Environmental Geology Exam #1
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94 terms
Terms | Definitions |
|---|---|
 Relative Time | The determination of the sequence in which events occurred, relative to each other. |
| Principle of Original Horizontality | Layers of sediment that are generally deposited in a horizontal or nearly horizontal position |
| Principle of Superposition | The principle that in a series of stratified sedimentary rocks the lowest layer is the oldest |
| Principle of Cross-cutting | Any rock cutting through another rocks is always younger |
| Principle of Intrusion | Particles from one layer deposited into another, those particles are younger then original rock |
| Dike | Sedimentary rock that has magma in between it |
| Unconformaty | Missing layers, mosting due to erosion |
| Atom | smallest particle into which an element can be divided while still retaining chemical characteristics |
| Electrons | Negatively charged subatomic particle that circles around the nucleus |
| Atomic Number | The number of protons in the nucleus of an atom |
| Atomic Mass Number | The total number of protons and neutrons in an atom's nucleus |
| Isotopes | Atoms of the same element that have different numbers of neutrons |
| Ions | Electrically charged atoms that have gained or lost electrons. |
| Ionic Bonding | The attraction between oppositely charged ions. |
| Covalent Bonding | Results from the sharing of electron pairs between two atoms |
| Mineral | A naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition |
| Pluton | A body of intrusive igneous rock |
| Sill | A tabular igneous body formed when magma is injected along sedimentary bedding surfaces |
| Magma | Hot molten rock material in the earth's mantle. Rich in silica. |
| Plutonic Rock | Large mass of intrusive igneous rock believed to have solidified deep within the earth |
| Lava | Magma that reaches Earth's surface |
| Volcanic | Igneous rock produced by eruption and solidified on or near the earth's surface. Basalt common in rocks. |
| Lithification | The process that converts sediments into solid rock by compaction or cementation |
| Contact Metamorphism | A change in the texture, structure, or chemical composition of a rock due to contact with magma. |
| Regional Metamorphism | Metamorphism caused by high pressures and temperatures that extend over large regions, as happens where plates collide. |
| Foliation | The metamorphic rock texture in which mineral grains are arranged in planes or bands. |
| Rocks | A naturally formed aggregate, or mixture, of minerals; have varied chemical compositions. |
| Weathering | The breaking down of rocks due to ice, water and wind. |
| Erosion | The process by which water, ice, wind, or gravity moves weathered rock and soil |
| Deposition | Laying down of sediments |
| Compaction | Pressure of overlying sediments |
| Cementation | The process by which dissolved minerals crystalize and glue particles of sediment together into one mass. |
| Sorting | Process of selection and separation of sediment grains according to their grain size. |
| Roundings | Well rounded particles that have traveled a long distance. |
| Lithosphere | The solid part of the earth consisting of the crust and outer mantle, which are solid, brittle and elastic. |
| Asthenosphere | The soft layer of the mantle on which the lithosphere floats. |
| Divergent Plate Boundaries | tectonic plates spreading apart, new crust being formed (ex. mid-ocean ridges, rift valleys). |
| Convergent Plate Boundaries | Two plates colliding and creating either a mountain range (2 continental) or a subduction zone (2 oceanic), or trench (oceanic and continental) |
| Crust | The outer layer of the Earth |
| Continental Crust | The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick |
| Oceanic Crust | Thin, more dense than continental crust, subducting crust |
| Mantle | The layer of the earth between the crust and the core |
| Outter Mantle | Solid and brittle plus the crust which is the lithosphere. Floats on top of inner mantle. |
| Inner Mantle | Solf and plastic known as the asthenosphere. Up to 200 miles into the mantle. |
| Outter Core | The liquid layer of earth made of nickel and iron. Causes an electric field along with magnetic field. |
| Inner Core | solid, dense center of the Earth |
| Pyroclastic Materials | The volcanic rock ejected during an eruption including ash, bombs, and blocks |
| Volcanic Plugs | Solidified magma that built up in volcano neck. Outter pyroclastic material eroded. |
