Weathering, Erosion & Deposition

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Weathering, Erosion, and Deposition Vocabulary

abrasion physical weathering chemical weathering soils erosion glaciers watershed drumlin stream tributary stream abrasion dunes meander vertical sorting mass movement longshore current till delta oxbow lake

Weathering

Directions: Read the following excerpts on mechanical and chemical weathering (on pages 2+3), then answer the questions on page 4.

Mechanical Weathering

Weathering is the process of breaking down the lithosphere by wind, water, ice, plants, animals, or chemical change. There are two kinds of weathering: mechanical and chemical. Mechanical weathering is the process of breaking down rock into smaller pieces. The makeup of the rock is not altered, only its size. There are five different ways that mechanical weathering can occur.

Temperature can produce mechanical weathering. During the day, the sun's energy heats a rock's surface. The internal temperature does not change. During the night, the rock's surface will cool. The following day, the heating and cooling begins again. The repeated change from hot to cold may cause the rock to peel or flake layers that are parallel to the rock's surface. This peeling or flaking is known as exfoliation.

A second type of mechanical weathering may be caused by frost. Water may enter a small crack or hole in a rock. As temperatures drop to freezing, the water will expand. As the water expands, it will make a larger crack or hole in the rock. When the water melts, it may move deeper into the bottom of the crack or hole and refreeze. Eventually the rock will break into pieces. The repeated freezing and melting is known as ice wedging. We are familiar with the effects of ice wedging—cracks in roads and potholes.

The third type of mechanical weathering is organic activity. This may be in the form of tree roots growing in a crack in a rock. As the tree grows and the roots expand, they will pry material loose. This is known as root-pry. Animals burrowing homes, such as ants, worms, and woodchucks, also contribute to organic weathering. People may also be responsible for organic weathering by digging, cutting stone, or even driving on roads.

Gravity is the fourth type of mechanical weathering. Landslides move downhill due to the force of gravity. As the rocks cascade down, they collide and break into smaller pieces.

The last type of mechanical weathering is called abrasion, which is the wearing away by solid particles carried by wind, water, or other forces. Wind-blown sand is an abrasive that will weather even some of the hardest rocks.

Mechanical weathering can be caused by exfoliation, ice wedging, gravity, organic activity, and abrasion.

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Chemical Weathering

Remember that weathering is the process of breaking down the lithosphere by wind, water, ice, plants, animals, or chemical change. There are two kinds of weathering: mechanical and chemical.

While mechanical weathering alters only the size of the rocks, chemical weathering alters the mineral composition, or the chemical makeup, of the rocks as well. There are three different kinds of chemical weathering.

Oxidation is the first type of chemical weathering. This is a process combining oxygen with another substance. The end result is the creation of an entirely new substance. An example of oxidation is the combination of iron and oxygen to form rust. If a material is colored differently on the inside than the outside, it is an indication that oxidation may be taking place.

The second type of chemical weathering is carbonation. When carbon dioxide dissolves in water, carbonic acid is formed. This acid reacts with other substances, creating chemical changes. An example is found with acid rain, created when carbon dioxide dissolves in rain water. Acid rain will dissolve some kinds of rocks. More evidence of the effect of carbonic acid can be seen in Mammoth Cave and Carlsbad Cavern, both formed by this process when rain water seeped underground.

The final type of chemical weathering is caused by plant acids, known as humic acids. Mosses and lichens provide a good example. As these plants grow on rocks, they produce acids that, in turn, break down the minerals found within the rocks.

Humic acids produced by plants and carbonic acids produced when carbon dioxide dissolves in water can break down rocks and are important agents of chemical weathering.

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Questions regarding the readings about mechanical and chemical weathering.

1. What is mechanical weathering?

2. What is exfoliation?

3. What is ice wedging?

4. What is root-pry?

5. What is an example of mechanical weathering by gravity?

6. How does chemical weathering differ from mechanical weathering?

7. What type of weathering produces rust?

8. How is acid rain formed?

9. Acid rain is an example of which type of chemical weathering?

10. What are humic acids?

Different Materials, Different Weathering Rates

Directions: Read the passage below.

