Physical Science

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Phyisical Science Test 4
Chapters 26-34

Terms

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Milky Way: The galaxy of over a hundred billion solar masses to which our sun belongs. As we observe it in the night sky, we see the faint band of light that marks the disk of our Galaxy.
Cosmological Constant: A constant introduced into the equations of general relativity by Albert Einstein in an attempt to cancel the predictions of the expanding nature of our Universe.
Peridotite: A rock made up mostly silicon, oxygen, iron, and magnesium that is denser than the basalt and granite that make up Earth's crust.
Volcanic Rocks: Igneous rocks that cool and solidify at Earth's surface.
Mantle Plume: A buoyant mass of hot rock rising through Earth's mantle. As it nears the surface of Earth, some of the plume melts and erupts at the surface forming a "hot spot."
Protostar: An object that will become a star in the early stages of formation before it begins to produce energy from fusion.
Subduction: What geologists call the process that occurs at the trenches where old oceanic lithosphere is sinking back into the mantle.The trench area is also called a "subduction zone," and as the plates sink they are said to be subducting.
Seafloor Spreading: The theory that the ocean floor grows on either side as the mid-ocean ridge moves apart. The rift created in this process is filled in with basalt as magma squeezes up into fractures created by rifting.
Feldspar: The name of a family of silicate minerals that are the most abundant minerals in Earth's crust.
Inner Core: The lower part of the core that is made of solid iron.
Mesosphere: The mechanical layer between the asthenosphere and the outer core. It is solid, but still plastic and able to flow.
Relative Time: The determination of the sequence in which events occurred, relative to each other.
Seamounts: An underwater mountain rising from the ocean floor and having a peaked or flat-topped summit below the surface of the sea.
S-Waves: Shear waves produced by an earthquake. They are slower than P-waves and so arrive later at seismic wave detectors.
Zone of Accumulation: The part of a glacial system where snow and ice are accumulating faster than they are melting away.
Supercluster: Clusters of clusters of galaxies. It appears uncommon for these groups of clusters to be held together by gravity.
Floodplain: A relatively flat region around a river where rich sediment has been deposited by the river's floods.
Hot Spots: Volcanoes that result from the lithosphere moving over a mantle plume. Hawaii is an example of an island-formed hot spot. As the plate moves over the mantle, a line of volcanic structures (such as the Hawaiian chain of islands) marks the passage. The trail of volcanism is called a hot-spot trail.
Hubble Constant: The constant of proportionality, H, in the Hubble Law. It gives the rate at which our Universe is expanding.
Curie Temperature: The temperature at which a material loses its magnetism.
Guyots: Flat-topped seamounts (underwater mountains usually of volcanic origin) that are the submerged equivalent of modern atolls.
Nuclear Fusion: The process by which elements heavier than hydrogen are formed by adding protons and neutrons to existing atomic nuclei.
Trilobites: A common animal that lived in Earth's oceans during the Paleozoic Era. They are most closely related to the modern Horseshoe Crab.
Guyots: Flat-topped seamounts that once were above the surface of the ocean, but have now subsided below it
Plutonian Objects: The category of celestial bodies defined as 'dwarf planets," Plutonian objects are those that a). orbit the sun b). have sufficient mass for their self-gravity to overcome rigid body forces in order to assume a nearly round shape, c). have not cleared the neighborhood around their orbital paths, and (d. are not satellites. Pluto is the prototype of this new category of trans-Neptunian objects.
Mineral: A naturally occurring, inorganic solid that has a specific chemical formula.
Distance Ladder: A method used in astronomy where greater and greater distances are determined using many different measuring techniques that overlap to establish a sequence of increasing distances.
Light Year: The distance light travels in a year, approximately ten trillion kilometers.
Permeability: A measure of the connectedness of the porosity in a rock.
Water Table: An underground surface that marks the level at which the rocks become saturated with water.
Brown Dwarf: An object that is like a star except that it is too small to sustain fusion reactions in its core.
Outer Core: The upper part of the core that is made of liquid iron.
Tectonic Plates: The brittle, rigid but thin outer part of Earth is divided into sections called tectonic plates.
Calcite: A mineral that is usually the main component of limestone. Calcite has the chemical formula CaCO3.
Radar Ranging: A technique for measuring distance where pulses of microwaves (radar) traveling at the speed of light are sent to a nearby object and the reflected pulse is timed in order to determine the distance.
