HOT, ARID LANDSCAPES
ACTION POINTS FOR TODAY:
1. The difference between WEATHERING and EROSION.
2. Paired research of an assigned PROCESS or LANDFORM.
3. Produce a one-slide info sheet to explain this process or
landform (should include annotated diagrams / images,
terminology, definitions etc…)
http://www.youtube.com/watch?feature=player_embedded&v=lyysL02ZvQ8#
DEFINITIONS
• Erosion is the breakdown of material that
involves some movement of the material
itself.
• Weathering is when a material is broken down
in situ (ie without moving).
PROCESSES
AEOLIAN (WIND) EROSION:
DEFLATION and CORRASION/ABRASION; Jasper and Claudia
WEATHERING:
EXFOLIATION and SALT CRYSTALISATION; Patricia and Edric
WIND LANDFORMS
CRESCENT DUNES; James and Rachel
YARDANGS; Heather and Nick
ZEUGENS; Victoria and Larry
WATER LANDFORMS
WADI’S and CANYONS; Tushaar and Kana
MESA’S BUTTES and SPIRES; Grace and Marco
INSELBERGS; Himani and Arpit
PAIRED TASK
Create a one-slide info
sheet to explain your
process / landform.
Include annotated
diagrams, terminology
and definitions.
http://youtu.be/Mzan8ktsWWs
Explain the occurrence of flash
flooding…
1. When it rains in deserts, it often floods because
there is little vegetation to intercept water in the
soil and slow the surface runoff.
2. Sandstorm conditions are also ideal for rain
storms, in which case flash flooding becomes a
threat. The desert sand has low absorption, so
heavy rains can produce flood conditions very
quickly and without warning. Dry channels, ditches
and lake beds will fill quickly and the water can be
strong and violent, sometimes creating a wall of
water 10 to 30 feet high. Remarkably, more people
drown in the desert than die of thirst.
Explain the occurrence of flash
flooding…
3. Flash flooding occurs when precipitation falls
too quickly on saturated soil or dry soil that is
impermeable (has poor absorption ability). This
is because there is limited opportunity for
infiltration. The runoff collects in low-lying areas
and rapidly flows downhill.
Fluvial processes
• Three main types of river are found in desert
areas:
1. Exogenous rivers – sources outside the desert
2. Endoreic rivers – these form near the desert
and never show beyond it
3. Ephemeral rivers – these flow for only part of
the year.
1. Exogenous
• These rivers continue to flow perennially, even
though some of their discharge may be
evaporated by high temperatures.
2. Endoreic
• An endoreic, or closed water system, ends its
journey inland rather than flowing into the
ocean. Most endoreic systems terminate as a lake
or a sea or, as in the Okavango River system, as a
delta.
• Both ephemeral and exogenous (perennial)
systems can be endoreic, and paleohydrological
evidence from around the world often shows that
a system has changed from exoreic (flowing to
the sea) to endoreic due to geological, climatic or
environmental factors.
3. Ephemeral
• In an ephemeral river, water flows sporadically and for
short periods following heavy rain or snow melting in its
catchment during spring. Water may flow for hours or even
days, but rarely longer.
• An ephemeral river is one in which measurable discharge
occurs for less than 10% of the year. Over time, a particular
river can change from perennial (where water flow is
continuous) to ephemeral, or vice versa, depending upon
climatic and environmental circumstances.
• Another important feature of an ephemeral river is that,
although the river channel’s surface may remain dry for
most of the year, there is usually a significant volume of
water stored beneath the channel.