sedimentary rocks lab

© 2018 Pearson Education, Inc.

SEDIMENTARY ROCKS LAB

• INTEGRATED EARTH SCIENCE

• LAB 06

• Dr. Gregg Wilkerson and Larry Dennen


Laboratory Manual

in Physical

Geology, 11e

Image PPTs

Chapter 6

Sedimentary

Processes,

Rocks, and

Environments


LABORATORY SIX

Sedimentary Processes, Rocks, and

EnvironmentsActivity 6.1, 6.5, 6.6

BIG IDEAS: Sediments include rock fragments, mineral grains eroded from rocks, minerals

precipitated from water, and the byproducts of life. Sedimentary rocks form

by precipitation and by the deposition, burial, compaction, and cementation of solid sedimentary

grains. Layers of sediments and sedimentary rocks are like pages of a book. Their fossils and geologic structures tell us about Earth’s history and past environments and ecosystems.

THINK ABOUT IT (Key Questions):• What do sedimentary rocks look like? How can they be classified into groups? (Activity 6.1)

• How does sediment form and change? (Activities 6.2–6.5)

• How do geoscientists describe, classify, and identify sedimentary rocks? (Activity 6.6)

• What can sedimentary rocks tell us about Earth’s history and past environments and

ecosystems? (Activities 6.7–6.9)


INSTRUCTOR NOTES

1. This lab involves the use of dilute hydrochloric acid as a means to identify carbonate minerals.

Students should be told (and should affirm their understanding) that their personal safety in the

lab is their responsibility. An appropriate first aid kit and a proper receptacle for disposing of broken

glass should be available in the lab, and the instructor should be aware of all relevant emergency procedures before any accident might occur.

The dilute hydrochloric acid (HCl) used to test for carbonate minerals should be about 3% HCl.

Stronger solutions may cause dolomite to effervesce even before it is powdered. Be sure to inform

students that they should place a sample on a paper towel to do the acid test and that they should

rinse the sample after the test. They should not drop the acid onto their clothing or skin. Their skin

may peel and their clothing may develop holes (after washing it several times) from exposure to the

acid solution. Follow your institution’s protocols for the use of chemicals in the labs, which might

include having a copy of the Materials Safety Sheet for hydrochloric acid available in the lab room. Hydrochloric acid supplies must be safely stored.

2. Rock samples for Activity 6.6 must be marked with an identifying number or letter, so they can be

organized on the Sedimentary Rocks Worksheet.


ACTIVITY 6.1: Sedimentary Rock Inquiry


LAB 6 ANSWER KEY


6.1A 1. The rock is made of rounded mineral/rock

grains and is a poorly sorted mixture of sand

and gravel, with the grains randomly arranged.

2. The rock is made of gravel-sized rounded shell fragments that are randomly arranged.

3. The rock is made of cubic crystals (halite) that

are randomly arranged and intergrown.

4. The rock is made of very fine-grained

sediment and appears to be layered.

5. The rock is made of layered fine-grained

sediment, and includes fossil ferns.

6. The rock is made of sand (quartz sand) and

shows no layering at the scale of the hand

specimen.

6.1B Reflect & Discuss Answers will vary widely.




6.1A 1. The rock is made of rounded mineral/rock grains and is a poorly sorted mixture of sand and gravel, with the

grains randomly arranged.



2. The rock is made of gravel-sized rounded shell fragments that are randomly arranged.



3. The rock is made of cubic crystals (halite) that are randomly arranged and intergrown.



4. The rock is made of very fine-grained sediment and appears to be layered.



5. The rock is made of layered fine-grained sediment, and includes fossil ferns.



6. The rock is made of sand (quartz sand) and shows no layering at the scale of the hand specimen.


ACTIVITY 6.5: Sediment Analysis, Classification, and InterpretationPg. 153


ACTIVITY 6.5: Sediment Analysis, Classification, and Interpretation

6.5A Sample A

1. Grain size range: ~0.2 mm to ~1 mm

2. clay 0% silt 0% sand 100% gravel 0%

3. The grains are well sorted.

4. The grains are well rounded.

5. Sediment composition is precipitated (maybe a bit bioclastic).

6. Student responses will vary.

This sediment consists of ooids that are typically associated with well agitated sands in a

shallow submarine shoal, near-beach, or even lake environment where the water contains abundant calcium and carbonate

ions in solution. The grains are polished, indicating that they might have been transported by waves or tidal currents.

