chapter 7 Flashcards
Why do geologists work in deserts?
protect the environment, assist people who live in these environments, study the origin of deserts
what is desertification?
process by which fertile land becomes desert
Why does desertification occur?
drought, deforestation, inappropriate agriculture
What province is great sand dunes in?
southern rocky mountains geographical province.
How many ranges are in the rocky mountains?
at least 100
Where is great sand dunes located?
near the rio grande, river runs through the rio grande rift (failed divergent plate boundary?
Four primary components of the great sand dunes system are the
mountain watershed, dune field, sand sheet, sabkha
What are the creeks of great sand dunes?
sand, medano, and mosca
Is a stream smaller than a river
yes
river>stream>creek
yes
Water can play a major role in creating desert landscapes. how?
dries up, leaves behind mud cracks. helps to drive the precipiation of minerals. water can carve sand, gravel
does great sand dunes have the tallest sand dunes in north america?
yes
sand dunes
low mound capable of movement that is created when strong winds pick up sand-sized grains from a valley floor and transport the grains by various methods
wind
flow of gasses from regions of high pressure to low pressure because of uneven heating of earth by sun
to create sand dunes what are the three requirements that must be met
wind (sufficient speed to carry), sand (specific grain sizes), trap (enough to trap sand)
many different types of sand dunes exist. which are the ones that exist in great dunes?
barchan, transverse, reversing dune, star dune
barchan
crescent-shaped dunes, always the products of limited sand supply and unidirectional winds
transverse dunes
form in arid regions where there is abundant sands
reversing dunes
occur when wind reverses direction, these appear to have a wall on top
star dunes
form when the direction of the wind changes a lot. these dunes hvae three or more arms. can form in abundant or lower sand regions, grow vertically
desertification causes
- climate
- population increase
-over-exploitation of water resources
-over-grazing, mining, forestry - clearing of land without reforesting
- surface mining with reclamation
- rapid growth of large desert cities
- depletion of groundwater
- replacement of native plants with non-native
- soil salinization (salt) due to evaporation of irrigation water
impacts of desertification
- expansion of deserts into formerly productive lands
- land degregation in arid, semi-arid and dry sub-humid areas results from various factors including climatic variations and human activities
what underlie great sand dunes national park and are essential in recycling sand in the park and water sources in the region
artesian aquifer
