geology exam 2
Rank each lava type according to the relative distance it can generally travel from a volcano vent before solidifying.
(least distance) felsic intermediate mafic (greatest distance)
Label the diagram of a convergent-margin orogen.
(left to right) incoming exotic terrane: outside sand in middle of water after incoming exotic terrane: active accretionary prism after active accrentionary prism: active arc after active arc: suture after suture: pluton after pluton: fold-thrust belt
Identify statements true of submarine landslides and tsunamis.
- As a submarine slide occurs, it can push water into a sea-surface bulge ahead of its path; this can result in tsunami initiation. - As a submarine slide occurs, it can result in a depression in the sea surface above the slide. A tsunami can form when water rushes in to fill the depression.
Which statements are true about brittle deformation?
- Brittle deformation can be preceded by small amounts of elastic deformation. - During brittle deformation, rocks can break or crack into pieces.
Select statements true of ductile deformation in solids. Note that ductile deformation is also called plastic deformation. Choose one or more: A.During ductile deformation, rocks can break or crack into pieces. B.Ductile deformation usually occurs at great depths and high temperatures. C.Ductile deformation is usually preceded by small amounts of elastic deformation. D.During ductile deformation, rocks can fold or bend.
- Ductile deformation usually occurs at great depths and high temperatures. - During ductile deformation, rocks can fold or bend.
Select statements true of the Hawaiian Hot Spot. Choose one or more: A.It has moved beneath the Pacific Plate over geologic time. B.It is no longer active. C.It produced the Emperor Seamounts. D.It produced the Hawaiian Islands.
- It produced the Emperor Seamounts. - It produced the Hawaiian Islands.
Identify statements true of landslides and tsunamis. Choose one or more: A.Landslides can trigger tsunamis by rapidly displacing a mass of ocean water. B.Landslides can trigger tsunamis by creating earthquake waves. C.Landslides and rockfalls are capable of producing only local tsunamis. D.Large landslides, such as those involving partial collapse of steep-sided islands, have triggered tsunamis of regional or global extent.
- Landslides can trigger tsunamis by rapidly displacing a mass of ocean water. - Large landslides, such as those involving partial collapse of steep-sided islands, have triggered tsunamis of regional or global extent.
Identify statements true of earthquakes.
- Most earthquakes occur along plate boundaries. - An estimated one million earthquakes occur each year, but most of them are small. - Most earthquakes are the consequence of plate tectonics.
Which statements are true about normal faults? Choose one or more: A.The hanging wall moves down relative to the footwall. B.The result is shortening of the crust. C.Their motion is dip-slip. D.They are associated with tensional stress.
- The hanging wall moves down relative to the footwall. - Their motion is dip-slip. - They are associated with tensional stress.
Which statements are true about reverse faults? Choose one or more: A.Their motion is dip-slip. B.The hanging wall moves up relative to the footwall. C.The result is shortening of the crust. D.They are associated with tensional stress.
- Their motion is dip-slip. - The hanging wall moves up relative to the footwall. - The result is shortening of the crust.
Which statements are true about synclines?
- They are the result of ductile deformation. - The limbs dip toward the hinge. - They form from compressional stress.
Which statements are true of anticlines?
- They form from compressional stress. - They have an arch-like shape. - They are the result of ductile deformation.
Select statements true of unconformities.
- Unconformities represent periods of non-deposition in the rock record. - There are three major types of unconformities - Unconformities represent periods of erosion in the rock record.
Which statements are true about strike-slip faults? Choose one or more: A.Vertical motion is minimal. B.They are associated with shear stress. C.Their motion is dip-slip. D.Magmas are generated during faulting.
