Karst topography develops in areas underlain by carbonate rocks like limestone and dolomite. Groundwater dissolves these rocks by mixing with carbon dioxide to form acidic water, enlarging cracks and creating underground caves and features. Sinkholes can form if underground rock dissolves near the surface or a cave roof collapses. Karst topography is common where sufficient rainfall supplies groundwater that continues dissolving the soluble bedrock over time.

1. A COMMON TOPOGRAPHIC FEATURE EFFECT BY POROSITY AND PERMEABILITY IS……
Karst Topography
 What is Karst topography?
 topography developed in areas underlain by carbonate rocks, including limestone and dolomite. Karst
topography includes features like caves and sinkholes and forms when limestone is slowly dissolved away by
slightly acidic groundwater.


3.  Groundwater mixes with carbon dioxide to
form carbonic acid.
 Limestone is a rock that is easily dissolved
by carbonic acid.
 As the acidic groundwater moves through
pores in limestone, the rock dissolves,
enlarging cracks until an underground
opening called a cave is formed.

4.  Groundwater not only dissolves limestone
to make caves, but it also can make
deposits on the insides of caves.
 Water dripping from the cave walls
contains calcium ions dissolved from the
limestone. If the water evaporates while
hanging from the ceiling, the calcium
carbonate is left behind and builds up to
form a stalactite.
 Where water drops fall to the floor, a
stalagmite forms.

5. Cave
Development

6. CAVE ENTRANCE

14. Disappearing Stream

15. NATURAL CHIMNEYS

16. NATURAL BRIDGE

17.  If underground rock is dissolved near the
surface a sinkhole may form.
 A sinkhole is a depression on the surface
of the ground that forms when the roof of
a cave collapses, or when rock near the
surface dissolves.
 These are common in areas that have lots
of limestone and enough rain water to
keep the groundwater system supplied
with water.

18. Sinkhole

19. SINKHOLE

20. Karst topography is common in the
Valley and Ridge Province of Virginia,
where limestone is abundant.

21. KARST TOPOGRAPHY FEATURES

23. Human Impact on Groundwater
 Groundwater accounts for 20% of all water
used in the U.S.
 Unwise use of this valuable resource can
damage or deplete groundwater reservoirs
 Some of the problems related to groundwater
use include:
 overpumping-lowering the water table
 subsidence
 contamination

25. Pollutants
 Contaminants introduced at the land surface may
infiltrate to the water table and flow towards a point
of discharge, either the well or the stream.

26. A SOURCE OF GROUNDWATER
CONTAMINATION: SEPTIC TANKS

27. Contamination results in a decline
in water quality.

29. ANOTHER SOURCE OF POLLUTION:
STORAGE TANKS

30. YET ANOTHER SOURCE OF POLLUTION:
LANDFILLS

31. Groundwater Moves – Usually
Slowly