Rock, Minerals, And Fossils

Front 1

Anion

Back 1

A negatively charged ion.

Front 2

Aphanitic

Back 2

An igneous rock texture that refers to the grains not visible to the naked eye, and therefore indicative of fast cooling.

Front 3

Aureole

Back 3

The zone of metamorphosed rock surrounding an igneous intrusion and showing the effects of contact metamorphism.

Front 4

Bar

Back 4

A unit of pressure equal to 106 dunes/cm2, approximately 1 atmosphere.

Front 5

Bowen's Reaction Series

Back 5

The sequence of minerals that form in the process of fractional crystallization of a magma.

Front 6

Burial Metamorphism

Back 6

A type of low-grade regional metamorphism affecting sediments in intetlayered volcanic rocks that has lower temperatures (200°C to 450°C), without any influence of orogenesis or magmatic intrusion.

Front 7

Cation

Back 7

A positively charged ion.

Front 8

Color Index

Back 8

A number that represents the percent by weight or volume of dark-colored minerals in a rock.

Front 9

Contact Metamorphism

Back 9

Metamorphism is associated with the intrusion of an igneous mass. Metamorphic changes are caused principally by heat, but also by magma composition and deformation related to the intrusion. Pressures are relatively low (<3000 bars) while temperatures range from 200°C to 1000°C.

Front 10

Diagenesis

Back 10

The physical and chemical changes undergone by sediments when compacted and lithified.

Front 11

Eugeosyncline

Back 11

The oceanic part of a geosyncline characterized by volcanism associated with clastic sedimentation.

Front 12

Extrusive Rocks

Back 12

Igneous rocks that have been erupted on the surface of the Earth.

Front 13

Facies

Back 13

A mappable, areally restricted part of a rock body that has different fossils or lithology from other contiguous beds deposited at the same time.

Front 14

Feldspars

Back 14

The most widespread mineral group in the Earth's crust.

Front 15

Felsic

Back 15

A descriptive term for an igneous rock that has abundant light colored minerals.

Front 16

Fossil Assemblages

Back 16

A group of fossils that occur at the same stratigraphic level.

Front 17

Geosyncline

Back 17

A major downwarp in the Earth's crust in which sediments accumulate.

Front 18

Index Fossil

Back 18

A fossil that identifies and dates the strata in which it is found. It combines a wide geographic range with an narrow stratigraphic occurrence.

Front 19

Intrusive Rocks

Back 19

Igneous rocks that have been formed within the Earth by emplacement of magma into pre-existing rock.

Front 20

Mafic

Back 20

A descriptive term for a igneous rock that has abundant dark colored minerals.

Front 21

Metamorphic Facies

Back 21

A set of metamorphic mineral assemblages that have reached chemical equilibrium during metamorphism within a restricted range of temperature and pressure conditions. The concept was introduced by Eskola.

Front 22

Metamorphic Grade

Back 22

The intensity or rank of metamorphism, measured by the amount or degree of difference between the original rock and the metamorphic rock. In general, the grade indicates the pressure-temperature environment or facies during metamorphism.

Front 23

Metasomatism

Back 23

The process of mineral replacement whereby a new mineral of a different chemical composition grows in an old mineral. Interstitial liquids or gases must be present for solution in deposition to occur.

Front 24

Mineral

Back 24

A naturally occurring inorganic substance, usually having an internal crystal structure.

Front 25

Mineral Assemblages

Back 25

The minerals that compose a rock, including the different kinds and their relative abundance.

Front 26

Pelitic

Back 26

Referring to a rock that is composed of clay or clay sized particles, or derived from metamorphism of fine-grained sediment.

Front 27

Phaneritic

Back 27

An igneous texture that refers to grain sizes that are large enough to be seen with the naked eye, and indicating a slower rate of cooling.

Front 28

Plutonic Rocks

Back 28

Igneous rocks that are generally coarsely crystalline (phaneritic) and are formed from a large intrusion at depth.

Front 29

Polymorphism

Back 29

The characteristic of a mineral to exist in more than one form.

Front 30

Provenance

Back 30

The place of origin from which the contituent materials of a sedimentary rock or facies are derived.

Front 31

Regional Metamorphism

Back 31

Metamorphism acting over large areas resulting from applied pressures of 3000 to 10,000 bars in temperatures of 400°C to 800°C. Regional metamorphism is also referred to as dynamothermal metamorphism.

Front 32

Regression

Back 32

The withdrawal of the sea from land.

Front 33

Rock Stratigraphic Unit

Back 33

A rock unit that is characterized by a particular lithology and stratigraphic position. A synonym is Lithostratigraphic Unit.

Front 34

Sessile

Back 34

A plant or animal that is attached and cannot move.

Front 35

Silicates

Back 35

Compounds whose crystal structure contains SiO4 tetrahedra, either isolated or joined to form groups, rings, single or double chains, sheets or three-dimensional frameworks.

Front 36

Solid-Solution Series

Back 36

A series of minerals of identical structures that contain a mixture of two or more elements over a range of proportions.

Front 37

Test

Back 37

The external hard part of an invertebrate.

Front 38

Time Stratigraphic Unit

Back 38

A rock unit that is characterized by formation during a specific period of time and serves as a reference for all rocks formed during the same time period. A synonym is Chronostratigraphic Unit.

Front 39

Transgression

Back 39

The advance of the sea onto land.

Front 40

Twinning

Back 40

The innergrowth of two or more crystals in a symmetrical way.

Front 41

Type Locality

Back 41

The place where a geologic feature (such as a fossil species) was first recognized and described. It contains the type section.

Front 42

Type Section

Back 42

The originally described strata that constitutes a stratigraphic unit to which other parts of the unit may be compared. i

It is preferable to describe the location where the unit attains its maximum thickness and where the top and bottom unit are exposed.

Front 43

Ultramafic

Back 43

An igneous rock comprised of 90% or more of mafic materials.

Front 44

Volcanic Rocks

Back 44

Igneous rocks that are generally finely crystalline or glassy (aphanitic), resulting from volcanic action at or near the Earth's surface (and including near-surface intrusions), either rejected explosively or extruded as lava.

Front 45

Zeolites

Back 45

A large group of hydroaluminosilicate minerals that are analogous in comparison to the feldspars. Chief metals are Na, Ca, and K. They occur and basalt cavities, saline lake in deep sea sediments, and volcanic tuff. They are used as water softener or desiccants.

Front 46

Zoning

Back 46

A variation of composition of a crystal, characteristic of feldspars. The interior or center is formed by a high temperature phase, while the exterior or margin is formed by a low temperature phase.