Red Giant: A large, bright, cool star that has exhausted most of the hydrogen fuel in its core.
Neutron Star: The remnant of a supernova explosion that is composed almost totally of neutrons. It is so dense that the entire mass of our Sun could be contained in a sphere only a few tens of kilometers in diameter.
Cosmological Principle: The concept that the large-scale structures of our Universe are the same no matter what direction you observe or where you are located.
Eras: The largest subdivision of geologic time.
Epicenter: The point on Earth's surface directly above the focus of an earthquake.
Slate: Metamorphosed shale. It still breaks into thin layers like shale, but the layers are much harder and more durable. In fact, slate is hard enough to use for roofing tile.
Cosmic Microwave Background: A uniform radiant field with an apparent temperature of 2.725 K that is observable in every direction.
Half-life: The time required for half the nuclei in a sample of a specific isotopic species to undergo radioactive decay.
Basement: What geologists call the igneous and metamorphic rock found in the continental shields and under the sedimentary rock cover in the stable platforms.
Terrestrial Worlds: The rocky planets, which include Mercury, Venus, Earth, and Mars.
Zone of Ablation: The part of a glacial system where melting of snow and ice occurs faster than accumulation.
Sandstone: A sedimentary rock made up mostly of grains of sand.
Desertification: The process of converting marginal dry lands into desert by overgrazing, farming, or other processes.
Quartz: A common mineral that has a chemical formula of SiO2.
Triangulation: A distance measuring technique that involves observing the angle to a distant object from at least two different locations with a known separation. It is then possible to determine the unknown distance by comparing the observed angles.
Asthenosphere: A soft, plastic, partially-molten mechanical layer in Earth located below the lithosphere.
Volcanic Island Arc: Arc-shaped chains of volcanoes that are always found associated with an ocean trench.
Spiral Galaxy: A galaxy flattened into a disk shape with a pattern of spiral arms wound about a central nucleus. Spiral galaxies usually include dust, gas, and active regions of star formation.
Planetary Nebula: A glowing shell of gas that has been blown off an old star.
Mesosaurus: A fresh-water dwelling reptile that lived from the late Pennsylvanian Period to the early Permian Period. It had an elongated head and snout with nostrils near its eyes and a flattened tail used for swimming. Typically it would have been about 1.5 feet long.
Black Hole: Any object where gravity is so strong that not even light can escape from its surface.
Geologic Column: A chart that shows the subdivisions of geologic time.
Core: The deepest or central compositional layer of Earth. It is composed mostly of iron.
Proton-proton Cycle: A process by which the protons in hydrogen nuclei combine in stars like our Sun to form the element helium.
Inclusion: Rock, fragment of rock, or fossil enclosed within another rock.
Anorthosite: A rock found in the area of the lunar highlands that is thought to be an ancient remnant of the original surface of our Moon.
Magnetite: An iron oxide mineral found in basalt. The magnetic field of the magnetite always aligns with Earth's magnetic field as molten basalt cools to solid form and makes a permanent record of the direction of Earth's magnetic field when the rock formed.
Rift Valley: A valley bounded by faults or breaks in the crust of the Earth. These valleys are formed as the plates of the Earth pull apart.
Focus: The place inside Earth where an earthquake originates.
Silicates: Minerals that contain silicon and oxygen bonded together.
Magnitude Scale: A measure of the size of an earthquake. The first widely used magnitude scale was developed by Richter and was called the "Richter Scale." Today the most widely used scale is called the "moment magnitude scale." All of these scales have one thing in common: they are non-linear logarithmic scales. As you increase the magnitude from, for example, a 7.0 to an 8.0, the amount of energy released goes up by 30 times.
Period-brightness Relation: A simple physical relationship that has been found for certain types of pulsating variable stars (including Cepheids) that indicates that the actual brightness of a pulsating star can be determined from a measurement of its pulsation period.
Abyssal Plains: Broad, flat areas on the ocean floor.
Slab Pull: Helps move the tectonic plates. As an oceanic plate becomes old, cold, and dense, it sinks back into the mantle, pulling the rest of the plate along with it.
Tsunami: A water wave produced by an earthquake. They can be extremely dangerous for people living near the coast.
Transform Fault: The break in Earth's lithosphere that connects segments of ridges or trenches together. These are the plate boundaries where the plates are sliding past each other.
