What term refers to underground layers of water-bearing rock?

• A. Aquifers
• B. Water Table
• C. Desalination
• D. Groundwater Withdrawals

Answer: (A)

Aquifers are underground layers of water-bearing rock or sediment that store and transmit groundwater. They consist of materials with enough porosity to hold water and enough permeability to allow it to flow, such as sandstone, fractured limestone, or unconsolidated sands. The ability to store water comes from porosity, while the ability for water to move through the layer comes from permeability. Some aquifers are confined, trapped between low-permeability layers called aquitards, while unconfined aquifers have the water table at the surface. The water table is the upper boundary of the saturated zone, not the rock layer itself. Desalination is the process of removing salt from seawater, and groundwater withdrawals refer to removing water from an aquifer, not describing the layer.