You and your lab partner, conducting research on the weathering rates of different rock types, collected the information you see in the data table to the right.

1. Using colored pencils, plot a line graph of the data into the graph below.

a. Please include your color scheme into the key.

b. Be sure to connect your data points.

2. Answer the conclusion questions below your completed graph.

Mass remaining (gm) Rock

Shaking Time (Min)

Shale A

Marble B

Rock Salt C

Limestone D

0 200 200 200 200 5 160 200 120 200 10 125 200 60 195 15 100 190 20 170 20 75 180 0 150 25 55 175 0 135 30 50 175 0 125

Mass of Rock Samples Remaining After Shaking (Grams)

0

20

40

60

80

100

120

140

160

180

200

0 10 20 30 40 50Time (min)

Mas

s (g

m)

Shale

Marble

Rock Salt

Limestone

Conclusion questions:

1. What rock weathered the most? 2. What rock weathered the least?

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Types of Weathering

Recall that weathering includes mechanical weathering and chemical weathering. Mechanical weathering is any process that breaks up rock without changing its chemical composition. Chemical weathering is any process in which water, air, or other substances react with the minerals in the rock and change the chemical composition of the rock. Directions: Decide if the following descriptions are examples of mechanical weathering or chemical weathering. Write the word “mechanical” or “chemical” in the blank at the left. ____________________ 1. Mosses growing on the surface of rocks, producing pits in the rocks

____________________ 2. The wedging of tree roots along natural joints in granite outcrops

____________________ 3. Limestone dissolved by carbonic acid

____________________ 4. The oxidation of minerals that contain iron

____________________ 5. Animal burrows dug in rock that let in water and air

____________________ 6. Repeated freezing and thawing of water that cracks rock

____________________ 7. The action of water, salt, and air on car fenders and panels

____________________ 8. Acids from plant roots which break up rocks

____________________ 9. Formation of potholes in streets during severe winters

____________________ 10. Lifted sections of sidewalk along tree-lined streets

____________________ 11. A small rock falling from a cliff

____________________ 12. Feldspar mixing with acidic groundwater and producing clay minerals

____________________ 13. Halite in rocks dissolving in water

____________________ 14. Decaying plants dissolving some of the minerals in rocks

____________________ 15. Tree roots cracking the concrete foundation of a house

WEATHERING RATES

The type of weathering that dominates in an area depends on the climate in that area. Specifically, the major factors that control climate, and thus weathering, are precipitation and temperature. The graph below indicates the general relationship between precipitation, temperature and the type and rate of weathering. Directions: In the graph below to the right, lightly shade (using colored pencils) each weathering type. Next, answer ALL of the questions that follow. I. Orientation 1. The range of temperatures on this graph is: ___________________________________________2. The range in precipitation (yearly) on this graph is: _____________________________________ 3. Weathering rates are described as (4 ways): a. b. c. d.

II. Interpretations 1. Determine the major type of weathering that occurs in Washington, D.C. if the average yearly temperature (AYT) is 13°C and the average yearly precipitation (AYP) is 111 cm. Plot and label this point on the graph. Key

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2. The AYT in Albany, N.Y. is 9°C and the

AYP is 98 cm. What is the major type of weathering that occurs in Albany?

● = Washington, D.C.

▪ = Albany, NY + = Phoenix, AZ Plot and label this point on the graph.

3. What is the major difference, in terms of weathering type, between Washington, D.C. and Albany, N.Y.? What might explain this difference?

4. Phoenix, Arizona has an AYT of 20 °C and an AYP of 22 cm. Plot and label this point on the graph. How would the climate of Phoenix have to change for moderate chemical weathering to become dominant?