- Vertical motion is minimal. - They are associated with shear stress.
geologic history of the orogenesis of the Appalachian Mountains
- a complex orogenic belt formed by 3 orogenic by 3 ("mountain-building") pulses - today are eroded remnants - a giant orogenic (mountain) belt existed before the Appalachians + grenville orogeny formed a supercontinent + much of it eroded away + rifted apart 600 ma + formed a new ocean (proto-atlantic) * eastern north America developed as a passive margin; thick pile of sediments, subduction zone - subduction carried the margain into the island arc - collision resulted in the TACONIC OROGENY - doubly dippling subduction zone developed - exotic blocks of continental crust carried in - these blocked were added to the margin during the ACADIAN OROGENY - ALLEGHENIAN OROGENY; africa collided with north america, assembled supercontinent PANGEA + pangea rift apart, faulting and stretching, divergent margin, sea floor spreading caused atlantic ocean
Stratovolcanoes can create several volcanic hazards both during and after eruption events. Based on the animation, place the following volcanic hazards in chronological order based on when they would likely impact a town near the volcano after an eruption occurs.
- a pyroclastic flow of lapilli and super heated gases - a lahar formed from volcanic ash mixing with quickly melted snow and ice - volcanic ash distributed by wind - a landslide caused by the collapse of coherent lava and friable ash deposits
The S-P value is a measure of the difference in time between the
- arrival of the secondary waves and the primary waves. - arrival of the shear body waves and the compressional body waves.
Identify examples of rock deformation
- breaking - shortening - bending - shearing
How can a submarine slide at the edge of a continental shelf create a tsunami?
- by pushing water being pushed into a bulge ahead of the advancing underwater debris flow - by the sudden drop of the seafloor as the mass of material breaks off the continental shelf
Identify clues to detect slumps before they move very far.
- cracked or displaced roadways - tilted utility poles - broken fences
increases stability of a slope
- decreasing the slope angle - terracing
Numerical Dating techniques
- dendrochronology (tree ring dating) - geochronology - measuring the ratio of radioactive elements to the products of decay
Cite natural phenomena that can cause tsunami formation.
- earthquakes - landslides - volcanic eruptions
relationship between earthquakes, fault types, and plate boundaries
- earthquakes occur at plate boundaries + shallow: divergent and transform boundaries * divergent-plate boundary: mid-ocean ridges + intermediate and deep: convergent boundaries * convergent-plate boundaries: shallow, intermediate, deep earthquakes
case studies: iceland
- hotspot - only example of mantle plume hot spot coinciding with a mid-ocean ridge
Seismographs
- instruments that record ground motion - weighted pen on a spring of traces movement of the frame
planes of weakness (failure surfaces)
- joints parallel to the land surface - saturated sand or clay layers - weak sedimentary bedding (shale, evaporites) - metamorphic foliation) failure triggers: - shock and vibrations - change in slope characteristics + angle, loading (water, waste, buildings) - changes in slope strength - removing support - slope strength - tectonic links
common hazards associated with earthquakes
- landslides and avalanches - liquefaction - fire - tsunamis - long-term recovery
Which tectonic processes are likely to be associated with earthquakes?
- mountain building - movement along plate boundaries - plate subduction - formation of ocean basins
Which of the following are methods used by geologists to predict a volcanic eruption? Choose one or more:
- observing changes in the shape of a volcano - measuring an increased incidence of earthquakes - measuring an increased occurrence of gaseous emissions - measuring an increase in heat flow
how deformation changes the character of rocks
- orogenesis applies stress (force/area) to rocks, causing deformation (bending, breaking, shortening, stretching, and shearing) - deformation results in: displacement, rotation, distortion
mountains
- reflect geologic processes of uplift, deformation, and metamorphism at work - occur in elongate, curvilinear belts.
decreases stability of a slope
- removing vegetation - saturating a slope with water - shaking a slope
The largest and most destructive tsunamis in human history have been associated with which of the following?
