DIVERGENT BOUNDARIES: The Dividing Plates

Summary

This educational video script explores the concept of divergent boundaries in plate tectonics, explaining how tectonic plates moving apart create new crust and contribute to the formation of oceans and rift valleys. It distinguishes between continental and oceanic divergence, detailing the processes of rifting, seafloor spreading, and the creation of mid-ocean ridges. The script uses relatable analogies, vivid examples, and even humor to make complex geological concepts accessible, concluding with a Marilyn Monroe quote to inspire curiosity about the next lesson on plate tectonics.

Takeaways

• 🌏 Divergent boundaries occur when two tectonic plates move apart, causing the Earth's crust to break and create gaps.
• 🔥 Earthquakes are common along divergent boundaries due to the movement of plates and the rise of magma from the mantle.
• 🌊 Divergent boundaries result in the widening of bodies of water and the formation of new oceanic crust through the solidification of lava.
• 🌿 There are two types of divergent boundaries: continental divergence, which splits continents, and oceanic divergence, which occurs at the ocean floor.
• 🏞️ Continental divergence involves the thinning and eventual splitting of continental crust, leading to the creation of new ocean crust and oceans.
• 🌋 Rift valleys and volcanoes are formed as a result of continental divergence, with magma filling the gaps between separating plates.
• 🌌 Oceanic divergence is characterized by volcanic activities at the ocean floor, leading to seafloor spreading and the widening of the ocean floor.
• 🌐 Convection currents in the mantle drive the movement of tectonic plates and are responsible for the formation of divergent boundaries.
• 🌄 Mid-ocean ridges are underwater mountain ranges formed by the upwelling of magma along divergent boundaries in the ocean floor.
• 🌍 The Mid-Atlantic Ridge is a prominent example of a mid-ocean ridge, resulting from the divergence of the North American and Eurasian plates.

Q & A

What is the main topic of the fifth lesson in the script?

The main topic of the fifth lesson is divergent boundaries, which involve the study of what happens when tectonic plates move apart.

What are the three objectives of the lesson on divergent boundaries?

The three objectives are: 1) to determine divergent boundaries, 2) to differentiate the types of divergent boundaries, and 3) to appreciate the results of diverging boundaries.

How are divergent boundaries described in the context of a breakup scene in drama?

Divergent boundaries are likened to a breakup scene in drama where the breaking and flowing of emotions are compared to the earth's crust breaking and magma flowing when plates diverge.

What happens at divergent boundaries?

At divergent boundaries, earthquakes are common, and magma rises from the earth's mantle to the surface, creating new oceanic crust and leading to the widening of bodies of water.

What are the two types of diverging boundaries mentioned in the script?

The two types of diverging boundaries are continental divergence, which occurs when continental crust splits apart, and oceanic divergence, which occurs when oceanic crust breaks up.

What is the process that leads to the formation of rift valleys during continental divergence?

During continental divergence, a concentration of heat beneath the earth's crust called a mantle plume causes the crust to expand and become uplifted, leading to the formation of normal faults and rift valleys.

How does the African Rift Valley relate to the concept of continental divergence?

The African Rift Valley is an example of ongoing continental divergence, indicating that the African continent is slowly breaking into two due to the separation of tectonic plates.

What is the term for the volcanic activity that occurs between the diverging plates during continental divergence?

The term for the volcanic activity that occurs between the diverging plates during continental divergence is 'rift volcanoes'.

What is the process called that results in the widening of the sea floor during oceanic divergence?

The process that results in the widening of the sea floor during oceanic divergence is called seafloor spreading.

What is a convection current and how is it related to divergent boundaries?

A convection current is the driving mechanism of plate tectonics where hotter, less dense particles rise and cooler, denser particles sink. It is related to divergent boundaries as it causes the earth's crust to thin and eventually split apart.

What is the significance of mid-ocean ridges in the context of divergent boundaries?

Mid-ocean ridges are significant as they are underwater mountain ranges formed by the process of seafloor spreading along divergent boundaries, indicating the earth's crust is splitting apart.

Outlines

00:00

🌏 Introduction to Divergent Boundaries

The video script introduces the concept of divergent boundaries in plate tectonics. The teacher, Dags, sets the stage for the lesson by drawing an analogy between the emotional drama of a breakup and the geological process of tectonic plates moving apart. The lesson has three objectives: to identify divergent boundaries, to differentiate their types, and to appreciate their geological results. The script explains that divergent boundaries are characterized by the creation of space or gaps between crusts, often associated with earthquakes and the formation of new crust as magma rises to the surface. The teacher uses the imagery of a dramatic breakup to illustrate the concept, highlighting the 'breaking' and 'flowing' aspects of the process.

