Studied by 83 peopleWhat are the 5 principles of relative dating?
Sediments deposited in horizontal layers Younger Sediment on top of older units Younger sediment has pieces of older rock Younger rock can cut across older rock Younger rocks can cause changes along their contacts with older rock
What is an angular unconformity?
if underlying rocks are tilted before formation of the erosion surface
What is a nonconformity?
Erosion forms on top of rocks that aren't layered
What is a disconformity?
if rock layers aren't tilted before they are overlapped by younger layers, but the boundary still represents millions of years of time
How are half lives distributed along parent and daughter atoms
every 50% of atoms are taken away from parent every half life, daughter receives same amount P=110-50-25 D=0-50-25
What are the four chapters of earth's history from youngest to oldest?
Cenozoic, Mesozoic, Paleozoic, and Precambrian
What was in the Cenozoic Period?
Mammals
What was in the Mesozoic Period?
Dinosaurs
What was in the Paleozoic Period?
Marine animals, fish, plants, and insects
What was in the Precambrian Period?
bacteria and algae
How do fossils change through a section of rocks?
they change upward through the sections of rock, leaving similar fossils in many rock layers, sometimes restricting to a layer or two
How was the geologic timescale developed?
It was developed to correlate rock units to describe geologic time, and it was separated by major changes in fossils and mass extinctions
Describe some evidence that suggests earth has had a long history
Tree rings, ice cores, 4.4 billion year old rocks,
What were the environments of early life in earth?
not a lot of oxygen was in the atmosphere before Precambrian organisms created oxygen, making it an oxygen rich environment. More complex organisms appeared during the Paleozoic era
What is the Cambrian explosion?
rapid evolutionary change in the Cambrian period that caused many new shelled organisms to appear on earth
Contrast the organisms from both the Mesozoic and Cenozoic Era
Early Mesozoic: small dinosaurs/mammals Middle Mesozoic: diverse marine animals and dinosaurs Late Mesozoic: diverse insects, plant eating dinosaurs, ocean thrived
What are the events that caused devastation near Indonesia in 2004?
faulting uplifted the Eurasian plate, displacing seawater and causing movement on the fault for several minutes. This caused an immense tsunami.
Describe how earthquakes and seismic waves are caused by volcanoes
Stress is released by: -volcanic eruptions (causing compression and transmits energy through seismic waves) -magma explosions (pushes rocks out of the way, uplifting earth's surface causing volcanic tremors)
Describe how earthquakes and seismic waves are caused by landslides
Landslides shake the ground as they break, causing seismic waves
Describe how earthquakes and seismic waves are caused by humans
Human activities like filling of reservoirs behind dams, and disposal of wastewaters for oil and gas also cause earthquakes. (compressing earth's surface by flexing and faulting)
What is a hypocenter?
place where earthquake is generated
What are normal faults?
hanging wall move down with respect to footwall
What are strike-slip faults?
two sides of the fault slip past each other horizontally (can cause large earthquakes)
What are reverse faults?
hanging wall moves up with respect to the footwall
How are earthquakes distributed and occurred?
Earthquakes occur along plate boundaries, as well as regions of elevated topography, active volcanism, and faulted blocks
12.3 How do you recognize a subduction zone?
Explain how earthquakes are associated with subduction zones
a subduction zone, where an oceanic plate underthrusts beneath another oceanic plate or a continental plate, undergoes compression and shearing along a plate boundary, causing earthquakes
What are P waves (primary waves)
fastest seismic wave that compresses the air through which it travels and travels through solids and liquids
What are S waves
2nd fastest seismic waves that shear the rock side to side or up and down perpendicular to the direction of travel and cannot travel through liquids
What are Rayleigh (vertical surface) waves?
displaces the surface in a vertical direction and moves up and down in an elliptical path. It also causes most damage in an earthquake.
What are Love (horizontal surface) waves?
it vibrates horizontally and shuffles side to side and is perpendicular to the direction in which it travels. It causes buildings to slide sideways off their foundations.