- subduction-zone earthquakes - volcanic eruptions
radioactive decay
- the half-life is the time it takes for half of unstable nuclei to decay - the half-life is a unique characteristic of each isotope
relative dating techniques
- using cross-cutting relationships to determine the age of an igneous intrusion - fossil succession
typical products of volcanic eruptions
- volcanic gasses: expelled vapor and aerosols - pyroclastic debris: fragments blown out of a volcano - lava flows: molten rock that moves over the ground. 2 types: pahoehoe (glassy) and a'a' (jagged, sharp, angular texture) + basaltic (mafic) lava flows are very hot, low silica, and low viscosity + basalt flows are often thin and fluid, which facilitates long flow distances - lava tubes - rhyolitic eruptions - pyroclastic flows - tephra - lahars: water rich debris flows - volcanic gas
case studies: krakatau
- volcano located between large islands in indonesia (java and sumatre) - erupted 2 months in may 20, 1883 - august 27th, island was obliterated in monstrous explosions and created a tsunami that killed 36,000 people in nearby islands
A horizontal line on the Earth's surface has a plunge of
0°
Order the steps in the formation of a nonconformity.
1) Sedimentary layers are deposited and lithified. 2) A granitic pluton intrudes sedimentary rock layers. 3) Erosion takes place, exposing the pluton at the surface. 4) Sedimentary deposition occurs again, covering the erosional surface.
Order the steps in the formation of an angular unconformity.
1) Sediments are deposited and lithified. 2) Regional mountain building takes place, and sedimentary layers are folded into anticlines and synclines. 3) Erosion takes place. 4) Sediments are deposited on top of an erosional surface.
Order the steps in the formation of a disconformity.
1) Sediments were deposited in a marine environment. 2) Sea level fell, exposing marine deposits subaerially. 3) Erosion took place. 4) Sea level rose, covering the erosional surface, which was buried by marine sediments.
Order events chronologically that can lead to a subduction-related tsunami.
1) The overriding plate "sticks" to the subducting slab. 2) The overriding plate deforms, and strain builds. 3) Slip occurs and the overriding plate moves back into position, displacing a large amount of the seafloor. 4) A bulge of water is created at the sea surface and spreads out as a series of waves.
Even though earthquake prediction is not highly reliable, what do geologists know about them? Choose one: A. We cannot predict when an earthquake will occur; we can only estimate the probability that an earthquake will occur over a set period of time. B. Recurrence intervals can provide a measure of annual earthquake probability. C. Earthquakes are more frequent along plate boundaries than at intraplate locations. D. All of the possible answers are correct.
All of the possible answers are correct.
Which of the following decreases the chances of a mass movement?Choose one: A. redistributing the mass on a slope by terracing B. pumping or draining water out of the ground along a slope' C. planting vegetation on slopes D. All of the possible answers are correct.
All of the possible answers are correct.
Which of the following statements about stress is true?
It may have different magnitude in different directions.
Sort attributes according to whether they are associated with faulting or folding.
Faulting - earthquakes - fracturing - brittle deformation Folding - ductile deformation
Identify the true statement.
Forest fires followed by heavy rains are likely to result in severe mud and debris flows.
Rank historical tsunamis based on their associated fatalities.
Highest Fatalities 1) Indonesia, 2004 2) Japan, 2011 3) Alaska, 1958 4) Greenland, 1995 lowest
Principle of Inclusions (relative dating
INCLUSIONS, or fragments of one rock contained in another, are OLDER than the rock they are found in
Plate tectonics theory explains why volcanic activity occurs where it does. Which example describes a geologic setting as it relates to its volcanic activity? Choose one: A. Krakatau is part of an Indonesian continental rift. B. Yellowstone National Park is part of a continental volcanic arc. C. Iceland sits on an oceanic hot spot located on the Mid-Atlantic Ridge. D. The Aleutian Islands are a chain of inactive volcanoes that formed above a hot spot.
Iceland sits on an oceanic hot spot located on the Mid-Atlantic Ridge.
case studies: mt. st. helens
Mt. St. Helens - dormant - may 18th, triggered earthquake and landslide that triggered a sideways blast, sheered and flattened 600 kl quare of forrest - killed 61 people - formed lahars
Match the following plate boundary characteristics to the corresponding fault type.
Normal Fault - associated with divergent plate boundaries Reverse Fault - associated with convergent plate boundaries Strike-Slip Fault - associated with transform boundaries
Which form of geologic dating is best used to identify when each rock type formed?
