Physical Geography-Midterm #1 – Flashcards
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Physical geography
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study of physical elements of the earth and how they interact with living organisms
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lithosphere
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solid earth
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hydrosphere
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water in all forms
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atmosphere
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gaseous layer around earth
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biosphere
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all living organisms
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system
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ordered, interrelated set of things and attributes. Linked by flows of energy and matter
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systems approach to geography
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emphasizes interconnection of natural processes; concerned with how/where matter & energy flow in these systems
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Steady-state equilibrium
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system where input equals output and the energy/matter stored is constant
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open system
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there are inputs and/or outputs of energy or matter in a system
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closed system
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no inputs or outputs in the system; cycles; moves endlessly in a series of interconnected paths
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positive feedback loop
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the enhancement or amplification of an effect by its own influence on the process that give rise to it
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negative feedback loop
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the diminution or counteraction of an effect by its own influence on the process giving rise to it
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terrestrial planets
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Earth, Mars, Venus, Mercury; have a compact rocky surface
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Jovian planets
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the gas giants-Neptune, Saturn, Jupiter, Uranus; larger than earth and gaseous in nature
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Nebular planetismal hypothesis
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The solar system formed from a nebula (large amorphous cloud of dust and gas) that contracted due to gravity. A protosun originated in the center and planets formed from outer "eddies" or disruptions in the flow
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aphelion
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the farthest position from the sun in earth's elliptical orbit; occurs on July 4th
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perihelion
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the closest position to the sun in earth's orbit; occurs January 3rd
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geodesy
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study of the earth's shape and size
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Oblate Ellipsoid
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The actual shape of the earth; a slightly flattened sphere because the equator moves more quickly than the poles and the outward force produces a bulge there. longer on vertical axis, shorter on horizontal
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Latitude
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Angular distance north or south of the equator; parallel=the imaginary line associated with the degree
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Longitude
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angular distance east or west of a point on earth's surface; range from 0 to 180 degrees; meridian=actual line associated with the angle
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To Convert DMS to Decimal
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1. Divide seconds by 60 2. Add result onto minutes 3. Divide minutes by 60 4. Add result onto degrees *Do the opposite to go from decimal to DMS
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great circle
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any plane or circle you can cut through the earth that goes through the core
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Arc
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Shortest distance between two points on a mercator projection (the most common one; poles very distorted)
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GPS
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Global positioning system; calculates latitude and longitude and elevation within 1 meter of accuracy; send out signal, satellite keeps track and based on direction/speed/time
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Remote sensing
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info acquired at a distance without physical contact with the subject
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GIS
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Geographic info system; keeps track of data
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seasons
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cylindrical changes in temperature that occur throughout the year; caused by changes in the amount of solar energy received
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March 21st
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Equinox
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June 21st
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Solstice
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September 22nd
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Equinox
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December 21st
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Solstice
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Equinox
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Equal hours of daylight and sunlight in each places; Circle of illumination cutting through earth's axis
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Circle of illumination
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division between the daylight/darkness on the globe; changes positions as the earth rotates
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subsolar point
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point at which the sun's rays hit directly
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declination
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latitude of the subsolar point; latitude at which the sun's rays hit directly; changes gradually throughout the year
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revolution
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movement of earth around sun (~365 days)
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axial tilt
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tilt of earth's axis; the tilt is with respect to a line perpendicular to the plane of the ecliptic; 23.5 degrees; affects day length and angle of sunlight and INTENSITY of the seasons
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polarity
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orientation of axis; the axis stays parallel to itself throughout the course of the year; affects when season occur/timing or seasons
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insolation
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incoming solar radiation; on the curve, x-axis is the calendar year and the y-axis is the insolation (w/m^2)
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Relative dating
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based on the positions of rocks relative to each other; sequential age
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absolute dating
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based on radiometric dating; actual age
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Radiometric dating
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based on the steady decay of isotopes; unstable parent isotope becomes stable daughter isotope
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isotope
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an element with the same number of protons but different number of neutrons
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atoms
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nucleus of protons and neutrons orbited by electrons
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half-life
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length of time it takes for half of the unstable isotopes to decay into stable isotopes
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p
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amount unstable parent at time
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Po
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amount unstable parent at time 0
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e
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2.718
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k
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Decay constant; .693/H
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H
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Half-life
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t
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time
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geologic time scale
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calendar of earth history; divided into eons, eras, and periods; we live in the phanerozoic
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Minerals
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1. found in nature 2. inorganic 3. special chemical formula 4. characteristic atomic structure 5. crystalline structure
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mineralogy
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study of composition, properties, and classification of minerals
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Mineral identification
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crystal structure, hardness, luster, streak, color, density
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Rock
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Assemblage of minerals or a single mineral in a solid state
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Igneous rock
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rocks that have solidified and crystallized from a molten state
