Earth Systems and Resources
What you must know
Understand Earth's spheres (lithosphere, atmosphere, hydrosphere, biosphere) and their interactions. Know plate tectonics: divergent, convergent, and transform boundaries and the hazards/landforms each produces (volcanoes, earthquakes, ridges, trenches). Identify rock types (igneous, sedimentary, metamorphic) and the rock cycle. Master soil - horizons (O, A, E, B, C, R), texture (sand, silt, clay), porosity vs. permeability, and how soil forms. Know atmosphere layers (troposphere, stratosphere with ozone, mesosphere, thermosphere) and global wind and ocean circulation driven by unequal heating, the Coriolis effect, and convection. Understand El Niño/La Niña and upwelling. Know mineral resources and the difference between reserves and resources.
Traps
- Confusing porosity (space for water) with permeability (ability to transmit water); clay is porous but low-permeability.
- Placing the ozone layer in the troposphere - it is in the stratosphere.
- Mixing convergent (destructive) with divergent (constructive) boundaries.
- Forgetting the Coriolis effect deflects winds, not the underlying pressure gradient.
Worked example / rule of thumb
A soil that is 40% sand, 40% silt, 20% clay is a loam - good for agriculture because it balances drainage and water retention. Rule: sandy soils drain fast and hold few nutrients; clay soils hold water and nutrients but drain poorly.