Relief

Le relief de la Terre

RELIEF

Rafael AGÚNDEZ BLANCO

IES « Fray Pedro de Urbina »

1. The structure of the Earth

The Earth is divided into layers :

1. The core

2. The mantle

3. The crust

1

2

3

The core, over 6 000 km deep, is

made of iron and nickel. Earth’s

core temperature is estimated at

around 5 000 ºC.

The outer core, is liquid, but the

inner core remains solid because

of the high pressure.

6 000 km

The mantle, over 3 000 km deep, is

divided into two layers:

a) the lower mantle ou

asthenosphere, viscous;

b) the higher mantle, solid.

3 000 km

The higher mantle and the crust, a

thin solid layer (5 km deep), form

the lithosphere.

Lith

osp

he

re

Crust

Higher mantle

30

km

5 k

m

2. Plate tectonics

The lithosphere is broken into

tectonic plates, which ride on the

asthenosphere.

Tectonic plates move because of

asthenosphere movements.

Tectonic movements cause the

collision or divergence of tectonic

plates.

Plate boundaries are commonly

associated with geological events

such as earthquakes and the

creation of topographic features

such as mountains or volcanoes

Continents move at a speed of 10

cm per year because of plates

tectonics.

Continental drift is the movement

of the Earth's continents.

Arthropodes (e.g. trilobites) prosper in the

oceans.

Trilobite

Cambrian 500 m. a.

Ordovician 470 m. a.

The water temperature close to the surface is

40 ºC. One day is equivalent to 21 hours.

Silurien 430 m. a.

Land plants evolve from algae.

Dévonien 370 m. a.

First amphibians evolved from fish.

Carboniferous 300 m. a.

Earth is covered by forests, which produced

large quantities of coal in Europe.

First reptiles developed in response to an

drier climate.

Trias 220 m. a.

Pangaea was the supercontinent that existed

250 million years ago, before the component

continents were separated into their current

configuration.

A warmer and wetter climate allows the

developement of large rainforests. Ice caps

don’t exist.

It was a golden age for dinosaurs.

Jurassic 150 m. a.

Asteroid

Cretaceous 65 m. a.

A massive asteroid impact of 10 km caused

the a mass extinction of animal and plant

species.

Éocène 50 m. a.

Mammals expand after the extinction of the

dinosaurs. Australia separated from

Anctartica. The Himalaya is a result of the

continental collision between the indo-

Asutralian plate and the Eurasian Plate.

In several million years,

Africa will collide with

Europe.

Finally, every continent

will form a new

pangaea.

+50 m. a.

+250 m. a.

3. Landscape transformation

Tectonic

movements

Volcanos Erosion

The collision of tectonic

plates can produce two kinds

of lithosphere deformation

depending on the material

composition:

• Faults (fractures)

• Folds (curved

deformation)

Fold

Fault

The oceanic ridges are submarine

mountain ranges that result from the

divergence of tectonic plates.

Europe America

Oceanic

ridge

Vaults and folds exist from the

microscopi scale at hundreds of

kilometers.

The large vaults and folds result

in orogenics movements, which

are the origin of most of large

kinds of relief.

.

A mountain is a natural elevation of the Earth surface.

A peak is the pointed top of a mountain.

Altitude and steepness are used as criteria for

defining a mountain.

If altitude is considered, the highest mountain is the

Everest. But if steepnees is considered, the highest

mountain is Mauna Kea (Hawai).

10 200 m 8 844 m

Everest Mauna Kea

If the altitude of an elevation is not significant, it

is a hill,

If its steepness is not significant, it is a plateau, a

large flat area of land at high altitude.

Hill Plateau

The biggest landform in the world is the

Tibetan Plateau, called “the roof of the

world”.

It is four times the size of France and

has an average elevation of 4 500 m.

A mountain range is a long

and narrow succesion of

mountains.

A massif is a compact group

of mountains.

Massif

A fault might cause an earthquake, a sudden

movement of the Earth’s surface.

An Earthquake’s point at ground level is called

epicenter.

A seismograph is a device which

measures and records the magnitude

(strengh) of an earthquake.

The magnitude is a logarithmic scale,

so an increase of 1 step corresponds

to a 32 times increase in the amount

of energy released.

Magnitude Description Effects Frequency

2 Micro Not felt 8 000 per day

4 Light Shaking of indoor items 6 000 per year

6 Strong Major damage to poorly constructed buildings

120 per year

8 Great Serious damage. 1 per year

A submarine earthquake might cause a tsunami, a

lseries of waves caused by the displacement of a large

volume of water.

The sudden elevation of a fault cause the displacement

of a large volume of water to sea surface.

200 km

This wave cause a raised line of

water not very high (1 m), but

very long (200 km) and

extremely fast (800 km/h).

This makes tsunamis dificult to

detect over deep water.

As the tsunami approaches the

coast, its wavelength and velocity

diminish, but its height grows

enormously: the wave might be

over 30 m.