How are seismic waves recorded? What are they order that the waves arrive to the machine recording the waves?
through a seismometer, which detect earthquakes. p-waves, s waves, then surface waves arrive to the seismometer, in order of what arrives first.
How can seismic record tell which one is closer to the epicenter?
By detecting how big each wave's P-S interval is (time interval between P and S wave) If interval is shorter (wave is shorter) then it's closer
How do you use arrival times of P and S waves to locate an epicenter?
Distance calculated from P-S Interval is how far away the waves are from the epicenter
How can earthquakes cause destruction both during and after?
Seismic waves, falling buildings, Aftershocks, liquefaction (loss of grain-to-grain contact on water-saturated sediment), and tsunamis cause damage during an earthquake. Fires, flooding, and uplift can cause damage after an earthquake
How do you limit your risk from earthquakes?
research earthquake hazard maps, use computerized warning systems/backup generators, and living away from faults can help
What occurred during the Tohoku Earthquake of 2011?
An earthquake occurred along an oceanic trench along the subduction zone (plate boundary) that caused magnitude 6 aftershocks. A tsunami formed a fault rupture grew upward
What occurred during the earthquake in Haiti?
An earthquake occurred at a strike-slip fault that was within a zone of complex faulting and caused numerous aftershocks, killing people through collapsing buildings
What occurred at the Canterbury/Christchurch earthquake in New Zealand?
The earthquakes occurred at a transform plate boundary and occurred on two different yet related faults. The first was a 7.1 magnitude but caused moderate damage and the second was smaller but killed many people through expulsion of water
Why does death and damage vary across earthquakes?
Damage and death are caused by poorly constructed buildings and tsunamis, as well as being situated along subduction zones or other areas.
How are tsunamis generated during an earthquake?
seafloor is unevenly uplifted or downdropped
How are tsunamis generated during a landslide?
A large mass of rock or shifting from one part of the water to another displace the water
How are tsunamis generated from eruptions?
collapsing of calderas, as well as the ground shaking
How come certain areas experience earthquakes while others don't?
Certain locations are along plate boundaries and are tectonically active
How do geologists do long-range forecasting and short-range prediction?
long-range forecasting is based on where earthquakes occurred in the past short-range forecasting is based off of monitoring the activity along an earthquake-prone fault (foreshocks)
How do volcanic inclusions provide observations of the subsurface
can infer the geologic processes that created the rocks at depth
How do mines provide observations of the subsurface
tunnels provide continuous exposures of rocks and structures
What is measured along the various types of geological surveys?
magnetic, seismic, gravity, and electrical
What are geophones?
seismic receivers stuck in the ground
What are drill cores?
samples of rock that are retrieved during the drilling process
How are magnetic data portrayed?
red=more magnetic blue=less magnetic
How is gravity measured?
gravity meters
What are refracted waves?
bending of energy as it crosses the boundary
How do seismic waves pass through the crust and mantle?
closer to the earthquake, waves that travel to crust arrive first farther than earthquake, waves that travel through mantle arrive first
How do you use seismic waves to infer the diameter of the core
as P waves and S waves travel through earth, they are refracted. They pass through the core
How do you use seismic waves to infer that the outer core is molten?
P waves reflect and refract around earths core. S waves cannot pass through the core
What are 3 ways we can model earths interior?
subjecting rocks to high temperatures examining rocks at great depths computer models that model processes too deep to observe
How does seismic tomography identify different regions within earth?
earthquakes and seismic waves are used to examine different internal parts of the earth
12.16 Describe some ideas about flow in the mantle and core-mantle boundary that have arisen from seismic tomography?
What is air pressure and how do you measure it?
exertion of force on an area from all directions, with molecules of gas striking the walls of a container. measured by a barometer which measures the density of molecules
How does atmospheric pressure change with altitude?
