2. THE STRUCTURE OF THE EARTH
Upper mantle and
crust form the
LITHOSPHERE
3. Continental Drift Theory (By Alfred Wegener)
Millions of years ago there was only one continent called Pangaea
4. What are Tectonic Plates?
• The Earth’s crust
is divided into
large blocks called
plates. The heat
inside the Earth
creates currents
which move the
plates around.
• Oceanic plates
carry the oceans.
• Continental plates
carry the
continents.
The movement of plates is called
Plate Tectonics
Plates on the Lithosphere
7. What happens where plates meet?
• The places where
plates meet are called
plate margins or
boundaries. It is often
in these places that
the Earth is unstable
resulting in
earthquakes and
volcanoes.
8. We can find three main zones
•The “Ring of Fire” is a boundary area around the Pacific Plate, which affects the coastal areas of Asia, western America and
Oceania.
•The mediterranian-asian area, which affects the Mediterranean Sea, the Himalaya and Indonesia.
•Mid-Ocean ridges which result from divergent plates separating from each otherand creating new crust.
9. What are the different types of plate
margins (boundaries)?
Boundaries between tectonic plates can be
of three types. Click on the links to view
animations of each plate boundary.
1. Constructive plate boundaries create
new crust, and often give rise to volcanoes
and earthquakes.
2. Destructive plate boundaries create
mountains and may give rise to volcanoes
and earthquakes.
3. Conservative plate boundaries do not
create or destroy land, but often give rise
to earthquakes (not volcanoes).
Key Words
Oceanic
Continental
Friction
Earthquakes
Magma
Volcanoes
Subuction
Fold Mountains
VIDEO
14. Continental Relief: Mountains
• Are high landforms
with steep sides. The
world´s highest
mountain range is the
Himalaya in Asia.
• Rocky Mountains, Canada
15. ALPS : example of young
mountains which are high and their
peaks are very prominent
SIERRA MORENA : example of old
mountains which are low and
rounded because of erosion
Shields or platform
(escudos y
penillanuras) are ancient
mountains ranges that
have eroded and become
plains or small rounded
hills
16. Continental Relief : valleys
• Are areas of low land
between mountains.
Rivers flow through
many valleys.
• Valley of Pas, Asturias
17. Continental Relief : plateaus
• Are large, raised
plains. The highest
plateaus are in Tibet
in Asia, and in Bolivia
in South America
18. Continental Relief: plain
• Are low, flat areas of
land. Large plains are
often found on the
coasts, and are
formed by large
rivers.
23. Peninsula: is an area of land surrounded
by water on all sides except one.
Isthmus connects a peninsula to a
continent.
24. Coastal Relief:Capes and Gulfs
Cape or headland is a part of the coast
which extends into the sea
Gulf: Is a large area of a sea or ocean
partially enclosed by land. A bay is a small
gulf.
27. Coastal Relief: Cliffs
• Are steep rock
formations in high
coastal areas
• Falaise d´Aval, Haute Normandie.
28. CLIFFS AND WAVE-CUT PLATFORMS
Cliffs are steep rock faces along the coastline, they tend to form along coastlines with resistant
rocks parallel to the coast.
29. Coastal Relief: Islands
• Are areas of land
surrounded by water
on all sides. A group
of islands is called an
archipelago
30. Fjords
• Are a long, narrow
inlets with steep sides
or cliffs, created by
glacial erosion.
37. CONTINENTAL WATERS
Rivers
Drainage Basins have a number of distinct
features:
•The edge of a drainage basin is
characterised by the highest points of
land around the river, this is known as
the watershed (cuenca fluvial or cuenca
hidrográfica).
•The point at which a river starts is
called its source.
•As the river continues to flow down
stream it may be joined by smaller
rivers called tributaries.
•The point at which these smaller
rivers join the main river is known as a
confluence.
•As the river continues its journey,
eventually reaches the sea - the point
where the river flows into the sea is
known as the river mouth.
Watershed
http://techalive.mtu.edu/meec/demo/Watershed.html
38. RIVER´S LONG PROFILE
Upper CourseUpper Course Middle CourseMiddle Course Lower courseLower course
SOURCESOURCE
MOUTHMOUTH
Course Gradient Valley and channel shape Cross profile
Upper Steep Narrow, shallow channel V-shaped valley, steep
sides, canyons, waterfalls.
Middle Medium Wider, deeper channel Gently sloping valley sides,
meanders.
Lower Gentle Very wide, deep channel Very wide, almost flat valley,
deltas, estuaries.
40. Landforms at the upper course of a river
http://www.cleo.net.uk/resources/displayframe.php?src=308/consultants_resources%2F_files%2Fintespur2.swf
V-shaped Valley - a valley which resembles a 'v' in
cross section. These valleys have steep sloping sides
and narrow bottoms.
