Plate tectonics theory proposes that the Earth's outer layer is made up of plates that constantly move atop a hotter, more mobile layer. There are three main types of plate boundaries - convergent where plates meet and one subducts under the other, divergent where new crust is formed as plates move apart, and transform where plates slide past each other. Plate tectonics causes landforms like mountains to form and is responsible for geological events like volcanoes and earthquakes.

1. REVIEWER SCIENCE
ERIN NEOBI
LESSON 1
PLATE TECTONICS THEORY - Abraham Ortelius ( Theatrum Orbis Terrarum) *first world atlas
- Interpreting the structure, composition, and internal process occurring inside Earth and its land surface.
*Plates - large or small fragments of the crust
* Tectonic - movement
- States that the outermost layer is fragmented on large and small plates that are moving on another, called
lithospheric or tectonic plates - are massive , irregular slab of solid rocks that envelope the surface of earth
- The earth’s outermost layer is riding atop a hotter and more mobile material known as the Asthenosphere. -
layer that the convection current is formed
THEORIES EXPLAINING THE CRUST
● RAISIN THEORY- where earth is like a grape contracted into a raisin due to the cooling process.
*Contraction- shrinking of Earth Surface due to cooling
- Scientists thought the cooling caused the contraction and pressure that allowed some
parts of the crust to move upward and produced mountains.
● Isostasy Theory - Clarence Edward Dutton
- There is an equilibrium that exists on the Earth’s surface, Lighter Materials make up the continental
crust, while denser/ heavier materials will make up oceanic crust.
- The arrangement of materials on Earth is explained by this Theory
*Oceanic Crust - Basalt, Gabbro
* Continental Crust - Granite
● Continental Drift Theory - Alfred Wegener
- When plates moves, they carry continents with them, the continents spread and drift away from
one another
- Wegener Explained his theory and presented evidence that Pangea (meaning “ ALL EARTH”) had
really existed during the Permian Period
*EARTH IS GENERALLY COMPOSED OF 58 CRUSTAL PLATES*
7 PRIMARY PLATES
● African
● Eurasian
● Indo- australian
● North american
● Pacific
● South American
● Nazca
8 Secondary Plates
● Arabian
● Caribbean
● Cocos
● Indian
● Juan de duca
● Philippine sea
● Scotia
● Nazca
*NAZCA can be considered both as Primary and Secondary Plate
LITHOSPHERIC/ TECTONIC PLATES

2. - Are massive, irregular slab of solid rocks that envelope the surface of the earth that are moving
- Made up of CRUSTAL PLATES & UPPER MANTLE
2 BASIC TYPES OF LITHOSPHERIC PLATES
1. Continental Lithosphere - it is lighter because it is composed of lower density materials
- It is made of granitic rock and volcanic materials
- Are formed through volcanic eruption
BASEMENT ROCK
-bottom most part of the foundation,oldest foundation
PLATFORM
-next to basement rock, the youngest part of the continental crust; it is made of sedimentary rocks.
CRATONS
When Platforms are connected with Basement Rock, oldest continental crust
CONTINENTAL MARGINS
Found at the edge of the cratons, it is also made of sedimentary rocks
.
2. Oceanic Lithosphere
- Made of denser materials ( Basalt Rocks & Gabbro)
- Younger layer of the lithosphere
- Younger rocks because there is cycling of rock materials from the ridge to trench
- Is formed by magma
* The Continental crust does not subduct, but the Oceanic does
EFFECTS OF PLATE TECTONICS
● EARTHQUAKES
● VOLCANOES
● MOUNTAIN BUILDING PROCESS
● OTHER LANDFORMS
● SEAFLOOR SPREADING
LESSON 2
MECHANISM OF PLATE TECTONICS
2 MAJOR THOUGHTS THAT WERE RAISED TO EXPLAIN THE MECHANISM OF TECTONIC PLATES
1. MANTLE CONVECTION - Arthur Holmes
- The pressure of the heated magma broke the continents apart forcing the pieces to drift in opposite directions
*CONVECTION - heat can be transferred from one place to another
- Is the idea that dense, cold things sink, and buoyant warm things rise
Cycle - the less dense fluid rises away from the heat source
- It pulls cool fluid down to replace it
- As the pulled fluid becomes heated, it also rises and pulls
down more cool fluid
- Hot rocks rise and , cooler rocks sink
● Inner Core’s main components are IRON & NICKEL
2. SLAB PULL THEORY
- This theory states that gravity and the plates
themselves are the ones responsible for the plate tectonics through the subduction process.
- The old rocks or slabs also subduct or sink into the mantle below it due to gravitation forces, as the
slab is pulled down into the mantle, it drags the rest of the plate along, causing tectonic plate
movement.
- The slow pull of mantle material where it moves from a rising location to a sinking location

