The Changing Earth

The Changing Earth

Chapter 1Changes to Earth’s Surface

4th Grade Science Standards4th Grade Science Standards

5 Waves, wind, water and ice shape and reshape Earth’s land surface. As a basis for understanding this concept:

a) Students know how some changes in the Earth are due to slow processes, such as erosion, and some changes are due to rapid processes, such as landslides, volcanic eruptions and earthquakes.

b) Students know natural processes, including freezing and thawing and the growth of roots, cause rocks to break down into smaller pieces

c) Students know moving water erodes landforms, reshaping the land by taking it away from some places and depositing it as pebbles, sand, silt, and mud in other places (weathering, transport, and deposition)

VocabularyVocabulary

landforms weathering erosion deposition mass movement

LandformsLandforms

Physical features on the Earth’s surface

See the Enchanted Learning web site for a glossary of landforms. http://www.enchantedlearning.com/geography/landforms/glossaryprintable.shtml

http://www.enchantedlearning.com/geography/landforms/glossaryprintable.shtml



WeatheringWeathering

The process of breaking rock into soil, sand and other tiny pieces or particles called sediment

ErosionErosion

The process of moving sediment from one place to another

This is a satellite picture of a giant dust storm in the Sahara Desert

DepositionDeposition

The process of dropping, or depositing sediment in a new location

Mass MovementMass Movement

The downhill movement of rock and soil caused by gravity

What are some forces that change landforms?


Wind



Water, in the form of rivers, or waves



Glaciers



Inside forces such as volcanoes and earthquakes

What is the difference between weathering and erosion?


Weathering breaks rocks into sediment



Weathering can also be caused over time by ice freezing and thawing in the crack of a rock until the rock breaks, or by root growth.



Erosion moves sediment from one place to another

Wind erosion forms unusual landforms such as tables, arches and columns.

Wind erosion also moves sand and dry sediments, forming sand dunes

How does wind erosion change landforms?

How does wind erosion change landforms?

What are glaciers?What are glaciers?Glaciers are thick sheets of ice that form

where more snow falls in winter than melts in summer. They actually move and erode everything underneath them.

What is mass movement?What is mass movement?

Mass Movement is the downhill movement of rock and soil because of gravity.

Examples are :LandslidesSinkholes

What new landforms are created by erosion and deposition?


Deltas



Oxbow Lakes



Terminal Moraines



Volcanic Islands

SummarySummaryWeathering breaks down rock and turns it into soil and other small

particles called sediment.

Wind, water and ice change the Earth’s surface by moving rock and soil.

Water can carve canyons and deposit sediments to create deltas.

Wind can form sand dunes.

Ice can form U-shaped valleys and leave landforms such as terminal moraines or it can break rock into smaller pieces.

Volcanoes can create new islands or change the existing surface.

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The Changing Earth