Test 1 Flashcards
what is geology and which types of real-world problems is It applied
locating and managing natural resources (like minerals and water), assessing environmental impacts, and mitigating natural hazards like earthquakes, volcanoes, and landslides
physical geology
scientific discipline that is concerned with all aspects of the Earth’s structure, composition, physical properties, constituent rocks and minerals, and surficial features.
historical geology
the study of the Earth’s history, including its origin, evolution, and changes over time
natural disasters
Natural disasters include all types of severe weather, which have the potential to pose a significant threat to human health and safety, property, critical infrastructure, and homeland security. Natural disasters occur both seasonally and without warning, subjecting the nation to frequent periods of insecurity, disruption, and economic loss.
natural hazards
those elements of the physical environment, are harmful to man and caused by forces extraneous to him.
hypothesis
a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
theory
A theory is a well-substantiated explanation of a natural phenomenon that is based on facts, hypotheses, and laws. It is constructed using the scientific method and is testable. Theories can make predictions about what should be observed if the theory is true. If new evidence is incompatible with the theory, it may be refined or rejected.
what is a system
encompassing all components of the Earth system – air, life, rock, and water – to gain a new and more comprehensive understanding of the world as we know it
What are the theories of Earths Formation
Big Bang Theory
Nebular Theory
Planetary Differentiation
what are the compositional layers of earth
crust, mantle, and core
what are the mechanical layers of earth
lithosphere, asthenosphere, mesosphere (lower mantle), outer core, and inner core
What is the difference between compositoinal or mechanical
“Compositional” refers to something based on its constituent parts or chemical makeup, while “mechanical” refers to something based on its physical properties, like strength, rigidity, or how it moves, rather than what it’s made of
which of the following is a natural disaster:
hurricane before reaching land,
landslide burying a section of a city,
volcano erupting on an unhabituated island, earthquake occurring in a remote desert
Landslide Burying a section of a city
what is the scientifically accepted age of Earth
4.6 Billion Years
When a scientist references something as a theory it means that _____.
it has stood up to scientific inquiry and is considered the most robust explanation to date
What caused our solar nebula to contract and spin, eventually creating the planets
Gravitational interactions between particles
How did the layers form on earth
differentiation, where denser materials like iron and nickel sank to the center of the planet to form the core, while lighter materials rose to the surface to create the crust, primarily due to the force of gravity acting on the molten Earth as it cooled during its early formation.
Natural Hazards
natural events that can cause damage to the environment, society, and economy
floods, tsunamis, volcanoes, wildfires, droughts, landslides
Natural Disasters
The negative impact that occurs when a natural hazard harms a community
Atmosphere
the gaseous layer surrounding a planet and the mood or feeling of a place or situation
Hydrosphere
the total amount of water on a planet, including water that is on the surface, underground, and in the air
Biosphere
the regions of the surface, atmosphere, and hydrosphere of the earth (or analogous parts of other planets) occupied by living organisms.
Geoshpere
includes the continental and oceanic crust and all other layers of the Earth’s interior. This includes all rocks, sediments and soils, surface landforms and the processes that shape the Earth’s surface.
Continental Crust (Density, Composition)
broadly granitic in composition and, with a density of about 2.7 grams per cubic cm, is somewhat lighter than oceanic crust
Oceanic Crust (Density, Composition)
primarily composed of mafic igneous rocks, like basalt, which makes it denser than continental crust, with an average density of around 3 grams per cubic centimeter
Mountain Belt
a group of interconnected mountain ranges that share similar geological characteristics, structure, and alignment, usually formed by the same tectonic event (orogeny), essentially forming a larger system of mountains rather than just a single, continuous range
Shield
a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas
Craton
table, ancient part of a continent’s crust that is made up of crystalline basement rock
What was the evidence that Wegner used to come up with the continental drift theory and why did it take so long to accepted
Wegener used fossil evidence to support his continental drift hypothesis.
Plate Tectonic Theory (+ evidence)
the theory that Earth’s outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core
How does plate tectonic theory differ from continental drift theory
(Wegner) a scientific theory called continental drift was proposed about this migration of the continents. That theory was initially ridiculed, but it paved the way for another theory called plate tectonics which scientists have now accepted to explain how Earth’s continents move.