1,80 m

30 m

The 2004 Indian Ocean

Tsunami killed over 200 000

people.

P:/3º ESO - Geografía (bilingüe)/02 - El relieve/PowerPoint - El relieve/Tsunami Hits Thailand South East Asia!.wmv

Before After

A tsunami can change the coast landscape.

A volcano is an opening in the Earth’s crust, which allows

magma, ash and gases to scape from below the surface.

Magma is molten rock that is found beneath the surface

of the Earth.

If the magma reaches the surface, it erupts as lava or

tephra.

Lava is hot liquid rock which comes

out of the earth through a volcano

Pyroclasts or tephra are solid

fragments which are blasted into

the air (ashes, lapilli, volcanic

bombs…)

Lapilli Volcanic bomb

Volcanic cones are structures built by the accumulation

and solidification of lava flows.

A lava dome is a circular mound-shaped structure from

the slow eruption of very viscous lava from a volcano.

Volcanic fissures are fissures through which lava

erupts, usually without any explosive activity.

Volcanic fissures produce often lava fountains.

An underwater volcano

might produce the sudden

formation of an island.

The conduit is the passage through which the magma

travels to the surface.

A crater is a circular depression formed at the top of a

volcano.

Volcanic eruptions cause the formation of an ash cloud

20 km high. Ash clouds can generate lightnings.

Lava flow is a moving outpouring of lava, caused by the

rise of magma to the surface.

A dyke is a vertical infiltration of magma.

A sill is an horizontal infiltration of lava.

A batholite is a large accumulation of magma.

A fumarole is an opening in Earth’s crust which emits

steam and gases.

A geyser is a spring characterized by intermittent

discharge of water ejected turbulently and accompanied

by steam.

A nuée ardente is a fast-moving

currents of hot gas which travels

away from the volcano at speeds

generally as great as 700 km/h.

The gas can reach temperatures of

about 1 000 °C.

In Martinique, a nuée ardente

killed 30 000 people.

A lahar is a type of debris flow composed of pyroclastic

material, rocky debris, and water. The material flows

down from a volcano, typically along a river valley.

Snow is suddenly melted by lava, the

flood can flow 100 km/h, causing

catastrophic destruction in their path.

Lahars can be deadly because of their energy

and speed.

The lahars from the Nevado del Ruiz

eruption in Colombia in 1985 caused

the Armero tragedy, which killed an

estimated 23,000 when the city of

Armero was buried.

A caldera is a cauldron-like volcanic feature usually

formed by the collapse of land following a extremely

violent volcanic eruption.

A collapse is triggered by

the emptying of the magma

chamber beneath the

volcano

An islet (a dome) is often

formed in the center of the

caldera..

The collapse of the volcano results in a large

depression.

The eruption of a caldera in Toba,

70 000 years ago, was the Earth’s

largest eruption.

This event resulted in a global

cooling of atound 15 ºC and 10

years volcanic winter.

The collapse of a volcan might

produce a megatsunami.

Tsunami gigante.avi

Volcanos often form landscapes of remarkable beauty.

Morning Glory Pool (United States) Giants Causeway (United Kingdom) Champagne Pool (New Zealand)

Dallol (Ethiopia)

Erosion is the process of

weathering and transport of solids

in the natural environment.

Coastal erosion

River erosion

Wind erosion

Kars erosion

Ice erosion

Coastal erosion is the

weathering and transport of

solids by oceans

A bay is an area of water mostly surrounded by

land.

A large bay may be called a gulf.

Gulf Bay

An island is any piece of land that is surrounded by

water.

Very small islands are called islets or keys.

Island Islet

An atoll is an island of coral that encircles a body of

shallow sea water or lagoon partially or completely.

Atolls are in tropical waters.

A beach is a landform along the shoreline of an

ocean, sea or lake

The color of sand depends on the composition: the

white sands contain coral and shell fragments; the

black sands have a volcanic origin.

White sands Black sands Pebbles Beachrock

A sandbar is a linear landform extending into a body of

water, typically composed of sand or small pebbles.

A spit is a type of sandbar that

connects to land and extends into

the sea.

A lagoon is a body of sea water

separated from the sea by a bar.

A tombolo is a landform in which

an island is attached to the

mainland by a sandbar.

Spit Tombolo

Lagoon

A cliff is a vertical landform due

to the processes of erosion.

Cliffs are common on coasts and

in mountainous areas,

A natural arch is a landform with

an opening underneath. It may

become in a needle.

Albufera (Valencia)

Etretat cliffs

Tombolo

River erosion is the weathering

and transport of solids by rivers

A river is a natural watercourse flowing toward an

ocean, a lake, a sea, or another river.

A tributary or affluent is a river which flows into a main

river.

The longest rivers in the world are the Nile (6 718 km),

and the Amazon (6 500 km).

However, the Amazon is by far the largest river

because it has the largest flooded basin in the world,

(350 000 km2). It is approximately one-fifth of the

world's total river flow.

Nile

Amazon

Rivers flow downhill from river

source through the river bed.

