Font size
WorksheetsStudy guide 2
Total questions: 163
Worksheet time: 2hrs 2mins
_______ _______ was a hypothesis proposed by Alfred Wegener, where Pangaea broke apart roughly ~200 Ma and shifted to the current position.
Continental Drift
What is Pangaea?
Supercontinent (continents fused together)
What was the evidence that supported continental drift hypothesis?
•Fit of the continents
Distribution of climate belts (glacier & swamp)
Distribution of fossils
Matching geologic units & mountain ranges
Why was continental drift hypothesis eventually discarded?
Didn’t provide a valid mechanism
What is the concept of seafloor spreading?
Harry Hess (American Professor)
Stretching apart at mid-ocean ridge forms new seafloor by volcanic eruptions.
Old seafloor is subducted at seafloor trenches.
To maintain Earth’s volume, amount of seafloor created at spreading centers must equal amount of seafloor destroyed at trenches in subduction zones.
Define Plate Tectonics Theory.
Lithosphere is broken into a series of plates that move
relative to each other
Move over underlying asthenosphere
What are the three types of plate boundaries?
What is the lithosphere?
Earth’s rigid outer shell (crust and uppermost mantle)
What is the asthenosphere?
Hotter and weaker rocks of the mantle
Beneath the lithosphere
Allows for gradual motion, slow flow
_________ plate boundaries are constructive margins, where
two plates move apart, and the mantle material upwells to
create new seafloor.
There are two types of divergent plate boundaries
_________ and _________.
Oceanic ridges at mid-ocean spreading centers from
basaltic lava (ex. Mid-Atlantic Ridge)
Continental rifts form at spreading centers within a
continent (ex. East African Rift Valley)
_________ plate boundaries are destructive margins, where
two plates collide, and the lithosphere is subducted into the
mantle.
What are the characteristics, features, and examples of
Oceanic-continential convergence ?
Denser oceanic slab sinks into the asthenosphere at
subduction zones
Pockets of magma develop and rise
Continental volcanic arc forms
Examples include the Andes (Southern America),
Cascades, and the Sierra-Nevadan system (North
America)
What are the characteristics, features, and examples of
Oceanic-oceanic convergence ?
Two oceanic slabs converge and one descends beneath
the other
Often forms volcanoes on the ocean floor
Volcanic island arc forms as volcanoes emerge from
the sea
Examples include the Aleutian, Mariana, and Tonga
islands (Pacific Ocean)
What are the characteristics, features, and examples of
continential-continential convergence ?
Two continents collide during continental collision.
Can produce new mountain ranges such as the Himalayas
________ plate boundaries are where plates slide past one
another and no new crust is created or destroyed
(earthquakes, but no volcanoes).
Transform fault
A good example of transform fault plate boundaries is the
_____________.
What is a hot spot?
Hot mantle material rises via rising
mantle plumes
Core-mantle boundary
Intraplate volcanism
Long-lived volcanic features
Ex: Hawaiian Island Chain and
Yellowstone
Define relative plate velocity.
The motion of a plate with respect to another
Define absolute plate velocity.
Rate of motion of a lithospheric plate with respect to a fixed reference point
What evidence supports the theory of plate tectonics?
Age & thickness of
sediment
Thin, younger near ridge
Thick, older further away
Hot spots and mantle
plumes
Paleomagnetism
Define paleomagnetism.
Remnant magnetization of iron- rich minerals (mafic/basaltic) in rocks
Polarity of Earth’s magnetic field is known to have experienced numerous reversal
Record of creation of seafloor
and motion of plates
What is subduction?
At convergent zones, oceanic lithosphere sinks into the
mantle
What type of rock is oceanic crust composed of?
Basalt, more dense
What type of rock is continental crust composed of?
ice
Granite, less dense
At a subduction zone, the down-going plate is
composed of what type of crust?
What is the main reason for differences in elevation
between continental and oceanic crust?
What are the 3 mechanism for plate motion?
Slab-pull
Ridge-push
Convection
What is convection?
Due to Earth’s internal heat
Heat transfer that involves movement
Less dense material rises
More dense material sinks
What is the most important driving factor of plate tectonics?
Slab-pull
Is the Earth mostly solid or molten?
