Earth Science 11th Edition Vocabulary Chapter 9

By Reshawn Brown (GLY 1001 Student North Campus Fall 2006)


1.              AA flow (p. 254) – A type of lava flow that has a jagged blocky surface.


2.              Batholith (p. 270) – A large mass of igneous rock that formed when magma was emplaced at depth, crystallized, and subsequently exposed by erosion.


3.              Caldera (p. 263) – A large depression typically caused by collapse or ejection of the summit area of a volcano.


4.              Cinder Cone (p. 259) – A rather small volcano built primarily of pyroclastics ejected from a single vent.


5.              Columnar Joint (p. 269) – A pattern of cracks that form during cooling of molten rock to generate columns that are generally six-sided.


6.              Composite Cone (p. 260) – A volcano composed  of both lava flows and pyroclastic materials


7.              Conduit (p.256) – A pipelike opening through which magma moves toward Earth’s surface. It terminates at a surface opening called a vent.


8.              Continental Volcanic Arc (p. 278) – Mountains formed in part by igneous activity associated with the seduction of oceanic lithosphere beneath a continent.


9.              Crater (p. 256) – The depression at the summit of a volcano, or that which is produced by a meteorite impact.


10.          Decompression Melting (p. 271) – Melting that occurs as rock ascends due to a drop in confining pressure.


11.          Dike (p. 269) - A tabular –shaped intrusive igneous feature that’s cuts through the surrounding rock.


12.          Fissure (p. 255, 265) – Volcano activity frequently begins when a (crack) develop in the crust as magma moves forcefully toward the surface.


13.          Fissure eruption (p. 266) – An eruption in which lava is extruded from narrow fractures or cracks in the crust.


14.          Flood basalt (p. 266) – Flows of basaltic lava that issue from numerous cracks or fissures and commonly cover extensive areas to thickness of thousands of meters.


15.          Furmarole (p.256) – A vent in a volcanic area from which fumes or gases escape.


16.          Geothermal Gradient (p. 271) – The gradual increase in temperature with depth in the crust. The average is 30*C per kilometer in the upper crust


17.          Hot Spot (p. 279) – A concentration of heat in the mantle capable of producing magma, which in turn extrudes onto Earth’s surface. The intraplate volcanism that produced the Hawaiian Islands is one example.


18.          Intraplate Volcanism (p. 279) – Igneous activity that occurs within a tectonic plate away from boundaries.


19.          island Arc (p.278) – See Volcanic island arc


20.          Laccolith (p.269) – A massive igneous body intruded between preexisting strata.


21.          Lahar (p.262) – Mudflows on the slopes of volcanoes that result when unstable layers of ash and debris become saturated.


22.          Mantle Plume (p. 279) – A mass of hotter than normal mantle material that ascends toward the surface, where it may lead to igneous activity. These plumes of solid yet mobile material may originate as deep as the core-mantle boundary.


23.          Muee Ardente (p. 262) – Destructive fiery flows, capable of racing down steep volcanic slopes at speeds that can approach 200 kilometers(125) per hour.


24.          Pahoehoe Flow (p. 254) – A lava flow with a smooth-to-ropey surface.


25.          Parasitic Cone (p. 256) – A volcanic cone that forms on the flank of a larger volcano.


26.          Partial Melting (p. 273) – The process by which most igneous rocks melt. Since individual minerals have different melting points, most igneous rocks melt over a temperature range of a few hundred degrees. If the liquid is squeezed out after some melting has occurred, a melt with a higher silica content results.


27.          Pipe (p. 256) – A vertical conduit through which magmatic materials have passed.


28.          Pluton (p. 267) – A structure that results from the emplacement and crystallization of magma beneath the surface of Earth.


29.          Pyroclastic Flow (p. 255) – A highly heated mixture, largely of ash and pumice fragments, traveling down the flanks of a volcano or along the surface of the ground.


30.          Pyroclastic Material (p. 262) – The volcanic rock ejected during an eruption, including ash, bombs, and blocks.


31.          Scoria Cone (p. 259) – See cinder cone


32.          Shield Volcano (p. 257) – A broad, gently sloping volcano built from fluid basaltic lavas.


33.          Sill (p. 269) – A tabular igneous body that was intruded parallel to the layering of preexisting rock.


34.          Strato volcanoes (p. 260) – See composite cone.


35.          Vent (p. 256) – surface opening


36.          Viscosity (p. 253) – A measure of a fluid’s resistance to flow.


37.          Volatiles (p. 253) – Gaseous components of magma dissolved in the melt. Volatiles will readily vaporize (form a gas) at surface pressures.


38.          Volcanic Island arc (p. 278) – A chain of volcanic islands generally located a few hundred kilometers from a trench where active subduction of one oceanic slab beneath another is occurring.


39.          Volcanic Neck (p. 267) – An isolated, steep-sided, erosional remnant consisting of lava that once occupied the vent of a volcano.


40.          Volcano (p. 256) – A mountain formed of lava and/or pyroclastics.