3. ● Subduction zones exist at the outer edges of plates, in these zones, rocks are older, they are cooler and denser compared
to those located at the inner layers
- Are the regions where a portion of the tectonic plates are diving beneath other plates into Earth’s interior.
● Slab Suction - the high density of cold ocean crust sinking into the mantle pulls crust with it
● Ridge Push - new ocean crust is warm and tends to rise above the ocean floor, pushing older cooler crust
away
PLATE BOUNDARIES
SEAFLOOR SPREADING - Harry Hess
Robert Dietz - coined the term seafloor spreading in 1961
- According to this theory, the seafloor was created as mid-ocean ridges, spreading in both directions from the
ridge system
- is cause by two plates moving apart
- New ocean floor is formed at the ridges and destroyed at the trench
- Oceanic crust is thinner near the ridge
- Effect: Widening of the Atlantic Ocean
BOUNDARY - the border between the 2 tectonic plates
3 TYPES OF PLATE BOUNDARIES
1. Convergent
- It occurs where two plates are pushing towards each other
- The crust is destroyed and recycled back into the interior of the Earth, while one plate
dives under another
3 types of Convergent Boundaries
1. Oceanic to Oceanic convergence- occurs when two oceanic plates meet and one oceanic plate is
pushed underneath the other.
- It rises on the seafloor through eruptions and builds an arc of Volcanic islands because
during the process of subduction, the subducting plate descends into the mantle. Due to
extreme temperature, the plate is heated and magma is generated. As magma is less
dense compared to the surrounding rocks
These are several structural and topographic features created at many subduction zones.
● A bulge/outer swell In the descending plate commonly develops where the plate bends to dive
down the mantle,closer to the island arc, a deep trench and a forearc ridge can be formed.
● The forearc ridge traps sedimentary deposits and is underlain by faulted and highly deformed
sedimentary and metamorphic rocks
● The back arc, which is located behind the volcanic arc, is a broad region of variable character that
may be compressed or extended
2. Ocean to continental Convergence- occurs when an oceanic plates pushes into and moves
underneath a continental plate
- As the ocean plate sinks,it glides into the newly formed trench and smaller pieces break
off, these small pieces are locked in their place for long periods of time before they
produce sudden movements
- The continental plate that overrides the oceanic plate lifts up to create mountain ranges
3. Continental to Continental Convergence- occurs when two continents meet head on.
- The continental crusts are too light to slide down into a trench, neither plate is pushed
underneath the other
- Result of this convergence is the formation of tall mountain ranges.

4. 2.Divergent
- Plates move away from each other
- Also known as Constructive Boundary
- Produces, long rift zones, normal faults, and basaltic volcanism
- Responsible for seafloor spreading
- New crust is created on both sides of the boundary, as the crust adds mass on both sides, a rift
along the boundary is also carved out
*Ridge- is composed entirely of basalt, and is deformed of extensional forces, resulting in Normal Faulting
& basaltic igneous activity
3. Transform
- Is a zone between two plates that slide horizontally past one another
- Also called conservative boundary
- When they occur on the seafloor, they form oceanic fracture zones
- While on land, it produce faults
TRANSFORM FAULTS CAN CONNECT CONVERGENT AND DIVERGENT PLATE IN 3 WAYS
1. RIDGE- RIDGE TRANSFORM FAULT
- Connects two segments of a divergent plate boundary
- Fault cuts through the entire lithosphere
- Active displacement occurs only between the ridge segments
- Plate movements are in opposite directions between the ridge crests
- Sustains formidable shearing movement
- By far the most abundant
2. RIDGE- TRENCH TRANSFORM FAULT
- Connects a ridge and a trench
- Longest transform faults are all of this kind
- Form an important connection between spreading and converging plates
- Much less common
3. TRENCH - TRENCH TRANSFORM FAULT
- Couple trenches at two different convergent plate boundaries
- rare
TRIPLE JUNCTION- is a point which three plate boundaries meet
Effects of Plate Movements
1. Land Formation- Orogeny
2. Recycling of Rock Materials - Seafloor Spreading
3. Creation of Faults ( major cracks in the layers of rocks), faulting- earthquake
4. Displacement of the mineral deposits, fossil fuels ( crude oil, natural gas, coal)
5. Change in Geographical Location- lead to climate change and biodiversity
● Ave. movement of the plate- 1 cm to 15cm
Land Formations & Processes of Formation
*Geomorphology- study of landforms and the process that shape them
*Topography- study of regions current terrain features and graphic representation of specific landform on
an map
* Orogeny- is the process of mountain building as a result of tectonic plate movements
- Landforms- are physical features in the Earth’s Surface
- They are formed by natural forces - wind, water, ice and plate tectonics

