Earth and Environmental Science
Earth and Environmental Science
This section samples plate tectonics, rocks and the rock cycle, the atmosphere and climate, the water cycle, and resource use. Expect data-based questions on seismic waves, greenhouse gases, and environmental trade-offs.
Core rules
- Earth's lithosphere is broken into plates; divergent, convergent, and transform boundaries produce distinct landforms and seismic patterns.
- Igneous rocks form from cooling magma or lava; sedimentary rocks from deposition and lithification; metamorphic rocks from heat and pressure.
- P and S waves travel at different speeds; S waves cannot pass through liquids. Arrival-time difference increases with distance.
- The greenhouse effect is a natural process; enhanced warming comes from increased greenhouse-gas concentrations.
- Weather is short-term atmospheric state; climate is long-term statistics.
- Water moves through evaporation, condensation, precipitation, runoff, and infiltration.
Worked example
A seismic station records P waves at 6.0 km/s and S waves at 3.5 km/s. If S arrives 10 s after P, estimate distance d. Travel times are d/6.0 and d/3.5, so d/3.5−d/6.0=10. The difference in reciprocals is 0.2857−0.1667=0.1190 s/km. Thus d=10/0.1190≈84 km. The result is an estimate: real crustal velocities vary with rock type and depth.
Traps that cost marks
- Mixing km and m, or seconds and minutes.
- Treating P and S velocities as equal.
- Confusing weather with climate.
- Claiming the greenhouse effect is entirely human-caused.
- Ignoring the difference between a hypothesis and a validated theory.