Midterm 2 Review
Fault formation
rock bends elastically, then cracks. Cracks link to fracture which causes sliding and generates vibration (earthquake)
Biochemical sedimentary rock
sedimentary rock formed from material (such as shells) produced by living organisms
Where do most earthquakes occur?
seismic belts; along plate boundaries
How to detect earthquakes?
seismometer
syncline fold
-bends downward (U shape)
Why do waves refract as they approach the shore?
Friction wth the seafloor
Ripple marks
Small waves of sand that develop on the surface of a sediment layer by the action of moving water or air.
Uplift
Vertical rise of a mountain belt
Characteristics of lava flow are dependent on?
Viscosity
Where do rapids develop?
When a stream flows down steep gradients
Modified Mercalli Intensity Scale
characterizes earthquakes size based on ground shaking and of damage
Large gyres
circulate water around each basin
4 major classes of sedimentary rocks
clastic, biochemical, organic, chemical
Speleotherms
consist of stalactites, stalagmites, limestone columns when limestone percipitates out of water
Ephemeral streams
dry up for part or most of the year
hydrothermal metamorphism
due to the circulation of hot water in oceanic crust at mid-ocean ridges
clastic sedimentary rock
eroded grains accumulate and through lithification, loose sediments becomes rock
Blueschist
form in accretionary prisms
fold-thrust belt
form on continental edge of collisional and convergent boundaries
Veins
form when minerals precipitate out of water while passing through joints
extrusive igneous rock
formed from erupted lava
intrusive igneous rock
formed from magma that froze in the Earth
pyroclastic debris
fragmented material that sprayed out of a volcano (varies in size), fall from air or flows down the sides of the volcano
recharge area
Any area of land allowing water to pass through it and into an aquifer.
Deformation produces:
geological structures
Clastic rock classification
grain size
Fragmental igneous rock classification
grain size
Crystalline igneous rock classification
grain size + composition
A'A' lava
lava that hardens into rough, jagged rocks with a crumbly texture
Basaltic lava
low silica, flows easily
Low-grade rocks
low temp
Wetland features
marshes or mangrove swamps
dynamic metamorphism
metamorphism that occurs along faults, plastic shearing
Index minerals
minerals used to estimate the temperature, depth, and pressure at which a rock undergoes metamorphism
Felsic magma is
more viscous than mafic
Orogeny
mountain building event
Joints
naturally formed cracks in rocks (under brittle conditions)
intraplate earthquakes
occur within the interior of plates
dome fold
overturned bowl
Active continental margins host. . .
plate boundaries
Why are rivers becoming a vanishing resource
pollution, damming and overuse
Wadati-Benioff zone
the band of earthquakes in a subducting plate
shock metamorphism
the changes that can occur in a rock due to the passage of a shock wave, generally resulting from a meteorite impact
Minimize volcanic consequences
-assessment maps -evacuation plans
Eruptions occur
-crater at summit -fissures (magma rising through cracks)
Rate Magma Cools
-depth of intrusion -shape and size -groundwater circulation
Volcanic eruption hazards
-overrun towns -ash blanket -lava incinerates towns -landlsides +lahars bury land -earthquakes rupture structures -tsunamis wash away the coats -gases suffocate people and animals
metamorphic foliation
-preferred orientation -compositional banding
What causes deformation?
-stress -compression -tension -shear
What are the differences among coasts
-tectonic setting -sea level rising or falling - sediment supply - clear water
Eruptive style depends on
-viscosity -gas content
Cross bedding
Structure in which relatively thin layers are inclined at an angle to the main bedding. Formed by currents of wind or water.
Coriolis Force
The apparent force, resulting from the rotation of the Earth, that deflects air or water movement.
Reef bleaching
The death of algae that live in coral polyps is called _____ and may be the result of global increases in seawater temperature.
What creates deep currents?
Upwelling and downwelling
When does a flood occur?
When more water enters the stream than the channel can hold
When does earthquake/seismic activity happen?
When rocks slip during faulting
Where does groundwater flow?
Wherever a hydraulic gradient exists (from under pressure to where its not under pressure)
Does groundwater exit the ground on its own at a spring?
Yes
Diagenesis
a collective term for all the chemical, physical, and biological changes that take place after sediments are deposited and during and after lithification
longitudinal profile of a stream
a concave-up curve
What happens when water is pumped too quickly out of a well
a cone of depression
oblique fault
a fault where the motion is diagonal. A combination of vertical and strike-slip movement
Mud cracks
a feature in some sedimentary rocks that forms when wet mud dries out, shrinks, and cracks
Orogen
a linear range of mountains
accretionary prism
a mass of sedimentary material scraped off a region of oceanic crust during subduction and piled up at the edge of the overriding plate.
