CHAPTER 23 Study Guide

23.1 Fresh Water

Key Concepts

• The water cycle is made up of several processes, including evaporation, transpiration, condensation, precipitation, and the eventual return of flowing water to the ocean.

• A small portion of Earth's fresh water is located in the atmosphere, streams, and lakes. Most is located in groundwater and glaciers.

Vocabulary

groundwater, water cycle, transpiration, glacier, runoff, tributaries, watershed, saturated zone, water table, permeable, aquifer, impermeable

23.2 Weathering and Mass Movement

Key Concepts

• Erosion acts through weathering, the force of gravity, and through the movement of streams, groundwater, glaciers, wind, and waves.

• There are two forms of weathering: mechanical weathering and chemical weathering. Both cause rocks to disintegrate.

• The rate at which mechanical and chemical weathering take place depends on three main factors: temperature, the availability of water, and the type of rock.

• Through the process of mass movement, gravity moves loose material down a slope.

Vocabulary

erosion, weathering, mechanical weathering, abrasion, chemical weathering, mass movement

23.3 Water Shapes the Land

Key Concepts

• A stream's ability to erode depends mainly on its speed.

• Water erosion forms V-shaped valleys, waterfalls, flood plains, meanders, and oxbow lakes.

• Features deposited by flowing water include alluvial fans and deltas.

• The process of chemical weathering causes much groundwater erosion, including the formation of caves and sinkholes.

Vocabulary

deposition, saltation, flood plain, meander, oxbow lake, alluvial fan, delta, stalactite, stalagmite, sinkhole

23.4 Glaciers and Wind

Key Concepts

• Glaciers form in places where more snow falls than melts or sublimates.

• Glacial erosion causes many distinctive features in the landscape, such as cirques, horns, U-shaped valleys, and glacial lakes.

• Most till is deposited at the front of a glacier.

• Wind erodes the land by deflation and abrasion.

• Features deposited by wind include sand dunes and loess deposits.

Vocabulary

continental glacier, valley glacier, plucking, cirques, till, moraines, deflation, dunes, loess

23.5 The Restless Oceans

Key Concepts

• Light and temperature decrease with the depth of the ocean, whereas pressure increases.

• Winds blowing across the surface of the ocean cause the continuous flow of surface currents.

• Deep ocean currents are caused by differences in the density of ocean water.

• In upwelling, winds blow warm surface water aside. This allows cold water to rise.

• Two physical processes, hydraulic action and abrasion, are responsible for much wave erosion.

Vocabulary

salinity, continental shelf, surface current, density currents, upwelling, hydraulic action, longshore drift

23.6 Earth's History

Key Concepts

• Geologists use the law of superposition to determine the relative ages of rocks.

• Geologists use radioactive dating to determine the absolute ages of rocks.

• The geologic time scale is based on the relative ages of rock layers and the use of radioactive dating to find the absolute ages of rocks.

• The four major divisions of Earth's history are Precambrian time and the Paleozoic, Mesozoic, and Cenozoic Eras.

Vocabulary

fossils, relative age, law of superposition, extinct, index fossils, absolute age, era, periods, mass extinction

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