Science Homework Help

. Introduction & Purpose:

The purpose of this laboratory exercise is to learn about Earth’s Cryosphere and drylands. Students should be able to answer what the Cryosphere is and how changes within it affect other parts of the Earth system. Students should also be able to identify characteristic processes, landforms, and hazards of drylands.

II. Cryosphere Inquiry

A. The Cryosphere is all of Earth’s snow and ice. Use Figure 1 (in the Glacier and Dryland Figures.pdf document above) to answer the following questions.

1. In Figure 1, what is the sequence of Cryosphere regions that you would encounter on the ground if you traveled from Mexico (a beige- to yellow-colored region with no snow or ice) to the North Pole?

1. Notice in Figure 1 that mountain glaciers and ice caps occur in parts of Greenland, Canada, Russia, Alaska, and the western conterminous United States. Some mountain glaciers also exist very close to the equator (not shown in Figure 1). How do you think it is possible for glaciers to exist at the equator?

1. If the temperature of Earth’s atmosphere were to rise, then how do you think it would affect the Cryosphere, hydrosphere, and biosphere?

1. If the temperature of Earth’s atmosphere were to cool, then how do you think it would affect the Cryosphere, hydrosphere, and biosphere?

B. How have glaciers affected landscapes? Use Figure 2 to answer the following question.

1. Name two resources (used by humans) that were created by glaciers?

1. In what ways have the glaciers affected the landscape in the above image, and what does it suggest about how extensive these glaciers must have been in the past?

C. Refer to Figure 3 to fill out the Nisqually Glacier Data Chart below. To do this, use a ruler and the map’s bar scale to measure the distance in kilometers from Nisqually River Bridge to the position of the glacier’s terminus (red dot) for each year of the chart. Be sure to record your distance measurements to two decimal points (hundredths of km).

1. Fill in the chart.

NISQUALLY GLACIER DATA CHART		NISQUALLY GLACIER DATA CHART
Year	Distance in kilometers from Nisqually River Bridge to terminus of Nisqually Glacier		Year	Distance in kilometers from Nisqually River Bridge to terminus of Nisqually Glacier
1997			1946
1994			1941
1976			1936
1974			1931
1971			1926
1968			1921
1966			1918
1963			1910
1961			1905
1956			1896
1951			1892

1. You should notice that the glacier terminus retreated up the valley at some times, but advanced back down the valley at other times. Summarize these changes and what they imply for temperature changes in this area.

D. Refer to Figure 4, which shows climatic data provided by the NOAA National Climatic Data Center (NCDC). NCDC’s global mean temperatures are mean temperatures for Earth calculated by processing data from thousands of observation sites throughout the world (from 1880 to 2009). The temperature data were corrected for factors such as an increase in temperature around urban centers and a decrease in temperature with elevation. Although NCDC collects and processes data on land and sea, this graph only shows the variation in annually-averaged global land surface temperature since 1880.

1. Describe the long-term trend in this graph—how averaged global land surface temperature changed from 1880 to 2005.

1. Describe how the changes in the position of the terminus of Nisqually Glacier ( C.) Compare to the variations in annually-averaged global land surface temperature. Be as specific as you can.

1. Based on all of your work above, do you think Nisqually Glacier can be used as a global thermometer for measuring climate change? Explain.

III. Dryland Inquiry

A. When most people think of drylands and deserts, they imagine hot sandy landscapes. Most of the southwestern United States is desert, including the Sonoran Desert of southern California and Arizona. However, most of the Sonoran Desert is rocky landscapes. Sandy areas are present, but limited, like the Algodunes Dune Field in Figures 5 and 6. This is the location where Star Wars producers filmed desert scenes of the film’s planet Tatooine.

1. Notice the sand dunes of the Algodunes Dune Field in Figure 6. Why do you think there are no plants growing on the dunes?

1. Winds in the Algodunes Dune Field can reach velocities up to 60 miles per hour. This can create hazardous conditions and the need for maintenance on the canal and Interstate Route 8. What would be the hazard, and what maintenance would be needed periodically on the canal and Interstate Route 8 as a result of the hazard?

1. The U.S. Bureau of Land Management as Imperial Sand Dunes Recreation Area manages this region. Portions of the dunes are available for operating off-road vehicles. What effect do you think the operation of off-road vehicles here would have on plant growth and the hazards you described above?

B. Death Valley occurs in the Mojave Desert. Analyze the images of the Death Valley region in Figures 7 and 8.

1. Notice in Figure 7 that steep mountainous slopes occur on both sides of Death Valley. Also notice that there is almost no soil or vegetation on the slopes. Describe what you think conditions would be like in the river valleys on these mountain slopes when heavy rain falls on them.

1. Notice the delta-like landforms that form at the mouths of the river in Figures 7 and 8, where the rivers enter the valley. Explain how you think these landforms form.

1. Notice that there is no standing water in Death Valley, even though you can see that water sometimes flows into the valley from the mountains. It is a closed basin (meaning that water has no way to drain from it). It is also the hottest and driest place in North America. When there is water on the floor of the valley, it is alkaline to salty and potable (drinkable). How do you think the water gets so alkaline and salty?

1. Suppose you could walk down to the white patches on the floor of Death Valley in Figures 7 and 8 and examine them. Predict what materials (minerals) and conditions you would find here.

1. Residents of Furnace Creek have grassy lawns, trees, and potable water to drink. Why do you think their water is potable?

1. The United Nations Convention to Combat Desertification (UNCCD) points out that many people live in drylands, and that more than half of the world’s productive land is drylands. The challenge is to manage the land so that it does not degrade to useless desert that supports no agriculture, and to live safely. Make a list of challenges that people face when they live in drylands, and some ways that the land could be managed to make it safer and more productive.

C. Mojave Desert, Death Valley California. Death Valley is located in the USGS 15-minute Furnace Creek, California quadrangle (provided on the back of this activity sheet). It is the large valley (graben) in the middle of the map and the lowest valley in the United States (Figures 7 and 8). The mountains on each side of the valley are horsts (Figure 9).

1. Notice on Figure 10 that the intermittent stream that drains from the upstream end of the alluvial fan/arroyo system A to the playa at E. How would the grain size of the sediments along this stream change as you walk downslope from the high arroyo to the playa (E)? Why?

1. The floor of most grabens is tilted, because fault movement is usually greater on one side of the graben than the other. There are also half grabens, valleys developed along only one normal fault. Carefully examine Figure 10 for evidence of faults on either or both sides of Death Valley. Do you think that Death Valley is a graben or a half graben?

1. Notice that people chose to build a ranch on an alluvial fan C, even though this entire region is dryland. What do you think was the single most important reason why those people chose this alluvial fan C for their ranch instead of one of the other fans?

IV. Glaciers and Drylands Laboratory Reflection

Directions: Write a reflection of the lab activity, explaining its purpose, the methods used, the results obtained, and a brief personal reflection of what you enjoyed and learned about doing this lab.

• What was the purpose of this lab? What did you actually discover and learn during this lab?

• What did you enjoy most about this lab? Also, what was challenging or thought-provoking?