Notes on Sedimentary Rocks, Weathering and Erosion ......soil profile solifluction talus* alluvial fan* mass movement (wasting) Sedimentary Rocks A. Introduction 1. _____ of the rocks

Notes on Sedimentary Rocks, Weathering and Erosion- Chapter 10, 12

Name _______________________

Date_____________Class_______

Vocabulary List (Number, write and define these words on another sheet of paper, those

that have a * please illustrate, be creative!) (45) cementation rock cycle* breccia* compaction*

sediment clastic sedimentary rock concretion*

erosion conglomerate* evaporate* soil*

strata* evaporites fossil* weathering*

stratification* abrasion butte* carbonation

chemical weathering creep* erosion exfoliation

horizon* humus* hydrolysis ice wedging*

landslide leaching* oxidation mechanical weathering

mesa* monadnock mudflow peneplain

regolith rockfall sheet erosion slump

soil profile solifluction talus* alluvial fan*

mass movement (wasting)

Sedimentary Rocks

A. Introduction

1. _________ of the rocks on the earth’s surface are sedimentary

2. Sedimentary rocks form on or very near _____________________

B. Kinds of sediments

1. ______- tiny fragments of clay minerals

2. ______

3. _______ - larger grains of quartz

4. ______________ - larger pieces of broken rock

5. ____________ - animals with shells die and form ocean sediments

6. _____________ - when water evaporates and leaves behind mineral deposits

C. Movement of sediments

1. Sediments are moved by ____________________

2. The faster the water moves, the larger the _______________ that will be moved

3. As moving water slows down, the larger sediments will drop out first

4. The smaller size particles remain _________________ in the water; they take a long time to settle to

the bottom

5. Eventually most sediments are deposited in the _______________________ in layers

D. Types of sedimentary rocks

1. ______________ (detrital or fragmental) sedimentary rocks

a. Formed from broken pieces or fragments of rocks, such as clay, sand and gravel

b. ____________________

-made of rounded pebbles mixed with clay and sand

-form in where streams/rivers slow down and deposit large sediments

-(angular rocks= breccia)

c. ________________

-made of small, sand-sized grains of quartz

-formed from sand on beaches, in river beds and in sand dunes

-Sand grains are usually glued together

d. ___________________

-the clay is fragments in shale are mica flakes, so it has a smooth texture

-the clay particles are flat and are easily pressed together

-rocks made of clay can be easily split apart in layers

2. ______________________

a. Formed directly or indirectly from material once alive

b. ____________________- sedimentary rocks made up mostly of calcium in the shells of clams,

oysters, etc.

c. ___________ - animals with shells that grow together in a reef

d. __________ - small pieces of animal shells and crystal pressed together

e. ________________________- formed from the remains of living thins that lived millions of

years ago

3. Chemical sedimentary rocks

a. formed by chemical means that do not involve any _______________________

b. formed when water evaporates and leaves deposits behind called _______________

c. limestone- formed from tiny grains of calcite deposited in _________________

d. ____________- natural form of halite (common table salt); form thick layers or beds

E. Formation of sedimentary rocks

1. __________________ - process which changes sediment into rock

2. The two parts of lithication are:

a. ______________ - caused by pressure of overlying layers

b. ______________- glueing together of sediments by minerals dissolved in water

3. Kinds of natural cement:

a. ________ (from quartz)

b. ___________ (from calcite) - most common

F. Destruction of rocks

1. ____________- the process of breaking rocks apart and moving away the sediments

2. __________________- the slow breakup of rock by the atmosphere

a. mechanical or physical weather (disintegration)

-takes place when rocks are split or broken into small pieces of the same material without

changing the composition

-Types of mechanical weathering:

1)___________- expansion and contraction splits rocks

2)________________- roots split rocks

3)___________- landslides move and break rocks

4)______________- colliding of tiny fragments with rock

b. chemical weathering (decomposition)

-takes place when the minerals in the rock change into different substances

-Agents (causes) of chemical weathering:

1)____________- dissolves minerals holding rocks together

2)____________- called oxidation; combines with iron to cause rust

G. Feature of (how to recognize) sedimentary rocks

1. ____________ (stratificiation)- layers or beds of sedimentary rocks

2. ___________ – remains or evidence of past animal or plant life

a. Imprints – leaf, feather, or bone impression

b. Petrification- bones or trees turn to stone

c. Trace fossils – dinosaur footprints

3. ________________- formed by action of wind or water on sand

4. _________________- when minerals precipitated from solutions, build up around an existing rock

particle- geodes

Rock Chart

Sediment Original Metamorphic Rock

Mud (Mica) Slate

Slate

Magma Gneiss

Sandstone

Marble

Fossils

Chapter 12 Weathering and Erosion

1.What are the two ways rock material weather?

-______________- physically breaking rock into smaller pieces

-_____________- breaks down rock by changing its chemical composition

A. Mechanical Weathering

1.How does granite exfoliate?

-long cracks called joints develop on surface and break into _________________

2. Describe ice wedging?

-Water seeps into cracks and joints of rocks, freezes its volume increasing by __________

-Each freeze causes the crack in rock to grow wider and deeper, eventually _________________

3.How can plants and animals aid in mechanical weathering?

-_____________- roots work their way into cracks in rocks, as the root grows it splits the rock

-_____________- burrowing (prairie dogs) exposes new rock surfaces to weathering

4. What is abrasion?

-The collision of rocks with one another caused by _____________________________

B. Chemical Weathering

1.What two changes occur in chemical weathering?

-change in the _____________________________ of the mineral and the physical appearance is

altered

2.What is hydrolysis?

-When water combines with certain minerals such as feldspar then it becomes altered through

______________________- to become a clay called kaolin

-when minerals are altered, the dissolved minerals can be carried through the soil into lower

layers of rock, this is called ___________________

3. Explain the process that creates limestone caves:

-carbon dioxide and water combine to form __________________, which slowly dissolves

limestone (made up of calcite), the process is called carbonation and produces underground

caves

4. Why is some soil red especially in the southeastern U.S.?

-through the process of ____________________, metallic elements (iron) react with oxygen

causing the soil to become a ‘rusty’ color

5. What does oxidation do to automobiles over time?

-Oxidation corrodes a car to begin to rust causing the appearance of the car to be ruined,

damaging the floor of the passenger compartment causing __________________________ to

enter the car, also weaken suspension, steering and brake systems

6.What is acid rain and what causes it?

-__________________ that is more acidic than ordinary rain, due to high levels sulfur and

nitrogen which is produced near cities (cars, power plants-pollution)

7. How can a plant chemically alter a rock?

-_________________________ (colonial organisms) can live on bare rock and release weak

acids breaking rock down over time (this is how life got started on land)

C.Rates of Weathering

1.Why does rock composition affect the rate of weathering?

-Some rocks are more resistant to weathering (_____________________________) because of

the mineral makeup such as quartz (one of the hardest minerals) is resistant to mechanical

weathering

-Sedimentary rocks such as _______________________ contain calcite that weather faster due

to carbonation

2.What is the second factor that affects rate of weathering?

-Amount of ______________________, the more of an outcrop that is exposed the quicker it

will erode without soil covering it

3. How do climates affect the rate of weathering?

-Lots of rainfall or a climate with constant freezing and thawing or variable weathering

conditions all accelerate weathering (rain forests, Eastern U.S.)

-Weathering takes place slowly in _________________________

4. What has happened to Cleopatra’s Needle from Egypt?

-A granite Egyptian obelisk over 3,000 years old was moved from Egypt (hot and dry) to

________________________________

-More mechanical and chemical weathering in past 100 years than previous

___________________!

5.How does topography affect the rate of weathering?

-The greater the elevation and slope of a landscape the faster the _________________________

D. Weathering and Soil

1.How are humus, bedrock, regolith and soil related?

