1.3: Fresh Water Flows Underground Groundwater: Water held underground Permeable: A substance that liquids can flow through. Ex: coffee filter, soil, sand and gravel. Impermeable: A substance that liquids cannot flow through.

Ex: A drinking glass holds liquids because it is impermeable. Clay is soft, but it is nearly impermeable. Groundwater collects because gravity causes rainwater to sink into the soil. Water sinks though permeable ground until it reaches an impermeable layer.

Water table: The top of the area of groundwater that is saturated or completely filled with water. This is called the saturation zone. Groundwater may collect in the spaces within soil, gravel and some kinds of rock.

Aquifers An aquifer is an underground layer of permeable rock that contains water. Some lie deep under impermeable rock, and others lie just beneath the topsoil.

3 Things Must Occur for an Aquifer to Form: (pg. 26) 1. Groundwater is stored in the pore spaces of gravel and rock in a layer of permeable material. 2. A neighboring area of impermeable rock keeps the water from draining away. 3. A source of water refills the aquifer.

Importance of Aquifers: The ground acts like a giant filter. Stones and sand in the ground can filter out bacteria. It removes harmful chemicals and minerals. It keeps water cleaner and more ready to drink.

Springs and Wells: A spring is a flow of water from the ground at a place where the surface of the land dips below the water table. A well is a hole in the ground that reaches down to the saturation zone- the wet region below the water table.

Most wells need a pump to draw up the water and are dug with motorized drills. An artesian well does not need a pump. The water flows to the surface naturally because it is under pressure.

The depth of the water table can vary from season to season, depending on the amount of rainfall. If water is used faster than it is replaced, wells may run dry causing the ground to settle and damage the environment.

Hot Springs Hot Springs- Hot water deep underground that is like an enormous boiling pot. Water heats to the boiling point and then becomes hotter because the liquid is under great pressure from the surrounding rocks. A geyser is a kind of hot spring.