1.2 Rock changes

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Recap 1.1 Mountains are formed, mountains wear down

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Instruction 1.2 Rock changes

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Plate tectonics

Plates can move in three different ways:

1. Towards each other: convergent
   
2. Away from each other: divergent
   
3. Alongside each other: transform
   

Old and young

The Himalayas

• young mountains
  
• high sharp peaks
  
• deep valleys
  

The Scottish Highlands

• old mountains
  
• worn-down peaks
  
• low height differences
  

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1.1: 1, 2, 3, 6

Weathering

The Himalayas and the Andes have much relief.

Mountain tops slowly break down. This is called weathering.

Mechanical weathering (1)

1. cracks and crevices are filled with water after a rain shower
2. the water expands as it freezes
3. cracks and crevices slowly get bigger
4. eventually the rock breaks

Mechanical weathering (2)

1. the rock expands when it is heated by the Sun
2. the rock contracts when the temperature drops below zero

What will eventually happen to the rock?
The rock will crumble.

Mechanical weathering (3)

1. plant roots grow between cracks
2. as the roots get wider, the rock may crumble

Chemical weathering

Old buildings and statues show traces of chemical weathering.

The speed at which this chemical weathering occurs depends on the climate.

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Chemical weathering

In a warm, humid climate, the chemical weathering process isfaster than in a cold, dry climate.

Caves

Caves are created by chemical weathering.

There is limestone below the surface of the Earth. Limestone dissolves faster in acidic water than most rocks.

In the Netherlands caves are found in?

• Limburg (southern part)
  

Place the processes in the correct order.

1

2

3

4

Precipitation becomes acidic by plant roots

Limestone dissolves

Precipitation falls

Precipitation seeps down through the rock

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1.2 Rock changes: 1, 2, 3, 8

Finished early? Improve your map skills: workbook p. 6 and 7 

Next week

1.3 Rock is moved

Homework:

1.2 Rock changes: 1, 2, 3, 8