What type of plate boundaries are there
Divergent, transform, convergent
What type of topography are there
Mountains, hills, plateaus, coastal areas, wetlands, urban areas, cliffs, plains, ridges, depressions, valleys
What kind of activity would you see around mountains
Folding, faulting, volcanic activity, igneous intrusion and metamorphism are all parts of the orogenic process of mountain building.
What kind of activity would you see around trenches
Trenches are formed by subduction, a geophysical process in which two or more of Earth’s tectonic plates converge and the older, denser plate is pushed beneath the lighter plate and deep into the mantle, causing the seafloor and outermost crust (the lithosphere) to bend and form a steep, V-shaped depression.
What kind of activity would you see around volcanoes
Volcanic activity ranges from emission of gases, non-explosive lava emissions to extremely violent explosive bursts that may last many hours.
What kind of activity would you see around earthquake activity
Aftershocks, Earthquake lights
Cascading events, Topographic relief
How does convection work
the movement of material within the Earth’s mantle due to density differences caused by temperature variation. This movement is responsible for the movement of tectonic plates, which in turn affects earthquakes, volcanoes, seafloor spreading, and mountain building.
How does mantle convection drive tectonic plates
by creating large-scale convection currents within the Earth’s mantle, which, due to temperature differences, cause hot, less dense material to rise towards the surface, pushing and pulling on the tectonic plates that float on top, resulting in their movement across the Earth’s crust
Density
the mass of a rock or mineral per unit volume, essentially how heavy a substance is for its size, and is a key property used to identify and understand different rock types, often expressed in grams per cubic centimeter (g/cm3)
Thermal Expansion
As the rock heats up and expands by day and cools and contracts by night, its outer layers undergo stress
Why do continents float and not subduct
The continental crust is not dense enough to subduct.
Where does the energy come from that drives plate motion
The energy source for plate tectonics is Earth’s internal heat while the forces moving the plates are the “ridge push” and “slab pull” gravity forces.
When considering evidence of glaciation on the southern continents, why did Wegener reject the explanation that the entire planet had experienced a period of extreme cooling?
Because geologic evidence supported the existence of tropical swamps in the Northern Hemisphere at the same time as the glaciers existing in the Southern continents
Why are the mid-ocean ridges higher in elevation than the surrounding ocean floor?
Warmer material near the ridge is less dense, so it is more buoyant on the mantle.
in which layer of the earth does the convection necessary for plate motion occur
the Earth’s mantle; specifically, within the asthenosphere
which of the following plate boundary is not usually associated with volcanism
Transform Plate Boundary
Convergent Boundaries
a location on Earth where two or more tectonic plates collide, with one plate eventually sliding beneath the other
Divergent Boundaries
a linear feature that forms when two tectonic plates move apart
Transform Boundaries
a fault that occurs when two tectonic plates slide horizontally past each other
Continental Drift (Wegner)
states that the continents were once joined together as a single landmass called Pangaea and have since drifted apart
Pangea
Pangaea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It was made up of almost all the landmasses on Earth, surrounded by a global ocean called Panthalassa.
Plate Tectonic Theory
a scientific theory that explains the movement of Earth’s tectonic plates and how these movements create geological features
Surface Heat Flow
the rate at which heat energy is transferred from the Earth’s interior to its surface per unit area, essentially measuring how much heat is escaping from the planet at a given point on the surface
Topography
the arrangement of the natural and artificial physical features of an area.
Bathymetry
the study of the underwater terrain of bodies of water, such as lakes, rivers, oceans, and streams.
Apparent Polar Wander
the movement of the pole with respect to a given tectonic element (plate, continent, craton, block, etc.) that is assumed to be fixed in the present-day geographic coordinate system.