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5. According to the graph, no frost action occurs at an AYT above 13 °C. What is a possible reason for this? 6. In terms of climate, how does a region that experiences strong chemical weathering differ for a region that experiences strong mechanical weathering? 7. Cleopatra’s Needle is a large granite monument, which stood in Egypt form 1450 B.C. unitl 1880 when it was moved to New York City. The sides of the monument were carved with hieroglyphics, the writing of the ancient Egyptians. However, shortly after it was moved to a NYC park, the hieroglyphics began to fade. Explain what process is taking place and why. 8. Describe how you think rocks outcrops and exposures in the Southwest would look in comparison with rocks in our area. Chapter 8

Soils Directions: Using the passage below, label the soil layers (horizons) diagram (using the word list) and answer the conclusion questions.

The soil that we walk on is an underground city. In this city, every organism does its part to make sure the city works together. The actions of the animals, insects, and microorganisms that live in the soil not only influence what happens in the soil but also what happens above the soil. Soil is made of inorganic matter (mainly rocks and minerals) mixed with organic matter. Soil is formed from the weathering of minerals derived from bedrock and contains living organisms and the products of their decay. Soil can be considered a mixture of mineral materials, organic matter, water, and air in varying proportions.

Topsoil, the A horizon, is usually the upper ten inches of a soil in a well-developed soil profile. Plant roots, bacteria, fungi, and small animals are abundant in this area along with plants that thrive in this type of environment. Topsoil has less organic matter than in the O horizon (the surface) which is the reason that topsoil is lighter than surface soil. Topsoil, composed of mostly leaf litter and humus (decomposed organic matter), is one of our most valued commodities since it provides the nutrients and environment for the growth of plants.

The eluviation (leaching) layer, the E Horizon, is light in color; this layer is beneath the A Horizon and above the B Horizon. It is made up mostly of sand and silt, having lost most of its minerals and clay as water drips through the soil (in the process of eluviation).

Subsoil or the B horizon, is the middle soil layer. It has fewer organisms and less organic materials than both the A and O horizons. Consequently, the B horizon cannot support the growth of plants very well. It contains clay and mineral deposits (like iron, aluminum oxides, and calcium carbonate) that it receives from layers above it when mineralized water drips from the soil above. If subsoils are clayey, they usually are harder when dry and sticky when wet than the surrounding soil layers.

The C horizon, also called regolith, is the second lowest layer and is partially weathered parent material from which the other horizons are formed. Plant roots do not penetrate into this layer; very little organic material is found in this layer. It is less altered and weathered than the layers above and has less living matter. The parent material, on the bottom, is sometimes named the R horizon.

Word Bank

R Horizon A Horizon E Horizon B Horizon C Horizon O Horizon

1. Which soil layer contains the most humus?____________________ 2. How far into the soil profile do plant roots extend? __________________ 3. Where in this soil profile are worms and insects breaking down organic matter in the soil? _______________ 4. Where in this soil profile is solid rock being weathered? ________________________

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5. What factors in an area help determine the type of soil—the thickness of the layers and their composition? _________________________________________________________________________________________

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Analyzing Soil

Directions: After reading the passage below answer the conclusion questions. The hydrangea is a bush with snowball-like flowers on it. When a certain kind of hydrangea grows on the East Coast of North America, the flowers are blue. When that same kind of hydrangea grows in the Midwest, the flowers are pink. What causes the flowers to be two different colors? The answer is the soil. Along much of the East Coast the soil is acidic. In the Midwest, some of the soil is alkaline—it has more calcium in it than acid soil does. Some plants grow best in fairly acidic soil— blueberries, cranberries, and pineapples, for example. Other plants, like cotton and alfalfa, need a soil that is neutral—neither acidic nor alkaline. Most plants seem to do well in a mildly acidic soil. Material can be added to soil to make it the right acidity for the crop that will be grown. To know what and how much material to add, the soil has to be tested. Samples of soil are analyzed by a machine to measure the soil’s pH— the measure of how acidic or alkaline it is. Soil that has a pH between 0 and 7 is acidic; the lower the number, the more acidic the soil. Soil that has a pH of 7 is neutral. Soil that has a pH between 7 and 14 is alkaline; the higher the number, the more alkaline the soil. Actually, in nature, soils don’t reach the extremes of 0 and 14. They range between about 3.5 and 11.

