2.7 To discuss sedimentary rocks as a type of rock formation

Natural sciences

The earth and beyond

Rock formations

Educator section

Memorandum

Sedimentary rock formations formed by earlier life forms

• Sketch: The search for fossil fuels (oil)

Key:

1. Oil drill

2. Ocean

1. Ocean floor

1. Penetrable rock
2. Pipeline
3. Oil
4. Sedimentary rock

8. Impenetrable rock

Sedimentary rock formations:

Layers of rock on the earth's surface and under water . Formed by debris or earlier life . Debris type forms through the breaking up of rocks and the scattering of the pieces by wind and water to lower levels where they form sand and mud . The ones formed by earlier life are created by the compression of skeletons to form limestone .

Leaner section

Content

Activity: to discuss sedimentary rocks as a type of rock formation [lo 2.3]

• Large areas of the earth are covered in sedimentary rocks. These rocks are not formed on the surface of the earth only, but frequently also under water. The formations occur in layers.

• Scientists distinguish between two kinds of sedimentary rock.

SEDIMENTARY ROCK FORMED BY “RUBBLE":

• Existing rocks are broken down through the action of wind and water. The small bits of rock that result from this are carried along in streams and rivers until they reach the sea, where it is deposited as layers of sand and mud.

SEDIMENTARY ROCK FORMED AS A RESULT OF EARLY LIFE:

• These rocks consist of material from organisms that were alive in very early times.

• The following illustrations show how these rocks were formed:

1. When fish and other organisms that live in the sea die, their remains sink to the bottom of the sea.
2. Their skeletons and the calcium of their shells form layers on the sea floor.
3. With many years passing, the layers become compressed. They become thick layers of rock known as limestone.
4. These are the main rocks that we see because they are formed on the surface of the earth. They usually are soft.

• Sedimentary rocks are of importance to people because they provide people with oil, earth gas, coal and stone for building. Sometimes they also contain fossils that provide information about what the earth was like millions of years ago. We'll be learning more about fossils in the rest of the module.

• Provide captions for the sketch:

The search for fossil fuels (petroleum)

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• Explain what you know about sedimentary rocks (in thirty words). Use your own words.

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Assessment

Learning Outcome 2: The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

Assessment Standard 2.3: We know this when the learner categorises information.