Lab 08: EOLIAN AND ARID LANDSCAPES

Note: Please refer to the GETTING STARTEDmodule to learn how to maneuver through, and how to answer the lab questions, in the Google Earth () component.

KEY TERMS

You should know and understand the following terms:

 

Abrasion	Loess	Rain shadow
Barchan dune	Longitudinal dune	Reversing dune
Barchanoid Ridge dune	Mesa	Star dune
Butte	Parabolic dune	Sub-tropical high
Canyon	Pinnacle	Transverse dune
Desertification	Plateau	Yardang
Dome dune	Playa

 

LAB LEARNING OBJECTIVES

After successfully completing this module, you should be able to do the following tasks:

·         Identify erosional processes and features created by wind

·         Identify depositional processes and features created by wind

·         Describe the processes that create eolian landforms

·         Distinguish different sand dune types

·         Calculate slope

·         Interpret the topographic profile of a landscape

 

INTRODUCTION

This module examines the eolian processes and arid environments. Topics include dune classification, eolian processes and features, and arid landforms. While these topics may appear to be disparate, you will learn how they are inherently related. The module starts with four opening topics, or vignettes, which are found in the accompanying Google Earth file. These vignettes introduce basic concepts of the eolian and arid landscapes. Some of the vignettes have animations, videos, or short articles that will provide another perspective or visual explanation for the topic at hand.  After reading the vignette and associated links, answer the following questions. Please note that some links might take a while to download based on your Internet speed.

 Expandthe INTRODUCTION folder and then check Topic 1: Introduction.

 Read Topic 1: Introduction.

Question 1: Which of the following was not provided in the Introduction as a characteristic of an arid environment?

A.   Little precipitation

B.   Drought resistant vegetation

C.   Sparse vegetation

D.   Hot temperatures

 Read Topic 2: Arid Land and Water

Question 2: What is not listed as a source of water for human use in arid environments in Topic 2?

A.   Wells

B.   Salt water

C.   Oases

D.   Rainfall

 Read Topic 3: Hot and Cold Deserts.

Question 3: What characteristics of polar deserts make them suitable for study by planetary scientists?

A.   Barren landscapes

B.   Cold climate

C.   Isolation

D.   All of the above

 Read Topic 4: Human Interaction.

Question 4: Which of the following is not one of the four techniques that humans have employed to stop desertification.

A.   Covering sand dunes in petroleum

B.   Building sand fences

C.   Covering sand dunes in plastic

D.   Planting vegetation

 Read Topic 5: Eolian Landscapes.

Question 5: Where is the thickest known Loess deposit and what is the depth?

A.   Kansas, 120m

B.   Nebraska, 95m

C.   China, 335m

D.   Iran, 40m

 Collapse and uncheck INTRODUCTION

GLOBAL PERSPECTIVE

 Expand GLOBAL PERSPECTIVE. Double-click and select Major World Deserts.

This map shows the location of major deserts (in tan) throughout the world.  It is important to note that while deserts are always considered arid environments, arid environments are not always deserts.  Arid environments also include Mediterranean regions and semi-arid lands, among others.  Areas where water is severely limited, eolian processes become the dominant mechanism for erosion, transportation and deposition of sediments.

 Expand and select Major Cities.

This map shows the location of major cities located in arid environments. At present, such cities are placing increasing pressure on water resources and contributing to desertification.

For Questions 6 to 9, type the information provided in the Search tab in Google Earth and press Enter. When you arrive at your destination, find the information to fill in the blanks below.

Question 6:         Cairo, Egypt (population : X)

Latitude/Longitude:

A.   30N, 31E

B.   31N, 30E

C.   C. 30S, 31W

D.   D. 31N, 30 W

Question 7: Riyad, Saudi Arabia (population : X)

Latitude/Longitude:

A.   24N, 46E

B.   46S, 24E

C.   24N, 46W

D.   46N, 24W

Question 8:         12° 2’49.53″S, 77° 0’37.67″W (population : X)

City:

A.   Santiago

B.   Lima

C.   Bogotá

D.   Paracas

Question 9:33°22’22.03″N, 112°34’48.60″W (population : X)

City:

A.   Las Vegas

B.   Los Angeles

C.   Phoenix

D.   Tucson

 Collapse and uncheck GLOBAL PERSPECTIVE

 

LOCATION OF ARID REGIONS

The following factors influence the location of deserts:

·         Subtropical high pressure systems

·         Rain shadow effect

·         Ocean current temperatures

·         Distance to large bodies of water

It is important to note that two or more of these factors may influence the location of deserts.

 Expand the LOCATION OF ARID REGIONS folder. Double‑click and select Sahara Desert.

