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Delta Modern Language School
Grade 4
Date ......./......./………

Important points on Unit (4) Concept 4.2

Changing landscapes

*Canyon: can be formed in many ways, such as weathering and erosion
due to wind, water and other factors. It takes millions of years to be formed.

❖ The shape of the valley depends on several factors such as:

1-Types of rocks on landscape.
2-The speed, age and size of the river in this landscape.

➢ Big streams or rivers cause more erosion than small streams.
➢ Rivers that flow fast cause more erosion than rivers that flow slowly.

Canyons Valleys

• Areas that were eroded in • Lowland areas in between

the mountains. mountains.

Differences • Their walls are very high, • They have gently sloped

steep, narrow and consist sides surround a wide and

of many layers of rocks. flat plain.

• Both of them can be formed by rivers or streams.

Similarities • Both of them often have rivers or streams flow through

the lowest points.

➢Deltas are formed by the process of deposition.
➢The most famous delta in the world the Nile River Delta.
➢Most deltas are formed in two cases, where flowing water enters

immovable water or slower moving water.
➢These two cases could be:

1. A river stream enters a lake.

2. A large river stream enters sea or ocean.

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