2. Carbonic Acid Most groundwater is slightly acidic due to carbonic acid. Carbonic acid forms when carbon dioxide gas dissolves in water and combines with water molecules. Groundwater Weathering and Deposition Section 10.2

3. Groundwater Weathering and Deposition Section 10.2 Dissolution by Groundwater The processes of dissolving, called dissolution, and precipitation of calcite both play a major role in the formation of limestone caves.

4. Groundwater Weathering and Deposition Section 10.2 Dissolution by Groundwater Caves A natural underground opening with a connection to Earth’s surface is called a cave or cavern.

5. Dissolution by Groundwater Caves As groundwater infiltrates the cracks and joints of limestone formations, it gradually dissolves the adjacent rock and enlarges these passages to form an interconnected network of openings. Groundwater Weathering and Deposition Section 10.2

6. CAVES: CARLSBAD CAVERNS

7. CAVES: MAMMOTH CAVE

8. Groundwater Weathering and Deposition Section 10.2 Dissolution by Groundwater Karst topography A sinkhole is a depression in the ground caused by the collapse of a cave or by the direct dissolution of limestone by acidic water.

9. KARST TOPOGRAPHY

11. Dissolution by Groundwater Karst topography Limestone regions that have sinkholes and disappearing streams are said to have karst topography. Groundwater Weathering and Deposition Section 10.2

12. KARST TOPOGRAPHY

13. SINKHOLES

15. CH Chemical weathering of limestone by water causes the characteristic topography of karst areas.  Groundwater dissolves limestone and forms underground caves.  Sinkholes form at Earth’s surface when bedrock is dissolved or when caves collapse. Section 10.2 Groundwater Weathering and Deposition Study Guide Key Concepts

16. CH  Irregular topography caused by groundwater dissolution is called karst topography.  The precipitation of dissolved calcite forms stalactites and stalagmites in caves. Section 10.2 Groundwater Weathering and Deposition Study Guide Key Concepts

17. CH Which statement describes a stalactite in a cave? a. It builds up from the floor. b. It connects floor and ceiling. c. It hangs from the ceiling. d. It builds on a wall. 10.2 Section Questions Groundwater

18. CH How does a sinkhole form? 10.2 Section Questions Groundwater Possible answer: A sinkhole may form as the roof of a cave collapses. A sinkhole may also form where dissolution of limestone occurs at the surface. This may happen if a particular location is affected by more water, is affected by more acidic water, or if the rock is more vulnerable to dissolution.

19. CH Pumping too much groundwater can cause the land surface to sink. 10.3 Section Questions Groundwater a. true b. false

20. CH Which terms best describe a region of karst topography? a. flat and featureless b. sinkholes and caves c. steep and mountainous d. rolling and hilly Chapter Assessment Questions Groundwater

21. CH a. sodium b. calcium c. potassium d. lithium Which positive ion enters groundwater as a result of the dissolution of limestone by carbonic acid? Standardized Test Practice Groundwater