Download Weathering Notes

Weathering
_____________ is the physical and chemical breaking down of
rock material into smaller fragments due to _____________ to
processes that occur at Earth’s surface
Weathering occurs when rocks in the lithosphere are
______________ and is exposed to the atmosphere,
hydrosphere, and biosphere
Weathering
The most important agent involved in the weathering of material is
_____________
Two Types OF Weathering:
1) ____________________ is breaking rock by force into smaller
pieces of the SAME material
ex: hitting, scratching, cracking
2) ____________________ is the chemical reaction of water and
water vapor breaking down rock by changing its chemical
composition
The _____________ that make up the rocks are changed into
another substance
4 Types of Physical Weathering
1) _________________
(ice wedging)- water seeps into cracks, freezes, expands and
wedges the rock apart!
Water and ice are more powerful than rock over time!
-Water seeps into small cracks in rocks.
-When the water freezes it expands creating great pressure.
-The crack widens and allows water to seep deeper into the rock.
Alternating Freezing and Thawing
Examples of Frost Wedging : Potholes
2) ______________________
tree roots grow into small fissures or wedges and expand rock
Tiny root hairs seek out small cracks and pits in rock.
Once the root hairs find a place they grow and expand.
The expansion causes great pressure and cracks the rock.
3) ___________
the peeling of rock due to release of pressure experienced when
rock was formed
-Rocks formed deep in the Earth are made under high
pressure.
-When the pressure is released the rocks expand &
crack.
-May also be caused by alternate heating and cooling of
rocks by weather conditions.
-This is basically the “peeling away” of rock
4) _____________
collision of rocks with one another
Scraping, grinding, and wearing away other rocks during erosion
(movement)
Types of Chemical Weathering
Oxidation
Hydrolysis (water)
Carbonation (acid rain)
_______________
rocks with metallic elements combine with oxygen (in
air and water) and rust away (rust stains the rocks
REDDISH BROWN)
ex.: rusting
Water (_________________)
Minerals are dissolved in water when they react with it
ex.: Feldspar reacts with water to form kaolinite
Much of the time these minerals will end up as clay
Acid-Carbonation:
carbon dioxide from air reacts with water to create carbonic acid
which breaks down rocks (especially limestone, marble, etc.)
Why? What mineral does these rocks have in them?
________________: Sulfur Dioxide in the atmosphere dissolves
in rain water forming a strong acid (sulfuric acid).
NOTE: _____________ weathering typically results in a
___________ appearance of the landscape…just like here in
the Catskills!
____________________ is the name given to a region where the
bedrock is easily chemically weathered
This leads to the rock weathering away and forming sinkholes,
caverns, disappearing streams
Differential Weathering
Masses of rock do not weather uniformly due to regional and local
factors- Results in many unusual rock formations
Rates of weathering (how fast rocks break down due to physical
or chemical processes) will be influenced by:
1) ____________________ - weathering occurs on the
surface. The more surface exposed, the faster the weathering will
occur.
Rates of Weathering will depend on:
2) _____________________________________- some minerals
are more resistant than others.
Sedimentary rocks are generally soft and weather fast.
–____________ is easily dissolved by acids.
–Igneous and ________________ rocks are usually dense, hard,
and more resistant to weathering.
–Any rock containing quartz (hardness of 7) will generally be
resistant to weathering (conglomerate, quartzite, granite, etc.)
Rate of Weathering will depend on:
_____________________: rocks exposed at surface weather
much more quickly than buried rock.
–Rock Outcrops are places where rock layers actually stick out
above ground…where they are quickly exposed to lichens, moss,
trees, rainfall, ice, and animals!
Rate of weathering will depend on:
__________________ – higher elevations tend to be colder and
experience more freeze-thaw cycles
Rates of Weathering will depend on:
___________________________:
Cold and/or dry climates favor physical weathering.
Warm and wet climates favor chemical weathering.
Frost action works best in areas where the temperature
fluctuates wildly.
Soil - The product of weathering
Soil-_____________ is the result of weathering of rock, which
produces smaller pieces called fragments, which combine with
organic matter, air, and water to comprise soil. •Soil = rock
fragments, humus (decayed plant and animal material), air and
water
Soil forms layers of different characteristics called
_____________.
Soil separates over time into distinct layers as follows:
A horizon (Topsoil): the upper layer of dark brown soil containing
humus and plenty of animal activity (bugs, worms, etc.)
B horizon: also called “subsoil”, containing many more minerals
leached down by water infiltrating through the A horizon, so often
stained red by oxidation of iron minerals
C horizon: made of weathered bedrock (parent material)
•Usually contains larger particles and rock fragments
Bedrock: the underlying rock that is still mostly un-weathered