1. THE EARTH´S PHYSICAL CHARACTERISTICS. PART 1: RELIEF
UNIT 2
THE EARTH´S PHYSICAL CHARACTERISTICS. PART 1: RELIEF

2. IN THIS UNIT YOU WILL … LEARN ABOUT THE STRUCTURE OF
THE EARTH AND HOW IT WAS FORMED …
LEARN ABOUT THE FORCES THAT
SHAPE THE EARTH´S RELIEF
IDENTIFY THE MAIN FEATURES OF THE EARTH´S RELIEF
LEARN ABOUT EARTHQUAKES AND VOLCANOES

3. THE EARTH´S SURFACE THE EARTH´S SURFACE IS MADE UP OF WATER AND LAND
OCEANS
ARE BODIES OF SALTWATER THAT COVER 71% OF THE EARTH´S SURFACE
CONTINENTS
THERE IS SUBMERGED LAND BENEATH THE OCEANS
ARE LARGE AREAS OF LAND THAT COVER 29% OF THE EARTH´S SURFACE
WE CLASSIFY MATERIAL THAT MAKES UP THE EARTH´S SURFACE IN DIFFERENT ZONES
LITHOSPHERE
HYDROSPHERE
ATMOSPHERE
BIOSPHERE
IS THE SOLID, ROCKY COVERING OF THE EARTH´S SURFACE
IS ALL THE WATER ON EARTH, INCLUDING OCEANS, SEAS, LAKES, RIVERES AND UNDERGROUND WATER
IS A LAYER OF GASES, INCLUDING NITROGEN AND OXYGEN, THAT SURROUNDS THE EARTH
IS THE THIN LAYER OF ATMOSPHERE, EARTH AND WATER WHERE LIFE EXISTS

4. OCEANS AND CONTINENTS

5. THE OLDEST MATERIALS ARE FOUND IN THE LOWEST STRATA
THE SCIENCE OF GEOLOGY
IS THE STUDY OF ALL THE MATERIALS THAT MAKE UP THE SOLID PART OF THE EARTH
GEOLOGISTS EXAMINE ROCKS TO FIND EVIDENCE OF ALL THE CHANGES THAT HAVE OCCURRED
THEY ALSO STUDY FOSSILS, WHICH ARE THE REMAINS OF LIVING THINGS PRESERVED IN THE ROCKS
BOTH ROCKS AND FOSSILS ARE FOUND IN LAYERS CALLED STRATA. THESE ARE FORMED OF SEDIMENTARY ROCKS, WHICH GRADUALLY ACCUMULATE AT THE EARTH´S SURFACE
THE OLDEST MATERIALS ARE FOUND IN THE LOWEST STRATA
6 minutes video about the science of Geology

6. The interior of the Earth is divided into layers based on chemical and physical properties.
The Earth has an outer silica-rich, solid crust, a highly viscous mantle, and a core comprising a liquid outer core that is much less viscous than the mantle, and a solid inner core.
Working from the centre of the Earth out we have:
The inner core is a primarily solid sphere about 1220 km in radius situated at Earth's center.
Based on the abundance of chemical elements in the solar system, their physical properties, and other chemical constraints regarding the remainder of Earth's volume, the inner core is believed to be composed primarily of a nickel-iron alloy, with small amounts of some unknown elements.
The temperature is estimated at 5,000-6,000 degrees Celsius and the pressure to be about 330 to 360 GPa (which is over 3,000,000 times that of the atmosphere!)
The liquid outer core is 2300 km thick and like the inner core composed of a nickel-iron alloy (but with less iron than the solid inner core).
Iseismic and other geophysical evidence indicates that the outer core is so hot that the metals are in a liquid state.
The mantle is approximately 2,900 km thick and comprises 70% of Earth's volume. (the core makes up about 30% of Earth's volume, with the outer crust [where we live] <1%!!).
The mantle is divided into sections based upon changes in its elastic properties with depth.
In the mantle, temperatures range between degrees Celsius at the upper boundary with the crust to over 4,000 degrees Celsius at the boundary with the core.
Due to the temperature difference between the Earth's surface and outer core, and the ability of the crystalline rocks at high pressure and temperature to undergo slow, creeping, viscous-like deformation over millions of years, there is a convective material circulation in the mantle (mantle convection cells). Hot material rises up as mantle plumes (like a lava lamp!), while cooler (and heavier) material sinks downward to be reheated and rise up again.
- We shall see that this process is very important for plate tectonic motion…
The outer most layer is the crust - this is the most familiar to us as it is where we live.
The distinction between crust and mantle is based on chemistry, rock types and seismic characteristics.
Presenter: Ask the students to guess what the most abundant element in the earth’s crust is…..they may be surprised to learn that it is actually Oxygen (46.6% Oxygen; 27.7% Silica; 8.1% Aluminum; 5.0% Iron; 3.6% Calcium; 2.8% Sodium; 2.6% Potassium; 2.1% Magnesium; plus trace elements)
Click to next slide for more on the Crust….

