Plate Tectonics

The Rage of the Earth

Why do some parts of the world erupt & the rest do not?

Why do earthquakes strike at some places and do not at other?

Why do Tsunamis strike at some coasts and do not at others?

Colonial

History

Pope Alexander VI

In 1493 Pope Alexander VI divided the world in two parts

- Eastern part to Portuguese and

- Western part to Spaniards

for looting and plunder, in the name of Christianity.

Dark Green = Spain’s Half

Light Green = Portugal’s Half

IndonesiaIndonesia

Thus Indonesia fell to Portugal.

But

Dutch replaced Portugal.

Colonial Indonesia under the Dutch rule

Modern Indonesia

Indonesia - Natural BeautyIndonesia - Natural Beauty

The Birth of Natural History

European dwellers of cold and arid North came into the contact with Nature in Tropical Land.

Indonesia was a Dutch colony with unusual concentration Indonesia was a Dutch colony with unusual concentration of scientistsof scientists

Philip Sclater & the Distinct FaunaPhilip Sclater & the Distinct Fauna

Western IslandsWestern Islands

- -

Eastern Islands Eastern Islands

Eastern IndonesiaEastern Indonesia

Western IndonesiaWestern Indonesia

Like this

Western Islands have…

Woodpecker

Barbet

Trogon

Shrike

Minivet

Drongo

Woodpecker DrongoWoodpecker Drongo BarbetBarbet Minivet Minivet Shrike Shrike TrogonTrogon

But these birds were not present at the Eastern Islands. In the Eastern Islands there were…

Bird of Paradise

Bird of Paradise

Cockatoo

Emu

Cassowary

CockatooCockatoo

Bird of Paradise Bird of Paradise Cassowary Cassowary EmuEmu

Animals were also different

Western Islands had…

Lemur

Tiger

Wolf

Mongoose

Otter

Tapir

Rhinoceros

Porcupine

Polecat

Scaly Anteater

Pole

cat W

olf

Pole

cat W

olf

An

teate

r A

nte

ate

r P

orc

up

ine

Porc

up

ine

Rh

inocero

s

Rh

inocero

s

Tap

irTap

ir

Lemur Lemur Tiger Tiger Mongoose Mongoose Otter Otter

And these were not present at the Eastern Islands. But there were some animals on the Eastern Islands…

Kangaroo

Wombat

Opossum

Platypus

KangarooKangaroo Wombat OpossumWombat Opossum PlatypusPlatypus

…which were not present at the Western ones

In making an eastward journey - the traveler will leave one world & entered

another one, utterly different.

The Eastern Islands had flora and fauna more akin to that of

Australia

Eastern Islands, Indonesia

Australia

Australia on the world Map

…while Western Islands had that akin to India

Western Islands, Indonesia

India

India on the world Map

Ist Break

Animals & birds of the Western Islands of

Indonesia were different from those of the

Eastern ones

Alfred Russel Wallace

Alfred Russel Wallace

• Plants and Animals are also different

Charles Darwin

Natural Evolution –

“…species mutate and grow into another species by the process of Natural Selection and Imperfect

species are eliminated & Perfect ones carry on.”

….they discovered crucial law

Geography is highly influential in the development of biology

…species evolve differently when they are separated geographically for

great distance & time.

So if two landmasses are diverse in their flora & fauna then it means that

they are two separate blocks.

Eastern Islands & Western Islands - two different landmasses.

But they are so near to each other. Then how is it possible?

The difference in the Indonesian islands come in just 15 kilometers.

If we cross from Bali in the West to Lombok in the East, then we get to see the difference, as if a very thin boundary is running between them

The position of Bali & Lombok

The difference comes in just 15 miles

West East

What invisible boundary is dividing these two 15 miles apart islands?

He postulated Wallace Line

Wallace’s Division of World Flora & Fauna

He explained that….

Such divisions could only be explained by vast changes in the surface of the earth.

Great Pacific Continent – broke up into separate islands – allowed such different varieties of plants

and animals to evolve in isolation.

IInd Break

Now we have learnt that the difference between the two landmasses is just 15 miles wide

And this is due to the Evolution. Wallace postulated that there was a large landmass in the

past which then broke up into several smaller landmasses.

Then came Alfred Wagner

World Map

He stated that South America fits into Africa

Earlier observed by Francis Bacon and Earlier observed by Francis Bacon and othersothers

Because of Biblical belief in the Because of Biblical belief in the immovability of land, people didn’t immovability of land, people didn’t

believe thembelieve them

These two continents had indeed been together in the past.