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igneous rock
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majority of crustal rock
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igneous rock
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consists of silicate minerals with metallic elements
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igneous rocks
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granite, basalt, obsidian, pumice
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magma
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molten rock BENEATH earth's surface; Lava is spilled onto the earth's surface
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Felsic
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Silicon and Aluminum, low melting point, low density, light color; Granite
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Mafic
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Iron and Magnesium, high melting point, high density, dark color; Basalt
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pluton
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large body of magma
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dike
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an igneous intrusion that cuts vertically through other layers of rock
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sill
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an igneous intrusion that cuts horizontally through rock
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Intrusive igneous rock
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cools under the surface, large crystals, slow cooling; Granite
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extrusive igneous rock
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cools above surface, small crystals, fast cooling; Basalt
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Sedimentary rocks
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formed through erosion, transportation, deposition, compaction, cementation, and hardening of sediment
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Sediment
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fine grained mineral matter transported by air, water, or ice
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Strata
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formed from accumulation of sediment at low elevation
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lithification
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hardening of sediment into rock
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Clastic
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Detrital; a form of sedimentary rock; derived from weathered and fragmented rock. Composed of sediment and goes through all the processes; Mudstone, shale, sandstone. MOST COMMON
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Chemical
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a form of sedimentary rock; dissolved minerals, transported in solution and precipitated out by a change in pH or temperature; limestone; most common with calcium carbonate
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organic processes
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sedimentary rock formed from the remains of dead organisms; Coal (accumulation of moss and plant material which is then put under pressure) and chalk (skeletons of tiny organisms)
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metamorphic rock
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rocks changed by heart and/or pressure; they have a changed structure, texture, composition, and appearance from the parent rock; slate, schist, gneiss
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country rock
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the rock that is exposed to rock melted rock
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Foliation
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layering in metamorphic rock caused by an increase in heat or pressure; forms through metamorphism, NOT deposition like with strata
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Endogenic
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Internal, building up; volcanism, diastrophism, massive crustal rearrangement
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exogenic
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external, breaking down; weathering, mass wasting, erosion
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geologic cycles
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the rock cycle, tectonic cycle, and the water cycle; powered by internal heat (From decaying radioactive material in the core) and solar energy
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Law of superposition
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younger rocks are deposited on top of older rocks
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law of original horizontality
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sedimentary rocks and lava are originally laid down horizontally because of gravity; if it is tilted, you know it has undergone folding after it was laid down
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Law of cross-cutting relations
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rocks that intrude into other rocks are younger than their host rocks; faults are younger than the rocks that they cut through
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uniformitarianism
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same physical processes active in the environment today have been operating throughout the geologic time (charles lyell)
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p waves
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compressional waves; push and pull, back and forth motion; can go through almost any type of rock
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s waves
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shear waves; side to side movement; cannot penetrate liquid layers
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crust
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thin, brittle layer; contains the continents and ocean basins, abundant elements-O, Si, Al, Fe
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Moho
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discontinuity between the crust and the mantle
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Lithosphere
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crust and uppermost mantle
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Mantle
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majority of earth's volume, composed of oxides of Fe, Si, Mg; divided into three zones
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Uppermost mantle
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Mantle zone that is rigid, brittle, and cracks with faulting
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asthenosphere
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mantle zone that is plastic, but not liquid; it moves independently of the lithosphere (hard earth); convection currents move the plates around
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Mesosphere
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mantle zone that is rigid and below the asthenosphere
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outer core
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molten, generates a magnetic field due to convective flow
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inner core
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solid due to increased pressure, but same composition (Fe and Ni) as the outer core
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Pangaea
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supercontinent
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isostacy
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maintenance of hydrostatic equilibrium of crust, of the tectonic plates; add weight=sink, remove weight=rise
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plate tectonics
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process for continental drift; thermal convection system within earth; conveyer belt type system for making crust and destroying crust; amount of crust made is the same as the amount of crust destroyed
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Seafloor spreading
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Making crust; magma rises up from the mantle, spreads out and cools; occurs at spreading boundaries (ridges) where plates are moving away; occurs underwater
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Rift valley
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formed when two plates move away with continental crust; fault blocks with eventually low enough elevation to flood with seawater and start a new ocean
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destroying crust
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One plate gets pushed under another plate; crust descends into the mantle and is recycled; occurs at converging boundaries (trenches)
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Subduction
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more dense oceanic crust gets pushed under less dense continental crust
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Composition of crust
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Continental=granitic, oceanic=basaltic
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Spreading Plate boundary
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divergent boundary, plates pulling apart
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converging boundary
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plates pushing together; can be oceanic-continental, oceanic-oceanic, and continental-continental
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transform boundary
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plates sliding past each other, associated with major seismic activity
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paleomagnetism
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modern evidence for plate tectonics; alternating bands of normal and reversed polarity because of the reversal of magnetic poles
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radiometic dating
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modern evidence for plate tectonics; increased distance from ridge is equal to increased age
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volcanism
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when molten magma extrudes onto earth's surface, not necessarily violently
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Composite (Strato-) volcano
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large steep-sided, cone-shaped, alternating pyroclastics (ash) and lava; has a magma chamber, central vent, and some side vents where most of the lava flows from
