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GLOSSARY of GEOLOGIC TERMS for Geology 2209

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Geology - the study of the earth. Physical Geology includes processes that affect the earth's internal and external structure, composition and other natural functions. Historical Geology is the study of the evolution of life on earth - especially the past life forms that are preserved as fossils. (J.Wittstrom)

Mafic - ocean crust contianing magnesium and iron. (Y. Tanoli)

Subduction Zone - place where two tectonics plates meet and one plate move under the other. (Y.Tanoli)

Asthenosphere - the layer of the mantle that lies directly below the lithosphere. (A.Senos)

Spreading Ridge - an elevated region where new crust material is being formed and where older crust moves away from the ridge. (B.Qaderi)

Harry Hess - In the 1960s Hess developed the theory that the seafloor is spreading. This theory was based on the discovery of the Mid-Atlantic Ridge, proving that the upwelling of magma breaking through the mantle is pushing the seafloor from the ridge crest.(J.Howley)

Volcanic Island Arcs - When either a oceanic crust subducts under another oceanic crust (oceanic arc) or a continental crust subducts under another continental crust (continental arc). (Q.Janmohamed)

Lithosphere - located above the asthenosphere the lithosphere consists of the outer layer of earth’s crust and upper mantle. The lithosphere also contains the Moho boundary. (H.Redoble)

Curie Point - The temperature a substance reaches when magnetism is lost. (J.Mellum)

Hardness - A property of a mineral. Its tolerance or resistance to scratching or abrasion. This is measured by the Moh's scale. (Christine Simoneau)

Carbonate - minerals that contain the carbonate anion ((CO3)2-), some of the most common include argonite, calcite and magnesite. (A. Senos)

Halide - a binary compound constructed of two parts, one halogen atom and one element or radical that has a electronegative value less than the halogen. (Q.Janmohamed)

Hot Spot- A stationary mantel plume which will form a series of Volcanoes or Sea Mountains as the earths crust moves overtop of it. (M.Laery)

Lustre- the refelctive quality of light on the freshly broken surface of a mineral. main divisions of lustre being metallic and non-metallic. (M. MacFadzen)

Native Element - occurs in nature and is not part of a compound. Examples are gold and silver. (J. Mellum)

Fracture - when a mineral breaks and does not cleave the mineral fractures. Fractures can be irregular, curved, jagged or splintery. Quartz actually has a conchoidal fracture which is dish shaped. (H. Redoble)

Paleomagnetism - Refers to the study of the magnetic properties of rocks and minerals. This demonstrates to us that both the strength and direction of Earths magnetic field is not constant. Each rock and mineral tells its own story at a particular moment in time. (A. Atwal)

Continental volcanic arch - mountain ranges produced by ingeouse activity due to the subduction of the ocean's lithosphere.

Cleavage - When a mineral is broken cleavage is shown by the pattern in which the mineral breaks in; along crystallographic planes. If it does not follow these planes then it is considered to fracture. (T. Bakic)

Magnetometer - One of the weapons WW2 left us with, it is used for measuring a magnetic fields magnitude and direction. (T. Bakic)

Pegmatite - A very coarse grained igneous rock like granite, commonly associated with large masses of plutonic rock. (M. MacFadzen)

Evaporite - Sedimentary rocks made up of minerals that are deposited from the precipitation of evaporated seawater. (M. MacFadzen)

Erosion - The transportation of material by amobile agent i.e water, wind or ice.(C Simoneau)

Magma - A body of molten rock found at depth this includes dissolved gases and crystals. (C Simoneau)

Aphanitic – refers to the texture of igneous rocks when you can’t distinguish individual minerals unless you use a microscope then it is said to have an aphanitic texture. (H. Redoble)

Basalt - a dark colored and fine grained extrusive igneous rock, it is the most widespread igneous rock (A. Senos)

Extrusive - the Term for igneous rocks that are formed when magma solidifies at the crust surface (J. Howley)

Exfoliation - occurs when a rock is exposed to continuous weathering. Slabs and pieces of the outer layer of the rock will fall off or flak away (J. Howley)

Plutons - A body of igneous rock formed beneath the surface of the earth by consolidation of magma. (S.Katarey)

Fissile – refers to a property of a rock when splitting occurs effortlessly into slim layers along closely spaced, parallel surfaces. An example would be bedding planes in shale. (H. Redoble)

