Earth's Internal Processes
Terms in this set (46)
A term, no longer used by geologists, that refers to the fact that continents are not stationary, but move across the Earth's surface. Continental drift is one feature of the modern theory of plate tectonics.
an instrument for measuring the intensity of a magnetic field, especially the earth's magnetic field
A change in the Earth's magnetic field resulting in the magnetic north being aligned with the geographic south, and the magnetic south being aligned with the geographic north
In the theory of plate tectonics, the process by which new oceanic crust is formed by the convective upwelling of magma at mid-ocean ridges, resulting in the continuous lateral displacement of existing oceanic crust
A tectonic boundary where two plates are moving away from each other and new crust is forming from magma that rises to the Earth's surface between the two plates
an actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide.
where the two plates slide against each other in a sideways motion
occurs when an oceanic plate subducts into the underlying mantle.any mass of igneous rock that has solidified below the surface of the earth
a discordant igneous intrusion having a surface exposure of less than 40 sq mi (100 km2)
a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock.
an opening at the earth's surface from which volcanic material, as lava, steam, or gas, is emitted.
forms when the top of a volcanic cone collapses into the space left after magma is ejected during a violent volcanic eruption. Its diameter is many times that of the original vent
A steep, conical hill consisting of glassy volcanicfragments that accumulate around and downwind from a volcanic vent.Cinder cones range in size from tens to hundreds of meters tall
A former "supercontinent" on the Earth. In the distant past a large landmass
revolutionized the field of geology by providing evidence for the existence and movement of tectonic plates
a line on an isotope ratio diagram denoting a suite of rock or mineral samples all formed at the same time.
Theory of Plate Tectonics
he theory that the earth's lithosphere is divided into large rigid blocks (plates) that are floating on semifluid rock and are thus able to interact with each other at their boundaries
A long, narrow valley lying between two normal geologic faults
the process of one tectonic plate sliding under another, resulting in tensions and faulting in the earth's crust, with earthquakes and volcanic eruptions
The hypothetical force, caused by the horizontal spreading of the near-surface asthenosphere at constructive margins, which is thought to be one of the two main driving forces for the movement of lithospheric plates (the other is slab-pull)
describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction
a large body of intrusive igneous rock believed to have crystallized at a considerable depth below the earth's surface; pluton
a dome-shaped body of igneous rock between two layers of older sedimentary rock: formed by the intrusion of magma, forcing the overlying strata into the shape of a dome
A body of igneous rock that cuts across the structure of adjoining rock, usually as a result of the intrusion of magma
the cup-shaped depression or cavity on the surface of the earth or other heavenly body marking the orifice of a volcano
a type of volcano usually built almost entirely of fluid magma flows. They are named for their large size and low profile, resembling a warrior's shield lying on the ground. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from stratovolcanoes.
a large, steep volcano built up of alternating layers of lava and ash or cinders
Solid matter, such as ash, dust, and cinders, that is ejected into the air by an erupting volcano
volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. They may be on, near to, or far from tectonic plate boundaries
how the object responds to stress
alternatingly compressional and extensional, and cause the rocks they pass through to change in volume. These waves are the fastest traveling seismic waves and can travel through solids, liquids, and gases. Also called P wave
A seismic wave that travels across the surface of the Earth as opposed to through it. Surface waves usually have larger amplitudes and longer wavelengths than body waves, and they travel more slowly than body waves do
The point on the Earth's surface that is directly above the focus (the point of origin) of an earthquake. The epicenter is usually the location where the greatest damage associated with an earthquake occurs.
a graph output by a seismograph. It is a record of the ground motion at a measuring station as a function of time. Seismograms typically record motions in three cartesian axes (x, y, and z), with the z axis perpendicular to the Earth's surface and the x- and y- axes parallel to the surface
developed in the 1930s, is a base-10 logarithmic scale, which defines magnitude as the logarithm of the ratio of the amplitude of the seismic waves to an arbitrary, minor amplitude.
Modified Mercalli Scale
Intensity Scale. The effect of an earthquake on the Earth's surface is called the intensity
the part of an active fault that has experienced little or no seismic activity for a long period, indicating the buildup of stresses that are useful in predicting earthquakes.
a fast-moving current of hot gas and rock (collectively known as tephra), which reaches speeds moving away from a volcano of up to 700 km/h (450 mph). The gas can reach temperatures of about 1,000 °C (1,830 °F).
the force applied to an object. In geology,stress is the force per unit area that is placed on a rock. ... Compression is the most common stress at convergent plate boundaries.
a crack in the Earth's crust. Typically, faults are associated with, or form, the boundaries between Earth's tectonic plates. In an active fault, the pieces of the Earth's crust along a fault move over time. The moving rocks can cause earthquakes
A type of seismic body wave in which rock particles vibrate at right angles to the direction of wave travel. ... Also called shear wave, S wave
also called the hypocenter of an earthquake. The vibrating waves travel away from the focus of the earthquake in all directions. The waves can be so powerful they will reach all parts of the Earth and cause it to vibrate like a turning fork.
equipped for measuring the direction, intensity, and duration of earthquakes by measuring the actual movement of the ground
a number that characterizes the relative size of an earthquake. Magnitude is based on measurement of the maximum motion recorded by a seismograph.
Moment magnitude scale
used by seismologists to measure the size of earthquakes in terms of the energy released.
A large wave on the ocean, usually caused by an undersea earthquake, a volcanic eruption, or coastal landslide. A tsunami can travel hundreds of miles over the open sea and cause extensive damage when it encounters land. Also called tidal waves