1. Natural Sciences Grade 7
Term 4: Planet Earth & Beyond
Relationship of the Sun to the Earth

2. Topic 1 Relationship of the Sun to the Earth
Stored solar energy
Natural Sciences - Grade 7

3. Dead plants and animals form coal, oil or gas
In term 3 you learnt about renewable and non-renewable energy.
Fossils, [the remains of animals and plants that lived long ago, about 300 million years] are examples of non-renewable energy.
Fossil fuels [e.g. coal, crude oil and natural].
The Earth was warmer then and there were huge swamps.
Oil was formed from the remains of sea animals.
Natural Sciences - Grade 7

4. Dead plants and animals form coal, oil or gas
Coal is formed from the remains of swamp or lake plants.
Plants and animals land in the water/ land/ swamps/ along the coast where they decay.
Natural Sciences - Grade 7

5. Natural Sciences - Grade 7
THE FORMATION OF COAL
Long ago plants absorbed the Sun’s energy and the animals ate the plants.
When the plants and animals died, it landed in the seas, lakes, swamps and on land.
They were covered by sediment layers which protected their remains.
Their dead matter formed peat [a substance].
The pressure increased above the peat, because more layers of mud, rock and soil formed on top of the remains.
Natural Sciences - Grade 7

6. Natural Sciences - Grade 7
THE FORMATION OF COAL
This pressure resulted in the remains being pushed further down where it was warmer.
The remains changed into fossils fuels due to the pressure on peat as well as the Earth’s heat.
All plant substances mostly became coal.
The combination of animal matter and dead plants formed oil and natural gas.
Natural Sciences - Grade 7

7. FORMATION OF OIL AND GAS
Plankton [very small sea plants and animals] lived millions of years ago.
Their remains dropped to the bottom of the sea when they died.
No normal decaying, because their remains were covered with sediments.
The three ways in which oil and gas are formed:
- Sediment layers turn into porous stone
[sandstone/limestone] through which the oil and gas seep.
- cavities form between the rock layers and the oil and gas
seep through these cavities.
- the rocks that form above the cavities trap the oil and gas because they a are non-porous.
Natural Sciences - Grade 7

8. FORMATION OF OIL AND GAS
The picture of an oil rig harvesting gas and oil from the sea floor.
Natural Sciences - Grade 7