---
title: "Weathering, Erosion and How Soil Forms"
description: "Rock at the surface is attacked chemically and physically before anything moves it, and the two processes help each other because breaking rock up gives the chemistry more surface. Soil is what remain"
canonical: https://lightmysky.com/learn/science/weathering-erosion-and-how-soil-forms-mt_nQOPOt1VTH
source: https://lightmysky.com/learn/science/weathering-erosion-and-how-soil-forms-mt_nQOPOt1VTH.md
retrieved: 2026-09-12
---

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# Weathering, Erosion and How Soil Forms

Rock at the surface is attacked chemically and physically before anything moves it, and the two processes help each other because breaking rock up gives the chemistry more surface. Soil is what remains where that breakdown mixes with the products of life, which is why soil depth and fertility vary with climate.

Subject: Science · Area: Earth's Systems · Ages 14 to 15
Page: https://lightmysky.com/learn/science/weathering-erosion-and-how-soil-forms-mt_nQOPOt1VTH

## Ready when they can

- Distinguish chemical from physical weathering and explain how each accelerates the other
- Explain why the same rock weathers at different rates in different climates
- Describe a soil profile and say what produced each horizon

## Lesson: From solid rock to living soil

Weathering breaks rock down where it stands, and it works three ways. Physical weathering cracks rock without changing its makeup, like ice wedging a crack wider. Chemical weathering changes the minerals, like faintly sour rain dissolving limestone. Roots prying slabs apart add the living help.

Breaking rock up gives chemistry more surface, so each kind speeds the other. Cracked rock dissolves faster, and dissolved rock cracks apart more easily. Weathering only breaks material down. Moving the broken pieces away by water, wind or ice is a separate job called erosion.

**Example.** Dig a slice of soil and read it top to bottom. The dark top layer mixes rotted plants and animals with weathered grit, and most roots live there. Below it a paler layer collects clay washed down from above. Deeper still sits partly broken parent rock, resting on solid bedrock.

**Tip.** Climate sets the pace. Warm and wet places weather rock fast and grow plenty of life, so soils turn deep. Cold or very dry places weather rock slowly, so soils stay thin. When two soils differ, ask about their weather first.

**Recap.** Weathering cracks and rots rock in place, erosion carries the pieces off, and climate plus life decide how deep the soil grows.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Erosion and weathering](https://lightmysky.com/learn/science/erosion-and-weathering-mt_vAP_A986IQ)
- [Strong and Weak Acids and the pH Scale](https://lightmysky.com/learn/science/strong-and-weak-acids-and-the-ph-scale-mt_Y4nSn5XH56)
- [Rocks and soil](https://lightmysky.com/learn/science/rocks-and-soil-mt_yhhprm7dZK)

## Opens up

- [Sediment on the Move: Rivers, Coasts and Where It Settles](https://lightmysky.com/learn/science/sediment-on-the-move-rivers-coasts-and-where-it-settles-mt_d1vVJBG6K7)
- [The Carbon Cycle on Two Timescales](https://lightmysky.com/learn/science/the-carbon-cycle-on-two-timescales-mt_OXBubQOPk7)