A wedge-shaped mass of sediment and rock scraped off the top of a downgoing plate and accreted onto the overriding plate at a convergent plate margin

plate boundaries; A continental margin that is colliding with another plate and as a result is geologically active

200 million years; has been determined by radiometric dating.

a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain SiO. 4. tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is Amp.

A path on the globe along which a magnetic pole appears to have wandered over time; in fact, the continents drift, while the magnetic pole stays fairly fixed.

The process of magma contamination in which blocks of wall rock fall into a magma chamber and dissolve.

The layer of the mantle that lies between 100-150 km and 350 km deep; the asthenosphere is relatively soft and can flow when acted on by force.

A layer of gases that surrounds a planet

A dark, dense, fine-grained, mafic, igneous rock with a fine texture, found in oceanic crust

A vast composite, intrusive, igneous rock body up to several hundred km long and 100 km wide, formed by the intrusion of numerous plutons in the same region.

all matter and energy--everything that now constitutes the Universe--was initially packed into an infinitesimally small point. The point "exploded" and the Universe began, according to current estimates, 13.7(+/- 1%) billion years ago.

The sequence in which different silicate minerals crystallize during the progressive cooling of a melt.

a salt of carbonic acid, characterized by the presence of the carbonate ion, a polyatomic ion with the formula CO²⁻ ₃.

(1) The tendency of a mineral to break along preferred planes; (2) a type of foliation in low-grade metamorphic rock.

The process of two buoyant pieces of lithosphere converging and squashing together.

The characteristic of a material due to the spectrum of light emitted or reflected by the material, as perceived by eyes or instruments.

Line of volcanoes on a continental plate; the volcanoes are on a continent above a subducting oceanic plate.

The meeting of two tectonic plates of continental lithosphere at a convergent plate boundary, wherein the continental crust on both sides resists subduction and instead crushes together, bending, buckling, and deforming layers of rock and forcing portions of the buckled crust upward, often creating mountain ranges.

The idea that continents have moved and are still moving slowly across the Earth's surface.

A linear belt along which continental lithosphere stretches and pulls apart.

A boundary at which two plates move toward each other so that one plate sinks (subducts) beneath the other; only oceanic lithosphere can subduct.

The rock that makes up the outermost layer of the Earth.

The flat surfaces of a crystal, formed during the crystal's growth.

Attainment of supersaturation or supercooling; Formation of critical sized nuclei, i.e., nucleation; and. Growth of the nuclei into crystal.

The arrangement of atoms in a crystal.

A single, continuous piece of a mineral bounded by flat surfaces that formed naturally as the mineral grew.

A rock that consists of minerals that grew when a melt solidified, and eventually interlock like pieces of a jigsaw puzzle.

A solid that is made up of crystals in which particles are arranged in a regular, repeating pattern

The kind of melting that occurs when hot mantle rock rises to shallower depths in the Earth so that pressure decreases while the temperature remains unchanged.

a process early in a planet's history during which dense iron alloy melted and sank downward to form the core, leaving less-dense mantle behind

A tabular (wall-shaped) intrusion of rock that cuts across the layering of country rock.

a magnetic field with a north and south pole, like that of a bar magnet.

A boundary at which two lithosphere plates move apart from each other; they are marked by mid-ocean ridges.

a group of silicate structures, in which the SiO4 tetrahedral may link into linear single or double chains (Si4O11)−6 of indefinite lengths by the sharing of oxygen of indefinite length, the ends, of which are at the surface of the crystal. Double chain or band such as amphiboles.

a vibration caused by the sudden breaking or frictional sliding of rock in the Earth.

The theory that the whole Universe must be expanding because galaxies in every direction seem to be moving away from us.

Rock that forms by the freezing of lava above ground, after it flows or explodes out (extrudes) onto the surface and comes into contact with the atmosphere or ocean.

The ground and polished surface of a gem, produced by a gem cutter using a grinding lap.

a group of rock-forming aluminium tectosilicate minerals, containing also other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the plagioclase feldspars and the alkali feldspars.

silica content more than 65%; 650 - 800 degrees Celsius; high viscosity

The process by which a magma becomes progressively more silicic as it cools, because early-formed crystals settle out.

The way a mineral looks when it breaks apart in an irregular way

A rock consisting of igneous chunks and/or shards that are packed together, welded together, or cemented together after having solidified.

consist of a three-dimensional polymerized network of Si or (Si,Al) tetrahedra.

A mafic, coarse-grained, intrusive, igneous rock composed predominantly of ferromagnesian minerals and with lesser amounts of calcium-rich plagioclase feldspar.

