science notes 4th quarter

crust, mantle, outer core, inner core

the 4 major layers of the earth

lithosphere

what the crust and the upper mantle make up, a rigid layer that can break under stress. it is composed of major and minor blocks called tectonic plates

asthenosphere

it is below the lithosphere, contains hot molten rocks or magma. can deform and reshape driven by heat energy which circulates as convection currents

crust

outermost layer of earth where life exists

continental crust

the type of crust that makes up the continents, made up of light granitic rocks

oceanic crust

the type of crust that underlies the ocean floor and is composed of dense basaltic rocks

tectonic plates

what the lithosphere is broken into and are made up of

mantle

below the crust that is semisolid, rocky, and very hot layer. it makes up 80% of earth and carries its mass. composed of ferro-magnesium silicate rocks.

liquid outer core, solid inner core

two distinct layers of the core

outer core

is the only layer of earth that is liquid and made up of molten nickel and iron.

inner core

composed mostly of solid iron and is extremely hot

boundaries between the layers of earth

mohorovicic, gutenberg, lehmann discontinuity

mohorovicic discontinuity

boundary between the crust and upper mantle

gutenberg discontinuity

boundary between the lower mantle and outer core

lehmann discontinuity

located between the liquid outer core and the solid inner core

driving and resisting forces

the 2 types of forces that makes tectonic plates move

slab pull, slab suction, ridge push, mantle convection

the driving forces

slab resistance, collisional resistance, transform fault resistance, drag force

the resisting forces

shape and fit of continents, similarities in fossils, similarities in rock types

evidence of continental drift

pangaea

it translates to “all of earth” or “all lands” surrounded by a vast sea called panthalassa (all seas)

contraction theory

proposed in the 20th century, suggested that earth cooled after its formation, the surface contracting and wrinkling, the wrinkles being the mountain ranges on earths surface.

contraction theory

this theory assumed that all other features on earth were formed during a single cooling event and that the planet was static

continental drift

it asserted that there once existed a single large landmass called pangaea that broke into different continents. this theory was rejected because of lack of compelling evidence for the mechanism that drives the movement

alfred wegener

proposed the continental drift theory

harry hess

proposed the seafloor spreading theory

seafloor spreading theory

asserted that the seafloors or ocean floors move and carry the continents along

theory of plate tectonics

theory that the lithosphere is made up of plates that are continually moving. may be continental or oceanic.

gondwana and laurasia

two small supercontinents

convection currents beneath the plate

the reason of why plates move and float on an inner pliable mantle

plates

independent massive slabs of solid rocks

15

how many major tectonic plates are there

7

how many primary plates are there

8

how many secondary smaller plates are there

primary plates

eurasian, australian, pacific, north american, south american, african, antarctic plates

secondary smaller plate

juan de fuca, nazca, cocos, caribbean, philippine sea, arabian, indian, scotia plates

driving forces

these forces either push tectonic plates toward one another or pull them apart

mantle convection

caused by rising of heat from the core. convection currents drive the plates from one another. the heat dissipates and creates a convection current due to difference in temperature

slab pull

it is when a subducting slab sinks into the hot mantle because of difference in temperature. the plate attached to the slab is pulled in as well.

slab suction

occurs when two plates collide, one subducting underneath the other wherein convection currents in the upper mantle suck the plates down

ridge push

when the lithosphere is pushed up by the asthenosphere because of convection currents from the mantle. gravity also pushes the plate down and a new crust is formed.

resisting forces

they act against the driving forces of plate tectonics

slab resistance

the force that resists all forces associated with plate movement in subduction zones

collisional resistance

occurs when a heavy plate is pulled into the mantle but resists subduction because of friction. it opposes slab pull

transform fault resistance

the frictional force due to the opposing movement of plates moving past one another between two spreading cores

drag force

resists movements of lithospheric plates

drag force

refers to the resistance encountered by tectonic plates as they move across the semi-fluid layer of the mantle

transform fault resistance

is the force that opposes the horizontal movement of tectonic plates along transform faults, contributing to the build-up of stress and potential seismic activity.

slab resistance

is the frictional force opposing the downward movement of a tectonic plate as it subducts beneath another plate at a convergent boundary.

collisional resistance

refers to the resistance encountered when two tectonic plates collide at a convergent boundary.

convergent, divergent, transform

the 3 types of plate boundaries

divergent boundary

a type of plate boundary wherein two plates move away from each other and a gap or rift between them is created.

