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Delta Modern Language School
Grade 4
Date ......./......./………
Important points on Unit (4) Concept 4.1
Breaking down and moving rocks
Factors that change the Earth’s surface: -
Wind, Water and Weather changes.
➢ Sand is formed by breaking down of some types of rocks into smaller
particles.
➢ Erosion of the sandcastles and coasts is a result of natural erosion (the
forces of water and wind).
➢ Some changes of the Earth’s surface can be very fast and other changes
can be very slow that may take hundreds of millions of years.
Fast Changes Slow Changes
• They are observed in • They are observed in coastal
Sandcastles. rocks over time.
• It may completely disappear in • Little differences can be observed
few minutes as a result of the in their shape after many years
force of sea waves. after breaking off some parts.
Canyons: They are deep valleys covered by flowing water.
➢ Canyons are formed due to the slow changes
that happened to their rocks over many
years.
➢ A canyon has needle-like parts and slopes at
the sides, it is formed by the action of water.
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