Geography Unit 3
Asthenosphere
* It is primarily molten, with some solid material and its top at ~43 miles bsl and a thickness of ~110 miles. * It is the main source (but not the only) of magma, the molten rock or lava which erupts onto the surface.
Inner Core
* The material in this layer is in a solid state and consists primarily of iron (Fe) and nickel (Ni). The top of the layer is about 3200 miles below sea level (bsl), and it is about 760 mi thick.
VOLCANISM
* The processes by which magma and gases are transferred from the Earth's interior to near or on the surface.
Upper Mantle
* This layer is a mixture of molten and solid material and consists of silicate minerals, among others. Its top is ~155 miles bsl and is ~255 miles thick. * The Upper and Lower Mantle comprise about 80% of Earth's volume and are often together referred to simply as the Mantle.
Lower Mantle
* This layer is primarily solid, but with molten material also present. It consists of Fe oxides, magnesium (Mg) and silicon (Si). Its top is ~ 415 miles bsl and it is ~ 1385 miles thick.
How to tell a plate boundary?
* This was originally done by mapping the distribution of volcanic and earthquake activity observed/recorded across the Earth's surface. The majority of this distribution is quite linear in shape and often yields the location of plate boundaries. EX: "Pacific Ring of Fire" which is a pattern of volcanoes on the Western side of both North and South America, then the eastern side of Asia down to New Zealand (also a zone of high earthquake activity). * Mid-Atlantic Ridge and other spreading zones also map as linear features of high earthquake and volcanic activity.
STRUCTURAL LANDSCAPES
* Those landscapes formed by tectonic forces: compression, tension, and shearing. * The relationship between geologic structure and the visible and scape, and how this is formed by various processes.; * The relationship between geologic structure and the visible landscape, and how this is formed by various processes.
Oceanic crust
*material of higher density * simatic rocks or sima (Si and Magnesium) * ~3-5 miles thick * EX: basalt, lava
Isostasy
* A state of equilibrium formed by the interplay between the lithosphere (landmasses) and the asthenosphere.
Lithosphere
* Consists of two solid layers, the Uppermost mantle, and the Crust. There are two types of crustal material, Continental and Oceanic. It varies in thickness because the different types of crust have different thicknesses, but goes to a depth of ~43 miles.
Gutenberg Discontinuity.
* The discontinuity between the Outer Core and the layer above it (the Lower Mantle)
Continental crust
-material of lower density -sialic rock or sial (Si and Aluminum) * ~19-37 miles thick * EX: granite, shale, marble
Igneous rocks form by the _______________________
Crystallization of magma/lava, the solidifying of molten material either below or on the surface.
How are earthquakes measured?
Magnitude and Intensity
** The interactions/interrelationships between the processes which form the different rock types can be expressed by the _______________
Rock Cycle.
GEOMORPHOLOGY
The science of landforms, their origin, evolution, form, and spatial distribution. * The development and changes on the Earth's surface over time.
Lithification is
a process of cementation, compaction and hardening of sediments to new rock.
Rock is
an assemblage of minerals bound together, usually 2 to 5 different minerals.
Laccolith is a concordant pluton which has ____________________________, and so forms a ________________with a horizontal floor but that is smaller than a batholith.
arched (pushed) up the strata into which it was injected; lens-shaped body
Hot spots are also
areas of high volcanic and earthquake activity.
Cinder cone is a volcano that ____________________ EX: _____
consists of cinder-sized tephra, withlittle or no lava and are usually less than 200 m (656 ft.) high.; Sunset Crater (AZ)
Extrusive Volcanic activity occurs when _________________
magma flows out onto the Earth's surface and then cools to form igneous rock.
P waves or Primary waves are
push or compression waves.
Magnitude measures the _________________by the amount of shaking of the ground during the event as measured by a seismograph or seismometer. It is a ________________. * It is measured on the __________________(formerly the RichterScale), and considers the amount of fault slippage, the size of the area that ruptured, and the nature of the materials that faulted in estimating the magnitude of an earthquake.
total amount of energy released by an earthquake ; quantitative measurement; Moment Magnitude Scale
Holecene began _________years ago
10000
where was the 1886 major earthquake and what was its scale
1886 Charleston, SC (6.7)
Quarternery began _____________ years ago
2 million
Mesoszoic began __________ yrs ago ends at ________years
250 million; 65 million
the oldest rocks on the planet are how old
4 billlion years old
Palezoic- began ___________ years ago ends at __________ yrs
540 million; 250 million
Cenozoic began ___________years ago and were still in it
65 million
Tercheriary began_____________ yrs ago end of dinasours ended 2 million yrs ago
65 million
* A volcano's level of activity is classified as either:
Active wherein the volcano is currently erupting, has erupted during recorded history, or still has a high potential to erupt. Dormant refers to a volcano that is in repose (rest), but still has the potential to erupt in the future. Extinct refers to a volcano that has little or no potential to erupt again.