05:02

🌋 Types of Divergent Boundaries

This section delves into the two types of divergent boundaries: continental and oceanic. Continental divergence is described as a process where the crust thins and eventually splits apart, allowing magma to rise and create new oceanic crust, leading to the formation of rift valleys and new oceans. Examples such as the Colorado Plateau, African Rift Valley, Red Sea, and the Atlantic Ocean are given to illustrate the stages of this process. Oceanic divergence, on the other hand, involves volcanic activities at the ocean floor as the crust splits, leading to seafloor spreading and the widening of the ocean floor. The script also introduces the concept of convection currents and mid-ocean ridges, explaining how they contribute to the formation of new crust and the widening of the ocean floor.

10:03

🌌 Oceanic Divergence and Seafloor Spreading

The script continues with a focus on oceanic divergence, explaining the process of seafloor spreading in detail. It describes how a mantle plume's heat concentration leads to convection currents that lift and stretch the lithosphere, creating a rift valley and mid-ocean ridge. As magma rises and solidifies along the ridge, new oceanic crust is formed, and the seafloor widens. The script clarifies the terms 'convection current' and 'mid-ocean ridge,' emphasizing their roles in plate tectonics. It contrasts divergent boundaries with convergent boundaries, highlighting that while divergent boundaries create new crust, convergent boundaries destroy it through subduction.

15:18

🔥 Volcanic Activity and the Formation of Oceanic Crust

This part of the script discusses the volcanic activity associated with divergent boundaries, particularly at mid-ocean ridges. It describes how underwater eruptions lead to the formation of pillow-like lava formations and underwater mountain ranges. The Mid-Atlantic Ridge is highlighted as an example of an active volcanic region, cutting through Iceland and creating a landscape of 'ice and fire.' The script summarizes the major results of divergent boundaries, including earthquakes, the formation of normal faults and rift valleys, the appearance of volcanoes, the creation of new oceanic crust, and the widening of oceans. It concludes with a playful challenge for viewers to solve word puzzles related to the lesson and a quote from Marilyn Monroe, suggesting that sometimes things must fall apart for better things to come together.

🎬 Conclusion and Upcoming Lesson

The video concludes with a reminder for viewers to watch the movie 'San Andreas' for insights into the next lesson's topic, which is likely about transform boundaries. The teacher bids farewell, emphasizing the importance of remembering the lesson on divergent boundaries and looking forward to the next class.

Keywords

💡Divergent Boundaries

Divergent boundaries are areas where two tectonic plates move away from each other, causing the Earth's crust to stretch and thin. This process is central to the video's theme of plate tectonics and is exemplified by the script's discussion of how these boundaries lead to the creation of new crust and the widening of bodies of water. The video uses the analogy of a breakup scene to describe the separation at divergent boundaries, emphasizing the concept's relevance to the Earth's dynamic geological processes.

💡Tectonic Plates

Tectonic plates are large slabs of the Earth's lithosphere that float on the semi-fluid asthenosphere beneath. They are a fundamental concept in the video, as their movement is responsible for the creation of divergent boundaries. The script mentions how these plates' movement away from each other at divergent boundaries leads to earthquakes and the rise of magma, illustrating the dynamic nature of the Earth's surface.

💡Magma

Magma is molten rock found beneath the Earth's surface, and it plays a crucial role in the formation of new crust at divergent boundaries. The video explains that as tectonic plates move apart, magma rises from the mantle to fill the gap, eventually solidifying to create new oceanic crust. This process is vividly described in the script, linking magma's role to the observable features such as mid-ocean ridges.

💡Continental Divergence

Continental divergence refers to the process where continental crust splits apart at a divergent boundary. The video script describes how this leads to the formation of rift valleys and eventually new oceans. An example given is the African Rift Valley, indicating the slow separation of the African continent into two, which is a direct result of continental divergence.

💡Oceanic Divergence

Oceanic divergence is the process occurring beneath the ocean where the oceanic crust breaks up, allowing for seafloor spreading. The script explains that this type of divergence is characterized by volcanic activities at the ocean floor and the widening of the ocean basin. The Mid-Atlantic Ridge is cited in the video as an example of oceanic divergence.

💡Seafloor Spreading

Seafloor spreading is the process by which new oceanic crust is formed at mid-ocean ridges due to the upwelling of magma at divergent boundaries. The video script describes this as a key result of oceanic divergence, where the seafloor becomes wider as the plates move apart. This process is integral to the formation of underwater mountain ranges and the expansion of ocean basins.

