Name:____________________________________________________ Date:__________
Period:
1
2
3
4
5
6
PARTICLE SIZE DISTRIBUTION
Background: When rock goes through weathering we saw that mass was lost.
Pieces of rock that come off during weathering will settle to form soil.
Different types of weathering produce different types of soil.
 Mechanical weathering tends to yield larger particles :
o small pebbles
o sand.
 Chemical weathering tends to yield smaller particles:
o clay
o silt
In this activity, you will determine the composition of a locally collected soil sample. Soil
consists of 3 main particle sizes:
 clay,
 silt
 sand
You will analyze the amount of each of the 3 main particle sizes in the sample and then
determine the soil type.
After the initial set up, the sample must settle overnight for interpretation on the next day.
Prelab Questions:
1. During the last two activities you learned about mechanical weathering and chemical
weathering. How are they similar? ___________________________________________
_____________________________________________________________________
_____________________________________________________________________
2. How are mechanical weathering and chemical weathering different? __________________
_____________________________________________________________________
_____________________________________________________________________
Read the procedure and answer the following questions:
3. What are the 3 types of soils will we be studying?
a.
_______________________________
b. ________________________________
c. _______________________________
4. What do you need to do to the clay and local soil sample before putting them in the jar?
_____________________________________________________________________
5. How long do you shake the jar? _____________________________________________
6. What is the purpose of the drop of detergent? _________________________________
_____________________________________________________________________
Day 1:
Materials
Grease Pencil
3 plastic jars with lids
4 A bowl of Sand
A bowl of Clay
A bowl of Collected Soil
A large beaker filled with water
Bottle of Detergent
Procedure
1. With the china marker, label 3 jars (one jar for each soil type):
 Sand
 Clay
 Local Soil Sample
2. Break up any clumps in the clay and collected soil samples.
3. Fill each jar halfway with the soil type that matches the label.
4. Add water from the beaker to just below the rim of each jar.
5. Tightly secure the lid of each jar.
6. Shake each jar for 1 minute each, one jar at a time.
7. Open the lids
8. Put 1 drop of detergent into each jar. (This will help settle the particles.)
9. Tighten the lids securely.
10. Place jars in designated area to settle overnight.
Day 2:
Materials
3 Labeled plastic jars with lids and soil samples
White paper
Pen or pencil
Ruler
Calculator
China Marker
Procedure
1. Place white paper behind each of the jars.
2. Look at the layers in each.
3. In the observations section, draw each of the jars with their layers.
 Show Ms. Grant to earn your stamp!
4. Compare your collected soil sample to the Sand and Clay samples. Identify what each layer
of your sample is made of: sand, clay, or something else.
 If it looks like either sand or clay, it is!
5. With the China Marker, label each of the layers on the jar.
**Note: The layer that forms between the sand and clay layers is the silt layer. The dark
layer at the top is humus, decaying organic material that makes up part of the topsoil.
6. Label the layers in your drawings in the observation section.
7. Measure in cm how high the soil is in your Collected Soil Sample.

Total soil depth: ___________________________
8. Measure how high each layer is in the Collected Soil Sample.

Clay layer depth: ___________________________

Silt layer depth: ___________________________

Sand layer depth: ___________________________
Observations
DRAWINGS of Jars after Settling, including: *BE SURE TO GET THESE STAMPED!!!!!
 Jar + Lid
 Each type of particle in that sample, labeled.
 The size of each layer, in cm.
CLAY
SILT
SAND
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Data Calcualtion
9. Take the “Total Soil Depth” in cm from question #7, and record it in each data table in the
column labeled “Total Depth.” TOTAL
sign.
DEPTH column is after the ÷
10. Take the “Clay Layer Depth” from question # 8, and record it in the correct table below
(below where it says depth of clay).
This is the column before the ÷ sign.
11. Take the “Silt Layer Depth” from question # 8, and record it in the correct table below
(below where it says depth of silt).
This is the column before the ÷ sign.
12. Take the “Sand Layer Depth” from question # 8, and record it in the correct table below
(below where it says depth of sand).
This is the column before the ÷ sign.
13. Ignore the top most layer (humus).
14. Calculate the particle size distribution of the sample by doing the following:
(÷) the number in the layer column by the number in the total depth

Divide


column.
Multiply by 100.
Record the result in your data table as % of each type.
% of Clay
Depth of Clay Layer
÷
Total Depth
x 100
= % Clay
Depth of Silt Layer
÷
Total Depth
x 100
= % Silt
Depth of Sand Layer
÷
Total Depth
x 100
= % Sand
Collected
Sample
% of Silt
Collected
Sample
% of Sand
Collected
Sample
4
Name:__________________________________________ Date:__________
Period:
1
2
3
4
5
6
PARTICLE SIZE DISTRIBUTION
DATA ANALYSIS
Use the chart to figure
out what type of soil
your collected sample is.
How to use the chart:
Each corner of the
triangle represents
100% of one of the 3
classes of soil: sand,
silt, or clay.
Loam is a mixture of all three soil types.
1. Your % Silt: _________ (from your data calculations)
Find the % silt of your sample on the chart above, and put a mark there.
2. Your % Sand: _________ (from your data calculations)
Find the % sand of your sample on the chart above, and put a mark there.
3. Your % Clay: _________ (from your data calculations)
Find the % clay of your sample on the chart above, and put a mark there.
4. Draw along the diagonal lines, starting at each of the points, until the lines
cross.
5. Where they intersect is the soil type of your sample.
6. If it lands on the border of two types, choose the type that takes up the most
space on the chart.
5
Clay:
60-100% clay
0-40% silt
No sand
Sandy Clay:
35-55% clay
no silt
60-85% sand
Sandy Clay Loam:
20-35% clay
60-70silt
60-90% sand
Clay Loam:
30-40% clay
60-73 %silt
30-75% sand
Silt:
No clay
87-100% silt
0-20% sand
Silty Clay:
60-40% clay
60-40% silt
No sand
Silty Clay Loam:
60-40% clay
60-73% silt
12-35% sand
Silt Loam:
0-30% clay
72-88% silt
20-50% sand
Sand:
0-10% clay
No Silt
90-100 % sand
Sandy Loam:
15-20% clay
80-93% Silt
70-50 % sand
Loamy Sand:
10-17% clay
80-90% Silt
70-88 % sand
Loam:
Equal parts of clay, silt and sand
6
Questions:
1. What type of soil is the Local Soil Sample? ________________________
2. After observing the control jars, which type of particle (silt, clay or sand) do
you think is smaller and lighter? ___________________________
Explain.______________________________________________
___________________________________________________________
___________________________________________________________
3. Which particle type is larger and heavier? __________________________
Explain. _____________________
___________________________________________________________
___________________________________________________________
4. Which particle was the most abundant?_____________________________
5. Explain one way these different-sized particles are formed.______________
___________________________________________________________
___________________________________________________________
6. Why is there mostly sand at the beach and mostly clay inland?_____________
___________________________________________________________
___________________________________________________________
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