Waterfall - Waterfalls usually occur where a band of
hard rock lies next to soft rock.They end up creating
steep sided valleys known as gorges or canyons.
42. •Here the river channel has become much wider and deeper as the channel has been
eroded and the river has been fed by many tributaries upstream.
•As well as changes in the river channel, its surrounding valley has also become wider
and flatter in cross-section with a more extensive floodplain.
•Unlike the relatively straight channel of the upper course, in the middle course there are
many meanders (bends) in the river.
Landforms at the middle course of a river
43. Over time meanders gradually change shape and migrate across the floodplain.
Meander Formation
44. As a river continues its journey towards the sea, the valley cross section continues to become
wider and flatter with an extensive floodplain either side of the channel.
Floodplains
Features in the lower course of a river
When the river floods over the surrounding land it loses energy and deposition
of its suspended load occurs. Regular flooding results in the building up of
layers of nutrient rich alluvium which forms a flat and fertile floodplain
45. Features in the lower course of a river
Deltas Deltas are found at the mouth of large rivers - for example, the Nile, Ebrus or Mississippi.
A delta is formed when the river deposits its material faster than the sea can remove it.
Estuary A partially enclosed body of water along the coast where freshwater from rivers and
streams meets and mixes with salt water from the ocean.
48. Rivers as hazards
Floods have some serious impacts
People are killed by flood waters, buildings are damaged or
destroyed and jobs are lost because of damage to premises and
equipment
The effects of flooding are worse in poorer countries than richer
countries because there´s less money to spend on flood
protection and to help people after a flood.
Flooding in Boscastle, UK (2004) Flooding in Bangladesh (1998)
49. MAIN CAUSES OF RIVER FLOODING
Physical factors: Prolonged rainfall
Heavy rainfall
Snowmelt
Type of soil
Human factors:
Impermeable rocks (clay) – water doesn´t percolate into the rock,
but flows over the surface
Deforestation
Building Construction
A flood occurs when a river bursts its banks and the water spills onto the floodplain.
The ground will become saturated and infiltration will be replaed
by surface run-off
Release water
Changes in the land use:
•Trees interdept rainfall, reducing the amount of water
reaching the river
•Impremeable tarmac and concrete surfaces – infiltration and
throughflow are reduced while surface run-off is increased.
Flash flood – There is a lot of run-off; increases the discharge
quickly.
50. Lakes are permanent masses of water which have
accumulated inland.
When they are small they are called lagoons.
If their water is salt water they are called inland seas.
The water in lakes has different origins:
• Precipitation: in this case, the volume of water changes
from one season to another.
•Rivers and groundwater
•Glaciers
53. Groundwater runs and is
stored under the ground. It
represents 25% of the
water on the continents.
Most groundwater comes
from precipitation. When it
rains, some water
penetrates the ground and
filters through porous
rocks.
When it reaches permeable
rocks, it cannot pass
through and forms
aquaifers and underground
rivers and lakes.
In limestone areas, water
dissolves the rock and
creates caves and
caverns with stalactites
and stalagmites.
54. Glaciers are large, slow moving, masses of ice, that deform and move downslope under their own
weight. They may be considered “rivers of ice”
Approximately 10% of the earth's surface is covered by glaciers. Large areas of glacial ice are found in high
latitude areas such as Greenland and Antarctica, however glaciers are also found in areas of high altitude
(e.g. the Rockies, Alps, Himalaya).
During the last ice age, glaciers existed in Britain and the last glaciers retreated from Britain and Ireland
around 10,000 years ago when the last ice age drew to an end.
60. •Glacial troughs are steep-sided valleys with flat bottoms. They start off as a V-shaped river
valley but change to a U-shape as the glacier erodes the sides and bottom, making it deeper
and wider.
V shaped valley
formed by river
erosion
Glacier
U shaped valley
61. Landforms resulted from glacial deposition: Morraine
•Glaciers can move material over very large distances.
The material is transported in the glacier, on the
surface, or pushed in front of it.
•When the ice carrying the material melts, the material is
dropped on the valley floor – this is called deposition.
Morraine: Are landforms made out of material dropped by a glacier as it melts.
It is a mass of unsorted rocks, clays and sands.
•Terminal morraine builds up at the snout (end) of the glacier when it remains
stationary. It is deposited in semicircular mounds.
• Recessional morraine
http://www.wwnorton.com/college/geo/egeo2/content/animations/18_1.htm
http://www4.uwsp.edu/geo/faculty/lemke/glacial_processes/MoraineMovie.html
62. Long pile of rocky material at the edge of a glacier is called a lateral moraine and one in the middle of
the glacier is called a medial moraine.