5. 1.AEOLIAN LANDFORMS
-is formed by the mechanical and chemical (weathering) action of the wind ( oxygen)
- the word is derived from the Greek god of the winds, Aeolus
● DUNES
- Are mounds or small hills made up of sand
- They may be dome- shaped, crescent- shaped, star- shaped, linear- shaped, or parabolic
- The most common type of dune found on earth is the barchans and it is formed in the
opposite direction of the wind.
● LOESS
- Silt sized sediment created by the accumulation of windblown dust
- It appears yellowish or brownish color and it exhibits “cat steps”
- Is a product of Glacial Activity in an area
● MUSHROOM ROCK/ ROCK PEDESTAL
-naturally occurring rock that is formed as a result of earthquakes or glacial action
2. EROSIONAL LANDFORMS
- Are created from exclusively erosional and weathering activities
● BUTTE
- Flat topped hill with steep sides
- Formed in arid to semi- arid desert
- It covers a smaller amount of area when compare to a mesa
● MESA/TABLE MOUNTAINS
- Are elevated areas of land with a flat top and sides that are usually steep cliffs
- Cap rock is a resistant rock that surrounds the mesa
● CANYON OR GORGE
- Is a deep ravine between cliffs
- Formed by a strong water current ( river), wind or glacier
LANDFORMS CREATED AS A RESULT OF PLATE TECTONICS MOVEMENT:
3.MOUNTAINOUS AND GLACIAL LANDFORMS
● MOUNTAINOUS LANDFORMS
- With higher elevations, may be steep or less steep, with slopes and summit peak
Hills
- Smaller than the mountains, with an elevation of 300 meters above the sea level,, often covered
with grasses
- Less than 666 meters in height
Volcanoes
- Have an opening at the top ( vent/ crater). May be active or inactive
● Glacial Landforms
- Are the results of the action of the glaciers
Valley or Dale - low-lying area of land situated between hills or mountains
-V shaped when carved by flowing water,
- U Shaped if carved by moving glaciers
4. FLUVIAL AND COASTAL LANDFORMS
- are those that underwent sedimentation, erosion, or deposition on the river bed.
glaciofluvial or fluvioglacial- if the bodies of water associated to the fluvial and coastal landforms
interacted with glaciers or ice caps
Delta

6. - A low-lying triangular area located at the mouth of the river where it meets an ocean, sea or
estuaries.
- It contains rich soil which has been washed away and deposited by running water
- Alluvium- a sediment that has accumulated due to the interaction of delta and bodies of water.
- Ganges Delta - the largest delta in the world
Peninsula or byland
- Is a piece of land that projects into a body of water and is connected to the mainland by an
isthmus
- This landmass is bordered by water on three sides
- Formed by lithospheric movement,water elevation, and erosion.
Meander
- Is a bend in the sinuous watercourse of the river.
- It is formed when moving water in a stream erodes the the out banks then widens its valley
- Has a concave bank (inner bank) when deposition of sediment occurs and a convex ( outer
bank) whereas erosions take place at the outer edge
Sea cliffs
- Are high rocky coasts that plunge to the edge of the sea
- Due to the erosional actions of water and wind
- Made of limestone and sandstone, these rocks are resistant to weathering
Plains
- Are flat and broad land areas that have no great changes in elevations
- It is created either by sedimentation of the eroded soil from hills and mountains or by flowing lava
deposits.
- Variations: Coastal, Inland, High, Abyssal Plains
-
Plateaus
- Is a flat, elevated landform what rises sharply above the surrounding area on at least one side
- Also known as table lands or flat- topped mountains
- They are the results of geologic uplifts or the slow movement of large parts of stables areas of
Earth’s crust
- some are formed by volcanic eruptions, lava from volcanoes spread out and creates lava or
basalt plateaus
- Weathering of land areas are also produces this type of landforms
- Tibetan Plateau- the world’s largest and highest plateau
❖ LANDFORMS CREATED BY PLATE MOVEMENTS
★ MOUNTAIN RANGE
- Is a group or chain of mountains that are close together. Are usually separated from other
mountain ranges by passes & rivers.
- Made of several spaced mountains
- This is Where the thickest part of the lithosphere is located in
- DOME MOUNTAINS
- Are the results of a great amount of melted rock pushing its way up under the earth
without folding or faulting resulting in a rounded dome
- As it is raised above its surroundings erosion occurs, and as a result of erosion, peaks
and valleys are formed
➢ Fold Mountains
- Are formed when two plates collided head on, and their edges crumbled
Ex. The Himalayas in Asia, the Alps in Europe,the Andes in South America
➢ Fault-block Mountains