💡Convection Current

Convection currents are the driving mechanism of plate tectonics, where hotter, less dense material rises and cooler, denser material sinks within the mantle. The video script explains that these currents are responsible for the movement of tectonic plates and the formation of divergent boundaries. The concept is illustrated through the animation of how these currents lead to the thinning and eventual splitting of the Earth's crust.

💡Mid-Ocean Ridge

A mid-ocean ridge is a large underwater mountain range formed by the upwelling of magma at divergent boundaries. The video script describes the Mid-Atlantic Ridge as an example, which is created by the divergence of the Eurasian and North American plates from the African and South American plates. This keyword is central to the video's explanation of oceanic divergence and seafloor spreading.

💡Rift Valley

A rift valley is a lowland area formed by the stretching and eventual breaking of the Earth's crust at divergent boundaries. The video script uses the African Rift Valley and the Rio Grande Rift Valley as examples, showing how these features are evidence of the continuous separation of continental crusts and the formation of new crust.

💡Volcanoes

Volcanoes are significant features associated with divergent boundaries, both continental and oceanic. The video script describes how rift volcanoes form as magma rises to fill the gap between diverging plates, with the Urda Ale Volcano in Ethiopia being highlighted as an example. Volcanic activity is a key indicator of the processes occurring at divergent boundaries.

💡Constructive Boundary

A constructive boundary, as explained in the video script, is a type of divergent boundary where new crust is created as plates move apart. This is in contrast to a destructive boundary, where crust is destroyed. The script emphasizes that divergent boundaries are constructive because they lead to the formation of new crust, contributing to the widening of ocean floors and the creation of mid-ocean ridges.

Highlights

Introduction to divergent boundaries and their role when plates move apart

Three learning objectives: determine divergent boundaries, differentiate types, and appreciate results

Analogy between dramatic breakups and the geological process of divergent boundaries

Description of the earth's crust breaking and separating at divergent boundaries

Earthquakes and magma rising at divergent boundaries leading to new oceanic crust formation

Expansion of bodies of water and ocean floor widening due to divergent boundaries

Two types of divergent boundaries: continental and oceanic crust breakup

Process of continental divergence with magma causing the crust to thin and split

Stages of continental divergence from heat concentration to new ocean formation

Examples of each stage of continental divergence: Colorado Plateau, African Rift, Red Sea, and Atlantic Ocean

Formation of rift valleys and their significance in tectonic plate movement

Volcano formation between diverging continental plates as seen in Africa and Arabia

Explanation of oceanic divergence and seafloor spreading

Convection currents as the driving mechanism behind plate tectonics

Definition and importance of mid-ocean ridges in the context of divergent boundaries

Discovery of mid-ocean ridges during World War II and their volcanic activity

Iceland's unique geology as a result of the Mid-Atlantic Ridge and its volcanic activity

Major results of divergent boundaries including earthquakes, fault formations, and crust creation

Constructive nature of divergent boundaries with continuous supply of new crust

Activity 'Wider and Wiser' to reinforce learning about divergent boundaries

Quotation from Marilyn Monroe to conclude the lesson on divergent boundaries

Transcripts

[Music]

good day science scoopers

welcome back to our online class we are

now about to tackle our fifth lesson

the divergent boundaries we will know

what happens when plates move apart

i am your teacher dags and i want to

drag you to our studies

have your notebook and pen ready so you

can take down important notes

here at the science scoop we will learn

science with fun

here are three objectives for today the

first objective is to determine

divergent boundaries

the second objective is to differentiate

the types of divergent boundaries

the third objective is to appreciate the

results of diverging boundaries

our lesson for today is somewhat related

to drama especially when there is

breakup scene

separation between two people who love

each other makes their hearts broken and

their tears flow from their eyes

these two the breaking and the flowing

are also observed when plates go

divergent boundaries

it may sound funny but watching breakup

dramas remind me of divergent boundaries

to officially start our lesson for today

i have here pictures showing the results

of divergent boundaries what word or

words can you use to describe these four

pictures

the two pictures above happen on

continental divergence and the two

pictures below

happen when oceanic divergence occur all

pictures show space or gap between

crusts

thus we can say that the earth's crust

is broken in separating boundaries

[Music]

