Key Words: GEOLOGY UNIT 4.4

Aggregate - the general name for unconsolidated construction materials of sand size and above

Bitumen - a semi-solid hydrocarbon fraction of crude oil

Quarry - an opencast mine for hard rocks

Drilling and blasting - where shot holes are drilled into rock and filled with explosives that are detonated to break up the rock

Pit - a opencast mine for poorly consolidated material such as sand, gravel, clay and coal

Dredging - the method by which material is scraped or sucked from the river or seabed

Dam - a structure that holds back water

Reservoir - a body of water behind a dam wall

Hydroelectric power - releasing water stored behind a dam to turn a turbine generating electricity

Ground improvement methods preventing leakage from reservoirs

Grouting - Holes drilled into rock and liquid cement pumped in to fill pore spaces, joints and fissures which reduces permeability and increases rock strength

Clay/Plastic lining - Before filling, the reservoir is lined with an impermeable material like clay or plastic to prevent water leakage into underlying rock. Clay is good because if there are local supplies it would be cheap

Cut off curtain - an impermeable barrier, usually made of concrete, constructed as an extension below the dam. Particularly good at preventing leakage from dams on synclines. Further benefits of strengthening foundations…