Numerical Dating - igneous - metamorphic Relative Dating - sedimentary
seismic waves (names and descriptions)
P-waves (vibration both ways, wave prep one way) - travel by compressing and expanding the material parallel to the wave-travel direction - fastest seismic waves, and they travel through solids, liquids, and gasses S-waves (wavy on top and bottom) - travel by moving material back and forth, perpendicular to the wave-travel direction - slower than P-waves, and they travel ONLY through solids, never liquids or gasses L-waves (wavy on sides) - surface waves travel along Earth's exterior - slowest and most destructive - L waves are s-waves intersect the land surface R-waves (wavy on top then flat on end) - R waves p-waves that intersect the land surface - most destructive
Which of the following lists the three Phanerozoic eras in order from oldest to youngest?
Paleozoic, Mesozoic, Cenozoic
Which of the following statements is true?
R-waves cause the Earth's surface to move up and down.
the amount of physical ground shaking
Richter scale
Why are geologists not able to date sedimentary rocks directly?
Sedimentary rocks are younger than their composite minerals.
Principle of Original Lateral Continuity (relative dating)
Sediments are deposited over a large area in a continuous sheet (laterally continuous with environment) ex) faulting, erosion, folding
Identify the true statement. Choose one: A. All of the possible answers are correct. B. Seafloor fracture zones are associated with frequent earthquakes. C. Earthquakes never happen in the interior of plates, only at their boundaries. D. Shallow-focus earthquakes are associated with divergent and transform boundaries; convergent plate boundaries also produce deep earthquakes.
Shallow-focus earthquakes are associated with divergent and transform boundaries; convergent plate boundaries also produce deep earthquakes.
Chemical composition is the primary control on the relative viscosity of a magma. Which of the following compounds is most influential in determining magmatic viscosity?
SiO2
Sort qualities of a slump scarp and toe.
Slump Toe - depositional feature - can break apart like small thrust faults Slump Scarp - exposes the failure surface - can break apart like small normal faults
Identify the true statement. Choose one: A. S-waves are compressional body waves, while P-waves are shear body waves. B. P-waves and S-waves are seismic surface waves. C. Surface waves typically have the largest amplitude. D. Surface waves are the first to show up on a seismogram recording of a quake.
Surface waves typically have the largest amplitude.
Identify the true statement.
The angle of repose is the steepest angle at which unconsolidated sediments can sit without slipping downhill.
Dipping sedimentary rock layers include a layer of basalt containing xenoliths of the overlying sedimentary rock. Which of the following statements must be true?
The basalt is a sill intruded into older sedimentary rock.
Principle of Superposition (relative dating)
The layers of sedimentary Rock/lava flows(beds of ash)are in layers from oldest @ the bottom & youngest @ the top.
What is true about volcanic activity in Yellowstone National Park?Choose one: A. The park has shield volcanoes. B. The park contains a 72-km-diameter caldera that formed during an eruption 600,000 years ago. C. Yellowstone is no longer active. D. All of the possible answers are correct.
The park contains a 72-km-diameter caldera that formed during an eruption 600,000 years ago.
Which statement describes glowing, hot, avalanche-like flows of tephra? Choose one: A. They are associated with basaltic volcanoes. B. All of the possible answers are correct. C. They are called pyroclastic flows, or nuées ardentes. D. They are associated with shield volcanoes.
They are called pyroclastic flows, or nuées ardentes.
Identify the statement that is true about tsunami events.
Tsunamis may be generated by underwater earthquakes, eruptions of island volcanoes, or submarine landslides.
What does the term uniformitarianism mean?
We can interpret the processes that formed ancient rock by examining the processes that form similar rock today.
Geologists use epochs to further divide geologic eras and periods. Put the following epochs from the Cenozoic Era in chronological order, from the earliest to the most recent.