Levees: Broad embankments built up along the banks of a river channel. These may be naturally created by floods or they can be artificially constructed to keep a river in its banks.
Iron Meteorites: Meteorites thought to represent the type of material found in Earth's core.
Seismograph or Seismometer: A seismic wave detector.
Paleoclimatology: The study of ancient climates.
Continental Shelf: Part of the continent that is under a shallow cover of water.
Quartzite: A metamorphic rock composed of sand grains that have been welded tightly together, unlike sandstone where the sand grains rub off in your hand.
Jovian Worlds: The giant gas planets, which include Jupiter, Saturn, Uranus, and Neptune.
Barred Spiral Galaxy: A galaxy that is similar to a spiral galaxy, except that the spiral arm pattern originates from a bar of material that passes through the nucleus of the galaxy.
Mantle Resistance, Plate Collision, & Transform Fault Friction: Forces that resist plate motion.
Abyssal Hills: Mounds of basalt on the deep ocean floor.
Mantle: The middle compositional layer of Earth. It is a thick layer made up of peridotie in the upper part and higher density rocks of peridotite composition in the lower part.
Shale: A sedimentary rock made up of fine particles of clay and mud.
Absolute Time: A numeric or quantitative measure of time.
Parent & Daughter Isotopes: The result of radioactive decay, in which one element decays to form another element. The element we start with is called the parent and the new element formed in the decay process is called the daughter.
Elastic Rebound: The point at which stress in Earth's lithosphere is strained to a point where it can bend no further and the lithosphere ruptures and rebounds somewhat like a rubber band that has just been pulled apart.
Plutonic Rocks: Igneous rocks that solidify underground.
Star Cluster: A group of stars that formed from the same cloud of material and have been held together in a cluster by gravitational forces. A small open cluster can consist of only a few dozen members while a large globular cluster can contain more than a million individual stars.
Occam's Razor: The rule that where two or more explanations exist for the same physical phenomenon, we should choose the simplest one that satisfies all of the observations.
Ice Age: A time in Earth's history when conditions are such that large continental glaciers can from and grow.
Basal Drive: May help the plates to move. As the asthenosphere flows along under a plate, it may help to pull the plate along like a conveyor belt.
Granite: An igneous plutonic rock that is made mostly of quartz along with sodium and potassium-rich feldspar.
Period: A subdivision of geologic time. Smaller than an era, but still several tens of millions of years long.
Lithosphere: The uppermost mechanical layer of Earth. It is brittle and is the only layer in which earthquakes can occur.
Structural Trends: Structural trends are the orientations of major geological features such as mountain belts, continental shields, stable platforms, and areas of folded and deformed rocks.
Lystrosaurus: A sturdily build, plant-eating reptile (not a dinosaur). Scientists disagree on wheter it spent most of its time in water browsing on plants like a modern hippo, or whether it lived mostly on land. An adult would have been about 3 feet long and weighed about 200 pounds.
Mare Basalt: A common igneous rock found in abundance on the lunar lava planes.
Cepheid Variables: A type of pulsating variable star that changes brightness in a regular and predicable manner. The changes in brightness are directly related to observed changes in the size and temperature of the variable stars.
Porosity: The amount of open space found in a rock.
White Dwarf: A small star that no longer sustains nuclear fusion and has shrunk to become a dense object about the size of Earth.
Galaxy: A large collection of stars, dust, and gas that is found in a wide variety of sizes ranging from a few million solar masses for a small galaxy to large galaxies with more than a trillion solar masses of material.
Seismic Discontinuity: A place where the velocities of seismic waves change abruptly.
Elliptical Galaxy: A galaxy with an elliptical shape and little dust or gas.
Turbidity Flow: A mass of water and sediment that flows down off of the continental shelf into the deep ocean. Because the sediment mixed with water is denser than plain water, these flows move along the bottom of the ocean.
Maria: The large, generally crater-free lava plains commonly found on the side of our Moon that faces Earth.
Seismic Waves: Waves produced by earthquakes.
Desert Pavements: A desert pavement is a surface of pebbles and cobbles created by the removal of all the finer grains by the wind.
Low-Velocity Zone: A region of the upper mantle where seismic waves travel slower than expected.
Igneous Rock: Rocks that have been formed by solidification from a molten state.