Sample B




4. The grains are subround to well rounded.

5. Sediment composition is siliciclastic.


This sediment is typically associated with beaches, some sand bars along rivers, sand dunes, and nearshore

submarine dunes. The sediment is composed of one mineral (quartz), so it is what a sedimentologist would

call a mature sediment, meaning that its composition has evolved to include only the most durable and chemically resistant major component.

Most of the grains are polished, so they probably formed in a beach or surf environment,

but the frosted grains might have been shaped and frosted by eolian transport in sand dunes. Thus, this sediment is

probably a mix of coastal dune and beach sands.

Sample C

1. Grain size range: ~1 mm to ~10 mm

2. clay 0% silt 0% sand ~10% gravel 90%

3. The grains are moderately to well sorted.

4. The grains are angular.

5. Sediment composition is bioclastic.


This group of shells and shell fragments might have accumulated along a beach or in a trough between dunes in a near-shore marine environment.

6.5B Reflect & Discuss Quartz sand would be the LEAST diagnostic of a specific environment, because it is so common in

many different environments.



6.5A Sample A




4. The grains are well rounded.

5. Sediment composition is precipitated (maybe a bit bioclastic).


This sediment consists of ooids that are typically

associated with well agitated sands in a shallow

submarine shoal, near-beach, or even lake

environment where the water contains abundant

calcium and carbonate ions in solution. The grains

are polished, indicating that they might have been

transported by waves or tidal currents.



Sample B




4. The grains are subround to well rounded.

5. Sediment composition is siliciclastic.


This sediment is typically associated

with beaches, some sand bars along rivers,

sand dunes, and nearshore submarine

dunes. The sediment is composed of one

mineral (quartz), so it is what a

sedimentologist would call a mature

sediment, meaning that its composition has

evolved to include only the most durable and chemically resistant major component.

Most of the grains are polished, so they probably

formed in a beach or surf environment, but the frosted

grains might have been shaped and frosted by eolian

transport in sand dunes. Thus, this sediment is

probably a mix of coastal dune and beach sands.



Sample C

1. Grain size range: ~1 mm to ~10 mm

2. clay 0% silt 0% sand ~10% gravel 90%

3. The grains are moderately to well sorted.

4. The grains are angular.

5. Sediment composition is bioclastic.


This group of shells and shell

fragments might have accumulated

along a beach or in a trough

between dunes in a near-shore marine environment.


6.5B Reflect & Discuss Quartz sand would be the LEAST diagnostic of a specific environment, because it is so common in many different environments.



ACTIVITY 6.6: Hand Sample Analysis and Interpretation

Exam

ple

The goal is to identify the sample and assign a provisional rock name



1

2

3

4

5

Sandstone

Breccia

Chalk

Diatomite



6

7

8

9

10

Coal

Limestone

Chert

Shale

Coquina



1

2

3

4

5

Sandstone

Breccia

Chalk

Diatomite



6

7

8

9

10

Coal

Limestone

Chert

Shale

Coquina


In case it’s a different sample set…• Answers for the alternative sample box follow



1

2

3

4

5

Shale / mudstone

Sandstone

Breccia

Chalk



6

7

8

9

10

Diatomite

Coal

Limestone

Dolomite

Chert



11 Coquina



1

2

3

4

5

Shale / mudstone

Sandstone

Breccia

Chalk



6

7

8

9

10

Diatomite

Coal

Limestone

Dolomite

Chert



11 Coquina

sedimentary rocks lab

Documents