Primary features formed:
Anticline Syncline
Two basic types of Sedimentary rock:
Clastic and Non-Clastic
There are three basic types of convergent plate boundary:
Continental-Oceanic, Oceanic-Oceanic, Continental-Continental
Types of Plate Boundaries or Interactions: ________________________________
Divergent, Convergent and Transform
Two General Types of Eruptions: _________________
Effusive and Explosive
Geomorphic Processes are of two basic types:
External Processes Internal Processes
Two basic types of volcanism:
Extrusive and Intrusive Volcanism
Two basic types of Metamorphic rock: ___________________
Foliated and Non-Foliated
Three components of the Geologic Cycle:
Hydrologic cycle which is the movement of water (H2O) through all four of Earth's spheres. Evaporation, Condensation, Precipitation, Runoff and Infiltration. Tectonic cycle, which is the movement of crustal material, to include volcanism, earthquakes, plate tectonics, etc. Rock cycle refers to the formation of the three basic types of rock, igneous, sedimentary, and metamorphic.
Two basic types of igneous rock: _________________
Intrusive and Extrusive
* One small plate is of interest to the U.S., that being the _______________ plate which lies between the Pacific and North American plates in northwestern U.S./southwestern Canada.
Juan de Fuca
Two general types of material (lava): ________ and _________
Mafic; Felsic
* The zone of contact between the Uppermost mantle and the Crust
Mohorovicic Discontinuity or Moho.
Orogenesis (________________) * The _____________ that occurs when large-scale compression leads to deformation and uplift of the crust, as seen at convergent plate margins.
Mountain building; process of mountain building;
Three basic types of seismic waves:
P, S and L
Types of seismic waves: ___________________
P, S, and L waves
* By 1980s the term _______________ was developed, which combined the ideas of sea-floor spreading, continental drift, paleomagnetism and other ideas.
Plate Tectonics
* In 1960, Harry H. Hess and Robert S. Dietz proposed a theory of ___________________. ______________ is the idea that the movement of oceanic crustal material is the result or a mechanism of upwelling magma along a system of ____________________ and the pull of gravity at the other end of the plate. * The upwelling pushes the crust away from the ridge forming _______________, while pulling of the tectonic plate by gravity at the other end forms __________________.
Sea-Floor Spreading; Sea-floor spreading; mid-oceanic ridges; spreading zones; subduction zones
* __________________ along ______________ is a prime example of a divergent plate boundary. EX: Along ______________, or the formation of the __________ as the Arabian plate spreads away from the African plate.
Sea-floor spreading; mid-oceanic ridges; Mid-Atlantic Ridge; Red Sea
Types of Faults: ____________________
Tensional, Compressional, Shear
What causes the plates to move? * Near the end of Wegener's life, a __________________ was developed (1928), which added a mechanism for moving the continents, which Wegener had not done. This theory suggested that the continents were driven by___________________ More recently, another theory has developed that states * Most likely plates move as a combination of these two actions.
Theory of Thermal Convection; huge convective cells within the Asthenosphere.
Volcanic dome is _________________________-
a mound of lava which may form inside a crater and be a cap over the vent. It may also be the only surface feature from an eruption.
Isostatic rebound is _______________________ * This is also seen when a continental ice sheet forms, pushing down on the crust and then the crust rebounds as the ice mass melts. * Over a broad area, say continental or plate size, this is called ____________________
a process by which the crust is first depressed or sinks with added weight, thus pushing downward on the upper-most mantle and asthenosphere. As the weight (load) is removed, say by erosion, the asthenosphere pushes upward lifting the crust back to its original position.; warping or broad warping.