Pulsar: A variable radio source that is thought to be a rapidly rotating neutron star.
Photosphere: The visible surface of our Sun or another star. This is the region where visible energy is radiated into space.
Moho: The seismic discontinuity at the base of Earth's crust.
Continent: The granite part of Earth's crust. The continent is divided into three major structural parts: shield, stable platform, and folded mountain belts.
Hubble Law: The proportionality between the observed recessional velocity of a galaxy and the distance to that galaxy.
Interstellar Medium: Gas and dust found in the space between stars.
Emission Nebula: A gaseous cloud that is glowing from the energy radiated by nearby hot stars.
Olbers's Paradox: A fundamental question in cosmology centered around the observed fact that the sky appears dark at night.
Quasar: A luminous galaxy with a large redshift and star-like appearance when viewed through a telescope.
Metamorphic Rock: Rocks that have been subjected to intense heat and pressure that cause the minerals in them to undergo chemical reactions, forming an "new" rock.
Dwarf Elliptical Galaxy: A small elliptical galaxy with only a few million stars.
Fission-track Dating: A type of radioactive decay clock that uses the trails or tracks created by uranium fission decay to determine the age of geologic events
Glossopteris Flora: An extinct group of seed plants that arose during the Permian Period. These plants went on to become a dominant part of the flora on the southern part of the supercontinent Pangaea through the rest of the Permian Period, though they dwindled to extinction by the end of the Triassic Period.
Impact Breccias: Rocks that have been formed as other rocks have been broken apart, mixed, and then fused together during a series of meteoroid impacts. Impact breccias are rare on Earth but common on the surface of our Moon.
Stable Platform or Covered Shield: An area of the continent where the old rocks of the shield have been covered by relatively flat-lying sedimentary rocks.
Ammonite: The name given to the fossil-shell remains of animals that lived in the oceans millions of years ago, but are now extinct. They were squid-like animals whose closest modern-day relatives are the nautilus.
Continental Shields: The oldest part of the continents. They represent the roots of very ancient mountains, long since eroded away.
Magma: Hot, liquid rock. It is called lava when it erupts onto Earth's surface.
Paleontologists: Scientists who study ancient life preserved as fossils in the rocks.
Marble: Metamorphosed limestone.
Fault: A break in the earth where rocks on one side of the break have slipped past the rocks on the other side. Faults are created by earthquakes.
Giant Elliptical Galaxy: A large elliptical galaxy that may contain more than a trillion stars.
Fault: A break in Earth's lithosphere along which earthquakes have occurred.
Irregular Galaxy: A non-symmetric galaxy that does not have a well-defined shape like either the spiral or elliptical galaxies. Irregular galaxies generally include dust, gas, and active star-forming regions.
Cluster of Galaxies: A group of galaxies that is gravitationally bound together into a cluster, which very greatly in size. A small cluster may have just a few members, while a large cluster may have several thousand.
Lithosphere: The rigid outer shell of Earth, which consists of the crust and the outermost part of the mantle that is too cool to be partially molten.
Local Group: A small group of about two dozen galaxies that is associated with our Milky Way.
Sink Hole: A depression created at Earth's surface when an underground cavern collapses.
Siltstone: A sedimentary rock made up mostly of grains of salt (smaller than sand-size particles, but still gritty, not smooth like clay or mud).
Black Dwarf: A black dwarf constitutes the remains of a Sun-sized star that has evolved to a white dwarf and subsequently cooled down such that it no longer emits light.
Theory of Plate Tectonics: The model of Earth in which Earth's rigid outer layer (lithosphere) is fractured into separate pieces (plates) that move relative to one another, carried by convection currents originating in the mantle and driven by heat released by radioactivity. The plates move on a partially molten layer (asthenosphere) underneath them and may push against one another (convergent boundary), move away from one another (divergent boundary), or slide past one another (transform boundary). The model unifies the ideas of continental drift and seafloor spreading.
Event: Something that has happened during Earth's history. Some examples might be the eruption of a volcano, the building of a mountain range, the deposition of sedimentary layers in the ocean, or the metamorphosis of rocks because of changes in pressure and temperature.
Lunar Highlands: The old, heavily cratered terrain on our Moon that is thought to contain material from the original lunar surface.
Pangaea: The name Alfred Wegener gave to the supercontinent that broke up at the start of the Mesozoic Era to form the continents we have today.