Subtropical high pressure systems are generally located between 15 and 30 degrees north and south. At these locations, high pressure systems exist, with descending air warming as it falls. The result is a climate of hot temperatures and little precipitation. The Sahara desert is a good example of a desert formed because of a subtropical high pressure system.

 Double‑click and select Oregon Great Sandy Desert.

The rain shadow effect can be seen on the leeward side on mountain ranges. An air mass approaching a mountain range is forced upward by the mountains and precipitation results on the windward side of the range. On the leeward side, the air mass loses most of its moisture and warms as it descends the mountain range. The result is a semi-arid to arid landscape. The Oregon Great Sandy desert is a good example.

 Double‑click and select Atacama Desert.

Cold ocean currents do not significantly heat air mass above them. The result is an air mass containing little moisture, and when the air mass reaches land, precipitation is almost non-existent. The Atacama Desert is a good example.

 Double‑click and select Gobi Desert.

The distance to a large body of water such as an ocean or sea, is a factor, because water bodies can provide moisture to air masses, which in turn lead to precipitation. The further an area is from a large body of water, the less likely it is to receive moisture. The Gobi Desert straddling the China-Mongolia border is an example of an arid region far from a large body of water.

 Double‑click and select Namib Desert.

Question 10: Which of the following factors is mainly responsible for the location of the Namib Desert?

A.   Subtropical high pressure

B.   Rain shadow effect

C.   Cold ocean currents

D.   Distance from large body of water

Question 11: Why did you pick the answer, or answers, you did in question 10?

A.   Lack of clouds in imagery shows it is a subtropical high area

B.   The coastal beaches create a rain shadow inland

C.   The cold ocean current limits moisture in atmosphere creating the coastal desert

D.  The desert is a long distance from any inland body of water

 Double‑click and select Patagonia.

Question 12: Which of the following factors are mainly responsible for the location of the arid lands in Patagonia?

A.   Subtropical high pressure

B.   Rain shadow effect

C.   Cold ocean currents

D.   Distance from large body of water

Question 13: Why did you pick the answer, or answers, you did in question 12?

A.   It is a noted subtropical high area

B.   The coastal mountains create a rain shadow inland

C.   The cold ocean current limits moisture in atmosphere creating the coastal desert

D.   The desert is a long distance from any inland body of water

 Double‑click and select Taklimakan Desert.

Question 14: Which of the following factors are mainly responsible for the location of the Taklimakan Desert?

A.   Subtropical high pressure

B.   Rain shadow effect

C.   Cold ocean currents

D.   Distance from large body of water

Question 15: Why did you pick the answer, or answers, you did in question 14?

A.   It is a noted subtropical high area

B.   The coastal beaches create a rain shadow inland

C.   The cold ocean current limits moisture in atmosphere creating the coastal desert

D.   The desert is a long distance from any inland body of water

 Double‑click, and select, Mojave Desert.

Question 16: Which of the following factors are mainly responsible for the location of the Mojave Desert?

A.   Subtropical high pressure

B.   Rain shadow effect

C.   Cold ocean currents

D.   Distance from large body of water

Question 17: Why did you pick the answer, or answers, you did in question 16?

A.   It is a noted subtropical high area

B.   The arid environment creates a rain shadow inland

C.   The cold ocean current limits moisture in atmosphere creating the coastal desert

D.   The desert is a long distance from any body of water

 Collapse and uncheck LOCATION OF ARID REGIONS

 

 

 

EROSIONAL AND TRANSPORTATION PROCESSES AND LANDFORMS

 Expand EROSIONAL AND TRANSPORTATION PROCESSES AND LANDFORMS.

 Expand Erosional Features.

 Double‑click and select Fly Over. Watch the fly over of the Spider Rock location to get an overview of the features and terrain in the area.

 Select Spider Rock. Use the transparency slide ruler to compare the aerial photograph to the topographic map. As you can see, there are several features common to this arid environment.

 

Identify the features labeled  through .

Question 18: Feature : D

A. Canyon	B. Alluvial Fan	C. Butte
D. Pinnacle	E. Plateau	F. Playa

Question 19: Feature : C

A. Canyon	B. Alluvial Fan	C. Butte
D. Pinnacle	E. Plateau	F. Playa

Question 20: Feature : E

A. Canyon	B. Alluvial Fan	C. Butte
D. Pinnacle	E. Plateau	F. Playa

Question 21: Feature : A

A. Canyon	B. Alluvial Fan	C. Butte
D. Pinnacle	E. Plateau	F. Playa

 Double‑click . This feature is found at the lowest elevation within the region, where high evaporation rates leave minerals (salt) from the water onto the ground surface.

