Question | Answer |
Earthquake | Shaking of the earth’s surface caused by a sudden release of energy, usually by slippage of rocks along around it devastating |
Aftershock | Following a large earthquake, smaller earthquakes can occur as the rocks settle |
Seismology | : study of earthquakes. The energy released by movement along a fault line travels as seismic waves outward in a concentric pattern from the place of movement |
Focus | Point within Earth were fracturing first begins; point where energy is first released |
Epicenter | the point on earth’s surface directly above the focus |
Discontinuity | A boundary across which seismic wave velocity or direction of travel changes abruptly, such as the mantle-core boundary |
Refraction | a physical phenomena: As P- and S-waves pass from one material into another with different density, the waves are bent much like light is bent when it passes from air to water; occurs because Internally Earth consists of concentric layers (crust, mantle, |
reflection | the return to the surface of some of a seismic wave’s energy when it encounters a boundary separating materials of different density or elasticity. |
Depth of earthquakes | 1) Shallow- at depths <70 km; Intermediate –at depths of 70-300 km; Deep- at depths > 300 km; 90% occur @ depths <100 km and only 3% are deep-focus…. If it is a deep earthquake it might not even reach the surface; |
Where earthquakes occur | 95% of all earthquakes occur in seismic belts along plate boundaries; Pressure is released and causes the earthquake; “Ring of fire” all around Pacific Ocean; Names of plates: San Andreas fault, Philippine Plate, Pacific Plate, African plate, Indo Austral |
types and characteristics of seismic and surface waves | P-Waves (Primary Waves) are fastest seismic waves; travel in solids, liquids, and gases; are compressional; cause material to vibrate back-and-forth in the direction of travel. AND S-Waves (Secondary Waves): Slower than P-waves; Travel only in solids; Mov |
Calculating location of earthquakes | Earthquake epicenters are located based on the difference; From the “P-S travel times” Calculate the distance of the seismograph from the earthquake |
Earthquake magnitude and intensity scales | Richter: magnitude <2.5 typically not felt but recordedl 2.5-6 usuually felt minor damage; 6-7 potentially destructive; 7-7.9 major; >8.0 TOTAL DESTRUCTION; #2 Modified mercali scale- intensity 1-12 |
Deformation | Earth’s dynamic forces cause fracturing and/or contortion of rock layers; all of Earth’s mountain ranges contain deformed rocks; occurs when STRESS is applied to a rock |
Structural geology | study of rock deformation |
Strike | direction from north of a horizontal line on the surface, measured as the angle east or west of north |
Dip | angle that plane is orientated beneath horizontal; angle(downward from horizontal);direction (e-w) |
fold | up- and down-arched features in a rock; type of plastic deformation ;usually occurs deep in crust where rocks are softer and warmer |
anticline | up-arched fold -opens downward; older rocks in center; Nittanny |
Syncline | down-arched fold; opens upward; Sideling Hill |
Fold axis | line defining intersection of axial plane and bedding plane |
Axial Plane | plane defining “center” of fold |
Fault | type of brittle deformation; fractures (cracks) in rock where measurable offsets can be measured in rocks; a______ is a plane, so we can measure strike and dip of _____ surface |
Hanging wall | block of rock overlying a fault; relative motion of ________ and footwall determines the type of fault |
Footwall | block of rock below fault; no hanging wall or ________ in vertical fault |
klint | an uplifted fossilized coral reef |
Jolly balance | a delicate spring balance to measure densities of minerals |
JOIDES | Joint Oceanographic Institutions for Deep Earth Sampling |
Glacial milk | a stream of turbid, whitish meltwater derived from glaciers |
Eurypterid | a large organism related to shrimp |
Hog wallow | faintly rolling land surface characterized by low rounded mounds that are slightly higher than surrounding depressions |
clinker | coal that has been altered by igneous intrusion |
cosmopolitan | said of organisms that are distributed worldwide |
gumbo | clay soil that becomes sticky when wet |
wake | a dirty sandstone |
Normal | hanging wall appears to move down relative to footwall; caused by tension; associated with stretching of crust or extension and divergent plate margins; Basin and Range of western US; Wasatch Mountains, Wasatch Fault; Sierra Nevada, CA is flanked on its e |
Thrust | special type of reverse fault; dips less than 45; develop at convergent plate boundaries; very common in mountain ranges such as Appalachian Mountains |
Reverse | hanging wall appears to move up relative to footwall; caused by compression; associated with pushing together of crust and convergent plate margins |
Left-lateral | when standing on one side of the fault, appears that other block has move to the left; Garlock fault, Mojave Desert, CA |
Right-lateral | when standing on one side of the fault, appears that other block has move to the right; san andreas |
Orogeny | specific (mountain building process) event; generally involves intense deformation, metamorphism, plutonism, and volcanism; usually caused by compressive forces at convergent plate boundaries |
Tectonics | study of orogenic evolutions of mountain ranges |
three types of deforming forces | compression(squeezed2gether), tension (pulled apart), shear (parallel but act in opposite directions to force rocks to move past each other) |
