Transcript Weathering - Paradise Valley

Weathering
GPH 111
Weathering Game Plan:
 What is WEATHERING and how
does it fit within gemorphology?
 Major TYPES of weathering
 How does climate affect weathering?
What is Weathering?
 The collective processes that lead to the
surface and sub-surface disintegration and
dissolution of rock. The major types include
physical, chemical, and biological weathering.
Weathering within Geomorphology
Sierra Estrella Mountains
and the Gila River
Weathering Processes
 Salt Weathering
 Sheeting
 Solution
 Frost Action
 Oxidation
 Hydration
 Hydrolysis
 Thermal Expansion
 Chemical
_________
_________
_________
_________
Weathering Processes
-
Minerals chemically combine with water
Mineral breakdown through contact with Oxygen (Rust)
Mineral absorption of water causes swelling and stress
Mineral dissolution by water
Examples: Spheroidal Weathering, Karst Topography, Gnamma Pits
 Physical
_________ - Water freezing induced expansion
_________ - Mineral crystal growth induced expansion
_________ - Pressure released expansion through unloading
_________ - Rapid heating from lightning and fires
Examples - Exfoliation Domes and talus slopes
 Extra
Weathering Processes
 Chemical
Hydrolysis - Minerals chemically combine with water
Oxidation - Mineral breakdown through contact with Oxygen (Rust)
Hydration - Mineral absorption of water causes swelling and stress
Solution - Mineral dissolution by water into their ionic form
Examples: Spheroidal Weathering, Karst Topography, Gnamma Pits
 Physical
Frost Action - Water freezing induced expansion
Crystallization - Mineral crystal growth induced expansion
Sheeting - Pressure released expansion through unloading
Thermal Expansion - Rapid heating from lightning and fires
Examples - Exfoliation Domes and talus slopes
 Extra
Chemical Weathering
Processes
 Weathering Processes
Hydrolysis
Oxidation
Hydration
Solution
 Associated Weathering Landforms
Spheriodal Weathering
Karst Topography
Gnama Pits
Chemical Weathering
 Hydrolysis
Minerals chemically
combine with water,
substituting silica
for hydrogen and
weathering
individual mineral
grains
This process
removes CO2
from the
atmosphere,
counteracting
global warming
Feldspar (K, Al, Si, O) + carbonic acid and water
residual clays (Kaolinite) + dissolved minerals + Si
Chemical Weathering
 Oxidation
Iron bearing minerals
(like biotite) combine
with Oxygen to
generate oxides and
softer clay minerals.
Rusted railway car; that
has undergone oxidation
Chemical Weathering
 Oxidation
The Wave, Southern Utah
Wupatki, Northern Arizona
Chemical Weathering
 Hydration - Clay minerals
absorb moisture along
their cleavage planes,
dramatically increasing in
volume.
Chemical Weathering
 Solution
Minerals can
dissolve into ions
with water, like
dissolving sugar in
coffee
Water is the
universal solvent,
capable of
dissolving at least
57 of the natural
elements
Weathering Landform
 Karst Topography - generated through
solution mostly into limestone bedrock
Weathering Landform
Caves and Caverns
Sinkholes
 Karst Topography
Can Be Associated
with Extensive
Damage (Sink Holes)
Weathering Landform
 Spheroidal Weathering - Chemical weathering
attacks all surface areas, rounding sharp edges into
spheroid shapes.
Weathering Landform
Weathering Landform
 Gnamma Pits - How do you think these guys form,
what chemical weathering processes could affect
their growth?
Physical Weathering
Processes
 Weathering Processes
Frost Action
Salt Weathering
Sheeting
Thermal Expansion
 Associated Weathering Landforms
Talus Slopes
Exfoliation Domes
Physical Weathering
 Frost Action - Where water seeps into rock
weaknesses during day, then freezes and
expands at night--breaking the rock apart.
Physical Weathering
Weathering Landform
 Chemical weathering rounds rocks--physical weathering
generates angular rocks.
 Talus Slope - A pile of angular rock fragments
Physical Weathering
 Crystallization Where mineral rich
water seeps into rock,
evaporates, and allows
the dissolved solids to
crystallize, breaking the
rock apart.
Physical Weathering
Only non-water
related process
 Sheeting - Buried rocks are under tremendous
pressure and once uncovered, pressure drop
sharply and the rocks rebound.
Sandstone
Granite
Weathering Landform
 Exfoliation Dome Develop after extensive
unloading and sheeting.
Enchanted Rock, Texas
Half Dome, CA
Physical Weathering
 Thermal Expansion Rocks dramatically heated
by forest fires can explode
when water absorbed in
the rock flashes to steam.
Physical Weathering
 Thermal Expansion - Rocks dramatically heated by
lightning can explode when water absorbed in the rock
flashes to steam.
Physical Weathering
 Thermal Expansion - Different rates of mineral
expansion and water absorption throughout numerous day
and night cycles.
Extra Weathering
 Root Growth - Root growth extends into rock fractures,
expand and bust the rock apart
Where do you think the different
weathering processes dominate
on the planet?
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In the Amazon (Tropical Rainforest)
Serengeti of Africa (Savanna)
Death Valley (Arid)
Minnesota (Humid Continental)
The Sierras (High Alpine)
Alabama (Humid subtropical)
Make a list for each one!!!
Importance of Surface Area
 What will weather quicker, one huge
boulder or a huge boulder broken down
into a bunch of smaller boulders? Why?
What does Weathering DO?
 The in situ disintegration of rock
supplied by tectonic (and isostatic)
rock input!
Things to Know:
 What is weathering
 Chemical processes round edges, physical
processes generate angles
 Types of chemical weathering and
associated landforms
 Types of physical weathering and
associated landforms
 Importance of SURFACE AREA
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