Sulfides-They are a group of minerials that are very important to the economy and are from igneous orgin. Some characteristics of sulfides are that most are metallic, they have a high density, and often leave black or dark colored streaks when rubbed against a harder surface. some examples of sulfides are most ores, and important metals such as copper, silver, and lead. (T.Purcell)

Phaneritic-Is a igneous rock which is classified as having a coarse texture. This rock is considered intrusive, meaning that it solitifies far below the surface allowing it to cool very slow forming large, visible crystals. (T.Purcell)

Graded Bed-They are a mixture of gravel, sand, mud that has been carried by moving water (stream, rivers) and deposited in layers. They show a range of particle sizes usually layered larger (coarse) to samller (fine). (T.Purcell)

Ripple marks-Small waves of sand formed on the surface by the presents of moving water or air. (Mark Leary)

Glassy Texture- A term used to describe the appearance of some igneous rocks that contain no crystals. (Mark Leary)

Sulfates - is a salt of sulfuric acid. The mineral Gypsum is in the form of hydrated calcium sulfate. (B.Qaderi)

Crystallization - the formation of crystals or assumption of crystalline structure from a liquid or gas. (B.Qaderi)

Dissolution - a form of chemical weathering, the process by which a solid, liquid, or gas is distributed homogeneously in a solid, gas or especially a liquid. (B.Qaderi)

Diagenesis - Any physical, chemical or biological change that occurs after a sediment has been deposited and lithified. (Q.Janmohamed)

Pangea - One large "super continent" that existed before continental drift. Pangea existed roughly 250 million years ago. (A. Straathof)

Mohs Scale - Used to determine a minerals scratch resistance by using another harder mineral to test it upon. Moh's Scale is a test to determine the hardness factor of a mineral. (A. Straathof)

Intrusive - Igneous rock that forms and cools underneath the earth from molten magma. (A. Straathof)

Oxidation - A form of chemical weathering, any mineral exposed to air may undergo this type of chemical weathering. (A. Straathof)

Back Arc Basin- an isolated marine basin that is formed behind a subduction zone. Associated with island acrs. (G. Kendall)

Specific Gravity- is the ratio of a substance's weight to the weight of an equal volume of water. It is expressed without units. (G. Kendall)

Geothermal Gradient- the change in the temperature as depth increases the further you go into the Earth's crust. (G.Kendall)

Lava - Liquid molten rock that has reached the Earth's surface through a volcano. (T. Stachiw)

Regolith - The layer of loose rock resting on bedrock, made from fragments of rocks and minerals. (T. Stachiw)

Oxides - A Compund of an element and Oxygen. Water is a oxide. (T. Stachiw)

Hydrolysis - the process of breaking down compound by adding water. (Y.Tanoli)

Viscosity - is based on how thick a fluid is and therefore its resistence to flow. Water is less viscous than honey. (J.Mellum)

Andesite - A medium-dark colored igneous rock that crystallizes at intermediate temperatures. It contains 53-63 percent silica. Due to this it has a moderate viscosity. (A. Atwal)

Lithification - The process by which sediments slowly turn into rock form. This is done so by the processes of compaction and cementation. Lithification is a broad term, including any process which turns sediments into sedimentary rock. (A. Atwal)

Syncline - a characteristic of folding rocks due to compression, syncline refers to the downward facing fold. (H.Redoble)

Elastic Deformation: Instantly recovering and retaining shape when force is applied( Deformation)(C. Simoneau)

Principal of Crosscutting relationships:States that any geologic feature is younger then the geologic feature it cuts across, for example, a river channel must be younger then the plain it crosses. (C. Simoneau)

Normal Fault - Vertical fault where one rock is displaced up and the other down, usually at a 60 degree angle. (B.Qaderi)

Permineralization :The preservation of organic hard partsby mineral-bearing groundwater infiltrating porous matter after the burial. The common preserving minerals are silica, clacite and iron oxides. (C Simoneau)

Unconformity – a break in the continuity of the rock record resulting from a cease of deposition and erosion. (H.Redoble)

Coprolite – fossilized excrement, this petrified dung can be analyzed to discover eating patterns of prehistoric animals. (H.Redoble)

Horst and Graben - elongate fault blocks of the Earth's crust that have been raised and lowered. They are relative to their surrounding areas as a direct effect of faulting. (G.Kendall)

