Surface processes
Bust a move!
Weathering
2
The breakdown of material.
◻ Two types of weathering
◻ Physical weathering and Chemical
weathering
◻
Physical Weathering
3
The surface is still made of the same stuff, it just
looks different.
◻ Abrasion
◻ Frost wedging
◻ Root tap
◻
Chemical Weathering
4
Substances in rain or
runoff cause a chemical
change in the surface.
◻ Oxidation (rusting)
◻
What affects weathering rates?
5
Exposure (Rain, sleet,wind, biologic activity)
◻ Particle size ( more surface area= more weathering)
◻ Composition (some surfaces weather faster than
others. Limestone weathers faster than volcanic rock)
◻ Climate (weathering is faster in moist, hot climates)
◻
6
What is Erosion?
Erosion is defined as removal of rocks and
soil by wind, water, ice and gravity. The
movement of weathered material!
◻ Wind, water, ice, humans and gravity are
known as the agents of erosion.
◻
Weathering vs. Erosion
Weathering involves two processes
[physical, chemical]
that often work together to break down
rocks. Both processes occur in place. No
movement is involved in weathering.
Wind Erosion
Wind can play a role by carrying material (especially
sand and clay) from one place to another.
As the wind blows, it picks up small particles of sand/
sediment and blasts large rocks with the sand/sediment,
cutting and shaping the rock.
The intensity of wind erosion is determined by:
Sum (amount of sand)
Speed
Slope
Surface
Wind Erosion
Water Erosion
When rain falls to the Earth it can evaporate, sink into the ground, or flow over the
and as runoff. When it flows over land, erosion occurs. Runoff picks up pieces of
rock and "runs" downhill cutting tiny grooves (called rills) into the land.
How much erosion takes place is determined by the:
•Sum (amount of water)
•Slope
•Speed
•Surface
Water Erosion
Ice Erosion
Glaciers wear down the landscape; by picking up
and carrying debris that moves across the land
along with the ice.
Glaciers can pick up and carry sediment that ranges
in size from sand grains to boulders bigger than
houses.
Moving like a conveyor belt or a bulldozer, a single
glacier can move millions of tons of material!
How much erosion takes place is determined by the:
•**Sum (Glaciers are massive!)
•Slope
•Speed
•Surface
Ice Erosion
Gravity Erosion
Gravity Erosion is better known as Mass Movement and is
defined as the transfer of rock and soil down slope by direct
action of gravity without a flowing medium (such as water
or ice). Some of the best examples of Mass Movement are:
Creep
Rock fall
Slump
Landslides
Avalanches
Human Erosion
Humans are constantly
influencing the nature of
our landscapes. HOUSES,
ROADS, BUILDINGS,
DEVELOPMENTS, CANALS,
etc., all change the shape
and appearance of the
land.
Deposition
17
Also called sedimentation.
◻ The final step in the process. Sediment gets
deposited in a new place.
◻ Agents- wind, water, gravity, glaciers.
◻
Factors affecting deposition
18
Size of sediment (larger is deposited faster)
◻ Shape (rounder settles faster)
◻ Density (more dense settles faster)
◻ Speed (slower moving sediments settle faster)
◻
Deposition
19
The whole
process is how
new rock is
made.
Erosion Lab
Preparation
◻
Put notes where you can see them, but out of the way of water and mud.
Procedures:
◻
Person 1 gets a plastic container and brings it to the dirt supply for 1 small shovelful of dirt at one end of the plastic container.
◻
Person 2 gets one pipette for each member of the group and something to tilt slightly the plastic container.
◻
Person 3 gets a cup and fills it up with water.
◻
Set up your container so it flows evenly down to the low side of the container. (Slanting in more than one direction can cause water to
accumulate in corners and cause unnatural features.)
◻
Add 100-150 mL of water to the lower end of the container to make a small lake.
◻
Everyone gets one pipette which can be used to drop (not squirt) on to the “mountain”. You have 20 minutes to do this. Make note of
erosional features because some features, such as sinkholes, slump, and landslides are very difficult to identify after they happen. Feel
free to experiment with height of the drop.
◻
After 20 minutes, have students answer the following questions:
Cleanup:
◻
Person 1: Puts dirt in disposal as directed and rinses/wipes the container.
◻
Person 2: Returns pipettes and wipes up any mess around lab area on floor
◻
Person 3: Returns beaker and dries up any water around lab area on desk
Weathering and Erosion Lab
Procedures; Step 1
◻ Make a pile of sand in the middle of the pan.
◻ Place pebbles on the surface of the new hill, and hypothesize what will happen.
◻ Now lightly blow across the sand and pebbles with the straws.
◻ Make a “sand mountain” by piling sand up on one side of your pan.
◻ Hold the ruler in the mountain so that the sand covers up to the 10 centimeter mark.
◻ Make a “rain cup” by taking one of your small cups and poking holes into the bottom
of the cup with your pen or pencil.
◻ Hold your “rain cup” over your mountain and fill the other cup with water.
◻ Pour the water from the second cup into your “rain cup” – the water will now “rain”
on your mountain.
◻ After the rain has stopped, measure the height of the remaining sand and record
that number below. Explain where some of the sand went to and why.
Weathering and Erosion Lab cont.
Step 2;
❑
Make a second mountain exactly like the first.
◻
Using the popsicle sticks, build a dam on one side of the mountain.
◻
Hypothesize what will happen when this new mountain is “rained” on.
◻
Now “rain” on your new mountain and record the height below. Was your hypothesis
correct? Explain your results below.
Weathering and Erosion Lab cont.
Step 3;
◻
Make a chemical weathering chamber by adding a piece of chalk to the last small
cup and filling it ½ full with vinegar.
◻
Put the lid on your chemical weathering chamber and shake it vigorously for ten
minutes – You might want to take turns with this one. ◻
Hypothesize what will happen to the chalk.
Sources
www.augusta.k12.va.us/.../lib/.../
Weathering_and_Erosion.ppt
◻ www.powayusd.com/.../Erosion/The%20Forces
%20of%20Weathering%20and%20Erosion.ppt
◻ mail.clevelandcountyschools.org/.../
Weathering_and_Erosion.ppt
◻ Bryce Shelly; Lehi Junior High School
◻