Lahar is ___________________. During the eruption of a volcano that is snow-capped, the heat of the magma melts the snow which mixes with any ash, soil, etc. on the mountain. This mix of ash, mud, and water then comes down the mountain side and may travel for dozens of miles. EX: One formed by the November 13, 1985 eruption of ____________ in Colombia killed over 20,000 of the ~29,000 townspeople of Armero, by covering the town in up to 100' of mud.
a special type of mudflow the result of a volcanic eruption; Nevado del Ruiz
Karst is
a type of landscape developed primarily by the chemical weathering (carbonation) of limestone.
Landform is
an individual element of a landscape, a mountain, a valley, etc.
Dip is the ___________________(which would be 0°). It indicates the _________________during the compression process.
angle (in degrees) at which the rock layer tilts from the horizontal ; amount of pressure exerted
Continental-Continental convergent plate boundaries ______________________________ * These are areas of __________________ and mountain building, both folded and fault-block mountains, often on both continental plates and thus _________________________ EX: The ______________ formed some 325-260 MYBP when the North American, African and Eurasian plates converged, and the _________________ currently being formed by the Indian plate converging with the Eurasian plate.
are areas where continental crustal material of one plate collides with continental crustal material of a second plate. There is little or no subduction of either continental plate, but subduction of oceanic material earlier may occur.; great compression; numerous earthquakes, but little or no volcanism.;Appalachians; Himalayas
Transform or Lateral plate boundaries are
are areas where plates are sliding past one another.
Convergent plate boundaries are
areas are under compressional stress and formed by gravity pulling the opposite end from a spreading ridge of a plate down toward the center of the Earth (slab pull). This causes the plate to collide with another plate, forming what is known as a subduction zone.
Oceanic-Oceanic convergent plate boundaries are ______________________________________________ * ______________ form at these boundaries and they are areas of high volcanic and earthquake activity * the formation of a _______________________(chain) is often common. These form on the plate that is not subducted EX: the ___________________________________
areas where oceanic crustal material of one plate collides with oceanic crustal material of a second plate. One plate will be subducted under the other and this is usually the faster moving plate or the one with more force moving it.; Deep trenches; volcanic island archipelago; Philippine islands, Japanese islands, and the Aleutian Islands of Alaska
* Intra plate earthquakes which are found not ___________________- This includes those which occur in Georgia, Missouri, Oklahoma and other areas of the U.S. away from the West Coast. These may be at continental hot spots like Yellowstone N.P.
at plate boundaries.
The ocean floor is primarily composed of _____________
basaltic igneous rock.
Clastic sedimentary rock forms from ________________________, such as the ___________, or _____________________. EX: ______________________, conglomerates
bits and pieces of former rocks that are/were visible pieces; sand at the beach; mud on a lake bottom, or soil material; shale, siltstone, sandstone
Mantle plume is a
buoyant mass of hot mantle material (magma) that rises to the base of the lithosphere. It commonly produces volcanic activity and structural deformation on the surface.
Basin is a
circular or elliptical downwarp (syncline), with the younger strata exposed in the central portion after erosion.
Dome is a ____________________
circular or elliptical upwarp (anticline), with beds dipping away in all directions from a central area.
Dynamic metamorphism is when the rearrangement of crystals in a rock is brought about by it _________________________. This occurs at convergent plate boundaries.
coming under high pressure and thus compacted or squeezed together
Strike is the __________________ of the________________(surface). It indicates the ____________________________.
compass direction; line of intersection between the rock layer and a horizontal plane ; direction of compression
Compressional or Reverse Faults are those which involve the _______________________
compression of crustal rock. The two pieces or blocks of crustal material are being pushed together which causes a shortening of the crust.
the Earth's interior is composed of or arranged in ____________________with heavier elements having settled toward the center and is the result of cooling since formation of the Earth, some 4.6 billion years before present (BYBP). * Each layer is distinct in __________________ and is either ___________or a combo of the two.
concentric layers or spheres, ; chemical composition and/or temperature (T°); solid, molten
Alfred Wegener, a German geologist and meteorologist, gave it serious consideration in 1912, and was the first scientist to suggest that ___________________________________for his idea in 1915.; evidence: __________________________ * Wegener proposed that one landmass existed some 225 MYBP (Triassic-Jurassic Period) and called it "Urkontinent", German for "primal continent" and analogous to the Greek ____________. This Pangea began to split over the next 10-20 million years. * By about 135 MYBP (Cretaceous Period) it had broken into two large pieces, ____________(basically present-day northern continents) and ___________(the southern continents). * His _______________ took a while to be fully accepted by the established scientific community, however, because he could not explain a mechanism for moving the plates.
