50 Cards in this Set
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Foreshocks
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activity before earthquake
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aftershocks
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small tremors following strong earthquakes. gradually diminish in frequency & intensity
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Where and why do earthquakes occur?
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Near plate boundaries due to the grinding of rocks past one another.
Earthquakes occur where tectonic plates move at boundaries. Transform Faults
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convergent boundary
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when two plates collide together
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divergent boundary
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plates move apart
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transform boundary
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when plates scrape past one another
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Benioff zone or wadati-benioff zone
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the band of earthquakes in a down going plate
controls subduction angle. the description of subducting zone angle and rate of subduction
fast rate = high angle
slow rate = low angle
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Intraplate earthquake
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An earthquake that does not happen on a plate boundary (very rare)
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What are some of the damages earthquakes cause
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Property damage
Loss of life
Physical or psychological trauma
Floods due to broken water mains
Gas leaks
Bridges buckle
Subways cave
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Earthquake Shaking: Control Factors
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earthquake magnitude
distance from the epicenter
local soil & rock conditions (solid vs. soft)
depth of hypocenter/focus
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Landslide
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Any mass movement of rock and/or regolith down a slope.
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earthquake prediction: when
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historic analysis; change in micro-elevation or topography; variation gasses, magnetic and electrical fields; animal behavior - could sense the early p waves
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Landscape
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Several different, primarily terrestrial ecosystems linked by exchanges of energy, materials, and organisms.
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Landform
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a natural shape we see on the surface of the earth
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What types of energy drive landscape evolution?
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- internal energy (heat within the Earth)
- external energy (energy coming to the Earth from the Sun
- gravitational energy (pulls rock/water from higher to lower elevations)
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what happens if the rate of uplift exceeds the rate of erosion
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diverted
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contour line
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lines that define the outer edges of forms and surfaces within a form, such as shapes or wrinkles and folds. used in contour drawings to suggest depth in addition to height and width
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Contour Interval
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The difference in elevation between two contour lines that are side by side.
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Factors Controlling Landscape Development
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agents of transpot and erosion: water, ice, wind
elevation distribution: relief, slope angle (steepness)
climate: mean temp. & precipitation amount
life: ecology/biota can weaken/stabilize the surface
exposed material type: erodibility
time.
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mass wasting
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aterm used to describe the movement of geological material (rocks, soils,sediments) under the effects of gravity
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Driving force behind Mass Wasting
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the weight of the slope material like vegetation, fill material, or buildings.
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common types of mass wasting
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creep
flows
rockfalls/rockslides
debris slides
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What is the fastest type of mass wasting process?
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rock avalanche
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Why do mass movements occur?
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* fragmentation and weathering
_ upper crust is broken by jointing and faulting
_ chemical and physical weathering produces regolith
_ surface material is weaker than solid crustal rock
* slope stability
_downslope force -gravity
_resisting force- material properties that repel moti…
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What 3 factors determine slope strength?
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Weathering
Vegetation Cover
Water
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Which mountain is called the “Top of the World” at 29,029 feet?
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Mt. Everest
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factors affecting deformation
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temperature: as temp increases, materials become more ductile
confining pressure: as pressure increases, materials become more ductile
rate of deformation: if stress is applied rapidly, rocks will tend to be brittle
composition of rocks: at the same temp and pressure, some rocks will b…
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3 types of stresses
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extensional, compressional, and shear
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Anticline
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upward folded arches
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monocline
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A geological structure in which all layers are inclined in the same direction.
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Syncline
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A trough or fold of stratified rock in which the strata slope upward from the axis.
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brittle deformation
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permanent change in shape or volume, in which a material breaks or cracks
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Ductile Deformation
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-Rocks deform by flow and folding
-Occurs in deeper crust
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exfoliation joints
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pressure release during erosion and fractures form like onion skin (things flake off)
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tectonic joints
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form as a result of tectonic stresses and movements. they show a systematic relationship
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Cooling Joints
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rocks (usually lavas at the surface or intruded
sills
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dome and basin
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dome - fold with the shape of an overturned bowl (older rocks in center)
basin - fold shaped like an upright bowl (younger rocks in center)
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two ways folds form
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flexural slip - layers bend, slip between layers
passive flow - soft rock behaves like a weak plastic
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mountain belt
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several mountains that lie parallel to one another
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Orogenesis
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Mountain building
Involves uplift, deformation, jointing, faulting, folding, foliation, metamorphism, igneous activity, erosion, and sedimentation
constructive processes build mountains up
destructive processes tear them back down again
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Isostasy
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a dynamic equilibrium between the lithosphere and the astenosphere
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craton
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is the stable interior of a continent undisturbed by tectonic events since precambrian time the past half billion years
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fossil
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A trace of an ancient organism that has been preserved in rock.
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What are the conditions for fossilization?
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1. Sterile, acid/base environments w/ few detrivores, bacteria, & fungi
2. low oxygen environments
3. sediment necessary to cover
4. quiet, isolated
5. near where lived / died
6. serendipity
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fossil types
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mineral rich
sedimentary
casts
trace
retain organic material
amber
ice/acid bogs
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trace fossils
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traces of ancient life including tracks, eggs, skin impressions, stomach stones, bite marks, and fossilized feces. These are the primary means by which paleontologists learn about dinosaur biology.
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Process of becoming a fossil
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1. die
2.decay--breaking down organic structures, but not too much or there is nothing left to fossilize
3. Burial- **essential element--get covered by sediment, eventually forming sedimentary rock
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How can fossils be found?
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1. buried before eaten or scattered.
2. escaped erosion, lava, water, wind
3.we have to actually find it.
4.hard bones or teeth.
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Distinguish between macrofossils and microfossils
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Macrofossils - fossils large enough to be seen with the naked eye
Microfossils - can be seen only with a microscope
Examples of microfossils - plankton, algae, bacteria, and pollen
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What are some distinctive invertebrate fossils of the Mesozoic?
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1 - Cephalopods,
2 - bivalves,
3 - gastropods
The Ammonoidea, Cephalopods with wrinkled sutures, constitute three groups: the goniatites, ceratities, and ammonites.
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GEOL 1040: Exam 3