Solid
Why is the Earth mostly solid even though temperatures
within the Earth are hot enough to melt rock?
Pressure too high
What factors aid in melting solid rock?
Addition of volatiles, especially water
Addition of heat
Decompression
Partial melting
• Heat-transfer melting
Where does decompression melting
occur?
Hot spots
Divergent plate
boundaries (continental
rifting & mid-ocean
ridges)
What are the 3 factors that determine the
violence of an eruption?
Composition of the magma
Temperature of the magma
Dissolved gases in the magma
What is the 2 major dissolved gases (volatiles) in magma?
Water and carbon dioxide
________ is a measure of a material’s resistance to flow.
What does viscosity control?
How fast a fluid flows.
What is viscosity of magma dependent on?
Temperature
Silica content
Volatile content
Melting occurs at subductions zones along convergent plate
boundaries due to what process?
Flux melting
Why does flux melting occur?
Water acts as a flux
Water lowers the melting temperature
At convergent plate boundaries, what type of volcanic feature
forms?
Continental volcanic arc
Volcanic island arc
How does the composition of the magma change with
partial melting?
Mixtures of minerals & melting over range of temperatures
Produces magma with higher silica content than original rock
What is the active zone of volcanoes that surrounds
the Pacific ocean?
What type of basaltic lava resembles
braids in ropes?
Pahoehoe lava
What type of basaltic lava
resembles rough, jagged blocks?
Aa lava
These pyroclastic materials are defined as:
Ash/dust-fine, glassy fragments
Pumice-from “frothy” lava
Lapilli-“walnut” size
Cinders-“pea-sized”
Particles larger than lapilli
Blocks -hardened lava, angular
Bombs - ejected as hot lava,
aerodynamic
Define effusive eruptions.
Low viscosity, basalt
Define explosive eruptions.
High viscosity, andesite & rhyolite
Define the characteristic of a shield volcano.
Broad, slightly domed
Made of layers of basaltic (fluid) lava
Effusive eruption
Generally large size
e.g., Mauna Loa in Hawaii
Define the characteristics of a cinder cone.
Piles of pyroclastics (mainly lapilli) fountain out of a vent
• Effusive eruption
• Steep slope angle
• Rather small size, less than 300 meter high
• Frequently occur in groups
Define the characteristics of a cinder cone.
Define the characteristic of composite cone (or stratovolcano)
• Most are adjacent to the Pacific Ocean (e.g., Mt. Rainier)
• Explosive eruption
• Large size
• Interbedded lavas and pyroclastic
• Most violent type of activity
What is a pyroclastic flow?
• Produced by composite cones
• Fiery pyroclastic flow made of hot gases infused with ash
• Flows down sides of a volcano at rapid speeds, up to 200 km
(125 miles) per hour
Define active volcano.
Actively erupting, erupted within the last 10,000 years
Define dormant volcano.
Active but not currently erupting
Define extinct volcano.
• Can never erupt again
• Completely eroded away, etc.
What is a volcanic neck?
• Resistant vents left standing after erosion has removed the
volcanic cone
• Shiprock, New Mexico
How does a crater differ from a caldera?
• Crater is smaller
• Caldera is greater than 1 km in diameter
• Formed by withdraw from magma
chamber and collapse
• Example: Crater Lake
What are some of the short-term indicators of a volcanic
eruption?
• Earthquake activity
• Changes in heat flow
• Gas and steam emission
• Changes in shape
What is a lahar?
A volcanic mudflow.
What is intrusive?
• Formed from magma
• Formed within the Earth
What is extrusive?
• Formed from lava
• Formed at surface of Earth
What is a pluton?
Underground igneous body
What is a dike?
• Tabular intrusion that cross-cuts the surrounding layers of
sedimentary rock
What is a sill?
Tabular intrusion that lies parallel to surrounding layers of
sedimentary rock
What is a laccolith?
Mushroom (or lens) shape intrusion that form due to inflation
of magma along a sill. It up arches the overlying layers.
How does columnar joining form?
Shrinking inward in a hexagonal shape while the magma cools.
What are the features of a batholith?