Youngest 1) Pliocene 2) Miocene 3) Oligocene 4) Eocene 5) Paleocene oldest
What is the chemistry of the material that remains solid?
a mixture of mafic and intermediate minerals
volcano definition
a mountain constructed by the eruption of molten rock from earth's interior (directed consequence of plate tectonics and mantle convection)
A lahar is Choose one: A. a lava lake in a summit crater. B. a volcanic mudflow that resembles fluid concrete. C. a glowing cloud of pyroclastic fragments and hot gas. D. a collapsed volcanic structure.
a volcanic mudflow that resembles fluid concrete.
Riprap added to the base of a steep slope
absorbs wave energy and can slow the undercutting of coastal cliffs.
Which of the following would increase the risk of having a landslide?
allowing water to infiltrate a slope
Label the diagram of a stratovolcano
alluvial apron: furthest outward on left and right sides landslide: second furthest outward (brown) magma chamber: lava inside (bottom) of volcano crater: top opening of volcano summit vent: lava about to come out of top flank vent: lava coming from side
Nonconformity
an unconformity where igneous or metamorphic rocks are capped by sedimentary rocks
The locations of major earthquakes and volcanic eruptions
are usually along plate boundaries.
startovolcano
ash, clouds, left over debree
pyroclastic flow
avalanche of hot ash, gas, and debris
Mt. Vesuvius erupted in a very violent explosion in 79 C.E. and buried the residents of Pompeii in ash. On the basis of this information, which of the following would you LEAST expect to find at Vesuvius?Choose one: A. rhyolite lava B. basaltic lava C. lapilli (cinders) D. ignimbrite
basaltic lava
Which of the following is a method to prevent mass movements?
bolting loose rock to its substrate
Faults are examples of what kind of rock deformation?
brittle
Seismometers
can "feel" (or record) large earthquakes that happen on the opposite side of the world.
Liquefaction
can cause wet, silty, or sandy sediment to turn into an unstable slurry.
Which of the following is a method used to determine numerical age?
counting tree rings
Which of the following processes most logically explains the different tilts of gravestones in a hillside cemetery?
creep
types of mass movement that moves slowly
creep solifluction slumping
geologic events in earth history
deposition- of sediment and formation of rock strata erosion- of the crust such that a gap is formed in the record of past events intrusion- of plutonic and volcanic igneous rocks faulting- of crustal rocks. (a break between rocks) deformation- of crust rocks such that they become folded, tilted, or inverted
faults vs folds and types of each
dip slips normal faults: hanging wall slipping down, footwall goes up reverse faults: hanging wall moves up thrust faults: low angle - strike slip faults: fault motion parallel FOLDS: layered rock may be deformed into complex folds by tectonic compression - anticline (fold looks like an arch, away from hinge) - syncline (fold that opens upward, dip Inward towards hinge) - dome (a fold with the appearance of an overturned bowl, exposes older rocks in the center) - basin (fold shaped like an upright bowl)
A caldera forms by
draining of a magma chamber beneath a volcano during an eruption.
brittle vs ductile deformation (deformation types)
ductile deformation: rocks deform by flow and folding - ductile deformation occurs in the deeper crust brittle deformation: rocks deform by fracturing- faults and fractures - occurs in the shallow crust - joints and veins (openings in rock, fractures filled with minerals are called veins) transition between the two occurs at 10-15 km depth
earthquake definition
earth shaking is caused by a rapid release of energy, most of which is due to tectonic forces - common - occur daily - most are small
eruption styles
effusive- runny (mafic volcanoes) explosive- catastrophic eruptions (felsic)
Which term describes the current theory of earthquake formation?
elastic rebound
Mount Vesuvius
erupted violently with pyroclastic flows that destroyed the roman city of Pompeii (killed 20k people, covered people in mudslide)
The principle of fossil succession states that
every fossil species spans only a limited range of rock layers, corresponding to the time period over which it lived.
shield volcano
explosive, visible lava
During gradual heating of a rock, which type of minerals melts first?
felsic materials
faults
footwall- block below the fault hanging wall- block above the fault - if hanging wall moves down, it is a NORMAL FAULT - if hanging wall moves up, it is a REVERSE FAULT THRUST FAULT- lower angle, hanging wall above fault STRIKE-SLIP FAULT- two blocks slide past each other
hot spots are not caused by
plate boundaries
principle of fossil succession (relative dating)
fossils in lower layers are older than those in overlying layers - plants and animals change throughout time - index fossils are diagnostic of a particular geologic time - the fossil range describes the first and last appearance of a species
numerical dating
giving a feature an absolute age in years
The Vaiont Dam disaster
happened because a properly engineered dam was built in a geologically unstable location.
