1. WEATHERING, EROSION & DEPOSITION

2. TYPES OF CHANGE…
1) Physical
2) Chemical

3. Physical Change
The new substance has the same properties as the old one.
No new substance(s) are produced. No change in chemical composition!
Examples;
ice - water – steam
paper cut into pieces

4. Chemical Change One or more NEW substances are created.
The new substance is different from the original.
Examples;
burning paper

6. Weathering
the chemical and physical breakdown of rocks at or near Earth’s surface.
Two types of weathering;
Mechanical (physical or disintegration)
the breaking of rock into smaller pieces.
Chemical (decomposition)
minerals are changed into different substances.

7. Ex of PHYSICAL WEATHERING
Ice wedging
aka frost action
water expands when it freezes
forms pot holes
Ex of PHYSICAL
WEATHERING
abrasion
rocks grind against each other
exfoliation
- decrease in pressure causes surface to flake off
Plant & animal action
root growth
animals digging in soil
Wetting & drying
- clays expand when wet, contract when dry

9. Winter ice in a canyon
near Ouray, Colorado,
high in the San Juan Mountains.

10. Result of ice wedging in
Arches National Park, Utah

11. In Colorado National Monument, Colorado, the bases of the cliffs
are surrounded by rock debris (talus) produced, in part, by ice wedging.

12. The east ridge of Mt. Brewer (the easy way up), near the summit.
This mountain, like most in the Sierra, is covered by a thick layer
of sharp-edged boulders produced by frost wedging.
Frost wedging is well-developed here because the temperature
cycles across the freezing point many days each year.

13. exfoliation
Yosemite NP, California
Southern British Columbia

14. Plant Action

16. CHEMICAL WEATHERING Reaction with acid carbonic acid (acid rain)
CO2 + H2O = acid
also acids from decaying material
acids dissolve some rock
CHEMICAL
WEATHERING
hydrolysis
reaction with water
water dissolves materials
oxidation
reaction with oxygen
rust

18. 1) Which type of weathering is most common where the average yearly temperature is 5°C and the average yearly precipitation is 45 cm?
(1) moderate chemical weathering
(2) very slight weathering
(3) moderate chemical
weathering with frost
action
(4) slight frost action

19. 2) Which activity demonstrates chemical weathering?
(1) freezing of water in the cracks of a sandstone sidewalk
(2) abrasion of a streambed by tumbling rocks
(3) grinding of talc into a powder
(4) dissolving of limestone by acid rain

20. 3) The diagram below shows granite
bedrock with cracks. Water has seeped
into the cracks and frozen. The arrows
represent the directions in which the
cracks have widened due to weathering.
Which statement best describes the physical weathering shown by the diagram?
(1) Enlargement of the cracks occurs because water expands when it freezes.
(2) This type of weathering occurs only in bedrock composed of granite.
(3) The cracks become wider because of chemical reactions between water and the rock.
(4) This type of weathering is common in regions of primarily warm and humid climates.

21. Factors that affect the rate of Weathering
1) Surface Area
as the amount of surface area increases, the rate of weathering increases.
cut the block
additional surface

23. 2) Mineral Composition different minerals weather at different rates.
calcite (limestone, marble)
weathers rapidly
– it is dissolved by acidic water.
quartz is mostly unaffected by chemical weathering.

24. Chemical Weathering is dominant in warm, moist climates.
the higher the temperature and humidity, the faster the rate of chemical weathering.
Physical Weathering is dominant in cold climates.
COLD
ARID
HUMID

25. Soil Formation
soil
the mixture of rock particles and organic matter on Earth’s surface that supports rooted plants.

26. Soils may be classified as either….
1) Residual Soil
soils that form in place from the local bedrock (parent material).
soil characteristics are similar to the parent material.

27. 2) Transported Soil
soil material has been transported into the area from another place
(usually by wind, moving water, or ice).
characteristics of the soil will not match the local bedrock.
most of the soil in New York state is transported.

28. Soil Profile
A soil profile is a cross section of earth (the soil) that has been exposed by digging.

29. A profile is composed of several horizons (layers).
(O) A, B, & C
Soils that have a distinct A, B and C layer are called mature soils.
It takes a long time to form a mature soil.

30. Soil Horizons (layers)
A Horizon (topsoil)
gray to black in color.
usually contains humus.
humus – organic material that forms from decayed plant and animal materials.
Sandy
(The upper most portion of the A horizon may contain an O horizon – dark, organic rich layer)

31. B Horizon (sub-soil)
usually red or brown (iron oxides from above).
contains clays from above.
also contains soluble minerals (Ca & Mg) from above.

32. slightly weathered parent material.
C Horizon
slightly weathered parent material.
Unweathered Bedrock
lies beneath the C-Horizon.
{complete “Soil Profiles” worksheet}

33. 1 3 2 A A C B C C
parent
parent
parent

34. D B A

35. Base your answers to the question on the graph below, which shows the effect that average yearly precipitation and temperature have on the type of weathering that will occur in a particular region.
The amount of chemical weathering will increase if
(1) air temperature decreases
and precipitation decreases
(2) air temperature decreases
and precipitation increases
(3) air temperature increases
(4) air temperature increases

36. 2) Landscapes will undergo the most chemical weathering if the climate is
(1) cool and dry (3) warm and dry
(2) cool and wet (4) warm and wet

37. 3) The cross section below shows layers of soil.
Which two processes produced the layer of dark brown to black soil?
(1) melting and solidification of magma
(2) erosion and uplifting
(3) weathering and biologic activity
(4) compaction and cementation

38. 5 Factors that affect Soil Composition.
1 – TIME
the older the soil, the more mature
(and deeper) the soil becomes.

39. 2 – PARENT MATERIAL
(“parent” is the rock from which the soil was formed.)
mineral composition of the soil, is similar to mineral composition of the parent rock.
this becomes less important as the soil matures.

40. 3 – PLANTS & ANIMALS
they increase the amount of organic material in the soil.

41. 4 – TOPOGRAPHY (SLOPE)
steep slope  water flows down the surface quickly.
water does not soak in
existing soil may be removed
steep slope = thin soil

42. 5 – CLIMATE
lots of weathering occurs in hot / wet climates = thick soil.
soils in wet tropical climates are all similar.
much material is washed out of the soil (nutrients, clays and silica).