groundwater Groundwater water that soaks into the ground

groundwater • Groundwater- water that soaks into the ground and collects in the pores of the rock underlying the soil. • 14% of all freshwater exists as groundwater • Soil and rock are permeable if water can pass through the pore spaces. Example: sandstone. • Soil and rock are impermeable if water cannot pass through them. Example: granite

groundwater • Aquifer- a layer of permeable rock that lets water move freely • Zone of saturation: the area where all pores in the rock are filled with water. • Water table- upper surface of zone of saturation.

groundwater • Water table • Many people get their water from groundwater through wells. • Groundwater flows into a well and a pump brings it to the surface. • Good wells extend deep into the zone of saturation, past the water table. • Wells can dry up during dry seasons or if demand is too high.

groundwater • Artesian wells- water rises to the surface under pressure. • Springs- the water table is so close to the surface that water flows out. • Geyser- a hot spring that erupts periodically, shooting water and steam into the air.

Groundwater • The work of groundwater • Groundwater mixes with carbon dioxide to form carbonic acid. • Acidic groundwater moves through cracks in limestone, dissolving the rock. • Gradually, the cracks in the rock enlarge until a cave is formed. • Stalactites- calcium carbonate deposit that hangs from a cave’s ceiling. • Stalagmites- calcium carbonate deposit that forms on a cave’s floor. If underground rock is dissolving near the surface, a sinkhole forms.