Lesson 1: Weathering of Rocks

Weathering

breakdown/alteration of rocks

What are the factors that affect the weathering of rocks?

Properties of Rocks, Climate, Soil and Vegetation, Length of Exposure

Properties of Rock

a. Composition(Limestone, Granite), b. Structure

Climate

Rainfall and Temparature

Rainfall

increases the rate of weathering

Temperature

the hotter the higher the rate of weathering

Soil and Vegetation

increase rate of weathering. Thickens. These are the biological activity that breaks down rocks.

Length of Exposure(time)

the longer the greater the chemical alteration and dissolution

What are the two types of weathering?

Physical Weathering and Chemical Weathering

Physical/Mechanical Weathering

without changing chemical composition

Enumerate the 6 types of physical weathering

Frost Wedging, Salt Crystal Growth, Abrasion, Biological Activity, Exfoliation, Heat and Cold Cycle

Frost Wedging

filling of water in rock cracks then it freezes. Water exerts pressure against the rock until it breaks

Salt Crystal Growth

salt solution precipitate in fracture of rocks. It exerts pressure to break it

Abrasion

sediment bump into each other causes it to break down

Exfoliation

reduction of pressure(bakbak)

Heat and Cold Cycle

due to contraction after exposure to heat and cold

Chemical Weathering

change in chemical composition

Enumerate the 3 types of Chemical Weathering

Dissolution, Hydrolysis, Oxidation

Dissolution

soluble minerals found in rocks is dissolved in water. Limestone

Hydrolysis

interaction in water. Granite: Feldspar- soft when exposed to water turns in clay

Oxidation

oxygen and water. Iron rich rocks turns into a rusty colored weathered surface