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In this section
1. Structure
2. Plate Tectonics
3. Weathering
4. Rock Cycle
5. Soils
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The Earth
Contents
Contents
Structure
Aims
The layered internal structure of the Earth
Monitoring of seismic waves to understand the Earth's internal structure
The predominant mass of the core and the mantle
The smallness of the Earth's crust and its crucial resource base for civilisation
The differences between the core, mantle and crust
The cause of the varied composition of the lithosphere (crust) relative to the mantle or core
Heating and melting diversifying the lithosphere (crust)
Analysis to estimate the average composition of the Earth's crust
Heterogeneity of the Earth's crust
The chemical abbreviations for each of the main chemical constituents of the Earth
Plate tectonics
Aims
Plate motion throughout geological time
Three different types of plate motion, and regions of volcanic activity
Constructive plate motion
Destructive plate motion
Conservative plate motion
Plate motion locally and globally
Plate movement and the creation of oceans
Ocean expansion and contraction with continual plate movement
Volcanoes and subducting plates
Plate tectonics and the bottom topography of the world's oceans
The continental shelf
The abyssal plain
Weathering
Aims
Weathering: the adjustment of rocks to new environmental conditions
Three main catalysts for physical weathering: heat; pressure and crystallization
Thermal expansion and contraction
Pressure release
Ice crystallization
Physical weathering and the reduction of massive rocks to small particles
Three distinct mechanisms of chemical weathering
Dissolution by water
Chemical weathering by acid hydrolysis
Acid hydrolysis and the neutralisation of the acid in rock waters
Mineral oxidation
Rock cycle
Aims
The formation, breakdown, transportation and re-deposition of rocks
The rock cycle and long geological time scales
Water as a medium for erosion transport
Variation in ionic bonding between different rock minerals
Ionic potential as a measure of element behaviour during weathering and erosion
Insoluble materials and materials transport
The fate of residual materials
Rivers and the deposit and erosion of material
Glaciers and the erosion and transport of materials
Wind erosion in arid regions
Weathered material in the oceans, and differences in grain size and sedimentation rates
Differences in the types of material found at different locations within the ocean basins
Patterns in marine sediments between different locations
Soils
Aims
The key role of soils in the ecosystem
The formation of soils over thousands of years
Particle sizes in soil parent materials
Parent material and the role of biological activities
Distribution of soil types and their wider environmental conditions
Soil horizons: the A horizon
The B and C horizons
The existence of A, B and C horizons in most soils
The influence of erosion on soil structure
The characteristics of different soils and the complex physical and chemical processes
Ion exchange and soil structure
The fertility of soils
The water retention characteristics of soils
Soil fertility, water retention and vegetation