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 DepositionSection 10.2

Groundwater Weathering and DepositionSection 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.

Groundwater Weathering and DepositionSection 10.2

Dissolution by Groundwater

Caves

A natural underground opening with a connection to Earth’s surface is called a cave or cavern.

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 DepositionSection 10.2

CAVES: CARLSBAD CAVERNS

CAVES: MAMMOTH CAVE

Groundwater Weathering and DepositionSection 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.

KARST TOPOGRAPHY

KARST TOPOGRAPHY

Dissolution by Groundwater

Karst topography

Limestone regions that have sinkholes and disappearing streams are said to have karst topography.

Groundwater Weathering and DepositionSection 10.2

KARST TOPOGRAPHY

SINKHOLES

SINKHOLES

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

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

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

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.

CH

Pumping too much groundwater can cause the land surface to sink.

10.3 Section Questions

Groundwater

a. true

b. false

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

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