Largest discordant
intrusive body
• Often occur in groups,
where plutons merge
• Surface exposure 100+
square kilometers
• Frequently form the
cores of mountains
Can scientist predict earthquakes?
No reliable way to predict earthquake in short-term or long-term.
Where are the majority of earthquakes distributed?
• Tectonic plates boundaries
• Shallow: Transform & divergent boundaries
• Shallow, intermediate, deep, ultra-deep: Convergent
boundaries
What 2 zones have the greatest amount of seismic activity?
Circum-Pacific belt
Alpine-Himalayan Belt
The _______ is the point within Earth where an earthquake takes
place.
Focus (hypocenter)
The ________ is the point on the surface of the Earth that lies
vertically above the focus.
Define earthquakes.
Shaking of the Earth caused by the rapid release of energy
caused by a sudden deformation within the Earth
Define fault.
• Fractures along which sliding or slip takes place
• Rock on opposite sides is offset by an earthquake-induced slip
Define displacement.
Quantity of motion that occurs along a fault
Define seismograph.
• Machine that measures the
size of earthquakes.
Define seismogram.
Record created by earthquakes waves
How do scientist locate the epicenter of an earthquake?
• Use the difference between the P & S waves to determine
distance to epicenter (360 degrees)
• Three seismic station needed to locate epicenter
What are the defining characteristics of P-waves?
• Push-pull (compressional)
motion
• Travel through solids,
liquids, and gases
• Fastest velocity
• Body waves
What are the defining characteristic of S-waves?
• “Shake” motion
• Travel only through
solids
• Slower velocity than P
waves
• Body waves
What are the defining characteristic of S-waves?
What are the defining characteristic of surface waves?
• Greatest destruction
• Travel at the slowest
velocity
What are the defining characteristic of surface waves?
What are the defining characteristic of Rayleigh (R) waves?
• Vertical undulation
• Like ocean wave
What are the defining characteristic of Love (L) waves?
Side-to-side motion
• Damaging to building
foundations
List some hazards that can occur from an earthquakes.
• Ground shaking and displacement
• Landslides
• Sediment liquefaction
• Fire (pipes broken)
• Tsunamis
• Disease
Define tsunami
Sea wave generated by a displacement of water.
Define liquefaction.
• Water saturated soil that mobilizes during an earthquake
and behaves more like a fluid.
What major factors determine structural damage caused
during an earthquake?
• Intensity/magnitude of the earthquake
• Duration of the vibrations
• Nature of the material upon which the
structure rests
• Design of the structure
How did scientist gain knowledge of our Earth’s interior?
• Behavior of P and S waves as travel through the Earth
What are the different layers of the Earth?
• Crust (surface)
• Mantle
• Outer Core
• Inner Core (center)
Which layer makes up 80% of the Earth?
What is the composition of the mantle?
• Peridotite (olivine)
What is the composition of the core?
• Iron and nickel alloy
What state is the inner core?
Why are S-waves unable to pass through the Earth's outer
core?
Outer core is liquid
• S-wave shadow zone
_________ is based on the measuring amplitude of the
seismic waves.
• Magnitude
The ___________ is measured using the amplitude of the
_________ seismic wave. But does not estimate adequately the
size of very large earthquakes.
Richter scale, largest
What 2 factors are Moment Magnitude based on?
• Amplitude
• Displacement
Define seismic risk assessment.
• Long-term prediction method
• Estimate the probability that an earthquake will happen
during a specified period of time
Define recurrence interval.
Average time between earthquakes
What is evidence used in paleoseismology?
• Offset layers
• Sand volcanoes
Define uplift.
• Upward movement
• Produces mountains
Define subsidence.
• Downward movement
• Produces basins
What drives uplift and subsidence?
Plate tectonics, internal energy
Define mass wasting.
Gravity-driven movement of materials downslope from higher
elevations to lower elevations
Define weathering.
Chemical and physical weathering break rock apart.
Define erosion.
Movement or transport of material due to a mobile agent (running
water, waves, wind, ice, etc.)
What is physical (mechanical) weather?
• Breaking of rocks into smaller pieces
What is chemical weathering?
• Chemical transformation of rock into one or more new compounds
What is the relationship between physical and chemical
weathering?
What powers external processes?
Solar Radiation
What powers internal processes?
