What is the term for rock that does not allow liquid or gas to flow through it?

The term for rock that does not allow liquid or gas to flow through it is impermeable rock. This type of rock has a dense structure and lacks the pores or fractures necessary to let fluids pass through, making it crucial in the context of groundwater movement and the ability to store natural resources like oil or gas. Impermeable rocks act as barriers and can retain groundwater, impacting the hydrology of an area significantly.

In contrast, permeable rock allows liquid and gas to flow through it due to the presence of interconnected pores or fractures. Sedimentary and metamorphic rocks refer to the formation processes of rocks and do not inherently describe their permeability characteristics.