7. STRUCTURE OF THE EARTH THE EARTH IS MADE UP OF 3 MAIN LAYERS: CORE
MANTLE
CRUST
Mantle
Outer core
Inner core
The interior of the Earth is divided into layers based on chemical and physical properties.
The Earth has an outer silica-rich, solid crust, a highly viscous mantle, and a core comprising a liquid outer core that is much less viscous than the mantle, and a solid inner core.
Working from the centre of the Earth out we have:
The inner core is a primarily solid sphere about 1220 km in radius situated at Earth's center.
Based on the abundance of chemical elements in the solar system, their physical properties, and other chemical constraints regarding the remainder of Earth's volume, the inner core is believed to be composed primarily of a nickel-iron alloy, with small amounts of some unknown elements.
The temperature is estimated at 5,000-6,000 degrees Celsius and the pressure to be about 330 to 360 GPa (which is over 3,000,000 times that of the atmosphere!)
The liquid outer core is 2300 km thick and like the inner core composed of a nickel-iron alloy (but with less iron than the solid inner core).
Iseismic and other geophysical evidence indicates that the outer core is so hot that the metals are in a liquid state.
The mantle is approximately 2,900 km thick and comprises 70% of Earth's volume. (the core makes up about 30% of Earth's volume, with the outer crust [where we live] <1%!!).
The mantle is divided into sections based upon changes in its elastic properties with depth.
In the mantle, temperatures range between degrees Celsius at the upper boundary with the crust to over 4,000 degrees Celsius at the boundary with the core.
Due to the temperature difference between the Earth's surface and outer core, and the ability of the crystalline rocks at high pressure and temperature to undergo slow, creeping, viscous-like deformation over millions of years, there is a convective material circulation in the mantle (mantle convection cells). Hot material rises up as mantle plumes (like a lava lamp!), while cooler (and heavier) material sinks downward to be reheated and rise up again.
- We shall see that this process is very important for plate tectonic motion…
The outer most layer is the crust - this is the most familiar to us as it is where we live.
The distinction between crust and mantle is based on chemistry, rock types and seismic characteristics.
Presenter: Ask the students to guess what the most abundant element in the earth’s crust is…..they may be surprised to learn that it is actually Oxygen (46.6% Oxygen; 27.7% Silica; 8.1% Aluminum; 5.0% Iron; 3.6% Calcium; 2.8% Sodium; 2.6% Potassium; 2.1% Magnesium; plus trace elements)
Click to next slide for more on the Crust….
Crust

8. THE CRUST This is where we live! The Earth’s crust is made of
CONTINENTAL CRUST
OCEANIC CRUST
thick (10-70km)
buoyant (less dense than oceanic crust)
mostly old
thin (~7 km)
dense (sinks under continental crust)
young
The Earth has two different types of crust: Continental crust and Oceanic crust. Each has different properties and therefore behaves in different ways.
Continental crust:
Continental crust forms the land (the continents, as the name suggests) that we see today.
Continental crust averages about 35 km thick. Under some mountain chains, crustal thickness is approximately twice that thickness (about 70 km thick).
- The mountains we see on earth have deep roots in the crust that we can’t see. The crust “floats” on the more dense mantle and, like how only the tip of an iceberg sticks up out of the water, we see only the tip of the continental crust - the mountain ranges.
Continental crust is less dense and therefore more buoyant than oceanic crust
Continental crust contains some of the oldest rocks on Earth.
- Ancient rocks exceeding 3.5 billion years in age are found on all of Earth's continents. The oldest rocks on Earth found so far are the Acasta Gneisses in northwestern Canada near Great Slave Lake (4.03 Ga) [Ga = billion years ago] and the Isua Supracrustal rocks in West Greenland (3.7 to 3.8 Ga), but well-studied rocks nearly as old are also found in the Minnesota River Valley in the USA ( billion years), in Swaziland ( billion years), and in Western Australia ( billion years).
Oceanic crust:
As the name already suggests, this crust is below the oceans.
Compared to continental crust, Oceanic crust is thin (6-11 km).
It is more dense than continental crust and therefore when the two types of crust meet, oceanic crust will sink underneath continental crust.
The rocks of the oceanic crust are very young compared with most of the rocks of the continental crust. They are not older than 200 million years.