-bedrock is solid rock that weathers over time to produce regolith (__________________), the

uppermost rock fragments further weather and become soil, soil also contains a dark organic

____________ which is the remains and wastes from organisms

2. How do soils differ from different bedrocks?

-parent rock containing feldspar will produce a ________________, granite would weather into a

___________________ (quartz)

3. How are soils different in a soil profile?

-_______________- the topsoil, a mixture of organic material (humus) and small rocks

-______________- the subsoil beneath the A hor. contains the minerals leached from the topsoil

-_____________- bottom layer consists of bedrock in the first stages of mechanical weathering

so it will eventually become B-horizon then A

4.Describe the soil found in humid, tropical climates:

-soils are called _______________, rich in iron and aluminum, a very thin A horizon due to so

much rainfall (usually a thin layer of humus due to all of the organic material above), not a good

soil for farming

5.Describe soil in an arctic and desert climate:

-Hardly any _______________________, soil is very thin containing mostly regolith

6.Describe the soil in a temperate climate:

-both mechanical and chemical weathering taking place, each soil horizon can be a

___________________________

-______________- soil that contains clay, quartz and iron, rainfall >65 cm, Eastern U.S.

-_____________- soil that contains calcium carbonate which combines with hydrogen to make

very fertile soil, West of the Mississippi

7.Based on topography what makes for the best and worst soils for cultivation?

-Worst- _________________, soils layers are not thick duo to slopes contain only weathered

rocks, no humus

-Best-_______________ retain water have a thick wet soil with a high concentration of organic

matter, the best area is fairly flat with good drainage producing a fertile soil

D.Erosion

1. What is erosion?

-Transport of weathered product to other areas caused by _______________________________

(ocean currents, waves, rivers, streams and groundwater)

2.What are two ways to upset the balance of soil erosion?

-_______________________ (over farming, development) and unusual climate conditions

3.How does gullying occur?

-_________________ in plowed land allow water to run swiftly over the soil as it is washed

away the furrow grows to become a gully making it useless farmland

4.What is sheet erosion?

-soil erosion that strips away layers of the topsoil that can eventually expose bedrock

-Farmers need A-horizon soil for the _______________, plants cannot grow in B-horizon soil

5.What are four methods that farmers can use to prevent soil erosion?

-__________________- soil is plowed in bands that follow the shape of the land, preventing

water from running down steep slopes

-Strip-cropping- crops are planted in alternated bands (corn than alfalfa), often combined with

contour plowing-reduces soil erosion by 75%!

-___________________- construction of step-like ridges, used in Asia for rice crops

-_________________- each year a different crop is planted gives soil a chance to recover

6.What is talus?

-Piles of sediment that accumulate at the base of a _____________

7.What is the difference between a landslide and a mudflow?

-both are rapid movement of material but landslides involve bedrock that has weathered and falls

down a slope, a mudflows occur in ______________________________ during sudden heavy

rainfall or a lahar that liquefies the land causing it to move down a slope houses and all!

8.What is slump?

-Loose soil slides down a hill due to ___________________ and loss of friction with underlying

rock

9.What is solifluction?

-A slow mass movement, which means ‘soil flow,’ occurs in _______________________ where

subsoil is permanently frozen, in the summer only the top layer thaws causing it to become

muddy and slowly flow downslope

10. What is the most effective of all mass (wasting) movements?

-_____________- extremely slow downhill movement of weathered rock usually going

unnoticed unless a fence or other object is present

11. What are the two forces that created landforms?

-One process bends, breaks and lifts the Earth’s crust, creating elevated landforms-

__________________________________

-Second process is the wearing action of weathering and erosion reducing the land surface to sea

level creating ___________________

12. What eventually happens to mountains when they get ‘old’?

-Weathering and erosion reduces them to __________________ (low rolling hills such as New

England) and _______________________ (protrusions above the peneplains of weather resistant

granite)

13.How does a mesa form?

-A ________________ grows smaller into a table-like area due to erosion

14.How is a butte formed, how do they differ in dry and humid regions?

-Mesa eventually erode into buttes

-Dry regions- have steep walls with flat tops, humid regions- _____________________

Name_____________________________

Go to http://www.classzone.com/books/earth_science/terc/content/investigations

Scroll down to chapter 12: How does soil vary from place to place?

Step 1: Give a definition of soil:

Step 2: Complete the following: The topsoil, also called the __ horizon, contains organic material, or humus.

