What is denudation The shaping of the earth

What is denudation? • The shaping of the earth

What shapes the land?

Denudation processes • Weathering What are they? • erosion • mass wasting/ mass movement

What is weathering? Processes leading to disintegration and decomposition of rock in situ processes

How does the rock break up? • 1. Mechanical weathering/ Physical weathering • 2. Chemical weathering • 3. Biotic / Biological weathering

Mechanical weathering • Caused by – temperature changes – unloading brought about by denudation – salt crystal growth

Block Disintegration With repeated expansion and contraction, the rock breaks up along joints

A Disintegrated block

Exfoliation

Rock peels off

Granular disintegration

Chemical weathering • Decomposition of rock caused by rain, air (e. g. Carbon dioxide) and organic acids. • Active in hot and wet areas

What Chemical Processes? • • • Solution Hydration Hydrolysis Oxidation Carbonation

Honeycomb weathering

They are always found near the coast. Why?

Spheroidal weathering Partially weathered core-stone Totally weathered outer layer

Biotic/ Biological Weathering • Physical break up of rock by plant roots or burrowing animals • Chemical decay of rock facilitated by organic acid produced by plants and animals

Weathered granite in HK