GEOL 1301 - Lab 04 - Sedimentary Rocks
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GEOL 1301
Lab 04
Sedimentary Rocks
Observe and record the properties of the sedimentary rock samples listed in the first table and
use them to identify the samples. Lists of properties can be found below, as well as links to rock identification keys. Please complete both attached worksheets, then upload your completed lab on Canvas.
Grain Size:
Gravel > 2 mm
Sand 0.06-2 mm
Silt 0.004-0.06 mm
Clay < 0.004 mm
Rounding:
Angular
Sub-rounded
Well-rounded
Sorting:
Poorly sorted
Well-sorted
Composition:
Can you identify any minerals in the rock?
Other Observations:
Layering
Fissility
Color
…
Identification Keys:
http://geology.about.com/od/rocks/a/Rock-Tables.htm
http://jersey.uoregon.edu/~mstrick/MinRockID/RockID/Sedimentary.html
Examining and Classifying Sedimentary Rocks
Use the following link to identify the sedimentary rock samples listed in the table:
http://profharwood.x10host.com/GEOL101/Labs/Sediment/index.htm
Sample
Number
Grain Size
Rounding
Sorting
Composition
Other Observations
Rock Name
1
No grain size
Angular
Well sorted
Calcite
Hardness = 3, Non-
Reactive to HCL
Limestone
3
No grain size
Sub-rounded
Well sorted
Gypsum
Hardness = 2, Non-
Reactive to HCL
Rock Gypsum
8
>2 mm
Sub-rounded
Poorly sorted
Rounded quartz, feldspar and rock fragments
Non-Reactive to HCL
Conglomerate
9
No grain size
Sub-rounded
Well sorted
Silica(quartz)
Hardness = 7, Non-
Reactive to HCL
Chert
10
1/16 – 2mm
Sub-rounded
Well sorted
Quartz, feldspar
Non-reactive to HCL
Sandstone
12
No grain size
Angular
Well sorted
densely compacted organic material
and plant fragments
Non-reactive to HCL
Bituminous Coal
How and in what environment might the rocks that you identified in the first part of the lab have formed?
Sample #/Rock Name
Formation/Environment
1 Limestone
Limestone forms from the crystallization of calcium and carbonate and can commonly be found in marine environments or former marine environments.
3 Rock Gypsum
Formed commonly in lagoons by the evaporation of water in mineral rich marine soil.
8 Conglomerate
Formed by the deposition of sediments from flowing rovers or by waves carrying sediments onto beaches.
9 Chert
Formed as a byproduct of plankton decomposing/dissolving, Silica is released by dead plankton
and marine life which forms Chert over time.
10 Sandstone
Formed as sand is cemented together under pressure for thousand to millions of years. Commonly forms in lakes, rivers, and the ocean floor.
12 Bituminous Coal
Forms as the result of organic material being subjected to natural compression in the ground until a mass of consisting
mostly of carbon is left.
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