MASS WASTING AND EROSIONAL LANDFORMS IN GOOGLE EARTH
objectives of this activity are:
- To become familiar with what geologic features formed from mass wasting and erosion look like in Google Earth.
- To become familiar with the Google Earth features: polygons, pins, and placemarks.
- To become familiar with the use of .kmz files of Google Earth.
In this activity, you are going to download Google Earth.kmz and open them on your computer. KMZ files are like to ZIP files. KMZ files will let you add images to the Google Earth locations using placemarks. You are also going to a KMZ files to turn in.
You will explore the following areas:
1) The Maipo River valley of central Chile
2) The Pigeon River Gorge between Asheville, NC and Newport TN.
- A current version of Google Earth - Google Earth is available for download for PC, Mac, or Linux.
- Maipo Valley Features.kmz (from Canvas)
- Pigeon River.kmz (from Canvas)
Part 1: The Maipo River Valley
The Maipo River valley of central Chile runs from some of the highest volcanoes on Earth into the souther suburbs of Santiago. The climate of this region of Chile is arid (~ 10 - 12 inches rain per year), so there is little vegetation covering its geological features.
Start near Puente Alto, where the valley begins to climb into the Andes Mountains. Locate Camino al Volcan, the main road in the Maipo valley. Now "fly" along the road using the hand cursor. You will be heading toward the south east from the city.
A) Near Bollenar, San Gabriel, and Queltehues you will see blue polygons that indicate fields planted with grape vines. The Maipo Valley is one of the major wine producing valleys in Chile thanks to its dry climate and rich soils.
1. Aside from those highlighted, can you see any other grapevine fields in the valley? Highlight those you see as polygons in Google Earth and save them on your computer.
B) Further up the valley, past the village of El Volcan, is a mountainside highlighted in yellow for its strongly tilted rock beds. As you move up the valley, you will see the rock layers become more and more tilted upward, until they are nearly vertical.
2. Can you find some vertically dipping beds further along the valley? Mark them with a placemark.
C) On the other side of the valley from the yellow-highlighted rock beds are several Alluvial Fans highlighted in red. Alluvial Fans are slowly developing mass wasting features that form when physical weathering and gravity (sometimes aided by rare episodes of rainfall) combine to move rocks downslope. Note that these fans all originate in steep valleys of various sizes.
3) Identify other alluvial fan deposits in the valley further along and highlight them in polygons. Save them.
D) Prominent just across from the alluvial fans, highlighted in yellow, is a large Landslide Scar, formed when a large and unstable body of rock and unconsolidated material lets loose and slides rapidly downslope.
4) Locate other Landslide Scars evident in the Maipo Valley and mark them with placemarks.
E) At the end of Camino al Volcan (and highlighted in gold) is a very rustic hotsprings and thermal baths area. It lies on the shoulder of Volcan San Jose (see the yellow placemark), one of the tallest active volcanoes in the world!
5) How tall is Volcan San Jose?
6) What features that you can see identify it as a volcano?
7) Add the answers to questions 5 and 6 to the placemark by editing the placemark identifying Volcan San Jose.
8) Save your polygons, pins, and your edited Volcan San Jose pin in a single .kmz file to hand-in for grading.
Part 2 - Pigeon River Gorge
Te Pigeon River Gorge is a somewhat infamous segment of Interstate 40 between Asheville, NC and Newport, TN. The aim for this route was to connect Asheville and Knoxville, TN, and there was a secondary ambition to have a working Interstate highway through the high Smoky Mountains before the Knoxville Worlds Fair of 1982. However, since it's opening in 1968, landslides have plagued the road.
Start at the intersection of Interstate 40 and US 276 near Waynesville, NC. Use the hand cursor to "fly" along the highway to Tennessee, checking out the placemarks and polygons along the way.
A) Dipping Beds: One can observe the dips of the rock layers very easily in the Google Earth images along the highway.
1) Compared to the Maipo valley rocks, are the Pigeon River Gorge rocks very steeply dipping? Create polygon around an example and write an answer in the information box.
B) Note the structure of the next several road cuts and the shape of the mountainsides they are on. Terracing is used to try and control rock sliding. This strategy is less effective if the cut walls are steep.
2) Look at the Google Earth imagery up close. Are the road cut walls very steep? Check the slope gradient with the ruler tool and the elevation. You will need to get close to do it well. Put a placemark on the spot you measured and note the gradient you calculated in the box
C) Wedge Failure Landslides are the particular kind of rockslides that occur in the Pigeon River Gorge. Basically a Wedge-like slab of steeply dipping rock breaks off and slides onto the road.
3) How many wedge failure landslide scars are marked in the Gorge?
4) Are the wedge failure landslides localized along the highway or distributed throughout?
5) In Google Earth, can you see any relationship between the topography of the mountains and where the wedge failure slides occur? Place a placemark in the center of the landslide area and responses in the information box.
6) What remediation strategies for dealing with these slides are evident from the images along the Gorge? Mark those you see with placemarks and identify the strategies in the information box.
7) Based on what you've looked at, will the roadcut highlighted in purple suffer from wedge failure slides in the future? Why or why not? Enter your response in the information box for this feature.
8) Save your responses in a single .kmz file to hand-in for grading titled "Pigeon Gorge Answers from [your name]"
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