Name:
Date:
Geology Unit Lab
Procedure:
In this activity you will examine samples of sediments and rocks from Florida. The properties of
these samples can help us to determine their histories and origin, and clues to what the Florida
coast and its sea level were like in the past.
Make the following observations of the samples and record them in the chart.
1) Sediments: You will identify color, size in mm, Wentworth Class (based on the size),
texture, sorting, composition, presence of shell material, and depositional environment
based on the characteristics of the sample.
2) Rocks: You will identify color, composition, presence of shell material, and depositional
environment based on the characteristics of the sample and the information provided in
the Vocabulary section.
Color: What color or colors is the sample? If there is more than one color, note which one is
most prevalent.
Size: You can measure the size of the particles by using a metric ruler or putting the sample
on a sheet of metric graph paper and comparing the size of the particles to the size of
the squares. If the particles are smaller than one square, divide the size of the square
by the number of particles that fit in it.
Wentworth Scale: Using the size that you determined classify the particles using the
Wentworth scale below.
Wentworth Scale
Grain Diameter
Classification
Greater than 256 mm
Boulder
64 to 256 mm
Cobbles
2 to 64 mm
Pebbles (or Gravel)
1/16 to 2 mm
Sand
1/256 to 1/16 mm
Silt
Mud
Less than 1/256 mm
Clay
NSF DRL-1316782
Texture: This is a measure of how round the particles are. Compare the particles in the
sample to the pictures in the illustration below to determine the roundness of the
particles in your sample.
Sorting: The sample sediment could have particles that are mostly the same size or vary in
size. Sorting is a measure of how much they are the same or different. Compare your
samples of sediment to the pictures in the illustration below to determine the sorting of
the particles in your sample
Composition: What types of materials make up the sand in your sample? Are they minerals,
rocks, or organic materials? Most sand in Florida is made of silica or calcium carbonate.
To see which it is put a drop of dilute hydrochloric acid on the sample and observe what
happens. If it bubbles, it is most likely calcium carbonate or has a combination of silica
and calcium carbonate grains (shell material). If it doesn’t, it is most likely silica.
NSF DRL-1316782
Name:
Date:
Sample
Number
Sample
Collected
From
1
Sediment
Ft. Pierce,
East Coast of
Florida,
Central FL
2
Sediment
Ft. Pierce,
East Coast of
Florida,
Central FL
3
Sediment
Florida Keys
4
Sediment
Florida Keys
5
Sediment
Pensacola,
West Coast of
Florida,
Panhandle FL
6
Sediment
Ft. De Soto,
West Coast of
Florida,
Central FL
Color
Size
(mm)
Wentworth
Classification
Texture
(Roundness)
Sorting
Composition
(Calcium
carbonate,
silica, or both)
Shell
Material
Depositional
Environment
NSF DRL-1316782
Name:
Date:
Sample
Number
Sample
Collected
From
Color
Size
(mm)
Wentworth
Classification
Texture
(Roundness)
Sorting
7
Rock
Florida Keys
NA
NA
NA
NA
8
Rock
South
Hutchinson,
East Coast of
Florida,
South FL
NA
NA
NA
NA
Composition
(Calcium
carbonate,
silica, or both)
Shell
Material
Depositional
Environment
NSF DRL-1316782