A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Unconfined Aquifer
An aquifer with no confining layer between the water table and the ground surface above. Under non-pumoing conditions, wells drilled in unconfined aquifers will have water levels the same as the surrounding water table elevation.

Unconfined Aquifer
An aquifer, the upper water surface (water table) of which is at atmospheric pressure, and thus is able to rise and fall.

Unconsolidated Rock
A rock that consists of fragments of weathered rock material (including sands, gravels and cobbles) that are not cemented to form solid rock. Alluvial deposits, glacial till, and sand dunes are typical unconsolidated rock formations.

Unsaturated Zone
Zone in the upper layers of the soil, unconsolidated sediments, and bedrock where the pore spaces are not completely filled with water (i.e. not saturated). This is sometimes also known as the Vadose Zone.