The USGS suggests that in North America there are five types of these entities, including a "carbonate-rock" type found in the Ozarks and one that contaminates easily in regions of karst topography.
One of these entities in Africa is being 3D modeled by the International Atomic Energy Agency using krypton-81 isotopes. The USGS suggests that in North America there are five types of these entities, including a "carbonate-rock" type found in the Ozarks and one that contaminates easily in regions of karst topography. Fractures and bedding planes provide most of the flow paths in the (*) sandstone type of these entities, whereas intergranular porosity is more common in their alluvial type. They often exhibit anisotropic hydraulic conductivity. Those that hold their contents for thousands or millions of years are said to contain "fossil water." For 10 points, name these entities that hold water underground.
One of these entities in Africa is being 3D modeled by the International Atomic Energy Agency using krypton-81 isotopes.
aquifer [or fossil water aquifer or sandstone aquifer until "five" is read]