continents were moving, and to supply some evidence ; similarities of fossil records, climatic records, and geologic records between distant continents, especially South America and Africa; Pangea; Laurasia ; Gondwana ; Theory of Continental Drift
Continental-Continental Continental-Oceanic ______________plate boundaries are areas where oceanic crustal material (which is of ______________ material) and continental crustal material (which is of ___________ material) converge. The oceanic crust is ___________ (pushed/pulled) under the continental crustal material and eventually remelted in the Asthenosphere. * This forms a deep underwater canyon or _________ on the seafloor at the area of subduction along the plate boundry * At the same time, continental crustal material is ____________, forming _______________, fault-block mountains and ___________________ as magma reaches the surface through cracks and weak points. * These are ___________________________ EX: _____________________ converge forming the Peru Trench and the Andes mountains (on the S. A. plate); also the Pacific northwest of the U.S. at the convergence of the _________________________
convergent ; higher density; lower density; subducted; trench; compressed; folded mountains; volcanic mountains; areas of numerous earthquake and volcanic activity; Nazca and South american plates; Juan de Fuca and North American plates
Sites of Orogenic events: * Primarily found at _____________________.
convergent plate boundaries
Plate Tectonics is the theory _________________________________
covering crustal movements and the foundation of crustal tectonic processes to include: upwelling of magma, plate movement
Eolian landforms are
developed by wind processes.
Cuesta is an ______________ formed on the __________________. It is a _______________ with a long, gentle slope corresponding to the dip of a resistant bed and a steep slope on the cut edges of the beds.
elongate ridge; tilted and eroded edges of gently dipping strata; symmetrical homoclinal ridge
Anticlinal Valleys and Synclinal Mountains are the result of _____________________
erosion of the original anticline and syncline.
Discontinuities
exist between layers and are broad, uneven transition zones from areas differing in chemical composition and/or density.;
The material may cool fast forming a fine-grained structure (______________rocks) or cool slowly forming a coarse-grained structure (__________________ rocks).
extrusive igneous ; intrusive igneous
Intrusive Igneous rocks are those that __________________ as the magma cools and crystallizes before it reaches the surface. The masses of rock formed in this process are generally known as __________.; EX: ______________
form below the surface, within the crust; plutons; granite, diorite; Stone Mt. (GA) is composed of granite
Fault is a ____________ in crustal rock _________________
fracture; involving the displacement (movement)of rock on one side of the fracture in respect to the rock on the other side.
* Because of this, the oldest oceanic crust (seafloor) is ________________________, and the youngest crust is at the __________
furthest from the ridge; ridge
Monocline is a _____________________, basically a half-fold. * The axis of the fold may be parallel to the surrounding terrain, or may ___________, dip (be tilted) along the axis.* In some areas and instances the rock strata may only be _________ and not folded.
gentle bend with a step-like form in horizontally bedded rock strata; plunge; tilted
Effusive eruptions are relatively ________________because they are associated with ______________ which flows more readily andgases can more readily escape, ________________.* If the eruption is through a vent, it may form a _______________. EX: _____________________ If the eruption is through a fissure, then it may form a ___________________ .EX: _______________ in the state of Washington (on land) and from mid-oceanic ridges under water to form sea floor.
gentle, non-violent events ; mafic magma; leading to less explosive eruptions; shield volcano; islands of Hawai'i, Galápagos islands, and Iceland ; plateau or flood basalt; Columbia Plateau
* The discovery of ________________, or paleomagnetism, first proposed in the 1920s and later connected to seafloor spreading in 1963, helped support the theory of sea-floor spreading and plate tectonics.
geomagnetic reversals,; paleomagnetism
Reverse faulting occurs along a steeply inclined fault plane in which the _______________ has moved upward in relation to the __________ and thus ____________it along the fault plane. This movement _______________________________
hanging wall; footwall; overrides ; results in the fault scarp of the hanging wall block overhanging the footwall.
Normal faulting occurs along a steeply inclined fault plane in which one block, the ____________, has moved downward in relation to the opposite block, the ______________. This movement results in __________________
hanging wall; footwall; the fault scarp of the hanging wall block not overhanging the footwall.
