Accelerated Weathering rates and soils
Name:__________________________
Block:_______
Part 1 Weathering and climate
The type of weathering in an area is mainly dependent upon its climate. The major factors that control
climate are precipitation and temperature. The graph below shows the relationship between precipitation,
weathering and temperature. Use the graph to answer the following questions. Answer in complete
sentences.
1.
Determine the major type of weathering that occurs in Washington, DC with AYT (avg. yearly
temp.) of 23 degrees and AYP (avg. yearly precip.) of 104 cm.
2.
If the AYT in Washington, DC dropped 26 degrees C but the AYP stayed the same, what kind of
weathering would dominate?
3.
Phoenix, Arizona has has an AYT of 20 degrees C and AYP of 20 cm. What type of weathering
occurs in Phoenix? How would the climate in Phoenix have to change for moderate chemical
weathering to become dominant?
4.
According to the graph, no frost action occurs at a mean annual temperature above 13 degrees C.
What is a possible reason for this?
5.
In general how does a climate with a strong mechanical climate differ from one with strong
chemical weathering?
6.
Why are the streets and highways in Massachusetts damaged so much more in the winter months
than in the summer months? Consider both chemical and mechanical weathering processes.
7.
How is the weathering of a bare mountain peak different than that of a soil in a covered forested
area?
8.
Which would weather faster, a sculptured marble statue or a smooth marble column? Explain your
answer.
PART 2 SOILS
1. The diagram shows a very generalized soil profile, Label the horizons with the appropriate letter
designation. Then list characteristics of each soil horizon (use your text to help).
2. Based on the descriptions, which layer would likely be considered the zone of leaching?____
Which would be the zone of accumulation (where leached minerals would build)?____
The diagram shows the soil texture classification chart used by the US Dept. of Agriculture. Refer to the
diagram to answer the questions below.
A
C
B
1. Referring to the texture diagram, what are the percentages of clay, of silt and of sand of the soil shown at
each of the following points? What is the classification for the type of soil
% clay
% silt
% sand
Soil name
POINT A
POINT B
POINT C
2. If a soil has 20% clay, 60% silt, and 20% sand, it is called a(n)__________________________________
3. Refer to table on the back side to determine the soil type that would most likely be found in each of the
following locations. Then list the major characteristics of each soil.
a. Vermont
b. Louisiana
c. Wyoming
4. What do you think a soil might be like in an area dominated by mechanical weathering?
5. The residual soil made of the weathering of which parent rock would likely form a pedocal?
6. Mafic minerals weather first, how might this account for the materials in subsoil?
7. Why is chemical weathering to slow to form true soil in the Arctic or desert regions?
Climate
humid continental,
temperate with
>63cm rainfaill
forest
steppes, temperate
dry
<63cm rainfall
grass and brush
typical area
soil type
topsoil
Eastern US
Pedalfer
sandy, light
colored, acidic
Western US
Pedocal
commonly
enriched in calcite,
whitish color,
fertile, basic
subsoil
Enriched in Al, Fe,
and clay, brown
color
enriched in calcite,
whitish color
Additional info
Extreme
development in
conifer forests
because abundant
humus makes
groundwater very
acidic. Produces
light gray soil from
removal of iron
caliche is the name
applied to the
accumulation of
calcite
vegetation
tropical wet
extreme Arctic or
desert
grass and trees
almost none, so no
humus develops
Laterite
(zones not definedwould appear as
one very thick
layer) Enriched in
Fe and Al; brick
red color
Regolith/Aridosol
no real soil forms
because there is no
organic material.
Chemical
weathering is very
slow.
All other elements
removed by
leaching, nutrient
poor.
Bacteria destroy
humus, so no acid
is available to
remove iron