___________ forms from decayed plant and animal materials.

Below the topsoil is the subsoil, also called the ___ horizon. The subsoil

contains clay and iron oxides washed from the topsoil. The bottom layer, also called the ___ horizon, is composed of rock

fragments of weathered parent material.

Step 3: List several similarities and differences across these soils? -

-

Step 4: Measure the depth of the top soil of each location below:

Massachusetts: Georgia: _____

Montana: _____

Arizona: _____

Hawaii: _____ Pennsylvania: _____

Step 5: Enter your topsoil measurements for each state in the chart on the left.

After you enter all the data, click the PLOT button to generate a graph comparing topsoil thickness to average annual precipitation in each state

When finish, sketch the graph in the space below make sure to label each state on

the graph:

Step 6: Click the link to the state soils. What is the state soil of Pennsylvania?

Step 7: Click on global soil resources: What are the three types of soils that can be

found along the East coast of the United States? ____________, _____________,

_____________

What parts of three types of land surface that do not contain soil? ___________,

_____________, _______________

Soil Texture Using a Soil Sieve Terrestrial Ecology Extension Activity

Chris Lundberg, Program Coordinator, Mathematics & Science Center

Developed with funding from the Mathematics & Science Center

Question Can one determine the texture of soil by examining the particles found in a particular sample? The purpose of this activity is to determine the amount of clay, silt, and sand particles in a given soil. This additional method of determining the profile of soil is to conduct a profile test using a soil sieve to separate out the different particles by their relative size.

Background Soil is made of both living and dead plants and animals (organic matter) and mineral particles such as sand, silt, and clay. It is said to consist of rocks and minerals (about 45%), water (25%), air (25%), and organic matter (5%). The profile and texture of soil indicate the relative types of rocks and minerals that compose the soil, chief of which are sand, silt, and clay. Soil texture is an important indicator of the ability of soil to absorb and hold both water and plant nutrients. Soil type can be classified as follows: Soil Types by Percentages Sands: 85-90% sand and <10% clay and silt Loamy Sands: 70-85% sand and <15% clay Sandy Loams: > 52% sand and < 20% clay Loam: 7-27% clay, 28-50% silt, and <52% sand Silt Loam: >50% silt, 12-27% clay; or 50-80% silt and <12% clay Clay Loam: 27-40% clay and 20-45% sand Clay: 27- .40% clay and less than 45% sand and less than 40% silt

Safety Remember to observe your rules for lab safety.

Terrestrial Ecology 1 http://MathInScience.Info

Procedure

1.

2.

Place your weighing paper on the pan of the balance and determine its mass. Record this on your data table. You will need to subtract the mass of the paper for all of your soil measurements Arrange the soil sieves so that the largest screen size is on the top, followed by decreasing screen size to the bottom.

3. Set the balance to 100g PLUS the mass of the weighing paper. Weigh out that mass of soil that has been broken up into loose particles.

4. Place your soil sample into sieve #1 (the largest). Shake your sample over sieve #2 for two minutes so that sieve #2 collects any smaller soil particles.

5. Place the remaining soil from sieve #1 on the weighing paper and determine its mass. Record this on your data table

6. Shake the soil collected in sieve #2 into sieve #3 (the smallest) for two minutes.

7. Place the remaining soil from sieve #2 on the weighing paper and determine its mass. Record this on your data table.

8. Place the soil collected in sieve #3 on the weighing paper and determine its mass. Record this on your data table.

9. Calculate the relative percent of sand, silt, and clay in the soil sample and record your data in the table below. % Sand = mass of sand / total soil mass x 100 % Silt = mass of silt / total soil mass x 100 % Clay = mass of clay / total soil mass x 100

10. Determine the type of soil based on the relative overall percents you calculated.

11. Answer the conclusion questions and clean up your materials.

Data Analysis Data Table Sample Mass measured Soil Percentage Weighing paper Total Soil sample Sieve #1: Sand particles Sieve #2: Silt particles Sieve #3: Clay particles

Type of Soil for Sample Collected: _______________________________

Terrestrial Ecology 3 http://MathInScience.Info

Terrestrial Ecology 4 http://MathInScience.Info

Conclusion / Questions

1. How would the size of soil particles affect the ability of soils to hold moisture?

2. Which type of soil would be most likely to allow for the greatest amount of ground water beneath the soil? Explain your choice.

