Geomorphology

Geomorphology: rocks and plate tectonics

Geomorphology here is how Earth’s crust is built and broken: plates, rocks, folds, faults, volcanoes and earthquakes.

CAPS

Grade 10 · Geography · Geomorphology

Geography examines physical and human processes, with map skills in both papers.

  • The papers

    Paper 1 is climate and weather, and geomorphology, with geographical skills. Paper 2 is rural and urban settlement, and the economic geography of South Africa, with geographical skills. Each paper is 150 marks.

  • Map work

    Direction, scale, gradient, cross-section and a calculation from the map must show the formula and the substitution. A place you cannot point to on the extract is a guess.

  • How a marker reads it

    A common mix-up is to put earthquakes only in volcanic countries, or to call every layered rock metamorphic. Layers usually mean sedimentary.

Paragraph questions want causes and effects in sequence. Naming a term without saying how it changes the landscape or the settlement is only the first mark.

plate

Diagram

Worked theory

Worked theory. The Great Rift in East Africa, which South African syllabi use as the pulling-apart case, and the Andes as the pushing-together case. On a rift, the land drops between faults and volcanoes appear where magma rises. At a collision, one plate is forced down, rocks fold, and earthquakes are deep as well as shallow. A sandstone layer full of pebbles was once sediment. Marble that started as limestone has been metamorphosed. You do not need a new rock type for every hill. You need the process that made the one in front of you.

More worked examples

  • Drakensberg basalt on cave sandstone

    Along the escarpment, dark basalt sits on paler sandstone. The basalt cooled from lava. That is igneous. The sandstone was sand, laid in layers. That is sedimentary. Where the sandstone has been baked at a contact, a thin band has become metamorphic. A fault offsets the layers sideways. A fold would bend them without that clean break. One cliff can show all four ideas if you read the contact.

  • A road cutting

    In a cutting, layers that bend but stay continuous have been folded. Layers that break, with one side dropped, have been faulted. The fold shortens the crust. The fault displaces it. Both can appear in one range, and they are not two words for the same crack. A learner who calls every bend a fault has missed the unbroken layers. If the layers are broken and shifted, folding is the wrong name.

In ordinary words

Earth has a crust, a mantle and a core. The crust is split into plates that move. Plates pull apart, push together, or slide past each other. Pulling apart makes new crust and rift valleys. Pushing together builds mountains, trenches and volcanoes and causes the stronger earthquakes. Rocks cycle: magma cools into igneous rock, erosion makes sediment and then sedimentary rock, heat and pressure make metamorphic rock, and melting returns rock to magma. A fault is a break with movement. A fold is a bend without a clean break.

In South Africa

Drakensberg basalt on top of sandstone is igneous over sedimentary in one escarpment.

Part 1 / 4

What it is

Geomorphology here is how Earth’s crust is built and broken: plates, rocks, folds, faults, volcanoes and earthquakes.

Diagram
Diagram
Diagram

More worked examples

Board walkthroughs on this topic. Open one, copy the working, then try the next.

Example 1 / 20

Identify the plate boundary and landform: the African and Arabian plates move apart forming the Red Sea.

How we got there

Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.

Explain in another language · 11

1. What is the question asking?

Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Identify the plate boundary and landform: the African and Arabian plates move apart forming the Red Sea.

In other words — as if you have never seen this before

If you have never seen this before: Plates move apart. We will name a method in words, write the formula with no numbers, then substitute one line at a time.

2. What do we already know?

Divergent boundary.

3. Which method — and why this one?

Plates move apart.

4. Step-by-step working

  1. 01 / 07

    Step A — Read the question twice

    Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.

    Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.

  2. 02 / 07

    Step B — Write the given in a column

    Divergent boundary.

    Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.

  3. 03 / 07

    Step C — Name the method in words

    Plates move apart.

    Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.

  4. 04 / 07

    Identify the given

    Divergent boundary; rift valley and new ocean floor (Red Sea, East African Rift).

    Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.

  5. 05 / 07

    Step G — Sense-check the size

    Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.

    Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.

  6. 06 / 07

    Step F — Box the answer with its unit

    Divergent — rift valley.

    Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.

  7. 07 / 07

    Step H — What the marker is looking for

    On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.

    Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.

5. The answer

Divergent — rift valley.

Copy onto your answer sheet — in this order

Answer: Divergent — rift valley.

6. Check it like a marker

Magma rises to fill the gap.

7. A trap first-timers fall into

First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”

Ntsako · fx-991ZA PLUS. Tap to calculate.