GEO 1013 Module 04 INV - notes PDF

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GEO 1013 – Investigation 4 Worksheet – Deserts

Go to the following link and answer the questions below. https://www.tulane.edu/~sanelson/eens1110/deserts.htm 1. Deserts are areas where rainfall is less than 250 mm (10 in.)/year, or where evaporation exceeds precipitation. 2. They are characterized by specialized ecosystems and low human populations. 3. List the five types of deserts. a. Subtropical deserts b. Rain shadow deserts c. Coastal deserts d. Continental interior deserts e. Polar deserts

4. Subtropical deserts are created when general atmospheric circulation brings dry, subtropical air into mid-latitudes. 5. Rain shadow deserts are areas where mountainous regions cause air to rise and condense, dropping its moisture as it passes over the mountains. 6. Coastal Deserts are areas where cold upwelling seawater cools the air and decreases its ability to hold moisture. 7. The Gobi Desert is an example of a continental interior desert found in the continental interiors, far from a source of moisture where hot summers and cold winters prevail. 8. Cold polar regions where cold dry air prevails and moisture available remains frozen throughout the entire year such as the ice-free regions of Antarctica are polar deserts. 9. Deserts have little soil because moisture is so low and the rate of chemical weathering is slow. 10. Exposed rock surfaces develop desert varnish a dark reddish-brown surface coating of of iron and manganese oxides. 11. The desert surface is dominated by mechanical weathering processes. 12. A mesa is a(n) _______________ a. Small flat-topped isolated hill. b. Flat-topped hill with an area of several square kilometers. c. Feature where their height exceeds their top surface. d. Asymmetrical ridge 13. A cuesta is a(n) __________________ a. Small flat-topped isolated hill. b. Flat-topped hill with an area of several square kilometers. c. Feature where their height exceeds their top surface. d. Asymmetrical ridge 14. A chimney is a(n) __________________ a. Small flat-topped isolated hill. b. Flat-topped hill with an area of several square kilometers. c. Feature where their height exceeds their top surface. d. Asymmetrical ridge 15. Streams in deserts tend to be ephemeral, meaning they flow only during rains typically as flash floods during the monsoon season. 16. Flash floods can have considerable discharge, so rapid erosion can occur during these rare events.

17. A(n) __________________________forms where a mountain stream enters a broad flat valley and deposits sediment as its velocity decreases on entering the flatter valley. a. Bajada b. Playa Lake c. Alluvial Fan d. Pediment 18. A(n) ________________ forms at the base of a linear mountain range when several alluvial fans coalesce. a. Bajada b. Playa Lake c. Alluvial Fan d. Pediment 19. A(n) _________________ is a shallow body of standing water in a desert basin that evaporates and leaves behind salt deposits that have a white appearance like a beach. a. Bajada b. Playa Lake c. Alluvial Fan d. Pediment 20. A(n) ______________________ is a broad bedrock surface with a gentle slope away from highlands. a. Bajada b. Playa Lake c. Alluvial Fan d. Pediment 21. Wind transports sediment near the surface by saltation. 22. Smaller particles can travel longer distances by wind. 23.Sand ripples form in lines perpendicular to wind direction and occur as a result of larger grains accumulating as smaller grains are transported away. 24. Wind can erode by deflation and abrasion. 25. Deflation concentrates the coarser grained particles at the surface, eventually resulting in a surface composed only of the coarser grained fragments that cannot be transported by the wind., such a surface is called desert pavement. 26.Sand dunes form when there is (1) a ready supply of sand, (2) a steady wind, and (3) some kind of obstacle such as vegetation, rocks, or fences, to trap some of the sand. 27. In the image below, which direction is the wind moving? a. Left to right b. Right to lef c. Top to bottom d. Bottom to top

28.

Dunes may cover large areas and reach heights up to 500 meters.

29. A(n) transverse dune is a dune ___________________ a. That consists of ridges of sand with a steep face in the downwind side, and form in areas where there is abundant supply of sand and a constant wind direction. b. That is "U" shaped with an open end facing upwind. They are usually stabilized by vegetation, they are common in coastal areas. c. That is crescent-shaped with the points of the crescents pointing in the downwind direction, and a curved slip face on the downwind side of the dune. d. With several arms and variable slip face directions that form in areas where there is abundant sand and variable wind directions. 30. A(n) star dune is a dune ___________________ a. That consists of ridges of sand with a steep face in the downwind side, and form in areas where there is abundant supply of sand and a constant wind direction. b. That is "U" shaped with an open end facing upwind. They are usually stabilized by vegetation, they are common in coastal areas. c. That is crescent-shaped with the points of the crescents pointing in the downwind direction, and a curved slip face on the downwind side of the dune. d. With several arms and variable slip face directions that form in areas where there is abundant sand and variable wind directions. 31. A(n) barchan dune is a dune ___________________ a. That consists of ridges of sand with a steep face in the downwind side, and form in areas where there is abundant supply of sand and a constant wind direction. b. That is "U" shaped with an open end facing upwind. They are usually stabilized by vegetation, they are common in coastal areas. c. That is crescent-shaped with the points of the crescents pointing in the downwind direction, and a curved slip face on the downwind side of the dune. d. With several arms and variable slip face directions that form in areas where there is abundant sand and variable wind directions. 32. A(n) parabolic dune is a dune ___________________ a. That consists of ridges of sand with a steep face in the downwind side, and form in areas where there is abundant supply of sand and a constant wind direction. b. That is "U" shaped with an open end facing upwind. They are usually stabilized by vegetation, they are common in coastal areas. c. That is crescent-shaped with the points of the crescents pointing in the downwind direction, and a curved slip face on the downwind side of the dune. d. With several arms and variable slip face directions that form in areas where there is abundant sand and variable wind directions. 33. A large deposit of wind deposited dust is called loess, much of which is derived from debris lef by glacial erosion and winds blowing across desert regions....