Lateral moraines form at the edges of the glacier as material drops onto the glacier from erosion of the
valley walls.
Medial moraines form where two glaciers join together. In this case, the lateral moraines from the edges
of each glacier meet in the middle to form the medial moraine.
Landforms resulted from glacial deposition: Morraine
Medial moraine
Lateral moraine
Lateral moraine
63. Did you know…
70% of Earth´s surface is formed by
water. However, only 2,5% is fresh
water, that is, can be used for
consumption. Most of it is retained in
glaciers in the form of ice.
Therefore, only a very small
proportion of water 0,6% can be
used for consumption.
64. Did you know …
• Water used for consumption has become a scarce
resource because:
• World population leads to an increase in water
consumption.
•Some aquifers are polluted.
65. Did you know …
Since 1900 world population has been doubled, but water
consumption has grown 6 folds due to improvemtns in
standards of living
66. Did you know …
Today, almost 40% of world´s
population have to face severe
problems related to water (shortage,
contamination…)
68. Uses of water
Agriculture is the
economic activity with
highest water
consumptions.
In Spain, 80% of water
available for consumption
will be used in crop fields.
It is therefore necessary to
improve irrigated
technologies in order to
avoid leakages in canals,
as well as taking certain
measures like not using
water during the hottest
times of the day.
69. Uses of water
In reservoirs, water
from rivers will be
stored. Also, we
build dams and
hydroelectrical
power stations in
rivers to produce
electricity.
Very often, water from rivers and
lakes are treated in water plants
before its consumption.
70. Uses of water
Rivers are used
to transport
people and
goods from one
place to another,
becoming very
effective means
of communication
71. Uses of water
Rivers and lakes attract tourism, because
they offer a beaituful scenery and the
opportunity to practice many sports in
contact with nature. Tourism creates many
jobs in these areas.
76. What are earthquakes and volcanoes?
Earthquakes
• Occur when plates are
moving towards or alongside
each other e.g. the
conservative plate margin at
the San Andreas Fault in
California, USA
• Pressure build up until there
is a sudden movement,
sending a shockwave
through the Earth’s crust
• Focus – point where the
shockwaves start
• Epicentre – the point above
the focus on the Earth’s
surface
Volcanoes
• Form when semi-molten
rock (magma) rises to the
Earth’s surface. When the
magma reaches the
Earth’s surface it
becomes lava.
Vibrations during an earthquake
are measure using a seismometer
this produces a seismograph.
The Richter scale measure the
energy released on a scale of 1 to
10.
79. Why do effects of tectonic hazards vary?
The effects of tectonic
hazards vary because
1. Some places are
nearer to the source
of earthquakes or
volcanoes
2. Some places are
better prepared than
others
3. Some places have
more resources to
deal with the effects of
the hazard
Primary effects
Immediate effects
•Death/injury
•Loss of land/buildings
•Damage to infrastructure
Secondary effects
Longer term effects
•Lack of shelter
•Poor water/food supply
•Loss of income
•Long-term damage to infrastructure
81. Gujarat Earthquake - IndiaLEDC
You may be asked to
compare impacts between
MEDCs and LEDCs
82.
83. Why do people live in hazardous areas?
• People feel that it “won’t happen to them” and that they
are well prepared
• Some areas like California (USA), have an excellent
climate, superb beaches and a wide range of job
opportunities
• In places like Iceland, geothermal energy can be
generated from the volcanic rocks
• Many minerals and precious stones are found in volcanic
areas
• Volcanic rock provide mineral-rich fertile soil, which is
excellent for agriculture
• Volcanic soil is often found in spectacular areas of
scenery which provide an excellent opportunity for the
development of tourism.
85. Preparing for Earthquakes
• It is very difficult if not impossible to predict earthquakes
• Therefore it is more worthwhile to invest money and resources in
preparing for earthquakes
• MEDCs tend to prepare better for earthquakes than LEDCs
86. Predicting Volcanic Eruptions
As a volcano becomes active, it gives off a number of warning
signs. These warning signs are picked up by volcanologists
(those who study volcanoes) and the volcano is monitored.
87. Preparing for Volcanic Eruptions
A detailed plan is needed for dealing with a possible eruption.
Everyone who could be affected by the eruption needs to
know the plan and what they should do if it needs to be put
into action.
•Planning for a volcano includes creating an
exclusion zone around the volcano
•Being ready and able to evacuate residents
•Having an emergency supply of basic provisions
such as food
•Funds need to be available to deal with the
emergency and a good communication system
needs to be in place
How to prepare?
88. Why are the effects of hazards
worse in LEDCs than MEDCs?