Nitrogen and gas have mass and are kept from escaping space by earth's gravitational field. atmospheric pressure is highest at low elevations
How does surface temperature differences result in variations in air pressure and changing wind directions along coasts?
during daytime, the wind from high pressure at sea goes to the land that's at low pressure during nighttime, the wind from high pressure at land goes to the sea that's at low pressure
What are the causes of the Coriolis effect?
Air is carried around the earth by rotation. the surface has a faster velocity near the equator than at the poles
How does water enter/leaves the atmosphere, causing rainfall along a mountain front and a rain shadow?
Sunlight heats the ocean, causing it to evaporate and be turned into clouds thanks to wind. the cloud causes precipitation and rains onto the mountain front below
How does large-scale atmospheric circulation affect precipitation?
atmospheric circulation patterns that develop draw cooler air towards zones of low pressure. these patterns result in different climatic zones
How do sea surface temperatures vary from place to place?
The sea gets warmer from the equator and gets colder the closer to the poles you go
What is the thermohaline conveyor?
a deep water current that takes deep water on a long journey based on density of seawater, which is based off of temperature and salinity
What is a monsoon and how does it affect rainfall in india?
a change in the prevailing wind direction from one season to another if brings in air toward the low pressure zones, increasing the amount of rainfall
Where do rain forests occur?
They lie in the tropics and align with the Intertropical Convergence Zone
What conditions produce enough precipitation to form a rainforest?
treetops forming a canopy or umbrella understory layer is shaded forest floor is very dark and soil contains few nutrients
What are arid regions?
land that receives less water as precipitation than it could lose to evaporation and other processes
What are deserts?
arid regions that have less than 10 inches of rainfall a year
Where do arid regions occur?
beneath descending air in subtropical belts, in rain shadows associated with mountain ranges, far inland from sources of moisture, near cold ocean currents, and in cold, dry regions
How does wind pick up and transport sediment
moderate winds roll/slide grains of sand strong winds lift sand grains then drop them wind can pick up and carry finer material
What are some expressions of wind deposits
sand dunes, dust storms, and whirlwinds
How does an alluvial fan form?
loose rocks transported from mountainous areas in streams and deposited in fan-shaped aprons
How do washes form?
normally dry, these washes can fill rapidly with water during a rainstorm
How do playas form?
shallow, closed basins that receive runoff but have no outlet
How do dunes form?
sand not held down by vegetation for dune if there is sufficient supply of sand
How do pediments form?
gently sloping erosion surface
How do desert pavements form?
rocks concentrated on the surface because finer materials have been blown or washed away
How do caliches form?
soluble minerals in water percolate down into the soil; water evaporates, and the minerals stay behind, coating clasts
How do desert varnish form?
exposed surfaces get coated with iron and manganese oxides forming dark, natural rock varnish
How do natural stains form?
vertical streaks of red, brown, and black deposited by water that flowed down the rock face and evaporated
What is climate change and how can it be measured?
global trends in warming, cooling, precipitation, etc and can be measured by a thermometer record, sea surface temperatures, and satellites
What are the major lines of direct measurement and proxy evidence indicating global warming in the last 100 years?
temperatures were increasing since 1970 sea temperatures were high ever since 1940-1998 el nino warming gets hotter and hotter Ice cores indicate temp change
What are the major factors that influence atmospheric temperatures?
greenhouse gases and human activities
How do greenhouse gases correspond to temperature changes?
they (h20 and co2) absorb heat radiated from the earth, warming the planet
What are ice sheets?
What are valley glaciers?
What are piedmont glaciers?
What are the characteristics of glaciers?
How is snow transformed into ice by pressure?
What is the difference between a glacier above and below the equilibrium line?
How do glaciers move?
What happens when glaciers encounter a lake or sea?
How do glaciers erode, transport, and deposit material?
How can glacial erosion modify a landscape?
What are the characteristics and origins of landforms formed by alpine glaciation?
Describe evidence that used to infer that glaciers covered a landscape.
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