Evaporites
a natural salt or mineral deposit left after the evaporation of a body of water.
thermohaline circulation
a result of variatons in temepratue, salinity, density
thrust fault
a reverse fault in which the hanging wall slides over to the foot wall.
strike-slip fault
a type of fault where rocks on either side move past each other sideways with little up or down motion
reverse fault
a type of fault where the hanging wall slides upward; caused by compression in the crust
Active faults differ from inactive faults in that
active faults will have future movement while inactive faults ceased being active long ago
Cone of depression
an area lacking groundwater due to rapid withdrawal by a well
anticlines fold
arch-like
Sedimentary structures
bedding, cross bedding, graded bedding, ripple marks, dunes, and mud cracks
What are streams?
bodies of water that flow down channels and drain land surface
basin fold
bowl-shaped
Shields expose. . .
broad areas of Precambrian metamorphic rocks
How to protect beach property
build groins, jetties, breakwaters, and seawalls
Delta
A landform made of sediment that is deposited where a river flows into an ocean or lake
Caldera
A large, bowl-shaped depression formed by the collapse of part of a volcano.
Richter scale
A scale that rates an earthquake's magnitude based on the size of its seismic waves.
normal fault
A type of fault where the hanging wall slides downward; caused by tension in the crust
artesian well
A well in which water rises on its own because of pressure within the aquifer
Permeability
Ability of rock or soil to allow water to flow through it
What determines porosity?
Amount of open space in rock or sediment
effusive eruption
An eruption that yields mostly lava, not ash.
Graded bedding
Bedding in which the particle sizes become progressively heavier and coarser toward the bottom layers
How can earthquake hazards be reduced?
Better construction practices and zoning, and educating people on what to do in case of an earthquake.
How do water channels grow?
Downcutting and headward erosion
Precambrian Era
Earth's first era that began 4.6 billion years ago that includes creation of the Sun, Earth, the atmosphere, oceans and life
Where do mountains occur?
Elongate ranges-mountain belts or orogens
Volcano shape is dependent on?
Eruptive style
Magma Composition Range
FIMU Felsic Intermediate Mafic Ultramafic
True or false: it is possible to pinpoint the exact time and place an earthquake will occur?
False
Alluvial fans
Fan-shaped deposits of sediments dropped by streams flowing out of mountains (canyon mouths)
What builds ocean waves
Friction from where the wind shears across the surface of the ocean
What generates tides?
Gravitational pull of the moon
What is subsurface water called?
Groundwater
What causes uplifts of rifts?
Heating of the lithosphere.
Surface waves
L and R waves (surface of the Earth)
Partial Melting-Magma
More felsic
Where can you find belts of metamorphic rocks
Mountain ranges
Can streams cut below the base level?
No
Pore collapse
Occurs if water is drawn out of aquifer and replaced with air. This process permanently decreases the ability to hold groundwater.
What is the larges known volcano and where is it?
Olympus Mons-Mars
How have regions lost their groundwater supplies?
Overuse or contamination
Body waves
P and S waves (interior of the Earth)
Where do wide continental shelves form?
Passive-margin basins
Origins of igneous rock
Plate tectonics (magma forms at volcanic arcs and convergent boundaries)
Epicenter
Point on Earth's surface directly above an earthquake's focus
organic sedimentary rock
Sedimentary rock that forms from the remains of plants or animals.
What determines the location and orientation of caves
soluble beds and joints
stick-slip behavior
stop-start movement along a fault plane caused by friction, which prevents movement until stress builds up sufficiently
Water table
surface in the ground where pores contain some air and below where pores are filled with water
Slow-onset flood
take time to develop and tend to happen seasonally
Viscosity depends on?
temperature and composition
Cooling time controls
texture
Glassy igneous rock classification
texture and gas bubbles
discharge area
the location where groundwater flows back up to the surface
preferred orientation
the parallelism of inequant grains in a metamorphic rock
Hypocenter (focus)
the place where fault slip occurs
Metasomatism
the process by which a rock's overall chemical composition changes during metamorphism because of reactions with hot water that bring in or remove elements
orogenic collapse
the process in which mountains begin to collapse under their own weight and spread out laterally
Metamorphism
the process in which one type of rock changes into metamorphic rock
Downcutting
the process in which water flowing through a channel cuts into the substrate and deepens the channel relative to its surroundings
elastic rebound theory
theory that rocks that are strained past a certain point will fracture and spring back to their original shape
Stream's capacity
total quantity of sediment carried by a stream
discharge of a stream
total volume of water passing a point along the bank in a second
What are volcanoes?
vents where lava, debris, gases and aerosols, erupt at Earth's surface
What happens during the hydrologic cycle?
water infiltrates the ground and fills the pores and cracks in rock and sediment
Rocky coasts features
wave-cut platforms and sea stacks
How do engineers prevent floods?
building reservoirs and levees
Why does magma rise?