If the soil needs to be more alkaline, then lime—a chalky material (not the fruit) containing calcium—is added to the soil. If the soil needs to be made more acidic, sulfur can be added to the soil. Most of the time, the soil needs to be made more alkaline rather than more acidic.

1. How would you classify a soil that has a pH of 8? ___________________________________ 2. Suppose a soil has a pH of 5.5, but the crop to be grown does best in a soil with a pH of 6. What would you do? ______________________________________________________________ 3. If a hydrangea has flowers that are part pink and part blue, in what kind of soil would you suspect it was planted? ______________________________________________________________ 4. Why is it important for a farmer to know the pH of soil? ________________________________________________________________________________________________________________________________________________________________________________

Erosion

Directions: Read the following excerpt on erosion and deposition then answer the questions on page 12.

Erosion and Deposition

Weathering is the process that breaks down rock into smaller pieces. There are several different ways in which this can occur. Once the weathering process has occurred, other processes take over.

Erosion is the process of carrying away weathered material. The agents of erosion include moving water, ice, waves, and wind. Deposition is the process of laying the weathered material down in a new location.

Most of the time, erosion is a gradual process. It may take millions of years for the agents of erosion to make noticeable differences in the Earth's surface. The Grand Canyon in Arizona is the result of what is believed to be close to three million years of erosion!

Erosion, however, can also act very rapidly. An unusually rainy period can cause rivers to overflow their banks and flood the areas surrounding them. The erosion caused by the rapid rivers and their flooding action can have very quick, devastating results for the Earth's surface and especially for its inhabitants.

In the next few pages, we will look at moving water, ice, waves, and wind as the agents of erosion. We will see how each agent works. We will also investigate the effects of deposition by each of these agents.

For an estimated three million years, the process of erosion has been creating the Grand Canyon.

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Questions regarding the reading about erosion and deposition.

1. Write the definition for each of these words:

weathering

erosion

deposition.

2. What are three agents of erosion?

3. What evidence do scientists have that erosion works slowly over long periods of time?

4. What is an example of erosion that works very rapidly?

5. What are some devastating results of a flood for the area's inhabitants?

Mass Movement

Directions: Use the information below on mass movements (taken from usgs.gov) to answer questions on page 14. Process Illustration Description Velocity

Rock fall

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Falls are abrupt movements of masses of geologic materials, such as rocks and boulders that become detached from steep slopes or cliffs. Falls are strongly influenced by gravity, mechanical weathering, and the presence of interstitial water.

> 4 km/hr

A mudflow is an earthflow consisting of material that is wet enough to flow rapidly and that contains at least 50 percent sand-, silt-, and clay-sized particles. In some instances, for example in many newspaper reports, mudflows and debris flows are commonly referred to as “mudslides.”

Mud Flow 1 to 5 km/hr

A debris flow is a form of rapid mass movement in which a combination of loose soil, rock, organic matter, air, and water mobilize as a slurry that flows downslope. Debris flows are commonly caused by intense surface-water flow, due to heavy precipitation or rapid snowmelt that erodes and mobilizes loose soil or rock on steep slopes.

Debris Flow

1mm/ day to 1 km/hr

Creep is the imperceptibly slow, steady, downward movement of slope forming soil or rock. There are generally three types of creep: (1) seasonal, where movement is within the depth of soil affected by seasonal changes in soil moisture and soil temperature; (2) continuous, where shear stress continuously exceeds the strength of the material; and (3) progressive, where slopes are reaching the point of failure as other types of mass movements. Creep is indicated by curved tree trunks, bent fences or retaining walls, and tilted poles or fences.

Soil Creep < ≈1cm/ yr

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Questions regarding the Mass Movements diagram.

1. Write the definition for each of these words:

Rock fall

Mud flow

Debris flow

Soil creep

2. The media commonly refers to mudflows and debris flows as:______________________?

3. List the three types of soil creep.

4. How could one tell that soil creep is happening on a slope side?

5. What are some devastating results of faster mass movements?

Stream Erosion

Directions: On the space provided, identify and define each of the features on the figure below.

