Infiltration

Process by which precipitation that has fallen on land trickles into the ground. 

Zone of saturation

Region below the Earth's surface in which groundwater fills all the pores of material. 

Water table

Upper boundary of the zone of saturation 

Zone of aeration

Area above water table.  Materials are moist, but not saturated. 

Permeability

Tendency of material to let water pass through it. 

Aquifers

Water flows through permeable sediment and rock into large pore spaces.

Aquicludes

Impermeable layers that are barriers to groundwater flow. 

Springs

Natural discharges of groundwater. 

Hot springs

Springs with temperatures higher than the human body. 

Geyers

Explosive hot springs. 

Cave

Natural underground opening with a connection to the surface. 

Sinkhole

A depression in the ground caused by the collapse of a cave 

Karst topography

Limestone regions that have sinkholes and disappearing streams. 

Stalacite

Hangs from the cave's ceiling 

Stalagmites

Grow from cave floor 

Drawdown

Difference between original water table and water level in a pumped well. 

Recharge

Water from precipitation replenishes the water content of an aquifer. 

Artesian well

An aquifer that contains water under pressure