buoyancy and pressure; less dense than surrounding rock
How do geologists classify rock and sediment
by permeability
Fluvial erosion
can bevel landscapes to a flat plain
causes of metamorphism
changes in heat and pressure, differential stress, hydrothermal fluids
Dissolved ions
charged atoms or molecules in a water solution to form cement or veins
Where do coral reefs form?
clear, warm coastal waters in tropical areas
explosive eruption
clouds and debris
Braided streams
consist of a series of intertwined channels that are overloaded with sediment
What causes underground caves?
when limestone dissolves just below the water table
dynamothermal metamorphism
when rocks undergo heating and shearing during mountain building
Where does flow velocity slow
when water comes in contact with the walls or bed of the channel
Geological configurations that lead to spring formation
when water reached the surface through a fracture or porous layer (usually along faults)
Meandering stream
curves back and forth across a floodplain
Tides
daily rise and fall of sea level
What does groundwater contain?
dissolved ions
passive continental margin
do not coincide with a plate boundary
Current Theory of Earthquake Formation
elastic rebound
Ordinary well
fills with water because it penetrated ground below the water table
Darcy's law
flow rate depends on permeability and the hydraulic gradient
2 classes of metamorphic rocks
foliated and non-foliated
tectonic foliation
grains flatten, rotate, or grow so that they align parallel with one another
Earthquake damage results from:
ground shaking, landslides, sediment liquefaction, fire, and tsunamis
Flash floods
happen very rapidly
High-grade rocks
high temp
panhoehoe lava
highly fluid lava, smooth, ropy texture due to the abundant gas content, basaltic
Dunes
hills of sand formed by the wind
Non-foliated
hornfels, marble, quartzite
Seamounts and oceanic form above . . .
hot spots
What releases hot water to the Earth's surface
hot springs and geysers
Aquitards
impermeable
Intermediate-grade rocks
in between extreme temps
How does earthquake energy travel?
in the form of seismic waves
monocline fold
is a step-like
Streams erode. . .
landscape and carry the resulting sediment
Bedding
layering visible in rocks that results from the settling of particles during deposition
Magma
liquid rock under Earths surface
Lava
melted rock that reaches Earth's surface
thermal metamorphism
metamorphism caused by heat conducted into rock from an igneous intrusion
burial metamorphism
metamorphism due only to the consequences of very deep burial in a sedimentary basin
What is groundwater used for?
municipal water supplies, industry, and agriculture
Where do abyssal plains develop?
old, cool oceanic lithosphere
Cratons
old, large, stable block of the earth's crust forming the nucleus of a continent.
Shield
older interior region of a continent
How is the water heated in a hot spring?
passing deep in the crust or by proximity of magma
Andestic and Rhyolitic Lava
pile into mounts at vent
What are the results of groundwater overuse?
pore collapse or saline infiltration
Aquifers
porous and mermeable
chemical sedimentary rock
precipitated from water by either inorganic or organic means
What does metamorphism involve?
recrystallization phase changes metamorphic reactions pressure solutions plastic deformation metasomatism
Stream competence
refers to the maximum particle size a stream can carry
Karst landscape
regions where abundant caves have collapsed t o form sinkholes
During brittle deformation
rocks break into 2 or more pieces
During plastic deformation
rocks change shape without breaking
grain characteristics
roundness, sorting, composition
What varies with location and depth in seawater
salinity, temperature and density
What happens during longshore drift?
sand moves alng the beach and extends outward to form sand spits.
Regression occurs when
sea level falls and the coastline migrates seaward
transgression occurs when
sea level rises migrates inland
Seismograms
shows the different times earthquake waves arrive to detect epicenter location
Karst landscape terrains
sinkholes, natural bridges, and disappearing streams
Foliated
slate, phyllite, schist, gneiss, metaconglomerate
Predicting Eruptions
-Earthquake activity -Changes in heat flow -Chnages in the shape -Emission of gas and steam
Magma Formation
-Partial Melting -Decompression -Volatiles Diffuse Heat transfer
What happens during mountain building?
-Rock undergoes deformation (change its location, orientation, shape)
Lithification
The process that converts sediments into solid rock by compaction or cementation.
metamorphic zone
The region between two metamorphic isograds, typically named after an index mineral found within the region.
stream rejuvenation
The renewed downcutting of a stream into a floodplain or peneplain, caused by a relative drop of the base level
How does water in the ocean circulate?
Through currents driven by wind
True or false: a hill or mountain produces by volcanism is also a volcano
Tru
Tru or false: human activities have led to the pollution of coasts?
True
True or false: Evidence of eruptions have been found on the moons of Jupiter and Saturn?
True
True or false: Flood basalts cover portions of the moon
True
True or false: crustal thickening occurs at mountain ranges?
True
True or false: seismologists can determine the recurrence interval for great earthquakes
True