1. ______________________ 2. ______________________ 3.____________________ 4. ______________________ 5. ______________________ 6.____________________

Directions: Fill in the blank to complete each statement. 7. A(n)______________________is a channel along which water is continually flowing down a slope. 8. A(n) ___________ _________is a separate body of water that was once part of the meandering stream. 9. A(n) ________________________ is the land area from which a river and its tributaries collect their water. Directions: On the diagram below, identify and label the following: 10. On this portion of the river, place an “X” on the river bank where it’s best to build a house.

Why did you choose this spot? 11. On this portion of the river, place a “●” on the river bank where it’s ill advised to build a house.

Why did you choose this spot?

Please note: The arrows show the stream movement.

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. 16

Directions: In each of the following statements, a word or phrase has been scrambled. Unscramble the word and write it on the correct line in the puzzle.

1. Fast-moving water erodes the side of a stream and forms a curve or rendeam. 2. Water in shallow areas may be slowed down by rubbing or finctior. 3. Some of the water in a river will aproveate when heated by the sun.

4. The land area from which a stream gets its water is the adearing insab. 5. Streams formed from runoff meet to form a erriv.

6. Broad, flat valley floors carved by wandering streams are sploodflina. 7. Water flowing rapidly downhill has a high level of nrgeey. 8. A young stream may have white water praids. 9. Rivers are formed when smaller smaters come together.

10. Fast-moving streams and rivers droee their beds.

11. Streams are classified as young, tuream, or old.

12. The largest drainage basin in the United States is the river basin of the ssssiiiippM.

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

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Earth Science Reference Tables Practice

Directions: Using the diagram below (to the left), complete the data table next to it as well as the questions underneath on stream velocity.

Relationship Transported Particle Size to Water Velocity Diagram

Name the following particle that has a particle diameter of:

PARTICLE DIAMETER PARTICLE NAME .0002 cm

4.5 cm 30.9 cm 7.5 cm .02 cm

.19 cm

1. What is the minimum water velocity needed to keep a particle of sand moving in a stream?__________

2. Which graph to the right best represents the relationship between stream erosion and the kinetic energy of a stream?

3. A stream with a water velocity of 150 centimeters per second decreases to a velocity of 100 centimeters per second. Which sediment size will most likely be deposited?

1. pebbles 2. sand 3. boulders 4. cobbles

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Ocean Erosion

Wave Action Directions: Answer all the questions below.

Fill in the four blanks in the drawing below.


Answer the following on the space provided below. 5. How does a wave change when it enters shallow water near shore? 6. When does longshore drift occur? 7. Name a way of preventing beach erosion. Match each term with its definition by writing the letter of the correct definition on the line beside the term.

________ 8. wave a. the movement of sand down a beach b. the movement of energy through water c. a long, low ridge of sand deposited offshore as waves go back

________ 9. frequency ________ 10. longshore drift out to sea

d. the number of waves that pass a point in a given amount of time

________ 11. sandbar

e. a wall of rocks or concrete built outward from a beach to

________ 12. rip current

prevent erosion f. a rush of water that flows out from the shore through a narrow opening

________ 13. groin

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My Beach Is Shrinking! Directions: After reading the passage below, answer the questions that follow in the space provided.

Last summer, Juan Sanchez sent a letter to his local city council. He was outraged. In just a year, the beach in his front yard had begun to shrink. Mr. Sanchez said he was worried that soon he would have no beach and no home. He blamed the council for giving the go-ahead for construction of a groin at the boundary of the public beach and the beach in front of his house.

A groin is a low wall extending into the ocean, built perpendicular to the shore. A groin interrupts the movement of sand carried by longshore current. Mr. Sanchez included the sketches below to prove his point. The first sketch shows the beach as it looked two summers ago. The second shows what it looked like last summer.

