(c) McGraw Hill Ryerson 2007 10.4 Water’s Effect on Shaping Earth’s Surface Water is always moving due to the water cycle Quick changes can happen due.

(c) McGraw Hill Ryerson 2007

10.4 Water’s Effect on Shaping Earth’s Surface

• Water is always moving due to the water cycle Quick changes can happen due to floods, storms or

tsunamis Slower changes occur due to glaciers, run-off and rivers

See page 386 - 388

Water’s Effect on Shaping Earth’s Surface

• Water helps in weathering, erosion and deposition Weathering is the breaking down of rock into smaller pieces

Physical weathering (aka mechanical) - rocks broken down by force, but still remain as the same kind of rocks

Chemical weathering - rocks broken down by chemicals into different types of matter

Erosion is the movement of pieces of broken rock to another location

Deposition is the dropping, and building up, of pieces of rock (eg. river deltas)



Weathering by Water and Ice

• Physical weathering Occurs most quickly where the climate includes high levels

of precipitation and large temperature changes (between night and day, and also from season to season)

Ice wedging (aka frost wedging) weathers rocks due to the expansion of water as it freezes

See page 389


• Chemical weathering Occurs most quickly where climate is warm, there is high

levels of rainfall and pollution Water + oxygen = much chemical weathering, including

rusting aka oxidation

Plants also aid in chemical weathering Lichens, decomposing plants




• Chemical weathering also occurs underground Water + carbon dioxide = carbonic acid, which dissolves

rock Groundwater becomes acidic, and reacts with calcium

carbonate in some rocks to dissolve the rocks Limestone has high levels of carbonate

Over time, large spaces are created underground Sinkholes, caves and karst are

formed this way

See page 390

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.


Erosion by Water and Ice

• Erosion by water Moving water breaks down rock into sediment

Sediment can be eroded far away and deposited V-shaped valleys are carved by flowing water

Rapids create more weathering as water moves faster Ocean waves continually erode shoreline Gravity can cause landslides and avalanches

See pages 392 - 393

Erosion by Water and Ice

• Erosion by ice Glaciers once covered all of BC (2 km deep, 10 000 years

ago) leave striations (scratch marks) on rocks form U-shaped valleys can move large rocks long distances



Glacial Effects

See page 394

Arête Cirque Fiord (or fjord)

Hanging Valley Horn

Narrow ridge (high ground) between two

cirques

Bowl-shaped valley at the

head of a glacier

A narrow inlet of ocean between

steep cliffs carved by glaciers

U-shaped valley cut off by a

bigger valley created by a larger glacier

Pyramid-shaped peak located

between threecirques

Images from http://pubs.usgs.gov/of/2004/1216/a/a.html


Deposition by Water and Ice

See page 395Take the Section 10.4 Quiz

• After erosion, sediments are eventually deposited A delta forms where a river empties into a calm basin Glaciers deposit many different forms of sedimentErratic Esker Moraine Outwash

Large boulder deposited on the

ground by a glacier

Winding ridge of material deposited

by a stream running under a glacier

Ridge of rocky material deposited

by a glacier, are found at the sides

and farthest advance of a glacier.

Material deposited by water from

melting glaciers

Images from http://pubs.usgs.gov/of/2004/1216/a/a.html

http://www.bcscience.com/bc8/pgs/quiz_section10.4.htm

http://www.bcscience.com/bc8/pgs/quiz_section10.4.htm

(c) McGraw Hill Ryerson 2007 10.4 Water’s Effect on Shaping Earth’s Surface Water is always moving due to the water cycle Quick changes can happen due.

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