2006-09-27 07:12:52 · 8 answers · asked by *~Tink~* 2 in Science & Mathematics ➔ Earth Sciences & Geology
The wind is just strong enough to move the sand grains which were sorted by size by the wind. Heavier grains were left in place where as smaller grains were carried away. These grains kept moving till they were concentrated in one place usually up a hill. The grains climb the flat slope on the windward side and then fall off the steep side. The dunes may migrate slowly as this process continues, the grains at the upwind side climb the dune with the help of the wind and then fall down the downwind side.
2006-09-27 07:52:37 · answer #1 · answered by JimZ 7 · 0⤊ 0⤋
http://www.npa.gov/archive/whsa/dunes.htm
Sand can only be moved by strong steady winds. The air must be moving at least 15 mph to be able to pick up sand grains. As the wind blows, it lifts small sand grains a few feet off the ground then drops them.When they hit the ground, they bump inot other sand grains and causes them to jump up and be caught by the wind. It is kind of like playing leap frog. Good LUCK
2006-09-27 15:54:42 · answer #2 · answered by confused/hurt/angry 3 · 0⤊ 0⤋
the sand dunes migrate by the movement of the winds that is what makes them move form one place to an other.
2006-09-27 14:16:21 · answer #3 · answered by wolf 5 · 0⤊ 1⤋
winds do all the work. Wind help dunes to migrate...
2006-09-27 14:15:07 · answer #4 · answered by Anonymous · 0⤊ 2⤋
The wind moves them grain by grain. Good luck I hope this helps.
2006-09-27 14:20:23 · answer #5 · answered by fast_bird94 3 · 0⤊ 1⤋
By wind. Have a sandy great day.
2006-09-27 14:14:39 · answer #6 · answered by firestarter 6 · 1⤊ 2⤋
they get green cards and move to the beaches of so cal
2006-09-27 14:17:35 · answer #7 · answered by scottishchristiansen 3 · 0⤊ 3⤋
'Cause they are just searching for a better life...
2006-09-27 14:14:38 · answer #8 · answered by TJD 4 · 0⤊ 3⤋