Groundwater exists below the surface in the saturated zone where all spaces between rock and sediment are filled with water. The water table marks the top of this zone, and groundwater moves slowly through porous and permeable materials. Springs form where the water table intersects the surface, and overuse or contamination can threaten groundwater supplies in some areas. Karst regions have irregular terrain with sinkholes caused by erosion of soluble rock by groundwater in caverns below the water table.

1. 6.3 Water Beneath the Surface

2. Zone of Saturation
• Zone where all open spaces in sediment and
rock are completely filled with water

3. Groundwater
• Water underground in the zone of saturation

4. Water table
• The upper level of the saturated zone of
groundwater

5. Porosity
• The volume of open spaces in rock or soil

6. Permeability
• A measure of a material’s ability to transmit
fluids

7. Aquifer
• Permeable rock layers or sediments that
transmit groundwater freely

8. Spring
• A flow of groundwater that emerges naturally
at the ground surface

9. Geyser
• A hot spring or fountain that ejects water at
the intervals

10. Well
• An opening bored into the zone of saturation

11. Artesian well
• A well in which the water naturally rises above
the level of the water

12. Cavern
• A naturally formed underground chamber or
series of chambers most commonly produced
by solution activity in limestone

13. travertine
• A form of limestone that is deposited by hot
springs or as a cave deposit

14. Karst topography
• An area that has a land surface or topography
with numerous depressions called sinkholes

15. Sinkhole
• A depression produced in a region where
soluble rock has been removed by
groundwater

16. Key Concept
• Much of the water in soil seeps downward
until it reaches the zone of saturation. The
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

17. Key Concept
• Groundwater moves by twisting and turning
through interconnected small openings. The
groundwater moves more slowly when the
pore spaces are smaller

18. Key Concept
• A spring forms whenever the water table
intersects the ground surface

19. Key Concept
• Overuse and contamination threatens
groundwater supplies in some areas.

20. Key Concept
• Erosion forms most caverns at or below the
water table in the zone of saturation

21. Key Concept
• Karst areas typically have irregular terrain,
with many depressions called sinkholes