Pangaea

Laurasia & Gondwanaland

He gave us terms like Continental

Displacement or

Continental Drift

He supported his theory by the fossil He supported his theory by the fossil evidenceevidence

Wegener stated that these two Wegener stated that these two continents had indeed been together continents had indeed been together

in the pastin the past

He He proposed proposed that in the that in the past there past there was one was one single single

continent continent called called

PangaeaPangaea

……which then broke into Laurasia and which then broke into Laurasia and Gondwanaland and then into other Gondwanaland and then into other

smaller islands and continentssmaller islands and continents

Gondwanaland drifting Apart

……which then broke into Laurasia which then broke into Laurasia and Gondwanaland and then into and Gondwanaland and then into

other smaller islands and other smaller islands and continentscontinents

Plate Tectonics

Continental Moves

IIIrd Break

This theory said that continents and landmasses float and drift, break apart

and converge.

Where they break away, cracks, rifts, trenches remain

Where they collide, ranges of folded mountains appear.

Other Evidences

Greenland Expedition & the clues from the

paleomagnetism of rocks.

Basalt Rocks - Fe2O3

• Made from the cooling of red-hot magma after a volcanic explosion.

• Small crystals of Fe2O3 – that are highly magnetic.

• Molten phase - crystals tend to act as miniature compasses - reflecting the magnetic orientation of Earth.

Scientific brought rock samples – magnetic composition.

• The magnets were not aligned in the direction of the present poles at all, but towards an altogether different direction.

First time a rock solid explanation for continental drift had been given,

which defeated the Church.

Discovery on the North Western US Coast of sea-floor spreading.

How South America & Africa got apart?

Sea-floor Spreading

Map of Oceanic Ridges

How the sea floor spreads?

It seemed that there is a hotspot at a particular point in the earth’s

mantle, a deep and stationary hot spot.

Convection Current

Structure of the EarthStructure of the Earth

It was proposed that Earth has It was proposed that Earth has convection currents like there would convection currents like there would

be in waterbe in water

Where land is created ridges are Where land is created ridges are formed…formed…

Where plates collide trenches are Where plates collide trenches are formed…formed…

The Early Earth & Tectonic Plates

Types of Boundaries

•Creative Boundaries – mid-oceanic ridges or rift valleys.

•Destructive Boundaries – subduction zones or mountain formation.

Types of Plates

• Oceanic – Heavy Plate

• Continental – Light Plate

Three types of Plate-BoundariesThree types of Plate-Boundaries

DivergentDivergentConvergentConvergentTransform (Side-Long)Transform (Side-Long)

Divergent Boundary

Convergent Boundary

Side-long Boundary

Types of Convergent Boundaries

Oceanic-oceanic – any plate goes down at random. Subduction occurs. Volcanoes, Earthquakes

Continental-continental – Crumpling Occurs. Mountains, Volcanoes

Oceanic-continental – Oceanic Plate goes down. Subduction occurs. Mountains, Volcanoes, Earthquakes

Types of Convergent BoundariesTypes of Convergent Boundaries

Convergent Boundary

Convergent Boundary

Types of Divergent BoundariesTypes of Divergent Boundaries

Rift Valley FormationRift Valley FormationOcean-Floor SpreadingOcean-Floor Spreading

Ocean Floor Spreading

Transform Fault – Only one typeTransform Fault – Only one type

San Andreas FaultSan Andreas Fault

San Andreas Fault – Transform Fault

Tsunami…Tsunami…

The

The

Fata

l

Fata

l

Wav

e

Wav

e

The

Mec

hanis

m

The

Mec

hanis

m

of of

Tsunam

i

Tsunam

i

Tsunami Tsunami

Large sea wave produced by a Large sea wave produced by a seaquake or undersea volcanic eruptionseaquake or undersea volcanic eruption

It is produced when there is a It is produced when there is a displacement of a substantial volume of displacement of a substantial volume of water or perturbation of the seawater or perturbation of the sea

Drawing of tectonic plate boundary Drawing of tectonic plate boundary before earthquakebefore earthquake

Overriding plate bulges under strain, Overriding plate bulges under strain, causing tectonic upliftcausing tectonic uplift

Plate slips, causing subsidence and Plate slips, causing subsidence and releasing energy into waterreleasing energy into water

The energy released produces tsunami The energy released produces tsunami waveswaves

Tsunamis have a small amplitude (wave Tsunamis have a small amplitude (wave height) offshore, and a very long height) offshore, and a very long

wavelength (often hundreds of kilometers wavelength (often hundreds of kilometers long), which is why they generally pass long), which is why they generally pass

unnoticed at sea, forming only a slight swell unnoticed at sea, forming only a slight swell usually about 300 millimetres (12 in) above usually about 300 millimetres (12 in) above the normal sea surface. They grow in height the normal sea surface. They grow in height when they reach shallower water, in a wave when they reach shallower water, in a wave

shoaling processshoaling process

Wave ShoalingWave Shoaling

Japan

Thank You