| A | B |
|---|
| aa | slow moving type of lava that hardens to forms rough chunks; cooler than pahoehoe |
| active | said of a volcano that is erupting or has shown signs of erupting in the near future |
| aftershock | An earthquake that occurs after a larger earthquake in the same area |
| alloy | a solid mixture of two or more metals |
| anticline | an upward fold in rock formed by compression of Earth's crust |
| asthenosphere | the soft layer of the mantle on which the lithosphere floats |
| atoll | a ring-shaped coral island found far from land |
| atom | the smallest unit of an element that retains the properties of that element |
| basalt | a dark, dense, igneous rock with a fine texture, found in oceanic crust |
| base-isolated building | a building mounted on bearings designed to absorb the energy of an earthquake |
| batholith | a mass of rock formed when a large body of magma cooled inside the crust |
| caldera | the large hole at the top of a volcano formed when the roof of a volcano's magma chamber collapses |
| cementation | the process by which dissolved minerals crystallize and blue particles of sediment together into one mass |
| chemical rock | sedimentary rock that forms when minerals crystallize from a solution |
| cinder cone | a steep, cone-shaped hill or mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening |
| clastic rock | sedimentary rock that forms when rock fragments are squeezed together under high pressure |
| cleavage | a mineral's ability to split easily along flat surfaces |
| compaction | the process by which sediments are pressed together under their own weight |
| composite volcano | a tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials |
| compound | a substance in which two or more elements are chemically joined |
| compression | stress that squeezes rock until it folds or breaks |
| conduction | the transfer of heat by direct contact of particles of matter |
| constructive force | a force that builds up mountains and landmasses on Earth's surface |
| continent | a great landmass surrounded by oceans |
| continental drift | the hypothesis that the continents slowly move across Earth's surface |
| controlled experiment | an experiment in which all factors except one are kept constant |
| convection | the transfer of heat by movements of a heated fluid |
| convection current | the movement of a fluid, caused by differences in temperature, that transfers heat from one part of the fluid to another |
| convergent boundary | a plate boundary where two plates move toward each other |
| coral reef | a structure of calcite skeletons built up by coral animals in warm, shallow ocean water |
| crater | a bowl-shaped area that forms around a volcano's central opening |
| crust | the layer of rock that forms Earth's outer surface |
| crystal | a solid in which the atoms are arranged in a pattern that repeats again and again |
| deep-ocean trench | a deep valley along the ocean floor through which oceanic crust slowly sinks towards the mantle |
| deformation | a change in the volume or shape of Earth's crust |
| density | the amount of mass in a given space; mass per unit volume |
| deposition | the process by which sediment settles out of the water or wind that is carrying it |
| destructive force | a force that slowly wears away mountains and other features on the surface of Earth |
| dike | a slab of volcanic rock formed when magma forces itself across rock layers |
| divergent boundary | a plate boundary where two plates move away from each other |
| dormant | said of a volcano that does not show signs of erupting in the near future |
| earthquake | the shaking that results from the movement of rock beneath Earth's surface |
| element | a substance composed of a single kind of atom |
| epicenter | the point on Earth's surface directly above an earthquake's focus |
| erosion | the destructive process in which water or wind loosen and carry away fragments of rock |
| extinct | said of a volcano that is unlikely to erupt again |
| extrusive rock | igneous rock that forms from lava on Earth's surface |
| fault | a break in earth's crust where slabs of rock slip past each other |
| fault-block mountain | a mountain that forms where a normal fault uplifts a block of rock |
| fluorescence | the property of a mineral in which the mineral glows under ultraviolet light |
| focus | the point beneath Earth's surface where rock breaks under stress and causes an earthquake |
| fold | a bend in rock that forms where part of Earth's crust is compressed |
| foliated | term used to describe metamorphic rocks whose grains are arranged in parallel layers or bands |
| footwall | the block of rock that forms the lower half of a fault |
| fossil | a trace of an ancient organism that has been preserved in rock |
| fracture | the way a mineral looks when it breaks apart |
| gemstone | a hard, colorful mineral that has a brilliant or glassy luster |
| geologist | a scientist who studies the forces that make and shape planet Earth |
| geology | the study of planet Earth |
| geothermal energy | energy from water or steam that has been heated by magma |
| geyser | a fountain of water and steam that builds up pressure underground and erupts at regular intervals |
| grain | a particle of a mineral or other rock that gives a rock its texture |
| granite | a usually light-colored rock that is found in continental crust |
| hanging wall | the block of rock that forms the upper half of a fault |
| heat transfer | the movement of energy from a warmer object to a cooler object |
| hot spot | an area where magma from deep within the mantle melts through the crust above it |
| hot spring | a pool formed by groundwater that has risen to the surface after being heated by a nearby body of magma |
| hypothesis | a prediction about the outcomes of an experiment |
| igneous rock | a type of rock that forms from the cooling of molten rock at or below the surface |
| inner core | a dense sphere of solid iron and nickel in the center of Earth |
