How do different mining methods reshape the geosphere and produce waste?
Compare mining methods and analyse their physical effects on the geosphere
A focused answer to the WACE Year 12 Earth and Environmental Science dot point on mining methods and geosphere impacts. Compares open-cut, underground, dredging and in-situ methods, and analyses landform change, overburden, waste rock, tailings and subsidence, with WA examples such as the Pilbara and the Super Pit.
Reviewed by: AI editorial process; not yet individually human-reviewed
Have a quick question? Jump to the Q&A page
What this dot point is asking
SCSA wants you to compare the main mining methods and analyse how each physically alters the geosphere. This is the structural foundation for the broader impacts and rehabilitation content, so be precise about what each method does to the land and the waste it generates.
Choosing a method
The method follows the geology and economics of the deposit.
- Open-cut (open-pit) mining is used for large, shallow, lower-grade ore bodies. Overburden is removed to expose the ore, creating a widening, deepening pit. Most Pilbara iron ore and Darling Range bauxite are mined open-cut, and the Kalgoorlie Super Pit is one of the largest open pits in the country.
- Underground mining is used where ore is deep or rich enough to justify shafts and tunnels. It disturbs less surface area but leaves voids that can collapse.
- Dredging extracts loose sediment from rivers, beaches or shallow seas, used for some mineral sands and alluvial deposits.
- In-situ recovery dissolves the target mineral underground and pumps the solution to the surface, avoiding bulk excavation but risking groundwater contamination.
Physical effects on the geosphere
Whatever the method, mining changes the solid Earth in characteristic ways.
- Landform change. Open pits, waste dumps and tailings dams replace the original topography permanently.
- Overburden and waste rock. Material removed to reach ore must be stored, forming large dumps that alter drainage and can be unstable.
- Tailings. The fine waste left after the valuable mineral is separated is stored as a slurry behind dams, which must be engineered to prevent failure and leakage.
- Subsidence. Underground voids can collapse, causing the surface above to sink.
- Loss of soil and exposure to erosion. Stripping vegetation and topsoil exposes ground that erodes more easily.
Comparing footprint and waste
Open-cut mining has the largest surface footprint and produces the most overburden and waste rock, but is cheaper for bulk ore. Underground mining has a smaller surface footprint but adds subsidence risk and is costlier. Dredging churns aquatic sediment and increases turbidity, while in-situ recovery has the smallest surface disturbance but the highest groundwater risk. A strong comparison links each method to its dominant geosphere impact and the volume and type of waste it creates.