* Seismic waves change in both speed and direction with changes in the Tº and density of material they pass through. * Cooler material yields ____________________
higher velocities while hotter material yields slower velocities. AND changes in density of the material may reflect or refract the waves.
Echelon faults are a series of nearly parallel faults, either normal, reverse or a combination which forms a landscape known as ______________________
horst and graben topography.
GEOLOGIC CYCLE * The vast cycling of material that occurs in and on the lithosphere, encompassing the ___________________. It is the building up and wearing down of landforms involving various processes and events.
hydrologic, tectonic, and rock cycles
the GEOLOGIC TIME SCALE and ROCK CYCLE assumes superposition, the ___________________
idea that younger rocks and sediments are near the top of a formation, and older material is near the bottom.
PLATE TECTONICS * The theory of global dynamics in which the lithosphere is believed to be broken into _____________________ that move in response to convection of the magma in the Asthenophere and upper mantle.
individual pieces or plates
Seismograph or seismometer is an _____________________
instrument that measures seismic waves and earth vibrations.
Tensional or Normal Faults are those which ______________________
involve the stretching of crustal rock. The two pieces or blocks of crustal material are being pulled apart which causes a lengthening of the crust.
Mineral
is a combination of elements that forms an inorganic, natural compound which has specific qualities, such as a unique crystalline structure, hardness, etc.
Syncline
is a trough-like downfold with the limbs dipping toward the axis. This often forms a valley-like structure.
Anticline
is an arch-like upfold with the limbs (beds) dipping away from its axis (or hinge). This often forms a mountain ridge-like structure.
Topography or Topographic relief
is the vertical difference between the highest elevation above sea level and the lowest elevation over a given area, as measured above sea level.
Volcano is a __________________
landform with a vent, or fissure (crack) on the surface that is the end of a conduit originating from below the crust in theAsthenosphere, or mantle.
Fluvial refers to
landforms/features developed by flowing liquid water (rivers)
Batholith is a ________________________ EX: __________________________
large discordant mass of intrusive igneous rock,measuring over an area of at least 100 km2.; Stone Mt. (GA) is the exposed portion (pluton) of a larger mass;as are the Black Hills of South Dakota and the Sierra Nevada Mts.along the California/Nevada border. One batholith in Idaho isnearly 41,000 km2.
Caldera is the term given a _____________________, with a _____________________. This may be the result of collapse or subsidence,or may also result from an explosive event. EX: _______________________
large, more or less circular depression or basin associated with a volcanic vent; diameter often many times greater than the original vent(s); Crater Lake (Oregon, USA), Yellowstone National Park (WY, USA)
Mafic or basaltic lava is high in Mg and Fe, is composed of< 50% silica which makes it _____________, meaning it______________________. This leads to_________________
less viscous; meaning it flows readily (more easily); less gas being trapped within the lava mass, leading to a less explosive eruption.
Outer Core- * This layer is in a _____________but also ______________________ The material in this layer is under less pressure since there is less material on top of it. This causes its melting Tº to be lower, thus the material is in a liquid/molten state. It is 1800 miles bsl and 1400 miles thick.; * The Outer Core also _________________ Because this layer is molten and the material moves within the layer, it causes ________________
liquid/molten state; consists of Fe and Ni.; generates most (~90%) of the Earth's magnetic field.; fluctuation in the magnetic field over time.
L wave (surface wave) is a seismic wave of _______________________, but not through the Earth, and at slower velocities than either P or S waves. ** L waves spread out from the ______________________
long wavelength and low frequency that travels along Earth's surface, ; Epicenter of an earthquake.
* Magma often collects in a __________________
magma chamber below the vent or fissure before being expelled.
Contact metamorphism is the rearrangement of crystals brought about when ___________________________, and slightly (but not completely) melts it. This causes the crystals to move and rearrange.