P-Waves: Compressional waves produced by an earthquake. They travel the fastest in Earth and so are the first to arrive at seismic wave detectors.
Big Bang Model: A cosmological model that indicates that or Universe expanded from a specific moment of creation. It was later realized that this beginning would have to have been very hot.
Laser Ranging: A technique for measuring distance that is similar to radar ranging, but instead of reflecting microwaves, laser light is reflected off of a nearby surface and the time for the reflected pulse is observed.
Ridge Push: Helps move Earth's plates. The ridge is high and has gravitational potential energy that is converted into kinetic energy as the plate moves.
Continental Accretion: The process by which continents grow. When continents collide with island arcs or with other continents, new material may be added and the continent grows.
Supernova: A rare celestial phenomenon involving the explosion of most of the material in a star, resulting in an extremely bright short-lived object that emits vast amounts of energy.
Main Sequence: A line of stars that runs diagonally from the upper left corner to the lower right corner of the H-R diagram. Stars on the main sequence are generating energy from hydrogen fusion in their cores.
Volcanic Island Arc: A chain of volcanoes, shaped like an arc, that form at some convergent plate boundaries.
Eccentricity: a measure of how elliptical Earth's orbit is. Higher eccentricity means a more elliptical, less circular orbit.
Continental Slope: The boundary between the continents and the ocean basins. It marks a distinct change in the composition of the rocks near the Earth's surface.
Rhyolite: A volcanic rock that has the same composition as a granite, but has erupted and cooled at the surface, rather than underground.
Dense Oxides: Minerals that form deep in Earth's mantle due to the enormous pressures.
Shadow Zone: A region of Earth where seismic waves cannot be detected by seismometers.
Uniformitarianism: The idea that the laws of nature do not change with time. This idea is also called the principle of "Time Symmetry."
Greenhouse Gases: Gases in the atmosphere that trap heat and keep Earth warmer than it would otherwise be, just like the glass in a greenhouse traps heat inside the greenhouse.
Unconformity: A break or gap in the geologic record.
Rift Valley: A long, linear depression that commonly forms along a divergent plate boundary as two plates pull apart.
Mountain Belts: Regions of the continents where the rocks have been highly deformed by enormous forces. These belts usually lie along the edges of continents.
Atoll: An ocean island that has no remaining central volcanic edifice, but exists only as a coral reef almost completely at or below sea level.
Oceanic Ridge: Mountain ranges that are under the oceans. They form very long mountain chains that essentially encircle the earth.
Comet: A small body composed of ice and dust that orbits our Sun. As a comet comes close to our Sun, some of the material is vaporized and a tail forms opposite the direction of the motion of the comet.
Paleomagnetism: Magnetism preserved or fossilized in rocks. It can often tell us about changes in the orientation of rock bodies after their formation.
Meteorite: A meteoroid that hits Earth's surface.
Sedimentary Rock: Rocks formed by the deposition of sediment.
H-R Diagram: A plot used for individual stars where luminosity is plotted on the y axis and surface temperature is plotted on the x axis.
Stellar Parallax: Apparent motion of the stars due to Earth's motion in its orbit.
Limestone: A sedimentary rock usually formed from the precipitation of the mineral calcite in the ocean.
Meteoroid: A small rock found in the space between planets.
Gabbro: An igneous plutonic rock made of the same minerals as basalt, but, because the minerals cooled slowly underground, they are coarse-grained.
Asteroid: One of the many thousands of small rocky objects that orbit our Sun. The orbits of asteroids generally lie between the orbits of mars and Jupiter, although some are in orbits that bring them close to our Sun. Asteroids are much smaller than a planet and are sometimes called minor planets.
Basalt: An igneous volcanic rock that is composed of calcium-rich feldspar and other iron-rich minerals.
Gneiss: A banded or foliated metamorphic rock, usually of the same composition as granite.
Stony Chondrites: Meteorites thought to represent material from small planetary bodies that had differentiated into layers and then were broken up.
Crust: The uppermost compositional layer of Earth. It is very thin and composed of two parts: granitic continental crust and basaltic oceanic crust.
Luminosity: Roughly equal to brightness or the rate at which energy is radiated from an object.
Dark Nebula: A cold cloud of dust and gas that blocks the light from background stars.
Trenches: Long, narrow, deep places on the ocean floor. They are usually found near or next to continents.

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