An immense system of hundreds of billions of stars.

The rate of change in temperature with depth.

A solid in which atoms are not arranged in an orderly pattern.

Igneous rock consisting entirely of glass, or of tiny crystals surrounded by a glass matrix.

A coarse-grained, intrusive, silicic igneous rock; A usually light colored igneous rock that is found in continental crust

A measure of the relative ability of a mineral to resist scratching, it represents the resistance of bonds in the crystal structure from being broken.

Melting that results from the transfer of heat from a hotter magma to a cooler rock.

A location at the base of the lithosphere, at the top of a mantle plume, where temperatures can cause melting.

A chain, of now-dead volcanoes transported off the hot spot by the movement of a lithosphere plate.

slow cooling allows large crystals to form, fast cooling yields small crystals.

Rock that forms when hot molten rock (magma or lava) cools and freezes solid.

Rock formed by the freezing of magma underground.

A string of islands formed by the volcanoes along a deep ocean trench

Olivine can be pure Mg2SiO4 or Fe2SiO4, or a combination of the two, written as (Mg,Fe)2SiO4.

Molten rock that has flowed out onto the Earth's surface.

The lowest temperature at which all the components of a material have melted and transformed into liquid.

The relatively rigid, nonflowable, outer 100- to 150-km-thick layer of the Earth, constituting the crust and the top part of the mantle.

The way a mineral surface scatters light.

silica content between 45-55%; temperature 1000-1200 degrees Celsius; low viscosity.

The history of magnetic reversals through geologic time.

A space below ground filled with magma.

The process whereby magmas of different composition mix together to yield a modified version of the parent magmas.

The composition of a melt reflects the composition of the solid from which it was derived. Not all magmas form from the same source rock, so not all magmas have the same composition.

Molten rock beneath the Earth's surface.

The difference between the expected strength of the Earth's magnetic field at a certain location and the actual measured strength of the field at that location.

The angle between the direction a compass needle points at a given location and the direction of true north.

the region affected by the force emanating from a magnet

The angle between a magnetic needle free to pivot on a horizontal axis and the horizontal plane parallel to the Earth's surface.

The change of the Earth's magnetic polarity; when a reversal occurs, the field flips from normal to reversed polarity, or vice versa

A process by which heat from Earth's inner and outer cores is transferred through the mantle

A column of very hot rock rising up through the mantle.

The difference between the expected strength of the Earth's main dipole field at a certain location on the sea floor and the actual measured strength of the magnetic field at that location.

1) decompression melting caused by lowering the pressure, 2) flux melting caused by adding volatiles (see more below), and 3) heat-induced melting caused by increasing the temperature.

a three-dimensional process that involves the migration of melt through large regions of the mantle, across ridge offsets, to the ridge axis vs. the principal controlling factor of lithology, chemistry, and preservation of sediment accumulations in their depocenters, the sedimentary basins.

molten, liquid rock

made of metal; polished

A piece of rock or metal alloy that fell from space and landed on Earth

a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates.

A 2-km-high submarine mountain belt that forms along a divergent ocean plate boundary.

Groups of minerals distinguished from each other on the basis of chemical composition.

a homogenous, naturally occurring, solid inorganic substance with a definable chemical composition and an internal structure characterized by an orderly arrangement of atoms, ions, or molecules in a lattice. Most minerals are inorganic.

The seismic-velocity discontinuity that defines the boundary between the Earth's crust and mantle. Named for Andrija Mohorovicic.

A list of ten minerals in a sequence of relative hardness, with which other minerals can be compared.

A sizable solid body locked in orbit around a planet

A cloud of gas or dust in space

Dull or transparent

The process by which the nuclei of atoms fuse together, thereby creating new, larger atoms.

An igneous rock consisting of a solid mass of volcanic glass.

The plate at a subduction zone that overrides the downgoing plate.

The record of ancient magnetism preserved in rock.

The supposed position of the Earth's magnetic pole in the past, with respect to a particular continent.

The melting in a rock of the minerals with the lowest melting temperatures, while other minerals remain solid.

A continental margin that is not a plate boundary.

An object that orbits a star, is roughly spherical, and has cleared its neighborhood of other objects.

Tiny, solid pieces of rock and metal that collect in a planetary nebula eventually accumulate to form a planet.

The border between two adjacent lithosphere plates.

The theory that the outer layer of the Earth (the lithosphere) consists of separate plates that move with respect to one another.

One of about 20 distinct pieces of the relatively rigid lithosphere.

