When it
precipitates, water will either run off the land, evaporate,
transpirate, or infiltrate the soil where it may become part of the
groundwater system. Groundwater is the water that seeps into cracks
or crevices in the earth, becomes part of the water table, or water
that is stored in aquifers – the layers of soil, sand and rocks
where water moves.
Aquifers usually consists of permeable
materials such as gravel, sand, sandstone, or
fractured rock such as limestone. It is easy for water to flow
through these materials because of the pore space, and size of the
materials. Clays and shales have small pore spaces, thus they are
“impermeable”, and water cannot pass through them easily.
