EXERCISE 1 DATA SHEET 1. What type of dunes are present at Location A? 2. What t

Question

EXERCISE 1 DATA SHEET

1. What type of dunes are present at Location A?

2. What type of dunes are present at Location B?

3. The dunes at Location B are in the same region as Location A, so why are they different here (i.e., what is the difference between the dominant processes forming these two dunes)?

4. What type of dunes are present at Location C? How are these types of dunes formed?

5. What type of dunes are shown at Location D?

6. The area around Location E looks like it is covered in snow, but it isn’t snow (the area gets less than 200 mm of precipitation a year). What is this feature called, and what is it mostly composed of?

7. Using your knowledge of wind processes, briefly describe how the rock in the photo title “Arbol de piedra-Bolivia” got its shape.

8. The dunefield at Location F is home to the tallest dunes in North America, and it covers 30 square miles. Why is this area called a dunefield instead of an erg?

9. Many of the rocks at Location G display a classic wind-generated texture. What is this texture called?

10. There have been many theories to explain the rock movements and their corresponding tracks at the “Race Track” (Location G). How do you think these tracks might be generated? It’s ok if you don’t know the answer; give it your best educated guess based on what you have learned about Earth processes.

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Explanation / Answer

1. At location A longitudinal dunes are present because these are large symmetrical ridges of sand parallel to the wind direction. these are also known as seifs.These are shaped by a prevailing wind from one direction interrupted by ocassional cross winds.

2.At location B barchans are present. These are asymmetrical, crescent shaped dunes in which wins of the crescent are directed down wind. These dunes are formed in strong winds and are situated perpendicularly to the main direction of the moving wind. These dunes tend to arrange themselves in chains extending in the direction of the prevailing wind and they also move forward.

3.The dunes in location B are same as dunes in location A but at Location B the dune i.e. barchans are formed in strong winds and are situated perpendicularly to the main direction of the moving wind. These dunes tend to arrange themselves in chains extending in the direction of the prevailing wind and they also move forward and at location A i.e. longitudinal dunes are shaped by a prevailing wind from one direction interrupted by ocassional cross winds.

4.At location C parabolic dunes are present. These are asymmetrical, crescent shaped dunes in which wins of the crescent are directed down wind. These dunes are parabolic in outline and they have their wings pointing towards the direction opposite to that of the blowing wind i.e. the curve of the dune crest is bowed convexly downwind and the horns pointing upwind. They commonly formed around blow outs, where sand supply is abundant and the wind is steady.

5.At location D pyramidal or star shaped dunes are present. They seldom stand alone and normally contain steep radiating ridges culminating in one or several peaks.They appear to have been formed due to the interference of air waves caused by wind reflecting from mountain barriers.

6.At location E salt flats are present. These seems like snow there. This glows in the midday sun. It is mostly composed of salt.

7.The rock in the photo title "Arbol de piedra-Bolivia" is Yardang. It is a grooved or furrowed topographic form produced by wind abrasion. The grooves are elongated in the direction of prevailing winds and are seperated by sharp ridges. These commonly develop where the exposed rocks have vertical layers, consisting of alternations of hard and soft strata, and when the winds are steady and blow in one direction, the softer strata are scoured away more rapidly than the hard and resistant strata.

8. At location E it is called dune fiels because a lage number of ergs are present here.

10.Cruising stones, otherwise called sliding rocks, strolling rocks, moving stones, and moving rocks, are a topographical wonder where rocks move and record long tracks along a smooth valley floor without human or creature intercession. Rather, rocks move when extensive ice sheets a couple of millimeters thick gliding in a transient winter lake begin to separate amid bright days. These thin gliding ice boards, solidified amid cool winter evenings, are driven by wind and push rocks at up to 5 m/min.

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