7. - It is formed when faults of cracks in the earth’s crust force some materials or blocks of
rock up and others down
Ex. Sierra Nevada mountains in North America and , Harz Mountains in Germany
➢ Volcanic Mountains
- Are formed when molten rock, or magma deep within the earth, erupts, and piles upon
the surface
- Ex. Mount st. Helens in North America, Mt. Pinatubo
➢ Plateau Mountains ( Erosion Mountains)
- Plateaus that have worn down from erosion
- The dictionary describes these as large areas of ‘high levels’ of flat land
Andes Mountains- longest mountain range in the world
The Alps- the largest mountain system in europe
Rocky Mountains- the major mountain range in Western North America
Great Dividing Range ( Australia) - a mountain range that forms a watershed; is also the third longest
land- based range in the world
The Appalachian - Oldest mountain range in the United States
★ MOUNTAIN BELTS
- Are groups of several mountain ranges that run roughly parallel to each other
THE INTERNAL STRUCTURE OF THE EARTH
➔ Seismic waves- as they travel through the earth, they are refracted and their speed gives vital
information on the composition of the different layers of the earth.
➔ Primary and Secondary waves- this is the basis for labeling the boundary between the crust and
the mantle/ or each layers of earth
- The Earth’s structure can be described chemically or mechanically
- The Chemical layers of the earth include the Crust, Upper Mantle, Lower Mantle, Outer Core & Inner
Core
- Chemically, the earth is made up of :
Oxygen: 46.6%
Silicon: 27.7 %
Aluminum: 8.1 %
Calcium: 3.6%
Sodium: 2.8%
Potassium: 2.6%
Magnesium: 2.1%
- Mechanically the earth has the following specific layers: Lithosphere, Asthenosphere (upper mantle)
,Mesospheric Mantle (lower), Outer Core, Inner Core
★ Arrangement of Layers of the Earth in Descending Thickness
MANTLE (THICKEST)
INNER CORE
OUTER CORE
CRUST (THINNEST
THE LITHOSPHERE
- It is the outermost layer of the earth,composed of the crust and the brittle part of the upper mantle
- The term lithosphere is derived from the Greek words “lithos” meaning stone, and “sphaira”
meaning globe or ball
- It is underlain by the Asthenosphere
THE CRUST
- Is the outermost layer of the earth
- The thinnest layer

8. - The outer covering of the crust is of sedimentary material and below that lie crystalline, igneous
and metamorphic rocks which are acidic in nature
2 types of crust:
● Continents
- Are composed of lighter silicates (silica + aluminum) - sial
- Acidic
- Lighter ( Felsic - feldspar, Quartz) composed of Sodium potassium aluminum silicate
rocks, like granite.
- Low density
● Oceanic
- Are composed of heavier silicates (silica + magnesium) - sima
- Base/ alkaline
- Heavier (Mafic) composed of iron magnesium silicate igneous rocks, like basalt.
- High density
MOHOROVICIC DISCONTINUITY ( MOHO)
- The boundary between the crust and the mantle
- It is discovered by the Croatian seismologist Andrija Mohorovicic, who inferred that the velocity of
a seismic wave is related to the density of the material that is moving through
THE MANTLE
- The largest layer of the Earth
- This layer is where the most of the internal heat of Earth is located, including the magma
chamber that drives volcanic processes.
- Composition:Iron, Aluminum,Calcium, Magnesium, Silicon and Oxygen
-
- Can be further divided into two:
★ THE UPPER MANTLE
- Semi- solid
- containing two distinct regions: ( Asthenosphere and the lower portion of the lithosphere)
- It is seen as highly viscous layer which lies between the crust and the lower mantle
- It is consists of Peridotite and dunite which are solid,ultramafic rocks made up of olivine and pyroxene
- Rocks in this area are cooler and brittle enough to break under stress
★ LOWER MANTLE ( also known as Mesospheric Mantle)
- Solid
- refers to the layer between the outer core and the asthenosphere
- Heat and pressure in the lower mantle are much greater than in the upper mantle
- The immense pressure keeps this layer solid despite the high temperature capable of softening
the rocks.
- It is solid because when pressure is high rock particles tend to be compressed and compacted
- Rocks in this area are hot and soft
atmosphere/ atm- unit of pressure
THE ASTHENOSPHERE
- A highly viscous, hotter and ductile region of the upper mantle that is involved in the plate tectonic
movement and isostatic adjustments
- Is a thick layer of the upper mantle that sits between the lower mantle and the lithosphere
Rocks in this area are on the verge of melting, but due to the high pressure, they behave in a
more ductile manner
- This is a weak layer which is denser and more fluid than the lithosphere above. The pressure
and heat are so high that rocks in this layer flow extremely slowly with a highly viscous molten-
fudge-like consistency.
- THIS IS WHERE THE CONVECTION CURRENT IS FORMED
THE CORE
- It is the planet’s source of internal heat because it contains radioactive materials which release
heat as they break down into more stable substances.
- It is composed mainly of an iron- nickel alloy.