An irregular or blob-shaped intrusion; can range in size from tens of meters across to tens of km across.

the phenomenon of the progressive changing through time of the position of the Earth's magnetic poles relative to a location on a continent; significant polar wander probably doesn't occur--in fact, poles seem to remain fairly fixed, while continents move.

a mineral that crystallizes in different forms because of differences in temperature or other conditions

A textural term for igneous rock that has phenocrysts distributed throughout a finer matrix.

A glassy igneous rock that forms from felsic frothy lava and contains abundant (over 50%) pore space.

Fragmented material that sprayed out of a volcano and landed on the ground or sea floor in solid form.

Rock made from fragments that were blown out of a volcano during an explosion and were then packed or welded together.

a group of dark-colored rock-forming minerals found in igneous and metamorphic rocks throughout the world.

a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar.

The movement of one lithosphere plate with respect to another.

A light-brown to gray, fine-grained extrusive igneous rock with a felsic composition. The extrusive equivalent of granite.

a split, break, breach

The gradual widening of an ocean basin as new oceanic crust forms at a mid-ocean ridge axis and then moves away from the axis.

An isolated submarine mountain.

Phyllosilicates; an important group of minerals that includes the micas, chlorite, serpentine, talc, and the clay minerals.

Minerals built from silicon-oxygen tetrahedra arranged in chains, sheets, or 3-D networks; they make up most of the Earth's crust and mantle.

Each tetrahedron is bonded to four other tetrahedra (with an oxygen shared at every corner of each tetrahedron), and as a result, the ratio of silicon to oxygen is 1:2. Since the one silicon cation has a +4 charge and the two oxygen anions each have a -2 charge, the charge is balanced.

a salt in which the anion contains both silicon and oxygen, especially one of the anion SiO42−.

The SiO44- anionic group, in which four oxygen atoms surround a single silicon atom, thereby defining the corners of a tetrahedron.

A nearly horizontal tabletop-shaped tabular intrusion that occurs between the layers of country rock.

constructed from a single chain of silica tetrahedra, where two corners of each tetrahedron are linked to neighbors in an infinite chain.

The force that downgoing plates (or slabs) apple to oceanic lithosphere at a convergent margin.

Our sun and all the materials that orbit it (including planets, moons, asteroids, Kuiper Belt objects, and Oort Cloud objects).

The highest temperature at which all the components of a material are solid; at the solidus temperature, the material begins to melt.

A number representing the density of a mineral, as specified by the ratio between the weight of a volume of the mineral and the weight of an equal volume of water.

An object in the Universe in which fusion reactions occur pervasively, producing vast amounts of energy; our Sun is a star.

The production of new, larger atoms by fusion reactions in stars; the process generates more massive elements that were not produced by the Big Bang.

The color of the powder produced by pulverizing a mineral on an unglazed ceramic plate.

in a convergent boundary, this is the land that bends to go under an overriding plate; always oceanic lithosphere.

The process by which one oceanic plate bends and sinks down into the asthenosphere beneath another plate.

an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions

A short-lived, very bright object in space that results from the cataclysmic explosion marking the death of a very large star; the explosion ejects large quantities of matter into space to form new nebulae.

a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle

A measure of the hotness or coldness of a material.

Planets that are of comparable size and character to the Earth and consist of metallic core surrounded by a rock mantle.

A boundary at which one lithosphere plate slips laterally past another.

A deep, elongate trough bordering a volcanic arc; a trench defines the trace of a convergent plate boundary.

A pyroclastic igneous rock composed of volcanic ash and fragmented pumice, formed when accumulations of the debris cement together.

All of space and all the matter and energy within it.

Open holes in igneous rock formed by the preservation of bubbles in magma as the magma cools into solid rock.

The resistance of material to flow; Increase in temperature decreases viscosity, Increases in pressure increase viscosity in liquids. In water, it decreases whereas, in gases, it remains the same.

Forms at locations where volatiles mix with hot mantle rock.

Elements or compounds such as H2O and CO2 that evaporate at relatively low temperatures and can exist in gaseous forms at the Earth's surface.

A curving chain of active volcanoes formed adjacent to a convergent plate boundary.

Tiny glass shards formed when a fine spray of exploded lava freezes instantly upon contact with the atmosphere.

(1) A vent from which melt from inside the Earth spews out onto the planet's surface; (2) a mountain formed by the accumulation of extrusive volcanic rock.

A sloping band of seismicity defined by intermediate- and deep-focus earthquakes that occur in the downgoing slab of a convergent plate boundary.

the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions.

A relict of wall rock surrounded by intrusive rock when the intrusive rock freezes.