Geology 120 Vocab List 1

Front 1

Define Plate Tectonic

Back 1

the theory that earth's surface is comprised of large and small plates which move and interact independently and randomly. They produce a variety of geologic features through interactions at their edges.

Front 2

Define Core

Back 2

The innermost portion of earth's concentric structure. Hot, dense, rocky and thick. Comprised of a molten outer adn solid inner core.

Front 3

Mantle

Back 3

Thick, hot, dense and rocky portion of earth's structure. between the core and lithosphere. Comprised of mafic rocks. Heating of the lithosphere through the mantle is thought to drive plate tectonics.

Front 4

Asthenosphere

Back 4

outermost portion of the mantle (apr 200km) mafic, hot dense. Has little structural rigidity i.e. non-brittle.

Front 5

Lithosphere:

Back 5

outtermost portion of the earth's structure. comprised of Felsic minerals. Contains the crustal plates due to its brittle nature.

Front 6

Define:Crust

Back 6

brittle, thin, outermost portion of structure. Felsic minerals. two types: continental (thick granitic) and oceanic (thin, balsitic).

Front 7

Define: Trench

Back 7

The deepest parts of ocean basins. Usually adjacent to continents but can be found in oceanic settings.

Front 8

Subduction Zone

Back 8

Convergent plate boundary in which the denser, heavier plate is pushed underneath the more buoyant one resulting in earthquates, volcanism, and trenches.

Front 9

Oceanic Ridge

Back 9

Divergent plate boundary characterized by submarine mountain chains with earthquakes and volcanism, Region of spreading adn generation os new basaltic oceanic crust.

Front 10

Transform Fault

Back 10

transform plate boundary. Fault common on oceanic ridges due to different rates of crustal spreading.

Front 11

Divergent plate Boundary

Back 11

plate boundary in which the lithospheric plates are moving away from eachother. generates basaltic volcanism, and many small earthquakes.

Front 12

Convergent plate Boundary

Back 12

plate boundary in which the lithosphereic plates move towards eachother resulting in collision or subduction. associeated with large earthquakes and deep foci. Andesitic volcanism.

Front 13

Transform Plate Boundary:

Back 13

plates move side by side, horizontally past eachother. No volcanic activity, but generates huge earthquakes.

Front 14

Volcanic arc

Back 14

chain of volcanos associated with a subduction zone.

Front 15

Andesite

Back 15

type of volcanic rock generated by partial melting of basaltic crust and its associated sediment.

Front 16

Andesitic Volcanism

Back 16

volcanic activity usually associated with subduction zones. andesitic volcanic rock produced by the partial melting of the basaltic crust.

Front 17

Partial Melting:

Back 17

process by which only some portions of basaltic crust are melted, generated a magma of more felsic compositions.

Front 18

Strato Volcano(composite Cone):

Back 18

conical, steep-sided, symmetrical volcano comprised of alternating layers of silicic lavas and pyroclastics. Typical of subduction zone volcanism. The ratio of height to width is relatively large.

Front 19

Lahar

Back 19

A pyroclastic deposit consisting of large and samll angulare fragmnets of volcanic rock in a matrix of muddy material. Generated by the liquefaction of debris on the sides of volcanoes. Also called volcaniclastic mudflows.

Front 20

Pyroclastic

Back 20

igneous rock formed form variable sized fragments of other igneous rocks.

Front 21

Silica:

Back 21

SiO4 molecules in lava. the silica content ranges widely, but is highest in felsic and intermediate volcanic rocks. Lowest in mafic volcanic rocks. Silica content controls gas escape and relative explosiveness of eruption; higher silica -more explosive.