A shield
has Precambrian metamorphic and igneous rocks at its surface.
Low-viscosity lava Choose one: A. indicates an area that has high potential for explosive eruptions. B. could logically build a composite volcano. C. is most often a cool-temperature lava. D. has low silica content.
has low silica content.
Different types of lava have different viscosities, depending on their composition or temperature, or both. Label the types of lava flows based on their relative viscosities.
highest viscosity lava: most explosive intermediate-viscosity lava: medium lava explosion lowest-viscosity lava: lowest lava explosion
earthquake origins
hypocenter/focus- location where fault slip occurs, usually on a fault surface epicenter- the land surface directly above the hypocenter
Identify where igneous, metamorphic, and sedimentary rocks would be found on the image of a mountain below.
igneous rocks: closer to volcanoes sedimentary rocks: dirt/rocks
inclusions
inclusions must be older than the material they are in
Mass movement
is a gravity-driven downslope movement of natural materials.
Geologists base their estimate that the Earth is 4.56 billion years old on
isotopic dating of meteorites thought to be from primitive solids of the early Solar System.
Which of the hazards below accompany earthquakes?
landslides liquefaction fires tsunamis (incorrect: creep, pyroclastic flows, storm surge)
Principle of Original Horizontality (relative dating)
layers of sediment are generally deposited in a horizontal position
Do felsic minerals have a lower or higher melting temperature than mafic minerals?
lower
volcanic architecture
magma chamber- located in the upper crust craters- bowl-shaped depression atop a volcano fissures and vents- calderas- a gigantic volcano depression
Mudflows, debris flows, and lahars
mass movements that move at a variety of speeds, tends to follow river channels down valley, spreads out into broad lobes at the base of the slope, and able to carry huge boulders, houses, and cars
A tsunami
may be just a broad, gentle swelling out at sea but grows as it approaches shore.
tectonic plate motion is a dominant control on volcanism. volcanic settings are:
mid-ocean ridges: spreading axes convergent boundaries: subduction zones continental rifts: incipent ocean basins oceanic hot spots continental hot spots
Which of these types of volcanic settings produced 70% of the Earth's surface? Choose one: A. large igneous provinces (LIPs) B. flood basalts C. mid-ocean-ridge volcanoes D. hot-spot volcanoes
mid-ocean-ridge volcanoes
intensity of shaking; based on reports of shaking felt
modified Mercalli scale
Lava is Choose one: A. the most life-threatening volcanic product of any eruption. B. always produced during any volcanic activity. C. molten rock that cools and hardens on the Earth's surface. D. all of the same chemical composition, whether it is rhyolite or basalt.
molten rock that cools and hardens on the Earth's surface.
slip area and displacement on a fault
moment magnitude
mountain building (orogenic) processes
mountain building is a process called OROGENESIS mountain building may involve many geologic processes including: - deformation - jointing - faulting - folding - foliation - metamorphism - glaciation - erosion - sedimentation
What changes in the crust do scientists look for when using seismology and seismic networks to mitigate volcanic hazards?Choose one: A. the composition of gases coming from a volcano B. noise/vibrations caused by magma moving through rocks C. temperature changes in magma beneath the volcano D. lava flowing from a volcanic crater
noise/vibrations caused by magma moving through rocks
What type of unconformity occurs when sedimentary rocks overlie either igneous or metamorphic rocks?
nonconformity
Flexural-slip folds
occur when each layer of rock slips relative to the layers above and below it.
Principle of Uniformitarianism
processes observed today were the same in the past
Brittle deformation
occurs when many atomic bonds are broken quickly and rock pieces separate.