Magnetic Pole Reversal
a phenomenon where the Earth’s magnetic north and south poles swap places, meaning the current magnetic north pole becomes the south pole and vice versa, essentially flipping the polarity of the Earth’s magnetic field; this happens irregularly over long periods of time due to complex movements in the Earth’s liquid outer core
Tectonic Plates
composed of the oceanic lithosphere and the thicker continental lithosphere, each topped by its own kind of crust.
Lithosphere riding over athenosphere
The Earth’s lithosphere is defined as its rigid outer layer including both the crust and a part of the upper mantle that moves coherently over the weaker, convecting asthenosphere
Divergent Plate boundary examples
Ocean Ridges, Continental Rifts
Ocean ridges
underwater mountain ranges that form the largest features in the ocean basins. They are created by tectonic plate movement and are the site of most of the world’s volcanic activity
Continental Rifts
a zone where tectonic activity causes the lithosphere to thin, which can lead to the rupture of a continent and the formation of a mid-ocean ridge. Continental rifts are a type of divergent boundary, where tectonic plates move apart from each other
Three types of Convergent Boundaries
Continent-Continent, Continent-Ocean, Ocean-Ocean Boundaries
Continent-Continent Convergent Boundaries
a location where two continental tectonic plates collide, forming large mountain ranges.
Continent-Ocean Convergent Boundaries
a location where an oceanic plate collides with a continental plate, causing the oceanic plate to subduct beneath the continental plate
Ocean-Ocean Convergent Boundaries
a location where two oceanic plates collide, and one plate subducts beneath the other
Subduction
the sideways and downward movement of the edge of a plate of the earth’s crust into the mantle beneath another plate.
Oceanic Trenches
steep depressions in the deepest parts of the ocean [where old ocean crust from one tectonic plate is pushed beneath another plate, raising mountains, causing earthquakes, and forming volcanoes on the seafloor and on land.
Volcanic Island Arcs
a chain of islands formed by volcanic activity that occurs above a subduction zone. Subduction occurs when oceanic lithosphere sinks beneath continental or oceanic lithosphere, melting into magma in the asthenosphere.
Continental Volcanic Arcs
a chain of volcanoes that forms along the edge of a continent where an oceanic plate subducts beneath a continental plate. The volcanoes in a continental arc are usually larger and more explosive than those in an island arc, which is formed when an oceanic plate subducts beneath another oceanic plate
Transform Boundaries
places where plates slide sideways past each other. At transform boundaries lithosphere is neither created nor destroyed
Transform Faults
a type of fault that occurs at the boundary between two tectonic plates, where the plates slide past each other horizontally
Mantle Plume
a localized column of hot magma rising by convection in the mantle, believed to cause volcanic activity in hot spots, such as the Hawaiian Islands, away from plate margins.
Hotspot
a region of the Earth’s mantle where magma is hotter than the surrounding magma:
Location: Hotspots are located deep within the Earth, below the crust
Cause: Hotspots are caused by a mantle plume, which is a narrow stream of hot mantle that rises from the Earth’s core-mantle boundary
Hotspot Track
A chain of volcanoes (hotspot track) forms as a tectonic plate moves over a plume of hot mantle material (hotspot) rising from deep within the Earth
Effusive Volcanic Eruptions
a relatively gentle eruption that occurs when a volcano releases lava onto the ground. Effusive eruptions are characterized by:
Low viscosity magma: The magma is runny, allowing gas to escape easily.
Lava flows: The lava flows downhill in various shapes, thicknesses, lengths, and widths.
Shield volcanoes: Effusive eruptions build up gently-sloping shield volcanoes, like those in Hawaii
Explosive Volcanic Eruptions
a violent eruption that occurs when a viscous magma with a high gas content explodes out of a volcano. This happens when gas bubbles form in the magma as it rises from the Earth’s depths, and the gas pressure builds up until it’s released in an explosion
Viscosity
a fluid’s resistance to flow
How does magma composition affect the magma’s properties and the type of eruption that can happen
primarily affects the viscosity (thickness) of the magma, which in turn determines the type of volcanic eruption; high-silica magma is more viscous and leads to explosive eruptions, while low-silica magma is less viscous and results in effusive eruptions with lava flows
Non-Viscous substances
a liquid that flows very easily with minimal resistance, meaning it is not thick and has low viscosity; the most common example of a non-viscous substance is water
How does silica content affect viscosity
The higher the amount of silica in the magma, the higher the viscosity.