E N R I C H 1. How has the groin changed the public beach? 2. How has the groin changed the beach in front of Mr. Sanchez’s house? 3. Why did those changes occur? 4. Why do you think the town council had the groin built? 5. Does Mr. Sanchez have good reason to fear loss of his beach and home? 6. What might happen if the groin were removed? 7. In your opinion, should the groin be removed? Give reasons for your answer.


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Wind Erosion

Directions: Answer all the questions below.

1. The cross section below shows the movement of wind-driven sand particles that strike a partly expose basalt cobble located at the surface of windy desert.

Which cross section best represents the appearance of this cobble after many years of exposure to the wind-driven sand?

Write the word that best completes the statement. 2. __________________________is wind erosion that can be compared to sandblasting. 3. _____________ regions, such as deserts, and lake or ocean coastlines are the most common places where loose sediments are available for wind erosion. 4. __________________ occurs when winds blow sand or silt grains against rocks or other objects. 5. Wind erosion called ________________causes sand grains to pit and polish rocks when the grains hit them.

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Glaciers: Destroy and Create As agents of erosion, glaciers wear down land surfaces. The debris that is frozen underneath the glacier

serves as an abrasive. It grinds and polishes the surfaces that the glacier drags across. The erosive effect of a valley glacier is very similar to that of a river. Most notably, as an alpine glacier

moves through an area, it erodes the V-shaped valley into a U-shaped valley, often leaving shear walls on either side.

Glaciers are also important agents of deposition. As the front end of a glacier moves into a warmer area, the ice begins to melt. The glacier continues to move, but it melts faster than it moves. At this point, scientists say a glacier is retreating. As the ice melts, it drops its load. Rocks, clay, and other debris are deposited, often great distances from where they were originally formed.

All material deposited by a glacier is known as glacial drift. Drift, however, may be subdivided according to how it is deposited. If the drift is directly deposited by the glacier, it is called till. Till is not sorted by water action, so it is a mixture of sizes. If the drift is first carried away by water and then deposited, it is called outwash. Outwash is sorted by size and deposited in layers.

Glaciers are responsible for forming several different landscape features. Moraines are ridges of till deposited by glaciers. Terminal moraines form at the front edge of the glacier. Lateral moraines form along the sides. Studying the contents of moraines helps scientists understand where the glaciers formed. The locations of the moraines help them understand the extent of the glacier's movement.

Meltwater is formed when glacial ice melts. Meltwater may form a stream, carrying away sand and gravel from the glacier. The meltwater stream may erode a channel and deposit outwash debris in layers, similar to a river's erosion and deposition. Meltwater may also form a sheet of water. This meltwater forms a fan-shaped area in front of a terminal moraine. The outwash is deposited across the area, forming a fertile plain. Many outwash plains are now used for farming.

Glaciers may also form lakes. As deposits pile up in low areas, they may block rivers and trap the water. This trapped water will form a lake covering much of the lowland area. Another type of lake is formed when blocks of ice are left behind as the glacier moves. The ice blocks become covered with debris and they melt slowly. When the melting occurs, the debris on top of the water sinks into the hole, and a kettle lake is formed.

Icebergs can also be formed by glaciers. Sometimes as glaciers move, they may reach the sea. Pieces of ice break off and float away. These are icebergs and are most commonly found near Greenland and Antarctica. The icebergs contain rock debris gathered by the glacier. When the iceberg begins to melt, the debris settles to the ocean floor, many miles from where the rocks were formed.

Continental Glacial Features Alpine Glacial features

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Glaciers: Continental and Alpine Glaciers are important agents of erosion; however, they are not the leaders in their effectiveness.

They carry a more massive load than rivers do, but they cover a smaller area and do their work over a shorter period of time.

What, exactly, are glaciers? They are large masses of moving ice and snow. They are found in areas where there is a great deal of snowfall that does not melt from winter to winter. Scientists have identified two basic types of glaciers: valley glaciers and continental glaciers. Let's see how they differ.

Valley glaciers form in mountains, high in old river valleys. Elevations are high enough and temperatures are low enough that snow, which falls during the winter and early spring, does not melt. It builds up from year to year and slowly turns to ice. Eventually, with the help of gravity, the weight of the ice begins to move the glacier down the mountain valley. Valley glaciers are also known as alpine glaciers.