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shield volcano
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large, gently sloping, cone-shaped volcano; much larger in diameter than composite volcanoes; characterized primarily by a lava composition; has a magma chamber, central vent, & side vents (flank eruptions)
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cinder cones
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small, steep-sided, cone-shaped volcano; made of volcanic cinders (rocks and ash); don't really erupt with active lava; has a magma chamber and central vent; can grow very quickly
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caldera
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basin shaped depression
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hot spots
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individual stationary sites of upwelling from mantle; also called a mantle plume; like a big conveyor belt
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flood basalts
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gradual eruption of basaltic lava from fissures or openings in the earth
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pahoehoe
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thin lava which is not viscous and flows quickly; not associated with explosiveness
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a'a
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thick, rocky lava; more viscous, gases cannot escape
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effusive
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type of eruption with gentle, low viscosity lava; shield volcanoes, basaltic lava, mafic (less thick) lava
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explosive
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type of eruption with violent, high viscosity lava; composite volcanoes; felsic (granitic) lava because of the silicon rings which make it thick (blow the top off the cone); associated with subduction zones
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fumarole
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degassing of a volcano
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pyroclastic flow
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avalanche of hot gas, ash, and rock fragments
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lahars
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mudflows from melted snowcap/glaciers following an eruption
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strain
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how rocks respond to stress
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Tension
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a type of rock stress; stretching
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compression
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a type of rock stress; shortening
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shear
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a type of rock stress; twisting or tearing
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folding
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bending; a type of strain
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faulting
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breaking; a type of strain
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Anticline
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simple upfold where the layer fold downward from the axis; younger rock layers on the outside
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syncline
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simple down fold where the layers slope upward from the axis; younger rock layers on the inside
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thrust fault
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push overturned anticline until it faults and one block is on top
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strike
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compass direction of the line marking the intersection of rock layers with earth's surface
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dip
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angle and direction that rock layers tilt
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faulting
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rocks on either side of the fracture are displaced relative to each other
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earthquake
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caused by a sudden release of energy along a fault
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joint
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a geologic crack with no movement
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fault scarp
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steep cliffs that makeup the edge of a displaced rock
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hanging wall
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the fault block with an acute angle between the surface and the fault plane
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footwall
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the fault block with an obtuse angle between the surface and the fault plane
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normal fault
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hanging wall is moving down relative to the footwall; tension
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reverse fault
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hanging wall is moving up relative to the footwall; compression
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thrust fault
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reverse faulting where one has moved on top of the other
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strike-slip fault
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moving along a strike; can be LEFT LATERAL OR RIGHT LATERAL (the way it's moving relative to you)
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orogeny
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mountain building episode which can involve deformation, uplift, plate tectonics, intrusion of magma or a combination of all
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earthquake
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vibration in the earth produced by shock waves from sudden movements along faults
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seismic
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pertaining to earthquakes
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focus
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center of fault motion
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earthquake
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surface directly above focus
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Why earthquakes occur
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movement along a fault, increased strain along a fault, and when strain is greater than friction
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Elastic rebound theory
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original position, deformation, rupture and release of energy, and then the rocks rebound to their original undeformed shape
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Richter magnitude scale
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Measures amplitude of seismic waves; is a logarithmic scale; has no maximum but underestimates the energy release in large quakes
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moment magnitude
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an alternative to the richter scale; measures the magnitude via amount of slippage, size of slipped area, and resistance of rock to slippage
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mercalli scale
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an alternative to the richter scale; measures damage intensity in roman numerals I-XII
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Paleoseismology
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study the history of movement along fault lines to predict earthquakes. Not reliable
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magnetism
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study local changes in magnetic field to predict earthquakes
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dilatancy
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study changes in rock volume and amount of radon gas in groundwater
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denundation
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the wearing away of landforms; involves weathering (breaking apart of rock) and mass wasting (land slides) and erosion (moving around of fragments) by moving water, air, waves, and ice
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weathering
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disintegration of rock near Earth's surface
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regolith
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rock fragments made by weathering; bedrock=parent rock
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physical weathering
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physical breaking apart of rock; cold and dry areas
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chemical weathering
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involves chemical processes; warm and wet areas
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What controls weathering
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bedrock, water availability, orientation, vegetation, climate
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frost action
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repeated freeze-thaw breaks rocks
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salt-crystal growth
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caused by the evaporation of H20 in dry climates and can actually pull the rock apart
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Unloading or exfoliation
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as surface rock erodes, the pressure on the buried rock decreases and sheets form and slide off; really common with granite
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Hydrolysis
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a type of chemical weathering; minerals and H20 react; really common in granite
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oxidation
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a type of chemical weathering; chemical term for rust when metals and oxygen react
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Acid action
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a type of chemical weathering; also called carbonation where minerals dissolve in solution