How does temperature affect viscosity
Viscosity will decrease with increased temperature
Shield Volcano
a broad, gently sloping volcano that is named for its resemblance to a shield on the ground. Shield volcanoes are formed by repeated eruptions of low-viscosity lava, which flows long distances from a central vent or vents
Cinder Cone Volcano
a steep, conical hill made up of loose fragments of lava that are created by explosive eruptions
Composite/StratoVolcano
large, cone-shaped volcanoes that are built up from layers of ash, lava, and other materials. They are known for their explosive eruptions and are some of the most dangerous volcanoes on Earth
How do dissolved gases drive volcanic eruptions
As magma rises, gas bubbles, contract, fragmenting the material and expelling it from the vent
Lava erupting from composite cones are generally ____-rich making them very viscous
Silica
How is magma generated along subduction zones?
pressure and temperature, which will rise as the oceanic plate sinks further into the mantle, causing water and other volatile substances from the rocks to be released
Colima volcano in Mexico is situated on continental crust near the Pacific ring of fire. What
type of eruptions should you expect it to have?
Explosive
Study the placement of things on a volcano (lava flow, vent, conduit, magma chamber)
Magma
a mixture of molten and semi-molten rock found beneath the surface of the Earth.
Lava
molten rock that flows onto the Earth’s surface from a volcano or other tectonic feature
Silica
a chemical compound made up of silicon and oxygen, the two most abundant elements in the Earth’s crust
Volatile/Gasses
gases that are emitted into the air from products or processes
Effusive Eruptions
a type of volcanic eruption where lava flows out of a volcano onto the ground in a relatively gentle, non-explosive manner
Explosive Eruptions
a violent volcanic eruption that occurs when gas trapped in magma is released, propelling magma and volcanic debris into the air
AA Lava Flow
a lava flow with a rough, spiny surface made up of broken lava blocks called clinkers
Pahoehoe Lava Flow
a type of lava flow that has a smooth, billowy, or ropy surface. It’s formed when basaltic lava cools and spreads out after erupting from a volcano.
Volcanic Ash
mixture of rock, mineral, and glass particles expelled from a volcano during a volcanic eruption
Lava Bombs
a large piece of lava that is thrown from a volcano during an eruption and cools into a solid fragment before hitting the ground
Cone (Volcanic)
a triangle-shaped hill formed as material from volcanic eruptions piles up around the volcanic vent, or opening in Earth’s crust
Vent (Volcanic)
an opening in the Earth’s surface where lava, volcanic gases, and other materials erupt from a volcano
Fissure (Volcanic)
a crack or fracture in the Earth’s surface that allows lava, gas, and pyroclastics to erupt from a volcano.
Acid Rain
any form of precipitation, including rain, snow, or fog, that is unusually acidic due to elevated levels of sulfuric and nitric acids in the atmosphere
Landslide
a mass of earth, rock, or debris that moves down a slope due to gravity
Volcanic Gases
a mixture of gases released by active volcanoes, primarily composed of water vapor, carbon dioxide, and sulfur dioxide
Lahars
a volcanic mudflow that’s made up of a mixture of water and rock fragments that flows down the side of a volcano
Volcano Caused Tsunamis
a tsunami caused by a volcano, and can be caused by a number of different mechanisms, including:
Submarine eruptions, Caldera collapses, Tectonic movement, Flank failure, Pyroclastic flow discharge, and Earthquakes.
Mantle Plume
a column of hot, buoyant material that rises from the Earth’s mantle and can have a significant impact on the Earth’s surface
What kind of signs do volcanoes give when they become active
An increase in the frequency and intensity of felt earthquakes. Noticeable steaming or fumarolic activity and new or enlarged areas of hot ground. Subtle swelling of the ground surface. Small changes in heat flow.