three types of deformation | Elastic (body returns to original state aftere force is released); Plastic(folding of rocks) ; Brittle (fracture deofrmations; faulting and fracturing) |
where on earth deformation occurs | India and Asia; Valley and Ridge province of Appilacian mounthas |
type of deformation that results from an applied stress | Compression causes folding as well as reverse and thrust faulting; Tension causes normal faults; Shear stress causes rocks to slip past one another in a horizontal plane as with strike-slip faults |
measuring orientation of planar features | 1. DIP ANGLE – angle measured downward from horizontal -0 = horizontal, 90 = vertical |
types of folds | monocline; anticline; syncline |
types of deformation that occurs @ plate boundaries | Ocean-ocean= trench, backa arc basin; Ocean-continent=wedge; volcanic arc; Continent- continent="suture" zone |
Mass wasting | the down slope movement of material under the direct influence of gravity |
fall | rocks of any size fall through the air from steep cliffs, canyons and road cuts |
slide | material slides down slope as a coherent mass |
flow | material going downhill in turbulent (random) mass |
talus | buildup of rocks from rock falls at base of cliff |
What controls the tides? | ocean rises and falls about twice a day due to gravitational pulls by the sun and moon (but the moon has a greater effect because it is closer to the Earth) |
Flood tide | tide moving in |
ebb tide | tide moving out |
spring tide | sun and moon aligned to produce highest high tide |
neap tide | sun and moon perpendicular to produce the lowest tide |
Emergent (raised) coasts | where the land has risen with respect to sea level (the west coast of the US) |
submergent (drowned) coasts | the east coast, where the land has sunk with respect to sea level. Forms an estuary (Chesapeake and Delaware bays) |
shoreline | the areas between the highest high tide and the lowest low tide. |
Nearshore current | area along coast where waves are breaking |
barrier reef | reef is separated from the coast by a lagoon |
fringing reef | solidly attached to the margins of an island or continent. They have rough, table-like surface and slope steeply down to the seafloor |
atoll | circular to oval reefs surrounding a lagoon. Form around volcanic islands that subside below sea level as the plate on which they rest is carried progressively farther from an oceanic ridge. |
What are reefs? | Mound-like wave-resistant structures composed of the skeletons of corals, mollusks, sponges and encrusting algae. Restricted to shallow water because organisms need sunlight. |
Abyssal plain | flat surfaces beyond the continental rise covering vast areas of the seafloor. Sometimes interrupted by peaks, but are so flat due to sediment covering rugged topography of the seafloor. |
Continental rise | gently sloping area at the top of the slope |
continental slope | a steeper area with slopes up to 25 degrees. |
continental shelf | a broad, flat area, whose width can vary considerably. |
shelf-slope break | the location where the shelf and slope meet, at an average depth of 136 meters. |
continental margins | separate land from deep ocean and are essentially flooded edges of continents |
factors influincing mass wasting | weather and climate; water content; lack of vegitation; overloading of slopes-building on a cliff; slope stability; slope angle; triggering mechanisms like winter snowmelt or EARFQUAKEDD |
types of mass wasting | falls (talus) ; slides (slump) ; flows (mud flow, creep, debris flow) |
how to minimize the effects of mass wasting | dewatering (diverting surface water with ditches, drainpipes); reducing the angle of the slope (cut and fill, benching); Retaining walls |
barrier island | long, narrow strips of sand separated from the mainland by lagoons; OBX is a barrier island. |
beach | unconsolidated deposits of sediment that extend landward from low tide to a line of sand dunes, cliffs, or the beginning of permanent vegetation. |
longshore current | waves approach the shoreline at various angles; this produces a component flow parallel to the beach |
stream | a channel of running water |
load | sediment transported in running water; (dissolved- invisible and consists of ions taken into solution during chemical weathering; suspended-consists of mud kept in suspension above the channel bed by turbulence; bed- sand and gravel to large for turbulenc |
braided | possess multiple channels that divide and rejoin, separated by bars of sand and gravel |
meandering stream | have single, winding channels that form broad looping curves known as meanders |
floodplain | low-lying, flat areas of land adjacent to channels. They create deposits when streams flood their banks and water carrying mud and fine-grained sand spreads across the ________. |
delta | forms where a river discharges into a standing body of water, a lake or the sea |
watershed (drainage basin) | land area from which a stream receives runoff |
divide | a topographically high area separates a drainage basin from adjoining ones |
wave | oscillations of a water surface and can erode, transport and deposit sediment |
tide | caused by the gravitational tracts or attraction between the moon and earth; causes bulges in oceans. As the Earth rotates the bulges migrate from one location to the other causing tides |
dune | localized mound of sand-sized, wind-blown sediment; most have an asymmetrical profile; windward side is gentler slope, leeward side (away from wind)is a steep slope; dunes migrate with wind through time as sand blows. |
playa lake | dried up lake bed in desert environment; periodically receives water, which evaporates to form clay, halite, and other evaporate minerals. |
