Which type of rock allows fluids to pass through its open spaces?

Permeable rock is characterized by its ability to allow fluids, such as water, to flow through its interconnected open spaces or pores. This property is crucial for various geological processes, including groundwater movement and the filtration of contaminants. Permeable rocks often include sedimentary types like sandstone and limestone, which can have sufficient pore space for fluid passage, making them vital for aquifers and natural water systems.

In contrast, impermeable rock does not allow fluids to pass through, which can lead to the accumulation of water and create surface runoff rather than groundwater flow. Ignoring the context of fluid movement, igneous and metamorphic rocks are not primarily defined by their permeability. While some igneous rocks can have fractures that might allow limited fluid movement, they are not inherently permeable. Metamorphic rocks typically have tightly interlocking grains, making them less likely to allow significant fluid flow compared to permeable rocks. Understanding the difference between these rock types helps clarify their roles in the hydrological cycle and geological formations.