How do earthquakes happen
when the Earth’s crust suddenly slips along a fault, releasing energy in the form of seismic waves that cause the ground to shake
Fault
a crack or fracture in the Earth’s crust that allows blocks of rock to move relative to each other
Stick-Slip Behavior
a phenomenon where two surfaces along a fault line alternately stick together, building up stress, then suddenly slip, releasing that stress, often causing small tremors or, on a larger scale, earthquakes
Focus
the place inside Earth’s crust where an earthquake originates
Epiccenter
the point on the Earth’s surface that is directly above the hypocenter, or focus, of an earthquake
Hypocenter
the specific place where an earthquake rupture originates
Elastic Rebound (what type of material behaves that way)
what happens to the crustal material on either side of a fault during an earthquake.
elastic materials
a material that can undergo stress, deform, and then return to its original shape after the stress is removed
brittle materials
a substance that breaks when stressed, rather than deforming plastically
ductile materials
a rock’s ability to deform without breaking into large pieces
Seismic Waves
of, subject to, or caused by an earthquake
Body Waves
A seismic wave that travels through the Earth rather than across its surface. Body waves usually have smaller amplitudes and shorter wavelengths than surface waves and travel at higher speeds.
Surface Waves
A seismic wave that travels across the surface of the Earth as opposed to through it. Surface waves usually have larger amplitudes and longer wavelengths than body waves, and they travel more slowly than body waves do.
Time- Travel Graphs
a graph that plots the time it takes for seismic waves (like P-waves and S-waves) from an earthquake to reach different recording stations at varying distances away
Triangulation for earthquake location
a method used to determine the location of an earthquake’s epicenter by using data from multiple seismic stations:
1. Record seismic waves
Recordings of seismic waves are collected from at least three seismic stations.
2. Draw circles
Circles are drawn around each station, with the radius scaled to the estimated distance from the station to the earthquake.
3. Find the intersection
The location of the earthquake’s epicenter is the point where all the circles intersect.
Earthquake intensity
the average number of earthquakes that occur in a given rock unit per year, divided by the volume of that rock unit.
Earthquake magnitude
a measure of the “size,” or amplitude, of the seismic waves generated by an earthquake source and recorded by seismographs.
Richter Scale
measures the intensity or magnitude of an earthquake and represents the intensity with a scale ranging from 1 to 10. The Richter scale uses the value of the amplitude of the highest seismic wave.
Moment Magnitutude
a physical quantity proportional to the slip on the fault multiplied by the area of the fault surface that slips
Earthquake Destruction
Damage or destruction of properties and good caused by an earthquake, either as a direct result of the ground shaking, or as an induced consequence
Earthquake Hazards
Ground shaking: The most significant effect of an earthquake, which can be caused by the sudden slip of a fault or volcanic activity
Landslides: Can be triggered by earthquakes
Liquefaction: A critical effect in areas that are susceptible to earthquakes
Surface rupture: A type of earthquake hazard
Paleoseismology
the study of prehistoric earthquakes, including their location, timing, and size, as preserved in the geologic record
Forecasting
he practice of predicting what will happen in the future by taking into consideration events in the past and present
Seismic Gaps
a segment of an active fault known to produce significant earthquakes that has not slipped in an unusually long time, compared with other segments along the same structure.
Mitigating Damage from Earthquakes
the process of reducing the damage and casualties that can result from earthquakes
what are tsunamis
a series of long waves that are caused by a sudden displacement of the ocean’s water. They are often triggered by geologic events like earthquakes, volcanic eruptions, and landslides
what conditions need to be met to generate tsunamis
Earthquakes
The most common cause of tsunamis, earthquakes must be large, shallow, and occur near or under the ocean. The size of the earthquake, the amount of movement in the ocean floor, and the depth of the water above the earthquake are all important factors.
Landslides
Major landslides falling into bodies of water can cause tsunamis. The largest tsunami ever recorded was caused by a landslide in Lituya Bay, Alaska.
Volcanic activity
Volcanic eruptions can cause tsunamis. For example, the eruption of Krakatau in 1883 generated at least three tsunamis.
Weather
Certain types of weather can cause tsunamis.