| Beta Particle | An electron emitted from the nucleus during some kinds of radioactive decay |
| Parent Material | Material from which a soil is formed, determines composition and properties of the soil |
| Daughter Material | The non-radioactive element from the parent material decay. |
| Absolute Time | The actual time (usually measured in years) as determined by radioactive decay of elements |
| Van der Waals | A slight attraction that develops between the oppositely charged regions of nearby molecules |
| Dipole | A pair of equal and opposite electric charges or magnetic poles separated by a small distance |
| Metallic | A mineral that has a shiny surface, does not let light pass through, and is a good conductor of heat and electricity. |
| Silica Tetrahedron | Basic building block of silicate minerals, made up of four oxygen atoms and 1 silicon aton |
| Mafic | Describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color |
| Felsic | Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color. |
| Intrusive | A type of ingneous rock that generally contains large crystals and forms when magma cools slowly beneath Earth's surface. |
| Extrusive | Fine-grained igneous rock that forms when magma cools quickly at or near Earth's surface |
| Phaneritic | Igneous rock texture where crystals are equal in size and identifiable to the naked eye--coarse-grained texture |
| Aphanitic | Rapid cooling at earth's surface results in tiny mineral crystals that can only be seen under a microscope. |
| Porphyritic | Rock texture, characterized by large, well-formed crystals surrounded by finer-grained crystals of the same mineral |
| Pyroclastic | Made of explosively ejected particles that are compressed and cemented, or welded. |
| Convection | The transfer of heat by movement of a fluid |
| Accretion | (geology) an increase in land resulting from alluvial deposits or water-borne sediment |
| Shadow Zones | Location on the earth's surface where no seismic waves or only P waves can be detected. No earthquakes felt in these zones. |
| Ring of Fire | A major belt of volcanoes that rims the Pacific Ocean |
| Mafic Magma | Magma with a low silica and gas content (non explosive eruptions) |
| Felsic Magma | Magma with a high silica content and large volume of gas (explosive eruptions) |
| Pahoehoe | A hot, fast moving type of lava that hardens to form smooth, ropelike coils |
| aa | A slow-moving type of lava that hardens to form rough chunks; cooler that pahoehoe |
| Columnar Jointing | Basalt in the form of six-sided, parallel, vertical columns |
| Volcanic Domes | Steep-sided, dome or spine shaped masses of volcanic rock formed from viscous lava that solidifies in or immediately above a volcanic vent |
| Cinder Cones | Small mountains with steep sides that blow cinders and rock particles into the air when they erupt. |
| Geothermal Features | Found in areas where water has been heated to temperatures higher than commonly found on the surface |
| Bombs | Blocks of lava that solidify in a stream like shape |
| Ash | The solid matter left after combustion of materials |
| Nuee Ardent | Flowing body of hot ash, dust, gases and solid particles. 200-450 degrees C, moving up to 300 k/hr |
| Vog | Volcanic fog/smog |
| Uniformitarianism | Is the idea that the geologic processes that operate today also operated in the past |
| Proton | A subatomic particle that has a positive charge and that is found in the nucleus of an atom |
| Nuetron | A subatomic particle with no charge |
| Half Life | The period of time in which half of a radioactive substance decays |
| Sillicate | Mineral that contains sillicon and oxygen and usually one or more other elements |
| Paleomagnetism | The study of changes in Earth's magnetic field, as shown by patterns of magnetism in rocks that have formed over time |
| Clastic | Sedimentary rock consisting of rock fragments compacted and cemented together |
| Subduction | The process by which oceanic crust sinks beneath a deep ocean trench and back into the mantle at a convergent plate boundary |
| Fissure Eruptions | The eruption of lava from a crack in the lithosphere rather than from a central vent |
| Shield Volcano | A low, flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava |
| Viscosity | Resistance to flow |
| Lahar | An avalanche of volcanic water, ash and mud down the slopes of a volcano |
| Caldera | A large depression typically caused by collapse or ejection of the summit area of a volcano |
| Composite Volcano | A tall cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials. |
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