Carbonization- process by which solid residues with increasing content of the element carbon are formed from organic material usually by pyrolysis in an inert atmosphere. (G.Kendall)

Petrification- process of fossilization, where dissolved minerals (silica) replace the organic matter in organisms. (M. MacFadzen)

Relative Dating - the sequence in which artifacts or events are arranged without the use of calender or time. (B.Qaderi)

Orogeny - are the geological processes that lead to mountain building. (J.Mellum)

Strata - the layers found in sedimentary rocks. (Y. Tanoli)

Extinction - the disappearence of species in all or some part of geographic area.(Y. Tanoli)

Index Fossil - a fossil that can be used to identify different geological time periods (A. Senos)

Debris Slide - an extremely fast form of mass movement consisting of mainly soil, along with trees, rocks etc. that roll through a narrow channel down a steep slope (A. Senos)

Slump - the collapse of a block of earth material along a curved surface (B.Qaderi)

Permafrost - A permanently frozen layer of soil or subsoil or even bedrock which occurs to variable depths below the earths surface in arctic and subarctic regions. It underlies approximately one fifth of the earths land area. ( C. Simoneau)

Rock Avalanche - the most rapid type of mass movement where very large rocks fall so fast they seem to flow like water taking out everything in its path (J. Howley)

Solifluction - slow moving, water saturated soil, mud or other earth material that moves down hill. This process is typical of earth movement in permafrost areas where there is a continuously frozen layer beneath the surface all year long. (Wittstrom)

Angle of repose - the maximum angle of a stable slope. (J. Mellum)

Trigger – an immediate cause that initiates an occurrence such as a sonic boom that triggers an avalanche. (H. Redoble)

Creep - A slow, continuous process that occurs in response to stress below the elastc limit. (M. MacFadzen)

Cutbank - An almost vertical cliff produced by erosion of the banks by a stream. (M. MacFadzen)

Headwater - The Source of a river. (M. MacFadzen)

Drainage Baisin - All area drained by a river system.(S.D.Katarey)

Divide - The line or zone of higher ground between two adjacent streams or drainage basins.Ex: the Great Divide that seperates Alberta and Canada.(S.D. Katarey)

Debris Flow- Debris flows occur when rain water begins to wash material from a slope or when water sheets off of a freshly burned stretch of land. Debris flows can contain anything from trees, cars, people, or buildings. (G.Kendall)

Base Level-the lowest level to which running water can erode the land. (G.Kendall)

Bed Load- the sand, gravel, boulders, or other debris transported by rolling or sliding along the bottom of a stream by a high velocity stream. (G.Kendall)

Dendritic drainage pattern – has a tree like branching pattern. The dendric drainage pattern forms where the under lying ground is uniform. (H. Redoble)

Alluvial Fan - An alluvial deposit with a semi - conical, downstream broadening shape formed where the topographic gradient reduces and the transporting capacity is diminished as the width of the flow increases, such as along mountain fronts, fault scarps, valley sides and glacier margins. (C. Simoneau)

Alluvium - Any stream-deposited sedimentary material. (B.Qaderi)

Delta - formed when a stream enters an ocean or lake and the sediment it is carrying is deposited at the mouth because the current slows rapidly (J. Howley)

Meander - an "S" like bend in a river or stream. (J. Howley)

Point Bar - the depositional area located on the inside bend of a meandering stream, are cresent shaped and formed by a river depositing its load as the velocity decreases along the inside bend. (A. Senos)

Braided Stream - a stream that divides and joins back up continuously around sediments that are too big to be moved by low energy stream. (A. Senos)

Dissolution - removal of bedrock through chemical weathering. (B.Qaderi)

Oxbow Lake - A lake distinctive for its curved shape as a result of being cut of from a wide meander. (J. Mellum)

Trellised Drainage Pattern - A rectangular pattern with nearly parallel tributary streams. The drainage pattern is due to the alternating bands of hard and soft strata as well as geological folding. (J. Mellum)

DRAINAGE BASIN - An area that drains precipitation (rain or melting snow) in to streams and rivers that are than carried into lakes and oceans (M. Leary)

STREAM LOAD - rock fragments and sediments that are carried within the flow of a river or stream (M. Leary) Snow Avalanche- A mass of snow, ice and possibly other material caused when a large slab of snow breaks free from the layers beneath (M.Leary)