Fossils provide evidence of ancient life by preserving remains of plants and animals buried in sedimentary rock millions of years ago. They come in a variety of sizes and can include shells, bones, or even trace marks of activity. South Africa has a rich fossil record, including some of the oldest bacterial fossils in the world as well as early dinosaur fossils. The movement of tectonic plates and continental drift help explain how climates have changed over time, as fossils found in South Africa indicate plants and animals that could not exist in current climates lived here in the past.

1. FOSSILS
UNIT 14

2. FOSSILS
• Remains of plants and animals which existed
long ago, found in rocks
• Provide evidence of what life was like millions
of years ago
• Not all former life preserved
• Most likely materials to survive fossilisation
are hard parts like coral, shells & bone

3. FOSSILS
• Come in a variety of sizes: minute traces to large
skeletons
• Trace fossils
– Clues to former life
– Result from the activity or presence of creatures &
plants
– E.g. footprints, burrows, root tunnels
• Large fossils
– Bones
– Largest belong to the dinosaurs (extinct 65 millions
years ago)

4. FOSSILS
• SA has a rich fossil record:
– Some of the oldest fossils (bacteria)
found in rocks near Barberton in Mpumalanga (±
3.5 billion yrs old)
– Fossils of some of the earliest
dinosaurs found in rocks around
Clarens (Free State)
– Cradle of Humankind – human (hominid) fossils

5. PALAEONTOLOGY:
The study of fossil records to discover
the history of life, ancient climates
and environments.
UNIT 10: BIOSPHERE, BIOMES AND
ECOSYSTEMS

6. THE FORMATION OF FOSSILS
Most are formed when a plant or animal dies in
a watery environment
And is buried in mud and silt (sediment)
Soft tissues quickly decompose leaving the hard
bones or shells behind
Over time sediment builds over the top
And hardens into rock
Bones decay, minerals seep in replacing
organic material cell by cell
......how fossils are formed.wmv
......How Fossils Are Formed(wmv).wmv

7. FOSSILS AND CLIMATE CHANGE
• Many fossils found in SA are of plants &
animals that could not exist in our present
climates
• Climate must have changed over geological
time
• How is this possible?

8. FOSSILS AND CLIMATE CHANGE
• SA’s position in the world must have changed
• At one time located closer to the equator
• Theory of continental drift: Alfred Wegener
• Continents were once all joined
• Single land mass called PANGAEA
• Was proven when found that east coast of South
America & west coast of Africa were formed of
same rock and contained the same fossils
......Continental Drift Theory Video PART 1.wmv

9. HOW DO THE CONTINENTS MOVE?
• Core of the Earth is hot mass of molten metal
• Heat from the centre is causing continents to
move
– Heat rises from the core though the mantle
– Deforms the crust
– Breaks it into large sections called tectonic plates
• Heat causes convection currents which cause
tectonic plates to move
• Plates move a few centimeters every year
......Plate Tectonics Theory.wmv

10. FOSSIL FUELS
• COAL
• NATURAL GAS
• OIL
• Formed from the remains of living things that
died millions of years ago

11. HOW COAL IS FORMED
• Coal is made from the remains of tropical
plants
• Vegetation was thick tropical forests
• Ground was swamp-like
• When trees died they sank into the swamps
• Rivers carried sediments into the swamps

12. HOW COAL IS FORMED
• Sediments formed layers on top of dead trees
• Prevented oxygen from getting to dead trees
• So bacteria could not exist & trees did not rot
• Dead trees were crushed & compressed
• Eventually became fossilised into a layer of
coal
......Coal formation.wmv
......PL2BIO1_COAL FORMATION.wmv
......Slices of Time clip.mov.wmv

13. QUALITY OF COAL
• Depends on percentage carbon it contains
• Higher percentage carbon, higher
temperature coal burns at
• ANTHRACITE is the highest grade coal
– Usually the oldest coal, has had the most pressure
exerted on it
– Usually deeper & more difficult to mine

14. QUALITY OF COAL
• When coal is burnt gases are given off as
smoke
– Carbon, nitrogen & sulfur combine with oxygen
– Form carbon dioxide, nitrous oxides, sulfur
dioxide
– Pollute the atmosphere