Unconformity Geological term that refers to an ancient surface that has been buried and now represents a discontinuity or break between coherent masses of rock or strata.

Vadose Zone A hydrogeological term that represents the volume of rock and unconsolidated materials between the ground surface and the underlying water table, in which pores and cracks are...

Vapor-Dominated Reservoir The highest grade of geothermal resource in which self-flowing wells produce dry steam from a reservoir containing a mixture of hot water and steam. Larderello,...