous. Ultrabasic Rock An igneous rock with a very low silica content and rich in minerals such as hypersthene, augite, and olivine.
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Geology Dictionary

Geological Terms Beginning With "Z"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Zeolite A group of hydrous aluminosilicates that are similar to the feldspars. They easily lose and regain their water of hydration, and they fuse and swell when heated. Zeolites are frequently used as catalysts, water softeners, and sorbents.
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Geology Dictionary

Geological Terms Beginning With "F"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Facies a) The characteristics of a rock or sediment unit that reflect its environment of deposition and allow it to be distinguished from rock or sediment deposited in an adjacent environment.
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Geology Dictionary

Geological Terms Beginning With "Y"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Yazoo Stream A tributary that parallels the main channel of a stream for a considerable distance. Joining of these streams is normally blocked by a natural levee along the larger stream. Shown in the image is Wakenda Creek paralleling the Missouri River before joining it near Miami Station, Missouri.
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Geology Dictionary

Geological Terms Beginning With "D"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Datum A reference location or elevation which is used as a starting point for subsequent measurements. Sea level is a datum for elevation measurements. Datums can also be arbitrary such as the starting point for stream stage measurements or based upon a physical feature such as the base of a rock unit.
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Geology Dictionary

Geological Terms Beginning With "M"

For terms beginning with other letters, please click below A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Maar A maar is a small, shallow volcanic crater with steep sides that forms in an explosive volcanic eruption that is triggered when rapidly ascending magma contacts groundwater at a shallow depth and a steam explosion occurs.
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