| inorganic | not formed from living things or the remains of living things |
| intrusive rock | igneous rock that forms when magma hardens beneath Earth's surface |
| island arc | a string of islands formed by the volcanoes along a deep ocean trench |
| lava | liquid magma that reaches the surface; also the rock formed when liquid lava hardens |
| lava flow | the area covered by lava as it pours out of a volcano's vent |
| liquefacation | the process by which an earthquake's violent movements suddenly turns loose soil into liquid mud |
| lithosphere | a rigid layer made up of the uppermost part of the mantle and crust |
| luster | the way a mineral reflects light from its surface |
| magma | the molten mixture of rock-forming substances, gases, and water from the mantle |
| magma chamber | the pocket beneath a volcano where magma collects |
| magnitude | the measurement of an earthquake's strength based on seismic waves and movement along faults |
| manipulated variable | the one factor that a scientist changes during an experiment |
| mantle | the layer of hot, solid material between Earth's crust and core |
| Mercalli scale | a scale that rates earthquakes |
| metamorphic rock | a type of rock that forms from an existing rock that is changed by heat, pressure, or chemical reactions |
| mid-ocean ridge | the undersea mountain chain where new ocean floor is produced; a divergent plate boundary |
| mineral | a naturally-occurring, inorganic solid that has a crystal structure and a definite chemical composition |
| Mohs hardness scale | a scale ranking ten minerals from softest to hardest; used in testing the hardness of minerals |
| moment magnitude scale | a scale that rates earthquakes by estimating the total energy released by an earthquake |
| normal fault | a type of fault where the hanging wall slides downward; caused by tension in the crust |
| operational definition | a statement that describes how a particular variable is to be measured or a term is to be defined |
| ore | rock that contains a metal or economically useful mineral |
| organic rock | sedimentary rock that forms where remains of organisms are deposited in thick layers |
| outer core | a layer of molten iron and nickel that surrounds the inner core of Earth |
| P wave | a type of seismic wave that compresses and expands the ground |
| pahoehoe | a hot, fast-moving type of lava that hardens to form smooth, ropelike coils |
| Pangea | the name of the single landmass that broke apart 200 million years ago and gave rise to today's continents |
| pipe | a long tube through which magma moves from the magma chamber to Earth's surface |
| plate | a section of the lithosphere that slowly moves |
| plate tectonics | the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle |
| plateau | a large area of flat land elevated high above sea level |
| porphyritic texture | an igneous rock texture in which large crystals are scattered on a background of much smaller crystals |
| radiation | the transfer of energy through empty space |
| responding variable | the factor that changes as a result of changes to the manipulated variable in an experiment |
| reverse fault | a type of fault where the hanging wall slides upward |
| Richter scale | a scale that rates seismic waves as measured by a particular type of mechanical seismograph |
| rift valley | a deep valley that forms where two plates move apart |
| Ring of Fire | a major belt of volcanoes that rims the Pacific Ocean |
| rock | the material that forms Earth's hard surface |
| rock cycle | a series of processes on the surface and inside Earth that slowly change rocks from one kind to another |
| S wave | a type of seismic wave that moves the ground up and down or side to side |
| scientific theory | a well-tested concept that explains a wide range of observations |
| sea-floor spreading | the process by which molten material adds new oceanic crust to the ocean floor |
| sediment | small, solid pieces of material that comes from rocks or organisms |
| sedimentary rock | a type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together |
| seismic wave | a vibration that travels through Earth carrying the energy released during an earthquake |
| seismograph | a device that records ground movments caused by seismic waves |
| shearing | stress that pushes a mass of rock in opposite directions |
| shield volcano | a wide, gently-sloping mountain made of layers of lava and formed by quiet eruptions |
| silica | a material that is formed from the elements oxygen and silicon; silica is found in magma |
| smelting | the process by which ore is melted to separate the useful metal from other elements |
| solution | a mixture in which one substance is dissolved in another |
| sonar | a device that determines the distance of an object under water by recording echoes of sound waves |
| streak | the color of a mineral's powder |
| stress | a force that acts on rock to change its shape or volume |
| strike-slip fault | a type of fault where rocks on either side move past each other sideways with little up or down motion |
| subduction | the process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary |
| surface wave | a type of seismic wave that forms when P waves and S waves reach Earth's surface |
| syncline | a downward fold in rock formed by compression in Earth's crust |
| tension | stress that stretches rock so that it becomes thinner in the middle |
| texture | the look and feel of a rock's surface |
| transform boundary | a plate boundary where two plates move past each other in opposite directions |
| tsunami | a large wave produced by an earthquake on the ocean floor |
| variable | any factor that can change in an experiment |
| vein | a narrow slab of a mineral that is sharply different from the surrounding rock |
| vent | the opening through which molten rock and gas leave a volcano |
| volcanic neck | a deposit of hardened magma in a volcano's pipe |
| volcano | a weak spot in the crust where magma has come to the surface |
