How Mountains Wear Down Over Time — Reading Comprehension

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This engaging Grade 4-5 science passage, aligned with NGSS standards, explains how mountains slowly wear down over time through natural processes such as weathering and erosion. Students will learn key vocabulary, understand the difference between mechanical and chemical weathering, and discover how forces like wind, water, and ice shape the Earth's surface. Real-world examples, such as the Rocky Mountains and the Appalachian Mountains, help students connect science to geography. The passage includes a glossary, Spanish translation, and is integrated with audio for accessibility. Activities include a multiple-choice comprehension quiz and writing prompts that encourage students to analyze cause and effect, apply concepts to daily life, and explain scientific ideas in their own words. This resource builds foundational Earth science knowledge and supports vocabulary development for elementary students.

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mountainous, mountain landscape, mountains, landscape, nature, mountain landscape, mountains, landscape, landscape, landscape, landscape, landscape — Over millions of years, mountains slowly wear down and change shape. Image by by 15147632 /
Source:Pixabay.

Mountains are tall landforms made from rocks. Over millions of years, mountains slowly wear down and change shape. This happens because of natural forces acting on the rocks. Two main processes that break down mountains are weathering and erosion.

Weathering means breaking rocks into smaller pieces. There are two types. Mechanical weathering happens when wind, water, or ice physically break rocks apart. For example, water can get into cracks in rocks and freeze. When the water freezes, it expands and makes the crack bigger. Over time, the rock breaks apart. Chemical weathering happens when rainwater mixes with chemicals in the air or soil and changes the rock. Acid rain is one example. It can slowly dissolve rocks.

After rocks are broken down, erosion moves the small pieces away. Erosion is caused by wind, water, ice, or gravity. For example, rivers can carry sand and rocks down from the mountains and deposit them in valleys. Glaciers, which are huge slow-moving sheets of ice, can scrape and move rocks over long distances.

These processes work very slowly, but over millions of years, they can change a tall, jagged mountain into a lower, rounded hill. For example, the Rocky Mountains are much younger and sharper than the Appalachian Mountains, which are older and more worn down by weathering and erosion.

The breaking down and moving of rocks is part of the rock cycle. This cycle helps shape Earth's surface and creates soil that plants need to grow. Without weathering and erosion, Earth would look very different.

Interesting Fact: The Himalayas are still rising because the Earth's plates are pushing together, but at the same time, weathering and erosion are wearing them down!

What breaks rocks into smaller pieces?

WeatheringErosionGravityAcid rain

What moves rock pieces away?

ErosionWeatheringChemical reactionVolcano

Which is an example of mechanical weathering?

Ice breaking rockRain dissolving rockRoots growingWind blowing sand

How do rivers help change mountains?

Carry rocks awayGrow tallerStop erosionMake new mountains

Why are the Appalachian Mountains rounded?

Older, more worn downYounger, just formedMade of soft sandCovered in glaciers

What would happen without weathering?

Earth would look differentMountains would grow fasterRivers would dry upSoil would be deeper