Continental glaciers form in the polar regions of the planet. They form large sheets of ice that may cover millions of square kilometers. Once again, snowfall does not melt, but accumulates. The weight of the piled snow pushes down on the glacier, moving it out from the center. (Try forming a mound of clay. Put it on a table and push down on the center with your hand. The clay will "squish" out, moving along the edges.) Continental glaciers are sometimes referred to as ice caps and are currently found primarily in Greenland and Antarctica.

The Earth material carried by a glacier is known as the glacial load It consists of both large and small particles of debris. Unlike a river load, the glacial load does not separate by size.

There are three ways that glaciers gather or move Earth materials. They push and carry debris in front of them as they move down the valley or across the land. They also pluck debris from the land beneath them. It becomes frozen in the ice and moves along under the glacier. Finally, the glaciers loosen debris from the valley walls as they scrape through the area.

A valley before (left) and after (right) a glacier has moved through.

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Directions: After reading the previous excerpts on glaciers (on pages 21+22), answer the following questions below.

Questions regarding the Glacier Readings

1. What is a glacier?

2. Where are alpine glaciers found?

3. What is an ice cap?

4. What causes valley glaciers to move?

5. In what direction do continental glaciers move?

6. What is a retreating glacier?

7. What is the difference between a terminal moraine and a lateral moraine?

8. Why would scientists want to study glacial moraines?

9. What is the difference between till and outwash?

10. How are kettle lakes formed?

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Glaciers

Directions: Complete the following tables to show the similarities and differences between continental glaciers and alpine/ valley glaciers.

Similarities Valley glaciers Continental glaciers

Differences

Valley glaciers Continental glaciers

Now that you have finished the table, use it to identify the glaciers described below. You may need both types to answer a question.

1. It has pieces that break off as icebergs. __________________________ 2. They are the kind of glaciers found in Montana today. __________________________ 3. They deposit till and outwash. __________________________ 4. They cover much of Earth during ice ages. __________________________ 5. They form U-shaped valleys. __________________________ 6. They are now located only in the polar regions. __________________________ 7. They form in areas that have cold temperatures all year. __________________________ 8. They weather rocks by plucking. __________________________ 9. They can create cirques on the side of mountains. __________________________ 10. They are slow-moving, thick masses of ice. __________________________


Stream Deposition

Directions: Complete the following questions below about streams.

Use the diagrams below to answer questions 1-3. The illustrations show two views of the same river flowing from a lake to an ocean bay.

1. Which diagram to the right best represents the profile of the river bottom between points C and B?

2. Which change will occur if the volume (discharge) of Turtle River increases? 1. Downcutting will decrease and riverbank erosion will increase. 2. Downcutting will increase and riverbank erosion will decrease. 3. Both down cutting and riverbank erosion will decrease. 4. Both down cutting and riverbank erosion will increase.

3. If no further uplift occurs within the mapped area over the next 200 years, the average gradient of the riverbed between points A and D will

1. decrease, only 2. increase, only 3. decrease, then increase 4. remain the same

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Base your answers to questions 4 - 7 on the map below, which shows a meandering stream as it enters a lake. Points A through D represent locations in the stream.

4. In the box to the right, draw a cross-sectional view of the general shape of the stream bottom between points A and B. The water surface line has already been drawn.

5. State the relationship between stream velocity and the size of the sediment the stream can carry. 6. The stream velocity at point C is 100 cm/sec and the stream velocity at point D is 40 cm/sec. Identify one sediment particle most likely being deposited between points C and D.

7. Deposition is affected by particle density. On the grid to the right, draw a line to show the relationship between particle density and settling rate.

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Base your answers to questions 8 - 10 on the diagram below, which shows a meandering stream. Letters

A, B, C, and D indicate locations on the streambed.