9. What is Plate Tectonics?
Presenter: Ask the class if they have heard of Plate Tectonics before (commonly students will have some idea of the general concept), and ask them if they can explain the theory.

10. IF YOU LOOK AT A MAP OF THE WORLD, YOU MAY NOTICE THAT SOME OF THE CONTINENTS COULD FIT TOGETHER LIKE PIECES OF A PUZZLE.
If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle…..the shape of Africa and South America are a good example.
This is because they DID used to fit together!
The Earth as we see it today was not always like it is now. Land masses have pulled apart and joined together by the process we call Plate Tectonics….
WHY?

11. THIS THEORY IS CALLED CONTINENTAL DRIFT
THE SINGLE SUPERCONTINENT THAT SCIENTISTS CALL PANGEA EXISTED ABOUT 200 MILLION YEARS AGO
OVER TIME, IT BROKE UP INTO SEPARATE CONTINENTS THAT GRADUALLY MOVED APART
THIS THEORY IS CALLED CONTINENTAL DRIFT
THE BOUNDARIES BETWEEN THE PLATES ARE VERY UNSTABLE. WHEN PRESSURE BUILDS UP UNDER THE EARTH´S SURFACE IT CAUSES EARTHQUAKES AND VOLCANIC ERUPTIONS ALONG THESE BOUNDARIES
THE EARTH´S CRUST IS MADE UP OF TECTONIC PLATES THAT MOVE CONTINOUSLY
Presenter: Ask the class if they have heard of Plate Tectonics before (commonly students will have some idea of the general concept), and ask them if they can explain the theory.
THERE ARE SEVEN OR EIGHT MAJOR PLATES AND SEVERAL OTHER MINOR ONES
THESE PLATES SLIDE AGAINST EACH OTHER OR MOVE APART

12. Interesting video (5:17) about tectonic plates
Presenter: Ask the class if they have heard of Plate Tectonics before (commonly students will have some idea of the general concept), and ask them if they can explain the theory.
Interesting video (5:17) about tectonic plates
3:19 m long video about the continental drift. Music , images and texts

13. World Plates This diagram shows the major Tectonic Plates.
Presenter: Point out the UK, sitting on the Eurasian Plate. Also the plate boundary between Africa and South America (note that it has the same shape as the coastlines in these countries).

14. The Earth’s surface is always changing!
True or False: The Earth’s surface has stayed the same for thousands of years
False
The Earth’s surface is always changing!

15. RELIEF FORMATION AND TRANSFORMATION
RELIEF IS THE SHAPE OF THE EARTH´S SURFACE. IT IS THE RESULT OF INTERNAL FORCES THAT FORM IT AND EXTERNAL FORCES THAT TRANSFORM IT
RELIEF FORMATION
RELIEF TRANSFORMATION
INTERNAL FORCES
EXTERNAL FORCES
THESE FORCES MAY MOVE, RAISE OR SINK LAND ON THE EARTH´S SURFACE. THEY ACT THROUGH CONTINUAL PRESSURES AND THROUGH EARTHQUAKES AND VOLCANOES
OROGENY
EARTHQUAKES
VOLCANOES
ATMOSPHERE
WATER
LIVING THINGS
IN ADDITION TO INTERNAL FORCES DEEP INSIDE THE EARTH, RELIEF IS ALSO SHAPED BY EXTERNAL AGENTS ON THE EARTH´S SURFACE

16. INTERNAL FORCES OROGENY EARTHQUAKES VOLCANOES
It is the process through which mountains are formed. It happens where tectonic plates are formed.
EARTHQUAKES
They are caused by violent movements of the terrestrial crust.
VOLCANOES
They are cracks in the crust that expel magma, ashes, rocks and toxic gases.