3. Why might trees and other terrestrial vegetation have difficulty growing in sandy or gravel-like soil?

4. Why would a soil texture analysis be important not only to an ecologist, but to a construction or a highway engineer?

5. What types of minerals do you think would be helpful to add to soil to make it a healthier substrate for plant growth?

Extensions Perform this experiment with different soil samples from different locations and compare your findings. Determine the reasons why these samples might have different percentages of sand, silt, and clay.

Name _________________________

Porosity and Permeability Lab Solid rock is often not so solid. Sandstone might have started out as a sand dune or a beach,

which got buried and compressed. But spaces remain between the particles. These spaces, or

pores, are where oil and gas may be found.

If you look at a sponge you can see many open spaces. Sandstone is like that, only the spaces

are generally much smaller, so small that they cannot be seen without a microscope.

How much open space is there in rock? In this experiment we check the porosity of gravel, sand

and silt, the raw materials that

sandstone is made of. Hypothesis: The _________________ beaker will retain the most water because ______________________ ________________________________________________________________________________

You will need:

Gravel, sand and silt

3 beakers, 250 milliliters each

A 100ml graduated cylinder

Water

What to do:

1. Fill one beaker to the 200 ml mark with gravel. Fill the second beaker with 200 ml of sand, and the third

with 200 ml of silt.

2. Fill the graduated cylinder to the 100ml mark with water.

3. Slowly and carefully pour the water into the first beaker until the water just reaches the top of the gravel.

Record exactly how much water you use. If you need more than 100ml of water, fill the graduated

cylinder again.

4. Follow step 3 again for the beaker with sand, and again for the beaker with silt.

Calculating porosity:

For each material, calculate the porosity by dividing the volume of water that you were able to pour into it by

the total volume of the material. Then express this result as a percentage. For example If you were able to add

90ml of water to 350ml of gravel, the porosity would be

51 ml

––––––– = .2571 = 25.71%

200 ml

Use the chart on the next page to record your data and calculations. Show your work for each below and

clearly label.

Lab Practice questions: 1. Permeability is __________.

A. the ability of a solid to allow fluids to pass through B. the process by which plants release water vapor to the atmosphere C. the amount of water vapor in the air relative to the maximum amount of water vapor the air can hold D. the percentage of pore space in the rock

2. Which of the following combinations make for the best groundwater reservoir?

A. low permeability and low porosity B. low permeability and high porosity C. high permeability and low porosity D. high permeability and high porosity

3. If the amount of discharge in an aquifer exceeds the amount of recharge, the groundwater table

A. will rise B. will drop C. will remain the same D. may rise or drop depending on the porosity

4. Which of the following statements about the water table is true? A. The water table changes when discharge is balanced by recharge. B. The water table has the same general shape as the topography. C. The water table is well below the land surface beneath lakes. D. The water table is elevated near high volume pumping wells.

5. What is the difference between the saturated and unsaturated zones of groundwater?

A. The saturated zone has a higher porosity than the unsaturated zone. B. The saturated zone has a lower porosity than the unsaturated zone. C. The pore spaces in the saturated zone are completely full of water; the pore spaces in the unsaturated zone

are not completely full of water. D. The pore spaces in the saturated zone are not completely full of water; the pore spaces in the unsaturated

zone are completely full of water.

6. Based on this experiment what kind of sediment would you want to build your house on, explain why?

-----------

-35­Chapter 4

ACTIVITY 4.3: Sedimentary Rocks

Objective: To identify sedimentary rocks.

Materials: Sedimentary Rock Classification Key, mystery rocks, HCI, hand lens, Sedimentary Rock Chart, and writing instrument.

Procedure: Follow the numbered instructions to aid you in using the Sedimentary Rock Classification Key and in identifying sedimentary rocks.

1. The Key is divided into two parts--clastic rocks and nonelastic rocks. If you recall, clastic rocks are those formed from fragments of material. Non­elastic rocks are from solutions resulting from various chemical or organic processes and then precipitated.