hydrologic cycle | consists of reservoirs (ie oceans, lakes, the atmosphere, glaciers) where water is stored and the pathways along which water moves at or near the earth's surface. water is mostly in the ocean 97% and glaciers 2% Glaciers have 77% of fresh h2o |
transportation of sediment | ___________ in running h2o is called LOAD; being transported by running h2o downhill; disolved load, suspended load and bed load |
stream erosion, transport, deposition | deposition takes place in the steam channel or in floodplains or deltas; load for transportaions (dissolved, suspended, bed), drainage (depositiong) 5 types= dendritic, rectangular, trellis, radial, deranged |
groundwater | Water filling open spaces in rock, sediment, and soil beneath the surface |
porosity | the percentage of the material’s total volume that is pore space and determines the amount of ground-water a material can hold |
permeablity | the capacity of a material to transmit flids; depends on porosity and inter connectedness of pore space |
aquifer | a permeable layer transporting groundwater; Sand and gravel deposits, fractured granite and limestone with solution cavities are good _______ |
acquilude | poor acquifiers; impermeable materials that prevent ground water movement |
water table | the surface separating areas where pores contain mostly air from areas where pores are filled with water. The elevations of the _______ mimics spring, geyser |
artesian well | are openings either dug or drilled that connect the zone of saturation with Earth’s surface; they form where groundwater in sloping aquifers is confined by an overlying aquiclude. If recharge is sufficient to keep the aquifer filled, pressure builds up a |
karst topography | Landscapes form in humid and temperate climates; lots of sink holes |
cave | a naturally formed subsurface cavity connected to the surface and large enough for a person to enter |
caverns | a VERY LARGE cave or system of connected caves |
stalactite | icicle shaped masses suspended from cave ceilings |
stalagmite | Spires projecting upward from cave floors |
how water well works, how it affects water table | made by digging or drilling down into the zone of saturation; groundwater pumped from a well; the water table in the area around the well is lowered forming a cone of depression |
artesian system | any system in which groundwater is confined and builds up high hydrostatic (fluid) pressure; When you drill into the aquifer the water is released without any pressure; where some bottled h2o is from |
how Karst topography forms | develops by groundwater erosion in many areas underlain by soluble rocks |
glacier | mass of ice on land consisting of compacted and re-crystallized snow that flows under its own weight; types =valley; continental |
transport by wind | BED LOAD: travels along surface and SUSPENDED LOAD: travels through air; generally only in silts and clays |
saltation | bouncing on surface |
wind erosion | ABRASION: impact of saltating grains on other rocks tends to round and smooth rocks; DEFLATION: removal of loose sediment by wind, explosing bare rock or concentrating pebbles and larger that can't be transported by wind |
wind deposition | DUNE: localized mound of sand-sized, wind-blown sediment; LOESS: deposits of silt and clay sized material |
distribution of deserts | controlled by global wind patterns; as the air at the equator heats up and rises, it is replaced by cool air and it rains. On either side of the equator the air is drier; most deserts are located here. |
desert characteristics | dense, dry, high pressure air masses are situated along 30 degrees N and S hemispheres; no deserts along the equator. |
valley glacier | tongues of ice confined to mountain valleys through which they flow from higher to lower elevation |
continental glacier | blanket-like accumulations of snow and ice that drape the land surface and flow outward in all directions from a central area |
Pleistocene Ice Age | (1.6 Ma to about 100,000 years) 4 main advancements of continental glaciers in NA, Europe, Asia in US, reached central Pennsylvania and Ohio, northern Kansas, Missouri, southern Illinois and Indiana, completely covered Wisconsin, S. and N. Dakota, Minnes |
Origin/Movement of Glaciers | exist when amount of winter snow is greater than amount of melting in summer, as snow compacts and recrystallizes it first forms firn which compacts to form glacial ice which accumulates to glacier; glacier reaches 40 m can flow downhill |
how and where valley and continental glaciers form | valley= mtn valleys through which they flow from higher to lower elevation- mounts all over world; continental= blanket-like accumulations of snow and ice that drape the land surface flow outward in all directions from central-- antartica and greenland |
glacial erosion, transport, deposition | as glacier flows over surface it scrapes soil, sediment, and rock off top and incorporates the material into glacier, deposition is called glacial drift and there are 2 types: till and Stratified Drift; till is depositied dir by g ice and strat is layered |
causes of glaciation | decrease in temperature on continents |
periods of glaciation | 3 periods in geo. history: about 1 bil. years ago in North America and the Pleistocene Ice Age [(1.6 mil-100,000 years ago) over that period there were 4 advancements of continental glaciers in N. America] and Little Ice Age (l. 1500s-1800s) |
What affects advance and retreat of glaciers? | plate tectonics (moves continents to poles in increase glaciation in those areas) and cyclical climate changes |