magma comes in contact with the adjacent rock
Intrusive volcanic activity occurs when ______________________________________________________________ Two Main Types: _______________________
magma cools to form igneous rock below the Earth's surface and thus is only exposedby erosion or uplift. These are known as Plutonic Landscapes.Pluton is the exposed portion of a mass of intrusive igneous rock. ; Discordant and Concordant
* Orogenic belts (or orogens) are Earth's_____________________ EX:______________________________
major chains of folded and faulted mountains.; Rockies (Laramide Orogeny, 80-40 MYBP), Appalachians (Allegheny Orogeny, 325-260 MYBP
Non-Clastic sedimentary rock forms from the __________________ which were _____________________. The material is various salts and other minerals originally dissolved in a river, lake or ocean. EX: _______________________________________ Most caves are in _________________
minerals dissolved in solution (water); deposited as a solid after evaporation of the water; limestone, coal, evaporites (salts), chalk, gypsum; limestone
Foliated Metamorphic rock is formed when ___________________________. The like minerals are essentially drawn together into more homogeneous groups. EX: ________________________
minerals/crystals of the same chemical composition within the original rock form distinct bands or striations after metamorphism; gneiss (most common rock in athens county), slate, schist
Non-Foliated Metamorphic rock exhibits a __________________________________and few, if any, striations. It often forms from more homogeneous rock (few different minerals). EX: _____________________________
more homogeneous mixture of the crystals after rearrangement ; quartzite, marble, greenstones
Felsic lava is richer in silica (> 50%) which makes it ______________________. This leads to more gas being trappedwithin the lava mass and _____________
more viscous, meaning it flows slower; more explosive eruptions.
L waves or Surface waves which ________________ and are the waves __________
move through the surface/ground ; you feel in an earthquake.
Sill is a relatively _____________________. It can range from a few cm to hundreds of meters thick and may extend for several kms.
narrow mass of cooled magma that was injected between preexisting strata of the surrounding rock in a horizontal orientation.
Hogback is a ________________ formed on ________________. It is a sharp-crested, ________________formed by differential erosion of a resistant bed of steeply dipping rock. Often seen on _________________.
narrow, sharp ridge; steeply inclined resistant rock; asymmetrical homoclinal ridge ; eroded monoclines
External Processes are those that : Internal Processes are those that:
occur on the Earth's surface, such as fluvial, glacial, wind, coastal, etc. occur or originate within Earth's crust, volcanism, mountain building, massive crustal rearrangement (plate tectonics), earthquakes, etc.
Extrusive Igneous rocks are those that form _____________________as the magma cools and crystallizes after it reaches the surface. EX: ___________________________
on the surface, on the crust or as new crust ; lava or basalt, volcanic ash, obsidian, pumice
* A mountain building episode, called an _____________, occurs over millions of years
orogeny;
Distribution of Plates: * Currently at least 15-20 plates are recognized, with 8 major plates. * Major plates: __________________________ * Smaller plates: ________________________
pacific, north american, south american, eurasian, african, aulstrailian, insian, antarctic; Nazca, Cocos, Caribbean, Arabian, Somalian, Scotia, Caroline, Fiji, China sub-plate, and Philippine plates are some of these.
* The discovery of geomagnetic reversals, or ____________________, first proposed in the 1920s and later connected to seafloor spreading in 1963, helped support the theory of sea-floor spreading and plate tectonics.
paleomagnetism
Strike-slip faulting involves movement that has occurred ____________________. In true strike-slip faulting this ____________________. The movement may be described as ________________.
parallel to the strike of the fault plane.; no vertical displacement only horizontal displacement ; right-lateral or left-lateral
Transform or Lateral plate boundaries are areas where _____________________________________
plates are sliding past one another.
Nuée ardentes, or ______________ is a ______________________. EX: A flow created during the 1902 eruption of ______________on the islandMartinique, West Indies annihilated the town of St. Pierre, killing approximately 30,000 people.
pyroclastic flow; cloud of hot volcanic gas and ash that moves down the flanks of a volcano; Mont Pelee
Absolute ages are determined by _____________________
radioactive isotope dating methods.
Metamorphic Process and Rocks: * Metamorphism is a process which involves the ____________________is the process of Metamorphism. This can be accomplished by either ________________ , and is often done under high pressure (_________________metamorphism) and/or high temperature (______________ metamorphism) situations. The new material/rock is usually more compact , ____________, than the original material and thus harder.
rearrangement of rock crystals in an existing rock ; physical and/or chemical change; dynamic ; contact; denser
Glacial
refers to landforms developed by glacial ice (solid water)
Dike is a __________________________that ____________________. May be a few feet in diameter to several kms wide, long, and deep. The largest known dike is in Zimbabwe and is 600 kmlong and averages 10 km wide.
relatively narrow mass of cooled magma ; cuts across preexisting strata or other structural features of the surrounding rock in a vertical orientation.