Jupiter's moon Io is thought to be volcanically active because Choose one: A. it has plate tectonics similar to Earth. B. of enormous tides that keep its mantle hot. C. it is continually bombarded by meteors. D. its interior is entirely liquid.
of enormous tides that keep its mantle hot.
Which of the following terms refers to the process of mountain building?
orogeny
earthquake waves
p waves: up and down (first) s waves: side to side surface waves: wavy, side to side rayleigh waves: curvy, most damage
any felsic magmas are produced when more mafic magmas chemically separate. What is the name of the process in which different minerals within a rock melt at different stages during gradual heating?
partial melting
Which of the following is a form of lava?
pillow
two methods of determining geologic time
relative dating - one geologic event is older than the other - the ranking of ordering of a sequence of geologic events absolute dating - a numeric age - primarily radiometric ages - three rings - some ice and sediment cores
the geologic time scale was made as a
relative time scale
relative vs absolute time
relative time= chronostratigraphic absolute time= chronometric-numerical age - uses radioactive decay of some elements to date the rock - generates a numerical age for the unit ex of simple absolute methods) trees, glaciers, some types of sediment
Viscosity
resistance to flow
types of mass movement that moves rapidly
rockfall lahar debris flow rockslide
The principle of lateral continuity says that
sedimentary layers began as continuous expanses of sediment.
volcano size and shape
shield volcano- the largest due to the fluidity of basaltic magma (low, broad, shallow slopes) stratovolcano- intermediate in size (cone-shaped volcano with steep slopes made of alternating layers) cinder cones- smallest (single symmetric cone with deep central crater)
Which of the following conditions will tend to make rocks change by plastic (or ductile) deformation rather than by brittle deformation?
slowly applied stress
What are slides with a spoon-shaped (concave side up) surface called?
slumps
Volcanic ash is
small shards of glass.
relative dating
specifying the age of one feature or rock layer with respect to others in a sequence
Select the answer that best describes a slump failure surface.
spoon-shaped
strain vs stress
strain: the change in shape caused by deformation stress: the force applied across a unit area - types of stress + pressure (object feels same on all sides) + compression (squeezes, shortens and thickens) + tension (pulling apart, stretching and thinning) + shear (sliding past, not thickened or thinned)
Place each of the four main types of seismic waves into the appropriate category based on where it travels.
surface waves - R-waves - L-waves body waves - P-waves - S-waves
principle of uniformities
surfaces of erosion or non-deposition
Rhyolite lava Choose one: A. may flow for many tens or hundreds of kilometers from a vent. B. has less silica than basalt lava. C. may form a lava fountain above the vent. D. tends to erupt explosively.
tends to erupt explosively.
Landslides are likely to happen when
the downslope force becomes greater than the resistance force.
deep time
the immense span of geologic time.
Classification of mass-movement events is based on
the type of material involved (rock, regolith, snow, and ice)
prediction limits
they CAN be predicted in the long term (tens to thousands of years) they CANNOT be predicted in the short term (hours and weeks) - earthquakes have precursors: + clustered foreshocks + crustal strain + level changes in wells + gases In wells + unusual animal behavior
the precambrian is 87% of Earth's history
true
types of volcanoes vary in eruptive style due to the COMPOSITION of the magma, which is determined by the plate tectonic setting
true
Lahars are a volcanic hazard that can occur both during an eruption and while a volcano is dormant. Which event below must happen for a lahar to form while a volcano is dormant? Choose one: - the dormant volcano reaches isostasy - the slope of the dormant volcano's flank exceeds its angle of repose - the opening of a fissure in the flank of the dormant volcano - very heavy rainfall over the dormant volcano
very heavy rainfall over the dormant volcano
Which of the following terms is used to describe a substance's relative ability to flow?
viscosity (ex: water)
stick-slip behavior (theory of elastic rebound)
when a fault moves, it is quickly slowed by friction due to asperities (bumps) along the fault. eventually, strain will build up again and cause another episode of failure and motion - resistance stress is overcome and breaks
principle of cross-cutting relationships (relative dating)
younger features cut across older features ex) faulting