rift valley

if a gap widens in a divergent boundary, what is it called?

mid-oceanic ridges

what divergent boundaries between oceanic plates produce, are mountain ranges formed underwater

divergent boundary

what type of plate boundary is the great east african rift valley?

cont

convergent boundary

it occurs when two plates slide toward each other and form either a subduction zone or an orogenic belt.

subduction zones

when one plate moves underneath the other

orogenic belt

when two simply collide and compress and a region of deformed rocks

oceanic-oceanic, continental-continental, oceanic-continental

the 3 types of convergent boundaries

mid-oceanic ridges

occur underwater where two oceanic plates are moving apart. as the plates separate, magma from the mantle rises up to fill the gap, creating new oceanic crust. they help move earth’s crust.

mid-atlantic ridge

most famous mid-ocean ridge

continental rift zones

boundaries occur within continents where a continent is splitting apart. over time, this can lead to the formation of new ocean basins if the rifting continues and is successful. they help move earth’s crust.

east african rift

example of a continental rift zone

oceanic-oceanic

refers to a type of tectonic plate boundary interaction where two oceanic plates converge, diverge, or slide past each other.

oceanic-oceanic

this interaction occurs exclusively between plates that are predominantly composed of oceanic crust. forms volcanic islands and underwater volcanoes

oceanic trench

a long, narrow depression in the ocean floor and is also created at the subduction zone

pacific plate - philippine plate, mariana trench

examples of oceanic-oceanic convergences

oceanic-continental

refers to a type of tectonic plate boundary interaction where an oceanic plate and a continental plate converge, diverge, or slide past each other.

oceanic-continental

occurs between a plate predominantly composed of oceanic crust and one predominantly composed of continental crust.

oceanic-continental

often leads to the formation of subduction zones, where the denser oceanic plate is forced beneath the less dense continental plate, resulting in volcanic activity and mountain formation at the continental margin.

continental-continental

no subduction happens and the continents suture themselves. the crust buckles and rocks pile up, creating mountain ranges.

transform plate boundary

in this boundary, plates slide against one another in opposite directions. only earthquakes and massive amounts of energy are produced.

normal, reverse, and strike-slip fault

three types of faults

fault plane

the surface where the blocks slip past each other

dip-slip

refers to the movement of faults along the angle of the fault plane. angle of movement = dip, movement = slip.

dip-slip

classified as normal or reverse faults.

normal fault

a dip-slip fault where a block that sits on a fault plane, called the hanging wall, slips downward with respect to the footwall along the dip angle.

reverse fault

a dip-slip fault where the block of earth’s crust pushes upward and along the dip angle.

thrust fault

is a type of reverse fault where the angle of the dip is 45 degrees or less.

strike-slip fault

vertical fault planes or surfaces slide in parallel but opposite directions. when plates get stuck and stop moving, energy builds up between them releasing seismic waves that causes earthquakes

oblique-slip fault

a combination of a strike-slip and dip-slip. slide horizontally or up and down from each other

mountains

large landforms that rise well above the ground and have steep slopes and a peak generally higher than a hill.

orogenesis

process of forming mountains and mountain ranges involving collision of plates and forces of compression

fold mountain ranges

mountains that are formed through plate convergence, when a continental plate is subducted beneath another, the immense forces of compression fold the crust

volcanic mountain ranges

usually have isolated peaks that formed for over thousands or millions of years. constructed from accumulated lava flows and may be produced by a hot spot

erosion-formed mountain ranges

they do not form because of earth’s internal activity but because of rock erosion or weathering

dome mountain ranges

upwarping of tectonic plates and are not accompanied by the collision of plate boundaries, can form isolated and large folds in flat regions, which produce domes.

hotspots

a hot part of the mantle that causes rocks to melt creating magma. this magma can rise to the surface, building up over time, and creating volcanoes.

seismometers

detect earthquakes

seismographs

record earthquakes

body waves and surface waves

two types of seismic waves

body waves

waves that travel through the inner layers of the planet

surface waves

waves that travel through the surface and do not provide information about the earth’s interior

primary waves and secondary waves

two types of body waves

primary waves

also known as compressional waves, first to be felt on earth’s surface, pass through solids and liquids. faster than secondary waves

secondary waves

are also known as transverse waves, up and down motion, do not travel through liquids. are slower than primary waves