9. 2 kinds of Core
★ OUTER CORE.
- LIQUID
- The temperature in this are is about 5,000 ° C, so it remains in its liquid state
- It is sandwiched between the inner core and the mantle, the boundary between the inner
core and the mantle is known as Lehman Seismic Discontinuity
★ INNER CORE
- It can be found at the deepest region of the planet
- It is very important region as the intense heat reflected from it mobilizes the materials of
the outer core and the mantle
- It is a solid hot ball that is submerged in the liquid outer core
- The inner core is solid because it is caused by the immense pressure that crystallized the
super hot iron into a solid ball
- This is where the densest materials on Earth is Located
- The primary contributors to the inner core’s heat are the decay of radioactive elements.
● As the Earth Rotates, the outer core spins over the inner core and generates Earth’s magnetic
Field
● Due to convection by heat radiating from the core together with the rotation of Earth on its axis,
the liquid iron (outer core) moves in a rotational pattern/ Swirling Motion which is believed to be
the source of the magnetic field of the earth. This circulating current is called the dynamo
effect/Geodynamo.
● Earth’s rotation causes the formation of large helices
● To generate additional force which can be enhanced through electrical force ( that can generate
magnetic field), when iron is liquid they start to swirls, the rotation of core is much faster than the
other layers,
GEODYNAMO
➔ Iron swirls through Earth’s Magnetic field
➔ This creates electric field
➔ Creates additional magnetic field which strengthens original field
For a planet to generate its own magnetic field by the geodynamo process it must have the following
characteristics:
- The planet rotates fast enough
- The interior must have a fluid medium
- The interior must have the ability to conduct electricity
- The core must have an internal source of energy that propels convection currents in liquid interior
D” layer
- is the boundary between outer core and the lower mantle
- Large thermal (heat) gradient
- Increased heterogeneity
- Slab graveyard or the place where subducted slabs eventually settle
Bullen Discontinuity
- The boundary between liquid outer core and dense solid inner core

10. EARTH’S MAGNETIC FIELD
- Also known as geomagnetic field
- It protects us from the harmful rays emitted by the sun
- It is generated in our planet’s interior and extends out into space, creating a region known as
magnetosphere.
- It exits at the South Geomagnetic Pole (found in Antarctica) and enters Earth at the North
Geomagnetic Pole (found in Ellesmere Island in North Canada) .
- It occurs in the outer core because the convective energy from the slow-moving molten iron is
converted to electrical and magnetic energy
- The magnetic field then induces electric currents which in turn generate their own magnetic field
which induces more electric currents, in a positive feedback loop
WHAT CAUSES EARTH MAGNETIC FIELD?
- For a planet to generate its own magnetic field by the geodynamo process it must have the
following characteristics.
● The planet rotates fast enough
● Its interior must have a fluid medium
● The interior must have the ability to conduct electricity
● The core must have an internal source of energy that propels convection currents in the
liquid interior
MAGNETOSPHERE
- Also known as “bubble”
- It protects us from harmful space weather such as solar wind.
- Without the magnetosphere, the solar wind would erode our atmosphere, devoiding our planet of
the life giving air we breathe
- It also protects Earth from large large quantities of particle radiation emitted during Coronal mass
ejection events,and also from Cosmic Rays,Atom fragments, raining on Earth from deep space
- The magnetosphere repels harmful energy away from Earth and traps in it zones called the “Van
Allen Radiation belts” these donut-shaped belts of radiation can swell when the sun’s activity
increases
-