Near-Earth objects
Asteroids and comets colliding with or exploding above the ocean can cause tsunamis.
how do tsunamis differ from normal water waves
sunami waves are distinguished from ordinary ocean waves by their long wavelengths (distance between two crests or highest point of the wave), often exceeding 100 kilometers in the deep ocean and by the long amount of time between the arrivals of these crests, ranging from five minutes to an hour.
On a seismograph, you would expect that the time interval between P and S-wave arrivals
Increases the farther the station is away from the earthquake hypocenter
Near which type of plate boundaries do you expect to experience the highest-magnitude
earthquakes?
convergent
When going from a 5 to a 6 on the Richter scale, what is the increase in amplitude of seismic
waves?
10 times
True/False: Earthquakes occur along preexisting faults only
T
Liquefaction
Seismic energy transforms stable soil into mobile material incapable of supporting buildings.
Landslide
Mass movement of material downslope, shaken loose by seismic events.
Tsunami
Large ocean waves generated
Subsidence
Collapse and lowering of the land surface
Seiche
Rhythmic sloshing of water in lakes and enclosed basins.
Mercalli Intensity Scale 1
Not felt except by a very few under especially favorable circumstances.
Mercalli Intensity Scale II
Felt only by a few persons at rest, especially on upper floors of buildings.
Mercalli Intensity Scale III
Felt quite noticeably indoors, especially on upper floors of buildings, but many
people do not recognize it as an earthquake.
Mercalli Intensity Scale IV
During the day felt indoors by many, outdoors by few. Sensation like heavy truck
striking building
Mercalli Intensity Scale V
Felt by nearly everyone, many awakened. Disturbances of trees, poles, and other
tall objects sometimes noticed
Mercalli Intensity Scale VI
Felt by all; many were frightened and ran outdoors. Some heavy furniture moved; there were a few
instances of fallen plaster or damaged chimneys. Damage slight
Mercalli Intensity Scale VII
Everybody runs outdoors. Damage negligible in buildings of good design and
construction; slight-to-moderate in well-built ordinary structures; considerable in
poorly built or badly designed structures.
Mercalli Intensity Scale VIII
Damage slight in specially designed structures; considerable in ordinary
substantial buildings with partial collapse; great in poorly built structures. (Fall of
chimneys, factory stacks, columns, monuments, walls.)
Mercalli Intensity IX
Damage considerable in specially designed structures. Buildings shifted off
foundations. Ground cracked conspicuously
Mecalli Intensity X
Some well-built wooden structures destroyed. Most masonry and frame structures destroyed. Ground badly cracked.
Mecalli Intensity XII
Few, if any, (masonry) structures remain standing. Bridges destroyed. Broad
fissures in ground.
Mecalli Intensity XIII
Damage total. Waves seen on ground surfaces. Objects thrown upward into air
asperities
areas on a fault where there is increased friction and the fault is stuck or locked
fault rupture
seismic waves that radiate outward in all directions, causing the ground to shake
propagation
a ground motion phenomenon that relates to the passage of body waves, including compression waves and shear waves, radially from the source of earthquake energy release (hypocenter) into the surrounding rock and soil medium.
Primary (p waves)
the fastest seismic waves and are the first to be detected by seismic stations during an earthquake
Secondary (S waves)
also known as “S waves” or “shear waves”, which are the second type of wave to arrive at a seismograph after a earthquake
Surface (Love Waves)
These waves move horizontally, with the largest amplitude at the surface and decreasing with depth. They travel at almost 10,000 miles per hour and are trapped near the surface as shear waves
Surface (Rayleigh Waves)
These waves have a more complex motion than Love waves, rolling along the ground in an elliptical pattern that is similar to ocean waves. They travel at about 7,800 miles per hour and cause the ground to shake with both vertical and horizontal components.
Compositional Layers
the crust, the mantle, and the core
Mechanical Layers
lithosphere, asthenosphere, mesosphere, outer core, and inner core.
How seismic waves are used to infer the properties and boundaries between the internal
layers
by analyzing how they change speed and direction when traveling through different materials, with sudden changes in wave velocity indicating the presence of a boundary between distinct layers, allowing scientists to map out the Earth’s interior structure based on the recorded travel times and behavior of P and S waves.
