What is the definition of an aquifer?

The definition of an aquifer is a saturated formation of the earth that can store and transmit significant quantities of water. This characteristic is crucial because aquifers serve as significant sources of groundwater for various uses, including drinking water, irrigation, and industrial processes.

An aquifer is typically made up of permeable materials, such as sand, gravel, or porous rock, which allow water to flow through it. When rainwater or surface water infiltrates the ground, it travels through these permeable materials and becomes stored in the aquifer, making it available for extraction.

The other options highlight concepts related to water movement and geological formations that do not accurately describe an aquifer. Non-permeable layers are often referred to as aquitards or confining layers, which do not allow water to pass through easily. Similarly, a layer that completely prevents water movement would not be considered an aquifer at all, as its defining feature is the ability to transmit water. A dry geological formation incapable of holding water is not relevant to the concept of an aquifer, as aquifers are explicitly saturated with water.