Keystone Foundation Archives

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• ROCKS AND THEIR HYDROLOGIC PROPERTIES_ POROSITY
  Porosity is the measure of voids in rocks, indicating their ability to hold water. It can occur in various forms, such as intergranular spaces between grains or fractures in hard rocks. Porosity is expressed as a percentage, calculated by the volume of openings divided by the total rock volume. There are two types: primary porosity, formed during rock creation, and secondary porosity, developed through weathering or fracturing. Specific yield refers to the water released by saturated rock due to gravity, while specific retention is the water retained after drainage. Understanding porosity is vital for assessing groundwater storage and movement in geological formations.