Earth’s interior energy
How does the angle of repose vary for different materials?
What is the relationship to water and sand particle
cohesion?
What are mass wasting triggers?
• Saturation of the material with water
• Oversteepening of slopes
• Water pressure
• Removal of anchoring vegetation
• Ground vibrations from earthquakes
• Weathering
• Removal of material at base of slope
What climate has the highest chemical weathering rates?
• Hot, wet climates
Define slump.
• Mass wasting that occurs when a relatively coherent rock or
regolith block moves along a concave-up, curved surface
Define mudflow.
• Saturated regolith or soil containing up to 30% water mixed with
mostly clay (fine-grain material) that flows down a slope
Define debris flow.
• A mudflow that contains cobbles and boulders suspended in the mud
Define rock slide.
Mass of rocks detaches from it substrate on a inclined failure
surface and moves downslope.
Define lahar.
• Mudflows or debris flows associated with volcanoes that
consist of a mixture of volcanic ash, pyroclastic debris,
and water
What is creep?
• Slow downslope movement of regolith.
What are some of indications that creep is occurring in this
area?
How much of the Earth’s water is saline?
97%
How much of the Earth’s water is freshwater?
What percentage of freshwater is frozen in glaciers and ice caps?
69%
What is the hydrologic cycle?
Transfer of water around the Earth System from one reservoir
to another
What is precipitation?
Rain, sleet, snow or ice fall from clouds to land surface
What is runoff?
• Water flows over land surface
• Flows into rivers, lakes, and the ocean
What is infiltration?
Water seeps or percolates into the ground
What is evaporation?
Liquid water changing into a gas
Define drainage basin.
Overall region that is drained or contributes water to a river
system
Define divide.
• Boundary between drainage basins, high point
What is base level?
• Ultimate base level: sea level
• What streams are eroding down to
Which results in a change in base level?
• Uplift of land surface
• Drop of sea level
What are the three zones in a river system and
the characteristics?
Which drainage network is this?
Rectangular (forms jointed bedrock)
Which drainage network is this?
Which drainage network is this?
Dendritic (uniform bedrock, gentle slope)
Which drainage network is this?
Trellis (alternating resistant/weak rock)
Which drainage network is this?
Radial (high point in middle)
Which drainage network is this?
Parallel (uniform bedrock with slope)
Define meandering stream.
•Snake-like curves in a stream channel
Define braided stream.
•Consist of a series of intertwined channels that are overloaded with
coarse-grain sediment.
What is a meander that is still filled with water that is cut off and
isolated from the main channel?
What is competence?
Maximum particle size that a stream can carry.
What is capacity?
Total quantity of sediment a stream can carry
What is discharge?
Volume of water in a channel passing a point in one second.
How are sediments transported in the stream?
•Dissolved load (invisible)
•Suspended load (suspended, clay & silt)
•Bed load (move along bed, sand to boulder)
Define Aquifer.
•Sediment or rock with high porosity and permeability
Define Aquitard.
•Sediment or rock with relatively low permeability;
relatively impermeable layer of rock or sediment
Define Porosity.
•Total volume of open space within a material specified
as a percentage
Define Permeability.
•Ability of a material to allow fluids to pass through an
interconnected network of pores
What are some of the issues of groundwater use?
•Contamination
•Heavy pumping
•Subsidence
Why does flooding tend to be worse in heavily populated
areas?
•Impervious cover, parking lot & roads
•Does not allow water to infiltrate into ground
•Follows into river and goes overbank faster
What is a flowing artesian well?
Water in the well rises higher than the initial groundwater
level without pumping
Define water table.
• Top of the saturated zone
When large quantities of water is pumped from a well, a lowering
of the water table is produced. What is this depression called?
• Cone of depression
What are some features associated with Karst topography?
•Limestone bedrock dissolved by groundwater
•Caves/caverns
•Sinkholes formed from cavern collapse
•Disappearing streams
•Perhaps artesian wells
What are speleothems that hang from the ceiling of cavern?
What are speleothems that grow upward from the ground of a
cavern?
What are speleothems called if a stalagmite and stalactite
merge forming a column shape?
What is the most important erosional agent (even in the desert)?
Running water