Explosive eruptions are _______________because they are associated with _____________ that flows more slowing often solidifying in the conduit and thus ______________________________ * Explosive eruptions are commonly located along subduction zones and often have a high content of pyroclastics. * These eruptions are commonly through a vent, and form a _______________ EX: ________________________________
relatively violent events ; felsic magma; trapping gases, increasing internal pressure and causing violent, explosive eruptions. ; composite volcano or stratovolcano. Mt. St. Helens, Mt. Rainier, Mt. Pinatubo, Mt. Vesuvius
Coastal landforms are the
result by ocean waves and current processes.
* A spreading center (divergent zone) can also exist on a contienent where it may form _________________ EX: _________________________
rift zones or valleys; Great Rift Valley of East Africa, where the Somalian plate is pulling away (eastward) from the African plate.
The dip and strike are always at ________________to each other.
right angles
Know volcano diagram
see slides
Tsunami is a Japanese term referring to a _________________which is the energy passing through the water, generated by an earthquake whose __________________. These may travel at speeds up to 630 mph and form crested waves in shallow water as high as 200', sometimes thousands of miles from the epicenter.
seismic sea wave ; epicenter is on the sea floor
* Analysis of the behavior of __________________ also helps us understand the interior. Analyzing their speed and direction as they pass thru the Earth.
seismic waves (the energy waves produced by an earthquake)
Earthquakes may be classified as ___________(<63 mi depth), ____________ (63- 150 mi depth), and ___________ (>150 mi depth). Some quakes have been recorded as deep as 400 mi below the surface.
shallow ; medium; deep
An earthquake is a _______________________propagated through the Earth at the moment of rupture along a fault. The______________________. They are also associated with volcanic activity.
sharp release of energy resulting in a series of elastic waves ; rupture is initiated where stress along the fault exceeds the elastic limit of the rock so that sudden movement occurs
S waves or Secondary waves are
shear or shake waves.
Transform or Lateral plate boundaries are areas that undergo ____________________ EX: ____________________
shear stress as the plates slide laterally past one another. They are areas of high earthquake activity and some crustal deformation (creation of hills and small mountains), but no subduction or volcanism.; san andreas fault zone in southern california
S wave (secondary seismic wave) is a seismic wave of _______________in which ___________________ to the direction in which the wave travels. * It is thus a _______________
short wavelength and high frequency ; particles of the material vibrate at right angles; shear or 'shake' wave which moves material at right angles to its direction of movement. S waves cannot pass through the Outer or Inner Core layers.
P wave (primary seismic wave) is a type of seismic wave, propagated like a sound wave, of________________________________ in which * It is this a compression or 'push' wave which moves material _____________to its direction of movement. P waves can ____________________ of the Earth.
short wavelength and high frequency; the material involved in the wave motion is alternately compressed and expanded.; parallel ; pass through all internal layers
Pyroclastics or tephra are __________________. Quite common with felsic magma and explosive eruptions
solid fragments of magma expelled explosively from a volcano;
Volcanic neck is the ______________________ of an ancient volcano, that has been exposed by erosion. EX: __________________
solidified magma that originally filled the vent and neck; Shiprock (NM), Devil's Tower (WY)
* To describe the nature and orientation of these structures, and deformed rock layers, we use the terms, ________________________.
strike and dip
* Circum-Pacific Belt is associated with the ________________ around the Pacific Ocean. 80% of shallow earthquakes occur in this belt and the vast majority of _____________________
subduction zones; deep earthquakes occur at subduction zones.
Intensity is a __________________________ It is measured using the ________________, and is a qualitative measurement.
subjective measure of the size and damage of an earthquakeas equated by its impact on the human landscape (structures and activities).; Modified Mercalli Scale
* Crater is the ______________
surface depression at the summit of the volcano, often the vent or opening is in the crater.
Hot spot is the _______________________ EX: Hawai'i is an ____________, while the Yellowstone NParea is a_________________ Iceland is also the result of a mantle plume associated with a mid-oceanic ridge(divergent plate boundary).
surface expression of a mantle plume that has formed an opening in the crust, creating a conduit to the surface.; oceanic hot spot; continental hot spot.
Concordant plutons are intrusive magma features ____________________________________
that did not disrupt or change, melt, the existing geologic structure. It may move the existing rock or simply form by filling existing spaces.