17. OROGENY: PRESSURES ON THE EARTH´S SURFACE
THERE ARE CONTINUAL PRESSURES ON THE EARTH´S SURFACE NEAR THE BOUNDERIES OF TECTONIC PLATES. FOLDS AND FAULSTS ARE CREATED AS A RESULT OF THESE PRESSURES
FOLDS
FAULTS
FAULTS ARE BREAKS IN ROCK LAYERS WHERE THE ROCK IS TOO HARD TO BEND
FOLDS ARE DEFORMATIONS OF THE EARTH´S SURFACE WHERE ROCK LAYERS BEND

19. EARTHQUAKES ARE CAUSED WHEN THE EARTH´S CRUST IS SHAKEN
EARTHQUAKES GENERALLY OCCUR ALONG THE BOUNDARIES OF TECTONIC PLATES, WHERE THE PLATES SLIDE AGAINST EACH OTHER.
ENERGY IS RELEASED IN SEISMIC WAVES FROM A FOCUS, OR HYPOCENTRE, INSIDE THE EARTH
EARTHQUAKES ON THE OCEAN FLOOR CAUSE TSUNAMIS, WHICH ARE HUGE TIDAL WAVES THAT CAUSE GREAT DESTRUCTION IN COASTAL AREAS
THE EPICENTRE IS THE POINT ON THE EARTH´S SURFACE THAT IS DIRECTLY ABOVE THE FOCUS. THIS IS WHERE THE EARTHQUAKE IS AT ITS STRONGEST
ACTIVITIES
WHAT IS THE FOCUS OR HYPOCENTRE OF AN EARTHQUAKE? WHAT IS THE EPICENTRE?

22. COPY THE DIAGRAM OF THE VOLCANO THAT IS IN YOUR BOOK (28)
VOLCANOES
A VOLCANO IS A CRACK IN THE EARTH´S CRUST
HOT LIQUID ROCK, CALLED MAGMA, RISES TO THE SURFACE WHEN IT ERUPTS. ROCKS, ASH AND GASES ARE EJECTED THROUGH ITS MAIN CHANNEL, OR VENT, AND MATERIAL IS DEPOSITED ALL AROUND THE CRATER
DURING THE ERUPTION, HOT LIQUID LAVA FLOWS OUT BEFORE IT COOLS AND BECOMES SOLID. TOGETHER WITH SOLID ROCKS, IT ACCUMULATES AROUND THE CRATER AND FORMS A CONE
ACTIVITIES
COPY THE DIAGRAM OF THE VOLCANO THAT IS IN YOUR BOOK (28)
WHAT IS THE RICHTER SCALE? WHAT DO THE DIFFERENT NUMBERS ON THE SCALE MEAN?

24. EXTERNAL AGENTS OF RELIEF
ATMOSPHERE
Changes in temperature and the wind erode, transport and deposit materials.
WATER
Water dissolves some elements in the rocks and acts as a transporter.
LIVING THINGS
Plants and animals transform the relief through their activities. Human beings make the fastest and most severe impact through activities such as building, mining and farming.

25. EROSION PROCESS EROSION OR DETACHMENT TRANSPORTATION TRANSLOCATION
SEDIMENTATION
DEPOSITION

26. PROCESS OF EROSION
EROSION
SEDIMENTATION
TRANSPORTATION

27. THERE ARE THREE MAIN TYPES
WEATHERING
ROCKS ARE EXPOSED TO AIR, WATER CHANGES IN TEMPERATURE AND VEGETATION, BECOME VULNERABLE TO WEATHERING. WEATHERING INCLUDES THE BREAKING UP (DISINTEGRATION) AND DECAY (DECOMPOSITION) OF ROCKS IN PLACES WHERE THEY FORMED. UNLIKE EROSION, WEATHERING NEED NOT INVOLVE THE MOVEMENT OF MATERIAL
It is when rock is broken into smollar pieces by phisical processes. It is most likely to occur in areas of bare rock where there is no vegetation to protect the rock from extremes of weather:
Freeze-thaw or frost shattering
Exfoliation or onion weathering.
PHISICAL
WEATHERING
It is when water and air activate chemical changes that cause rock to rot and decay. Chemical reactions are greatt where the climate is very warm and wet.
Limestone solution is an example of chemical weathering.
CHEMICAL
WEATHERING
It occurs when either tree roots penetrate and widen cracks in a rock (phisical) or acids, released by decaying vegetation, attack the rock (chemical).
BIOLOGICAL
WEATHERING
THERE ARE THREE MAIN TYPES