Question 22: Feature : F

A. Canyon	B. Alluvial Fan	C. Butte
D. Pinnacle	E. Plateau	F. Playa

 

Depositional Processes and Landforms

 Double-click Depositional Feature. Double-click and select .

Question 23: Identify Feature : B

A. Canyon	B. Alluvial Fan	C. Butte
D. Pinnacle	E. Plateau	F. Playa

 

 Double-click and select Measure Distance

Question 24: Compute the distance (in km) across the Feature :

A.   2km

B.   4km

C.   6km

D.   8km

Question 25: What evidence exists of human activity on Feature ?

A.   Landing strip

B.   Trailer park

C.   Road

D.   Beach

 Double-click and select Slope 1. Right‑click the title Slope 1, and then select Show Elevation Profile.

Using the elevation readings (that is, place your cursor over the elevation profile chart), compute the slope of the lines. Recall that slope is rise/run and the units need to be the same when dividing (that is, both in feet).

Question 26: What is the RISE (elevation gain) in feet? (Select the answer closest to the one you see in the Elevation Profile Window)

A.   400 ft

B.   51.4 ft

C.   21.8 ft

D.   35 ft

Question 27: What is the RUN of the line (distance) in miles? (Select the answer closest to the one you see in the Elevation Profile Window).

A.   7.73 miles

B.   4.11 miles

C.   2.05 miles

D.   5.14 miles

Question 28: What is the slope of the line (average slope)? (Select the answer closest to the one you see in the Elevation Profile Window).

A.   25%

B.   -51.4%

C.   3.8%

D.   -35%

 Double-click and select Slope 2. Right‑click the title Slope 2, select Show Elevation Profile, and then compute the slope of the red line.

Question 29: What is the RISE (elevation gain) in feet? (Select the answer closest to the one you see in the Elevation Profile Window)

A.   3000 ft

B.   -449 ft

C.   1005 ft

D.   2077 ft

Question 30: What is the RUN of the line (distance) in miles? (Select the answer closest to the one you see in the Elevation Profile Window)

A.   8.0 miles

B.   3.3 miles

C.   0.28 miles

D.   26.5 miles

Question 31: What is the slope of the line (positive average slope)? (Select the answer closest to the one you see in the Elevation Profile Window)

A.   84.4%

B.   -39.4%

C.   22.5%

D.   -10.9%

The x-axis is the distance along the elevation profile.  

Question 32: The greatest slope is located between which distance markers on the x-axis?

A.   0.75 miles and 1 mile

B.   2.25 miles and 2.5 miles

C.   2.5 miles and 2.75 miles

D.   2.75 miles and 3 miles

Question 33: Describe the topographic profile of an arid landscape that would produce Feature

A.   Steep slopes gradually giving way to a gentle slope

B.   Steep slopes along the entire profile

C.   Gentle slopes along the entire profile

D.   Alternating steep and gentle slopes

SAND DUNE CLASSIFICATION

 Click SAND DUNE CLASSIFICATION.

Use the animation to identify characteristics of dune types and to complete the table below. The first one has been done for you as an example

Dune type	Wind	Sand	Vegetation
Barchan	A.   Periodic reversing of direction B.   Two directions C.   One constant direction D.  Variable directions	A.   Limited B.   Moderate C.   Abundant D.   Variable	A.   Yes B.   No
Question 34: Barchanoid Ridge	A.   Periodic reversing of direction B.   Two directions C.   Variable directions D.   One constant direction	A.   Limited B.   Abundant C.   Moderate D.   Variable	A.   Yes B.   No
Question 35: Transverse	A.   Periodic reversing of direction B.   Two directions C.   One constant direction D.   Variable directions	A.   Limited B.   Moderate C.   Variable D.   Abundant	A.   Yes B.   No
Question 36: Longitudinal	A.   Periodic reversing of direction B.   One constant direction C.   Two directions D.  Variable directions	A.   Limited B.   Moderate C.   Abundant D.   Variable	A.   Yes B.   No
Question 37: Parabolic	A.   Periodic reversing of direction B.   One constant direction C.   Two directions D.  Variable directions	A.   Limited B.   Moderate C.   Abundant D.   Variable	A.   Yes B.   No
Question 38: Star	A.   Periodic reversing of direction B.   One constant direction C.   Two directions D.  Variable directions	A.   Limited B.   Moderate C.   Abundant D.   Variable	A.   Yes B.   No
Question 39: Dome	A.   Periodic reversing of direction B.   One constant direction C.   Two directions D.  Variable directions	A.   Limited B.   Moderate C.   Variable D.   Abundant	A.   Yes B.   No
Question 40: Reversing	A.   Periodic reversing of direction B.   One constant direction C.   Two directions D.  Variable directions	A.   Limited B.   Moderate C.   Abundant D.   Variable	A.   Yes B.   No