APES 12.3 and 12.4
Please take out module 25 for
check-off!
Get a computer
Module 25 Multiple Choice
1. D- acid rain only causes chemical weathering. Erosion is a
natural process
2. E- main soil formation factors are climate, parent material,
topography, organisms, time
3. D- correct horizon order is OAEBC
4. A- clay isn’t as permeable and won’t allow as much water
to seep out
5. E- aluminum would lower the base saturation because (Al
and H are the main soil acids)
6. E- tailings are the waste materials from mining
End of Chapter MC
1. D- heavier elements make up the earth’s core and
lighter elements are towards the surface
2. C- after the core, the order of layers is mantle,
asthenosphere, lithosphere, soil
3. E- all 3 are evidence of Pangaea
4. E- subsurface mining is most dangerous to miners
because of build up of toxic gases and chance for
collapses
5. E- each step up the richter scale is 10x more
powerful (like the pH scale!)
End of Chapter MC
6. D- plate move laterally at transform plate boundaries
7. C- subduction occurs at convergent boundaries
8. B- seafloor spreading occurs at divergent boundaries
9. E- an epicenter is the point above an earthquake
10. E- fossils are found in sedimentary rock
11. C- extrusive igneous rock comes from cooling of
magma, so it must be on the ocean floor where magma
comes up (best answer)
12. A- soil DOES change constantly
13. C- the B horizon is subsoil
Homework Accuracy Check
Module 24:
a. From #19: what are some unique characteristics
of igneous rock?
Module 25:
b. Write down your answer to #7
c. Define two different mining methods
Finish Rock Cycle Notes
Soil Formation and
Properties
Soil Formation
•The type of soil found in an ecosystem is
determined by:
1. Parent material (underlying rock)
2. Climate (affects amount of decomp., types
of vegetation)
3. Topography (losing/gaining sediment from
erosion)
4. Organisms (decomposers, detritivores, etc.)
5. Time (usually more time = more nutrients)
Soil Formation
•Soil’s profile is made up of several distinct
horizontal layers called Horizons
O Horizon – “Organic” Layer,
contains dead/decomposing
plants & animals; supplies
nutrients for the soil
A & E Horizon – Topsoil (darker
brown); where majority of roots
located, thickness dependent on
amount of decomposed material
B Horizon – Subsoil
(Lighter/Cinnamon) ; materials
from A & O deposited, few roots
C Horizon – Parent material (gray);
weathering of this horizon creates
upper horizons
Leaching and Accumulation
• http://serc.carleton.edu/NAGTWorkshops/visualizat
ion/collections/soil_horizons.html
• From the top  Decomposition and the leaching of
water through the soil move nutrients
• From the bottom  Weathering causes the parent
material to break apart
Soil Profile
Eluviation/Zone of
Leaching – water
percolates down the soil,
transporting materials.
Happens in Horizons A & E
O
A
E
Illuviation/Zone of
Accumulation – where
transported materials are
deposited. Happens in
Horizon B.
B
C
Soil Analysis Lab
Which soil horizon will you be testing?
Soil Texture
•Find
•40% Sand
•45% Silt
•15% Clay
•Loam
•Mixture of
all 3
•Loam?
http://www.isaarbor.com/education/onlineresources/CDDem
os/triangle.swf
Soil Lab Steps
1. Read introduction and do pre-lab q’s
2. Lab 1- Soil Texture
a.(do the quantitative “feel” test and the
quantitative soil triangle test)
b. Answer the analysis q’s as homework!
3. Lab 2- Soil Porosity (percent pore space)
a. Read the background and examine the rock
samples first
b. Do the porosity procedure and calculation (see
formula in the background)
Soil Lab Steps
Lab 3- Soil Percolation
a. Read the background and answer the prelab questions
b. Do the test using your phone for a timer
Lab 4- Soil pH
a. Read the background and answer the prelab questions
b. Use the pH probes instead of test strips
Eastern WA soil is more suited for farming
than Western WA. Why?
• Eastern WA
• No glaciers  sandy soil
that weathers easily
• Hotter  Speeds up
decomposition
• Less dense canopy 
more water hits soil and
soaks in
• Grasslands  Easily
decompose
• Western WA
• Glaciers  Gravel and
silt
• Colder  Slower
decomposition
• Dense canopy  A lot of
rain caught in trees
• Conifers  Needles very
acidic and don’t
decompose
Due Next Time
•ALL of Soil Lab!
(Pre-lab, data, analysis
questions all in lab
book!)