Dwight Sutherland 2014

February 26, 2014Lesson on: Canyons, Wadiis and salt pans

Key question:1. How are the above landforms created?

Dwight Sutherland 2014

TASK: Read the poem about the Grand Canyon. What geographic features of the Grand Canyon can you identify from this source?

Glen Canyon Damby Wilfred A. Elders(composed during the 2013 trip)

Time and a river flowing,The river flowing free, From snowy mountain summits,To a balmy tropic sea.The Colorado River,A river running free, It carved a stupendous canyon,For all the word to see.Six million winter snow falls,The snowflakes falling free,Six million years of spring melts,Have rushed to meet the sea.The Kaibab Plateau rising, The river keeping pace? The tidal delta growing,An isostatic race?As upward went the Plateau,

• So downward cut the stream,Its riffles and its rapids,Down cut a mighty seam.Each surge of the raging river, Laid bare a rocky page, Layer after layer eroding,Each of an older age.Time and a river flowing, The river running free, The book of time was opened,To reveal earth's history.Time and a river flowing,Now concrete spillway drops,Restrain the annual flooding,And irrigate the crops.Vulcan tried to dam the canyon,Such conflict of water and fire! Though the lavas dammed the canyon,They fell to the river's ire.Two billion years of Earth's time, Or three score years and ten?How mighty is the canyon, How frail the works of men!Time and a river flowing, The river flowing free,Past the ruins of former dam-sites, After man has ceased to be!

Dwight Sutherland 2014

Canyon – An example of hot arid landforms

A canyon has 3 main characteristics• Narrow valley• Steep sides• Created by river

erosion

Dwight Sutherland 2014

TASK: Describe how canyons like the Grand Canyon are formed.• http://

www.bbc.co.uk/learningzone/clips/how-the-grand-canyon-formed/14092.html

Key ideas you may want to include:• Flash floods• Baked surface• River aims to get to baseline flow• Little vegetation• Layers of soft material between harder material• Abrasion• Infiltrate water• Exogenous river

Dwight Sutherland 2014

Canyon LandscapeTASK: Study the diagram of a canyon (see below). As you watch the video (next slide) try to identify some of these.

ButteMesa

Steeped sides

Exogenous river

Dwight Sutherland 2014

Canyon LandscapeTASK 1: Watch the video and try to identify some of these.

http://www.youtube.com/watch?v=UT3hQlY4oek

http://www.youtube.com/watch?v=to4Tz748s4U

Optional TASK 2: Study the image of the Grand Canyon Label a mesa, butte and steep sides.

Dwight Sutherland 2014

TASK: Explain how wadis are formed. Use text, page 145-146.

Wadi Degla in Egypt

Key ideas you may want to include:• Ephermeral river• Braiding• Steep sides• Deposition• Dry valley• Transportation• Hot arid and semi arid regions

Dwight Sutherland 2014

Progress check discussion TASK: What’s the main difference between canyons and wadis?

Canyon Wadi

Dwight Sutherland 2014

TASK: Explain how salt pans are formed. Use text, page 148.

Etosha Salt Pan in Namibia. It can even be seen from space. See google earth link below.https://maps.google.co.uk/maps?q=etosha+pan&ie=UTF-8&ei=YgMSU5P0FdSrhAfOm4CAAw&sqi=2&ved=0CAgQ_AUoAg

Key ideas you may want to include:• Repeated process• Ephermeral lakes• Rate of evaporation• Gentle sloping a relief (height of land) • Loose grains can be transported• Salt crystals• Deposition

Dwight Sutherland 2014

Lesson summary TASK: Classify these hot arid features as either water or wind features.

• Pediments• Canyons• Yardangs• Sand dunes• Wadis• Pavements• Salt pans