1. GL4 E1 Key Idea 2 b i SEDIMENTARY ROCKS
The mineralogy and texture of sedimentary rocks are controlled by processes of weathering, erosion and deposition

2. GL4 E1 KI2 b (i) Weathering
WEATHERING: physical breaking up of rock into smaller pieces and chemical breakdown of rock at the Earth’s surface
Geoscience page 80 figure 5.11 COPY (NB: of importance in specification: heating/cooling, freeze/thaw, hydrolysis, carbonation, solution and oxidation)

3. What does weathering do?
Breaks down SILICATE rocks into:
QUARTZ
MUSCOVITE
CLAY MINERALS
SOLUBLE SALTS
IRON OXIDES
RESISTANT HEAVY MINERALS

4. Rates of weathering: Controlled by local conditions
Temperature, Humidity, chemical composition of Rainfall, amount and type of Vegetation
Mainly controlled by CLIMATE
Geoscience page 81 Figure 5.12 COPY
Also plot rainforest (high rainfall, high temperature), periglacial desert (low rainfall, low temperatures), Saharan desert (low rainfall, high temperatures)