divergent boundaries occur when two

tectonic plates move away from each

other

along the divergent boundaries

earthquakes are common and magma or the

molten rock rises from the earth's

mantle to the earth's surface

the molten material on the earth's

surface or lava will solidify to create

new oceanic crust

aside from frequent earthquakes or

shaking divergent boundaries result to

wider bodies of water like ocean

the new ocean crust deposits turn ocean

floor wider

there are two types of diverging

boundaries the first one happen when

continental crust splits apart

and the second one occur when oceanic

crust breaks up

let us first tackle the continental

continental divergence

let us know the mystery why this land in

africa splits apart

a divergent plate boundary on land rips

apart continents

in continental rifting magma rises

beneath the continent

causing the continental crust to become

thinner and thinner

as this event continues the continental

crust breaks and ultimately split apart

the new ocean crust erupts creating an

ocean between the splitting continents

let us see what happens to the diverging

continental crusts

the first event happens when there is a

concentration of heat beneath the earth

crust called mantle plume

as the crust is heated it is expanded

making a broad area become uplifted

this second illustration shows that both

normal faults and rift valleys are

formed

rift valleys are lowland formed when

diverging boundaries take place

as time goes by and the continental

crusts are ultimately broken apart

the hot molten materials from the mantle

rise and form new oceanic crust

the gap between crusts is filled by

water creating new ocean

after so many years the crust become

thinner and thinner due to erosions

the crust cools contracts and sinks

beneath the sea forming wider ocean

the splitting boundaries around the

globe can make us see their results in

each stage

for stage 1 we have colorado plateau

for stage two we have african rift

valley and rio grande valley as examples

for stage three we've got the red sea

and for the last stage we have the

atlantic ocean

as the tectonic evolution happens the

concentration of heat beneath

makes the crust expanded and uplifted as

observed in colorado plateau

these pictures show the african rift

valley and the rio grande rift valley

both are evidences on the continuous

separation of continental crusts

the great rift valley of africa is an

indication that african continent is

slowly breaking into two

a rift valley is a lowland region that

forms where earth's tectonic plates move

apart or rift

rift valleys are found both on land and

at the bottom of the ocean

where they are created by the process of

seafloor spreading

as continental continental divergence

occurs rift volcanoes are being formed

as magma rises to fill the gap between

diverging plates

thus you can see series of volcanoes

between the african plate and the

arabian plate

also as africa is torn apart volcanoes

in between its pieces are seen

[Music]

