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

(30. 1%)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

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 the zone of saturation

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

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

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 dissolved near the surface, a sinkhole forms