A lake is a body of water of

considerable size that is

surrounded by land.

It is larger and deeper than a pond.

A waterfall is a place where

flowing water rapidly drops in

elevation as it flows over a

steep region or a cliff.

Niagara Falls (52 m)

A canyon or gorge is a deep valley

between cliffs often carved by a river.

The Grand Canyon in Arizona is 446 km

long, up to 29 km wide and attains a

depth of 1 830 m.

A meander is a curve of a river.

It is formed when the moving water

in a river erodes the outer banks

and widens its valley.

The mouth is the place where a river flows

into the sea.

An estuary is the wide part of a river at the

place where it joins the sea.

A delta is a low land formed at the mouth of

a river, often shaped like a triangle.

Estuaire Delta

A ria is a drowned river valley that results

of sea level changes.

Colorado Canyon

Black Canyon

Glen Canyon

Meandering river

Angel Falls (Venezuela)

Niagara Falls

Havasu Falls

Iguazu Falls

Wind erosion is the weathering

and transport of solids by rivers.

Wind erosion is very important in deserts because

of the lack of vegetation.

A desert pavement or reg is a desert surface that is

covered with pebbles. An erg (also sand sea) is a large

area of desert covered with sand.

Reg Erg

A dune is a hill of sand built by aeolian processes

in the ergs.

A barchan dune is an arc-shaped sand ridge.

Wind

direction

Barchans

Riples are structures with a

sinusoidal profile.

Yardangs are rocky structures

carved from bedrock by the wind

abrasion.

Ripples

Yardangs

Examples of wind erosion

Utah (United States)


Atacama (Bolivia)

Las Gredas (Murcia)



Urulu (Australia)

Man-Pupu-Nyor (Russia)


Lençois Maranheses (Brazil)


Karst erosion is a landscape

shaped by the dissolution of

limestone.

A doline or sinkhole is a natural depression or hole in

the Earth’s surface.

If the depression is very large and flat, it is called a polje.

Polje

Doline

A limestone pavement is a natural karst landform

consisting of a flat, incised surface of exposed limestone.

Stalactites

A stalactite is a structure that hangs from the ceiling of

limestone caves.

A stalagmite is a structure that rises from the floor of

the cave due to the dripping of calcium carbonate.

Stalagmites

Examples of karst erosion

Tazka (Croatia)


Witch Finger (United States) Tien Son (Vietnam)


Ciudad Encantada de Cuenca


Antelope Canyon (United States)


Chocolate Hills (Philippines)


Pamukkale (Turkey)


Huanglong (China)


Blue Hole (New Zealand)

Ice erosion is the weathering

and transport of solids by

glaciers.

A glacier is a large persistent body of ice.

Nowadays glaciers cover a small area of the Earth. However,

20,000 years ago, glacier covered large regions.

During glaciation, water was

taken from the oceans to

form the ice, thus global sea

level dropped by about 110

meters

Nowadays there are two types of glaciers:

1) the indlandsis or ice sheet, masses of glacier

ice that are greater than 50 000 km2 (Antarctica

and Greenland);

2) the alpine glaciers, formed on the crests of

mountains.

Indlandsis Alpine glacier

Inlandsis.ppsx

The indlandsis must be

distinguished from the sea ice,

formed from seawater that

freezes.

Sea ice cyclically freezes and

melts due to the seasons.

An iceberg is a large piece of

ice from freshwater that has

broken off from a glacier and is

floating in open water.

Alpine glaciers form on the crests and

slopes of mountains.

An alpine glacier that fills a valley is

sometimes called a valley glacier.

A cirque is a concave landform

found among mountains as a

result of alpine glaciers. .

A moraine is an accumulation

of glacial debris.

An arête is a thin ridge of rock.

The meeting of three or more arêtes creates pointed

pyramidal peaks, called horns.

A U-shaped valley has steep, straight sides, and a flat

bottom. It is formed when a glacier travels across and

down a slope, carving the valley by the action of

scouring. When the ice recedes, the valley remains.

Vallée glaciare.ppsx

A glacial lake is a

lake with origins in a

melted glacier.

In Finland, the Ice Age resulted in

a vast quantity of lakes.

In fact, more than 10 percent of

Finland is covered by water.

A fjord is a drowned glacier valley

with steep sides that results of sea

level changes.

fjord.ppsx

Coasts having the most pronounced

fjords include the northwest coast of

Europe, the west coast of North

America, the west coast of New

Zealand, and the west coast of South

America and to south-western

Tasmania.

4. Relief representation

A topographic map is a type of map

characterized by large-scale detail and

quantitative representation of relief,

A contour line (also isohypse)

is a curve that joins points of

equal elevation (height).

Contour lines are represented

using numbers (100 m, 200 m,

etc.) or colors (green for

depressions, white for

mountains, etc.).

A topographic profile is a

vertical view of a topographic

map.

Profil topographique

Carte cartographique

carte_topographique.ppsx

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Relief

Education

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