this is urda ale volcano of ethiopia

africa

the natives of ethiopia africa named the

urta ale as lava lake

when continental divergence is on its

third stage linear sea is evident

red sea is formed due to the diverging

african and arabian plate

as the divergence continues for million

years the ocean formed has turned bigger

the atlantic ocean has gone very vast as

the plates of north american plate and

south american plate move separately

from eurasian plate and african plate

the atlantic ocean becomes wider and

wider as divergence among plates

continues

now let us discuss the second type of

divergent boundaries

oceanic oceanic divergence do you know

that there are lots of volcanic

activities happening at the bottom of

the sea

these volcanic eruptions at the ocean

floor occur as oceanic crusts split

apart

also due to this ocean floor becomes

wider in the process called seafloor

spreading

oceanic divergence leads seafloor

spreading

seafloor spreading means that the sea

floor becomes wider

let us discuss this process step by step

when a divergent boundary occurs beneath

oceanic lithosphere

the concentration of heat in the mantle

plume forms convection current

this convection current lifts the

lithosphere

the extensional forces due to convection

currents stretch the lithosphere and

produce a deep fissure

this will lead to the formation of the

rift valley and the mid-ocean ridge

the hot molten material rises to the

crack along the mid-ocean ridge

as the lava solidifies new oceanic crust

is formed

the seafloor becomes wider thus we can

say oceanic divergence leads to the

seafloor spreading

okay we have to unblock our vocabulary

for convection current and mid-ocean

ridge

so we had better take a pause on our

discussion about diverging boundaries

for a while to know the meaning of those

words

convection current is the driving

mechanism of plate tectonics

in convection current hotter and less

dense particles rise and the cool and

denser particles sink

the hot less dense rising material

spreads out as it reaches the mantle

causing upward and sideward force

this is evident in divergent boundaries

the downward movement of the convection

current occurs along a convergent

boundary where the sinking force pull

the tectonic plate downward

this illustration shows the

cross-sectional view of the earth

this is the mantle plume at the mantle

plume

there is a great concentration of heat

as the temperature increases

the materials become less dense causing

the hot molten rock or magma to rise

as the magma rises there is a decrease

in its temperature causing the magma to

move and sink

sideward this process happens repeatedly

which turns the earth's crust thinner

and thinner

as time goes by the earth's crust split

apart

this is how convection current cause

divergent boundaries

this animation shows how convection

currents move

remember the hotter materials are less

dense and move upward

as the materials become farther from the

plume it cools down a bit and become

denser

thus the materials move and sink

sideward going back to the plume

as convection currents continue the

earth's crusts move

as divergent boundaries happen at one

part of the globe

convergent boundaries occur at the other

side of the planet

at divergent boundaries the gap formed

between the crusts is being filled by

the magma

at convergent boundaries the crust goes

under subduction

however you should know that the rate of

the processes of divergent boundaries

and convergent boundaries are not the

same

right the converging boundaries destroy

crust when it reaches the subduction

zone

the high temperature of the

asthenosphere or the upper part of the

mantle melts the crust

thus convergent boundary is also called

as the destructive boundary

however in diverging boundaries hot

molten materials are released and become

new crust as it cools down

for this reason diverging boundary is

called as the constructive type

according to some references mid-ocean

ridges were first discovered during the

world war

ii as soldier submarine accidentally

observed patterns of unusual structures

underwater

this is the map of the world's mid-ocean

ridges

mid-ocean ridge implies that the earth's

crust split apart

as the lava fills the gap along the

underwater rift underwater mountain

ranges is formed

this is called as the mid-ocean ridge

this picture shows the mid-atlantic

ridge

like other ocean systems mid-atlantic

ridge has developed as a consequence of

the divergent motion between eurasian

and north american plates and african

and south american plates

this video of mynegai 101 shows how new

oceanic crust is formed as mid-ocean

ridge

also starts developing in an underwater

eruption the molten lava comes in direct

contact with the cold sea water

and forms characteristic pillow-like

shapes

[Music]

[Music]

in underwater eruption the molten lava

comes in direct contact with cold sea

water

as it solidifies mountain ranges

underwater or the mid-oceanic ridges are

formed

these are the ridges of the world among

these

the mid-atlantic ridge is considered as

one of the most active ridges in terms

of volcanic activity

the mid-atlantic ridge formed due to the

diverging boundaries of north american

plate and the eurasian plate

the mid-atlantic ridge is well known for

it cuts iceland directly separating or

dividing the country into pieces

because of the diverging movement of

north american plate and eurasian plate

happens

fisher volcanoes along the splitting

parts of iceland appeared

iceland is directly cut by the

mid-atlantic ridge

mount helka is one of the active

volcanoes of iceland

because of its uniqueness iceland has so

many attractions

it has cold weather at the same time

volcanic activities happen to the

country

here are some pictures of iceland

showing how it has gotten its nickname

as the land of ice and fire

overall here are the major results of

divergent boundaries

earthquakes often occur along the

splitting plates

as these plates continue moving apart

normal faults and rift valleys are

formed

volcanoes appear along the diverging

plates

the creation or lengthening of the ocean

floor happens as the separation

continues

formation of new crust becomes possible

as magma rises at the ocean floor

this event leads to underwater mountain

ranges or mid-ocean ridge

since new crust is created the divergent

boundary is called as constructive type

the splitting plates assure the

continuous supply of new crust

the upward and sideward forces when new

materials are released cause the

sideward movement of oceanic crust as it

spreads

thus both sides of the crack left and

right

receive the same materials at the same

time

the newest or youngest crust is found

nearest to the crack

the oldest crust is found farthest from

the source of hot molten materials

the ocean becomes wider and wider as

this volcanic activity goes on between

the divergent boundaries

remember when things split or broken

apart water flows

i'm sorry for that joke kidding aside

the result of both types of divergence

is the formation or lengthening of ocean

floor

now that you already know the two types

of divergent boundaries

you can explain how these earth features

formed

at the meantime i feel that you are now

ready to do our activity

now let us have our challenge today

let's call this wider and wiser

wider because i believe that after our

discussion you get wider ideas

about plate tectonics thus you have

turned wiser

the mechanics of this activity is very

simple

i have set of yellow letters for every

item

the description of the answer that i am

looking for is in the box

in 10 seconds you have to tell the word

being described using the given shuffled

letters

let's have this as our example i have

the set of yellow letters

and here is the box containing the

description of my words

you have time limit after 10 seconds

the answer will be revealed in our

example the answer is teacher dags

i believe that you are ready let's start

our activity

the answer is divergent boundaries

the description is for the rift valleys

for this item the answer is the

mid-ocean ridge

the answer is convection current

[Music]

for the last item the answer is wider

ocean

for our next lesson you may watch san

andreas movie to get ideas on our next

topic

before we end our class today here is

the quotation from miss marilyn monroe

sometimes good things fall apart so

better things can come together

our class for today is now dismissed i

hope you won't forget the lesson you

have just learned

see you next class goodbye

[Music]

[Music]

you