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Desert LandformsYOU MUST… Describe the characteristics of the fluvial and aeolian landforms listed
YOU SHOULD… Explain the physical processes that created these landforms
YOU COULD… Support your knowledge of the above with specific facts and figures
What you need to knowLandforms resulting from wind action:• Yardangs• Zeugen• Sand dunes
Landforms resulting from water action:PedimentsInselbergsMesas and buttesSalt lakesAlluvial fansWadisBadlands
NB: Desert pavements, ventifacts, deflation hollows and rock pedestals are NOT mentioned by name in the spec, these can be used as supporting examples in essays but you cannot be asked a direct question on them.
What you need to know• Yardangs• Zeugen• Sand dunes• Pediments• Inselbergs• Mesas and buttes• Salt lakes• Alluvial fans• Wadis• Badlands
Just like with River landforms you must be able to:
- Draw a sketch of each one
- Describe what is looks like, giving specific facts and figures if you can
- Explain how it formed
Wind Action (aeolian landforms)• Yardangs• Zeugen• Sand dunes
Yardangs• Form where there are
vertical layers of hard and soft rock aligned to the direction of the prevailing wind.
• Practise drawing this sketch and use the information in your booklet to explain how they form.
• Also see the diagrams on p. 138 of your textbook.
Yardangs on Mars
Zeugen• Form where there
are horizontal layers of hard and soft rock.
• Practise drawing this sketch and use the information in your booklet to explain how they form.
• Also see the diagrams on p. 138 of your textbook.
Up to ____m per year
Steeper, slightly ____________ ______________ slope
The bottom of the slope contains ________ grained sand so it is more gentle. It may have ________ _____________
Sand is transported up the __________ windward slope by the processes of ___________________ and __________ _________
Prevailing wind _________________
Up to _______ m high
The _________ of the dune face downwind. They contain less sand so they are easier to move
Sand continually ____________ over the sharp crest
The top of the leeward slope is steep because it’s made of ___________ grained sand and it’s kept steep by wind ___________
direction concave 30 horns 30 leeward eddies fine coarse
saltation surface creep avalanches gentle sand ripples
Sand dunes• Make sure you know
about barchans dunes in detail
• Practise sketching and labelling this diagram
• You could mention one or two others e.g. star dunes
• Also see the diagrams on p. 139 of your textbook.
Water Action (fluvial landforms)• Pediments• Inselbergs• Mesas and buttes• Salt lakes• Alluvial fans• Wadis• Badlands
Pediments• Gently sloping
surface (between 2o and 7o) formed at the foot of a cliff.• Cut in solid rock or
covered with graded debris (finer material furthest away from cliff).
Mesas and Buttes• Isolated highlands left behind after the surrounding rock has been eroded away by water• Usually formed in flat-bedded (rock with horizontal layers) sedimentary rock or lava flows.
Valley cut by river
Butte
Resistant rock
Softer rock covered with scree
Mesa
Walt hiding his money
Scree slope
Inselbergs• Similar to Mesas and Buttes except
more rounded and smooth sided• Usually formed in unbedded
(uniform, without layers) igneous or metamorphic rocks• Can vary in size and shape, e.g.
Murphy’s Haystacks in Australia, which are around 8m high…
Uluru, Australia, 350m high
Wadis• A desert valley
that contains an ephemeral river• Can vary greatly
in size and shape• May be relict
landforms• Usually have a
lot of debris and thick sediment from flash floods
Wadi Rum, Jordan
Alien planet in movie Prometheus
Good. Only suggestion I might make is to make it narrower to allow you to show desert plateau on either side. Also label deposited debris/braiding on channel bed.
Alluvial Fans• Material is deposited in a
fan shape as a river leaves a highland area• Sediment is sorted in size
from largest to smallest• Several fans may coalesce
to form a bajada
Badlands• Arid or semi-arid
terrain with soft sedimentary rock that has been deeply eroded by rapid overland flow.• Contain landforms
such as wadis and alluvial fans• Thought to erode
about 1 inch per year
Desert Landforms Challenge!• Get into pairs• Around the room are places to draw each landform• You will have 1 minute on each landform• The first person must draw it, everyone else can add
labels/annotations or extra parts to the sketch