Seismic Ray Paths
lines that show the direction seismic waves travel through the Earth. They tend to curve due to refraction, which occurs when seismic waves pass through different rock layers with different seismic velocities
Shadow Zones
areas on the Earth’s surface where seismic waves from earthquakes are not detected by seismographs
Where does Earth’s internal heat comes from
the residual heat left over from the planet’s formation (primordial heat) and the ongoing radioactive decay of elements within the Earth’s mantle and crust; this heat drives geological processes like plate tectonics and volcanism
the ways in which heat propagates
conduction (direct contact between materials), convection (movement of hot material within a fluid), and radiation (electromagnetic waves), although within the Earth’s interior, radiation plays a very minor role, with most heat transfer occurring through conduction and convection.
geothermal gradient
the rate at which the temperature increases as you go deeper into the Earth’s crust. It’s affected by the flow of heat from the mantle, and can vary depending on the region and the type of rock
shape and gravity field of earth
slightly flattened at the poles and bulges at the equator due to its rotation, and its gravity field is not perfectly uniform across its surface, with stronger gravity at the poles and weaker gravity at the equator, reflecting this shape; this variation in gravity is primarily caused by the Earth’s rotation and uneven mass distribution within its interior.
what causes earth’s magnetic field
powered by the solidification of the planet’s liquid iron core. The cooling and crystallization of the core stirs up the surrounding liquid iron, creating powerful electric currents that generate a magnetic field stretching far out into space
magnetic inclination
the angle at which the Earth’s magnetic field lines dip below the horizontal plane at a given location, essentially measuring how much the magnetic field is tilted relative to the Earth’s surface
magnetic declination
the angular difference between the direction a compass needle points (magnetic north) and the true geographic north pole, essentially showing how much a compass deviates from true north at a specific location on Earth
magnetic reversals
a phenomenon where the Earth’s magnetic field flips, causing the magnetic north and south poles to swap positions
What is the major difference between the inner core and the outer core?
The inner core is solid while the outer core is liquid.
Why do seismic waves follow strongly curved paths as they move through the interior?
Their velocities are changed because of increasing pressure with depth.
Where is oceanic crust generated?
Along divergent plate boundaries.
The ________ is a seismic boundary between the crust and the mantle where there is a dramatic increase in seismic wave velocity.
Moho Boundary
How does water get from the surface to the middle of the mantle?
Subducting oceanic lithosphere.
Which layer of earth makes up more than 82 percent of the volume of the planet?
Mantle
Which layer of layers of the interior are believed to have convection cells?
Mantle and outer core.
The composition of the upper mantle is defined by ________.
Peridotite
Which layer is thought to be the birthplace of deep mantle plumes?
D” layer
How is the shape of Earth affected by its rotation?
The Equator is further from the center of the Earth than the poles.
Which process is responsible for Earth’s magnetic field? In which layer does this process
occur?
Convection; outer core
Continental Crust
Granitic material composing the outermost layer
Inner Core
Solid nickel and iron with trace materials
Asthenosphere
Ferromagnesian silicates mostly in a ductile state
outer core
Liquid nickel and iron with trace materials
Oceanic Crust
Basaltic material composing the outermost layer
Geodynamo
Earth’s magnetic field is generated from liquid iron within the planet’s outer core, which constantly moves as the earth cools.
Mountains
Have steep slopes, valleys, ravines, and steep peaks
Hills
Have gentler slopes and lower elevations than mountains
Coastal areas
beaches, bays, marshes, and are flat to gently sloping towards the sea
Wetlands
Pose flooding risks but offer recreational opportunities and conservation
Urban areas
varied topographical characteristics and limited space, but present redevelopment prospects
Cliffs
Have closely spaced contour lines and are steep slopes
Plains
Are low flat areas
Ridges
Have contour lines that are parallel to each other on each side of the ridge
Depressions
Are indented holes in the Earth’s surface, such as volcanic calderas and sinkholes
Valleys
Have “V” shape contours that point upstream