GEOLOGIC TIME SCALE and ROCK CYCLE * Is a depiction or representation of _______________ using a sequence of rock strata arranged by both their relative and absolute age. It is thus both a ____________ and an ______________and is governed by ______________
the Earth's age and geologic history; relative time scale; absolute time scale; uniformitarianism.
** The P and S waves are generated at ______________________________
the Focus of an earthquake.
Footwall is _________________
the block or surface of rock beneath a dipping fault plane.
Hanging wall is _______________________
the block or surface of rock that lies above an inclined fault plane.
Shear or Strike-slip Faults are those which involve
the blocks of crustal material being moved laterally (horizontally) along a fault plane.
Topography refers to
the elevation changes of the Earth's surface over a given space or distance. The ridges, valleys, etc
Graben is
the elongate fault block that has been lowered in relation to the blocks on either side.
Horst is ___________________
the elongate fault block that has been uplifted in relation to the blocks on either side.
Fault scarp is
the exposed cliff-like face of a fault plane formed by faulting with a vertical displacement component.
Uniformitarianism is
the idea that the processes of change we see today are the same as they were in the past and will be in the future.
Geomagnetic reversals (paleomagnetism) refers to
the magnetic alignment of charged particles (especially iron material) in a rock which exhibit a symmetrical pattern as you move away from the mid-oceanic ridge. The polarity, the orientation of positive (+) and negative (-) particles to the Magnetic Poles of the Earth, changes as you move away from the mid-oceanic ridge. This occurs because as the upwelling magma cools forming new sea-floor (basalt), the charged particles of the iron in the magma are aligned according to the Earth's magnetic alignment. Different sections of magma cool at different times and thus the polarity changes as the magnetic alignment of the Earth changes. (Remember that the Earth's magnetic alignment changes because of the movement of magma in the Outer Core which forms the Earth's magnetic field.) (Paleomagnetism does not cause the plates to move. It only shows that they are moving.)
Lava is the term used for ___________________that is now ____________, as opposed to the term ________used for the molten rock that is still underground.
the molten rock issued from a volcano; on the surface,; magma
Focus is
the place of origin of an earthquake, the point from which the 'P' and 'S' waves originate. It may be at or near the surface, or deep within the crust or upper mantle
Epicenter is
the point on the Earth's surface directly above the focus of an earthquake and the point from which the 'L' waves spread out (originate)
Seismic waves are ________________. Transmission speed and direction can vary according to the T° and density of the various layers within the planet.
the pulses of energy generated by an earthquake that pass through the Earth as shock waves. ;
Tectonic landforms are developed by
the rearrangement of Earth's crust, driven by internal energy. Earthquakes, volcanoes, etc.
Fault plane is
the surface of contact along which blocks on either side of a fault move.
Folding is
the the process that bends, warps, deforms rock strata when subjected to compressional forces. Comely seen at convergent plate boundaries.
Discordant plutons are _____________________________________
those that disrupt or change, melt, the existing geologic structure into which it intrudes. It often creates the space it then occupies.
Sedimentary rocks are formed by a ________________in which existing material (rocks) ______________________________ (dirt, sand at a beach, mud in a river, etc.). These are often then transported and deposited some distance from the location of the original rock. The second step involves __________________ in the process of ____________________ to form new rocks.
two-step process ; are first weathered/eroded down into smaller pieces of the original rock called sediments; these sediments being "put back together"; Lithification
Phreatic eruptions are ________________made more severe by __________________, increasing pressure fromsteam, and increasing the explosive power of the eruption. EX: ____________(1883), Tambora (1815), Santorini (1645 BC)
violent, explosive eruptions ; water entering the magma chamber; Krakatau
Hydrothermal (Geothermal) Features * These are located in areas where ____________________ * This may be the result of ______________________________ * Or it may be the result of contact with a shallow magma chamber, sometimes associated with mantle plumes and hot spots. * Types:
water below the surface has been heated to temperatures higher than commonly found on the surface.; water flowing deep below the surface and heated as a result of the geothermal gradient (T° increases with depth at approximately 3°/100m).; hot springs, geysers, fumaroles, etc.
Divergent plate boundaries are ___________________________ * These areas are under _________________ and formed by the upwelling of magma (ridge push) and the pull of gravity (slab pull). They are areas of abundant earthquake activity and relatively mild volcanic activity.
where plates are moving apart from eachother; tensional stress
* To date, the oldest seafloor has been dated to ___________
~200 MYBP
