Ground Water

 Much of the water in soil seeps downward until it reaches the zone of saturation  Zone of Saturation  Is the area where water fills all of the open spaces in sediment and rock. Groundwater is the water within this zone  The upper limit is called the water table

 Water within the ground does move  The movement depends on the porosity of the soil  Groundwater moves by twisting and turning through interconnected small openings  The smaller the pores the slower the movement  When an impermeable layer of rock exist underground it creates an aquifers that hold water  These are used as a source of well water

 Springs exist when the water table crosses the ground surface  Springs are groundwater that moves it’s way to the surface  Hot springs are a springs that are about 6-9 degrees warmer then the surface area  Many of these springs are in center to western United States

 Geyser is an intermittent hot spring or fountain in which a column of water shoots up with great force  These tend to occur at consistent intervals  Old Faithful in Yellowstone National Park  These geysers usually have extensive caverns  Geysers occur where extensive underground chambers exist within hot igneous rocks

 1 st Groundwater sinks into the underground caverns  2 nd The water is then heated due to a close magma chamber  3 rd As the water is heated some of it turns to steam and increases the pressure  4 th The pressure is released through a crack in the surface

 A well is a hole bored into the zone of saturation  Irrigation for agriculture is by far the single greatest use of well water in the United States  The water table level may change within one year  As a large amount of water is used from a well it lowers the water table in that location  Artesian wells occur when water is under great pressure and rise on their own

 Sometimes wells can be overused and that will deplete the water table  As it depletes irrigation may need to be found elsewhere  This could also lead to the ground sinking due to compaction  Runoff of pollution could sink into the ground and contaminate the water supply

 As water runs through the ground it may dissolve some rocks (limestone)  This leads to extensive limestone caverns  A cavern is a naturally formed underground chamber  The remaining rocks form due to evaporation of water with limestone being left behind  These are called “drip stones”  Stalactites & Stalagmites

 Karst Topography occurs in areas that have extensive underground caverns  If a cavern collapses from the top down this is what we call a sink hole