28. EXFOLIATION OR ONION WEATHERING
PHISICAL WEATHERING
EXFOLIATION OR ONION WEATHERING
OCCURS IN VERY WARM CLIMATES WHERE EXPOSED ROCK IS REPEATEDLY HEATED AND COOLED. DURING THE DAY, THE SURFACE LAYERS OF ROCK ARE HEATED AND EXPAND. AT NIGHT, THEY COOL AND CONTRACT. IN TIME THIS CAUSES THE OUTER LAYERS TO PEEL OFF, LIKE THOSE OF AN ONION, TO LEAVE STEEP-SIDED, ROUNDED HILLS AND BOULDERS.
FREEZE-THAW OR
FROST SHATTERING
IS COMMON WHEN TEMPERATURE IS AROUND FREEZING POINT AND WHERE EXPOSED ROCKS CONTAINS MANY CRACKS . WATER, ENTERING CRACKS DURING THE DAY, FREEZES DURING COLDER NIGHTS. AS THE WATER TURNS TO ICE IT EXPANDS AND, DUE TO THE ICREASE IN PRESSURE, CAUSES CRACKS TO WIDEN. WHEN THE TEMPERATURE RISES, THE ICE MELTS AND PRESSURE IS RELEASED. THIS REPEATED PROCESS WEAKENS THE ROCK UNTIL PIECES BREAK OFF..

29. SIMPLE LANDFORMS ON THE CONTINENTAL RELIEF LANDFORMS OF COASTAL RELIEF
THE EARTH´S RELIEF
OCEANIC
CONTINENTAL
SIMPLE LANDFORMS ON THE CONTINENTAL RELIEF
LARGE RELIEF FORMS
LANDFORMS OF COASTAL RELIEF
The continental Shelf
The continental slope
Abyssal plains:
Oceanic ridges
Oceanic Trenches
Plains
Plateaus
Mountains
Depressions
The Shields
- Sedimentary
basins
Young mountains
Capes or headlands
Gulfs or bays
Peninsulas
Estuaries
Deltas
Isthmus
Fjords
Islands
Archipelagos
Beaches
Cliffs
Pages 26-27

30. SIMPLE LANDFORMS ON THE CONTINENTAL RELIEF
PLAINS
LARGE AREAS OF FLAT TERRAIN
PLATEAUS
PLAINS HIGHER THAN 200 METERS ABOVE SEA LEVEL
MOUNTAINS
ELEVATIONS OF TERRAIN ABOVE THE SURROUNDING LAND WITH STEEP SLOPES
DEPRESSIONS
SUNKEN OR DEPRESSED AREAS BELOW THE SURROUNDING AREAS

31. CONTINENTAL RELIEF LARGE RELIEF FORMS THE SHIELDS SEDIMENTARY BASINS
The oldest parts of continents.
SEDIMENTARY BASINS
Large depressed areas that we find in the shields.
YOUNG MOUNTAINS
Steep, younger mountains at high altitudes

32. LANDFORMS OF COASTAL RELIEF
CAPE OR HEADLAND
PENINSULA

33. LANDFORMS OF COASTAL RELIEF
ESTUARY
ISLAND
DELTA
ARCHIPELAGO

34. LANDFORMS OF COASTAL RELIEF
FJORD
BEACH
RIA
CLIFF

35. ISLAND GULF “CALA” STRAIT POINT BEACH CLIFF BAY
ISTHMUS
CCAPE
ISLAND
PENINSULA
GULF
“CALA”
STRAIT
POINT
BEACH
CLIFF
ARCHIPELAGO
BAY

37. LAGOON ARCHIPELAGO BAY GULF BEACH CAPE CLIFF RIA ITHSMUS PENINSULA
BASIN OR DEPRESSION
YOUNG MOUNTAIN
DELTA
LAGOON
ARCHIPELAGO
BAY
GULF
BEACH
CAPE
CLIFF
RIA
ITHSMUS
PENINSULA
OLD MOUNTAIN

38. OCEANIC LANDFORMS OCEANIC LANDFORMS CONTINENTAL SLOPE OCEANIC RIDGE
CONTINENTAL PLATFORM OR SHELF
CONTINENTAL SLOPE
ISLANDS OF VOLCANIC ORIGIN
OCEANIC RIDGE
ABYSSAL PLAIN
OCEANIC TRENCH
RIFT
OCEANIC LANDFORMS

39. ANY QUESTIONS?