8. At which two locations is the rate of erosion greater than the rate of deposition? (1) A and B (3) C and D (2) B and C (4) D and A 9. What are the largest particles that this stream can transport when its velocity is 200 centimeters per second? (1) silt (3) pebbles (2) sand (4) cobbles 10. A decrease in the velocity of this stream will most likely cause an increase in (1) the amount of sediment carried by the stream (2) the size of the particles carried by the stream (3) deposition within the stream channel (4) abrasion of the stream channel

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Deposition by Oceans

Many different features can develop from the deposition of sediments in a shore zone. Study the following terms associated with shore erosion and deposition.

●headland—point of high land that juts out into the sea, a cape

●bay—inlet of the sea that is usually smaller than a gulf

●bay barrier—spit that extends across the mouth of a bay cutting the bay off from the sea

●spit—load of sand that is deposited as soon as a longshore current turns into a bay

●lagoon—shallow pond that a bay can become when it is cut off from the sea

Part I directions: Identify the features above from the letters of the illustration. Also, identify the barrier island.


Part II directions: The diagram below represents a shoreline along which several general features have been labeled. Use this to answer question 1 below to the right.

1. Which feature was formed because more erosion took place than deposition?

1. spit 2. wave-cut cliff 3. baymouth bar 4. beach

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Kinds of Sand Dunes A sand dune is a sand dune is a sand dune. Right? Not really. There are five main kinds of sand dunes, as you can see and read about below. The type of dune that forms depends mainly on the wind direction and the amount of sand that is available.

Transverse dunes form when the wind direction stays the same and the supply of sand is large.

Longitudinal dunes form when the wind blows in two slightly different directions and the supply of sand is limited.

Barchan dunes form when the wind direction stays the same and the supply of sand is limited. They are often found as a single dune.

Star dunes form when the wind blows in three or more different directions. Star dunes are often found as a single dune.

Parabolic dunes form along coasts and point away from the wind blowing in off the water. Vegetation often covers parts of a parabolic dune.

S E C T I O N 8 - 6 E N R I C H Directions: Answer the following questions in the space provided. 1. If the wind is constant and there is a great amount of sand, what kind of sand dunes form? 2. Suppose you were going to an area where sand was in limited supply and the wind generally blew from the same direction. What kind of sand dunes would you expect to see? 3. Describe the conditions in which star dunes form. 4. In a desert area where the wind shifts to a slightly different direction, what kind of sand dunes would result? 5. Which kinds of sand dunes are you most likely to see as single dunes? 6. What kind of sand dunes would you expect to see at the sea shore?


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Deposition by Continental Glaciers Directions: Using the word bank below, label these terms in their proper location on this diagram of a retreating continental glacier. Esker – a ridge made by water deposition within a tunnel under the ice.

Outwash – layers of sediment deposited by meltwater.

Drumlins – Large hills of till streamlined by the advancing ice.

Braded Stream – the “stringy” streams that are choked by sediment.

Terminal moraine – an irregular mound of till that marks the end of the glaciers forward progress.

Kames – deltas deposited by the water at the edge of a glacier.

Erratics – the large boulders dropped by the ice.

Bedrock – The underlying surface which the glacier scratches and scrapes as is passes over.

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Glacier Questions 1. The diagram to the right represents a side view of a hill (drumlin) that was deposited by a glacier. This hill is most likely composed of:

1. cemented sediments 2. unsorted sediments 3. vertically layered sediments 4. horizontally layered sediments

Base your answers to questions 2 through 5 on the map below, which shows the different lobes (sections) of the Laurentide Ice Sheet, the last continental ice sheet that covered most of New York State. The arrows show the direction that the ice lobes flowed. The terminal moraine shows the maximum advance of this ice sheet.

2. During which geologic epoch did the Laurentide Ice Sheet advance over New York State? 3. Describe the arrangement of rock material in the sediments that were directly deposited by the glacier. 4. According to the map, toward which compass direction did the ice lobe flow over the Catskills? 5. What evidence might be found on surface bedrock of the Catskills that would indicate the direction of ice flow in this region?

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Weathering, Erosion & Deposition

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Transcript of Weathering, Erosion & Deposition