2. Look at your rock. Determine whether it is clastic or nonelastic.

3. If the rock is a clastic, use chart A. Consider the grain size. Are the grains gravel size, sand size, silt size, or clay size?

4. If the grain size does not determine the identity, consider the composition. Now you should have your rock name.

5. If the rock is nonclastic, refer to chart B. First determine its composition. Is it composed of cal­cite, dolomite, chalcedony, gypsum, or halite? By determining the composition, you can eliminate several possibilities.

6. Now, if your rock is still not identified, look at the texture. After determining the texture and finding it on the Key, you have your rock name-­Bingo!

7. Refer to the Sedimentary Rock Chart. From the Key, you can fill in nearly all the necessary information about your rock--Texture, Clastic or Nonelastic, Com­position, and Name. You can find Environment in part III C of Chapter 4.

Below are a few examples to give you practice:

This rock is a clastic rock. It is extremely fine-grained, of clay­sized particles. The rock is

(over)

-36­Chapter 4

ACTIVITY 4.3: Sedimentary Rocks (continued)

A nonelastic, the composition is calcite. What are the possibil ­ities?

It has fossils that are held together by a concretish mixture. It is

Obviously clastic, this rock is composed of gravel-sized fragments. What are your guesses?

The fragments are rounded. O.C. is

SEDIMENTARY ROCK CLASSIFICATION KEY -37­

A. Clastic Rocks

TEXTURE COMPOSITION/CHARACTERISTICS ROCK NAME

Rounded fragments of any rock type; quartz, quartzite, chert dominant CONGLOMERATE

Gravel Size Range Angular fragments of rock type;any

quartz, quartzite, chert dominant ~r B<:..Z; 0..

~ECCnl'

(over 2 mm) Glacial deposits, rounded

various sizes, JrIL_LI 'fE

Sand Size Quartz with minor accessory minerals (sand)may be any color SANDSTONE

Range (1/16 mm

2 mm) to Quartz

(sand) with at pink to

least 25% feldspar brown in color

ARKOSE

Silt Size Range (1/256-1/16 mm)

Quartz and layered

clay minerals (mud) SIL':PS'fONE

Clay Size Range ( less than 1/256 mm)

Quartz and clay minerals laminated (layers)

(fine mud) SHALE

B. Nonelastic Rocks

CHARACTERISTICS Visible crystals of calci te, variety of colors

COMPOSITION

--------------------­

ROCK NAME

eRY~'fALLIHf: LH1ESTOW:E:.

Massive, smooth shell-like fracture composeo 01 oontes (small. circular features)

--------------------­

--------------------­

MICRITE LIMESTONE

OOLITIC LIMESTONE

Loosely cemented shells .(actually piec-es of shells) ---Calcite (CaC03)--­ COQUINA

Abundant fossils in calcareous matrix

--------------------­ 4~~~~LIFEROUS

L~~'f'eM~

White to gray, soft scopic shell fossils

micro­ --------------------­ ..et!1tLK

Banded layers of calcite, found near springs --------------------­ 'PRA vf:fffI M:I!: -Char. similar to limestone tl}!l reacts very slowly wIth

Massive (Microcrystalline) vari~ty ~t ~f.?trs, doesn't.~PA(> ·wi Crystalline, layered soft, ligh t colored

Dolomite CaMg( C03)2

Chalcedony (Si02)

Gypsum (Ca S0 4 + 2H20)

'"1J'OLOSTONE (Dolomite)

8flERT, etc".

~

Layered white to gray, "saltv" Brown to black, layered, may .contain orgaruc plant remains

Halite (NaCl)

vegetation--Carbon plant remains

ROCK SALT

COAL

SEDIMENTARY ROCK CHART

NAME CLASTIC NON-CLASTIC

TEXTURE / COMPOSITION

IDENTIFYING CHARACTERISTICS

FORMATIVE ENVIRONMENT*

/

:

* Formative environments are found in the text, Chapter 4,111 D. You may use the major subdivisions: Marine, Transitional, Continental and Replacement. Remember, you may have to use more than one. ,

w co I