In this Geoshortqa we are going to know about types of Sand Dunes. Types of Sand Dunes, Geoshortqa Sand Dunes Sand dunes are heaps of sand found in deserts . Generally , their heights vary from a few metres to 20m , but in some cases dunes are several hundred metres high and 5 to 8 km long . The formation of sand dunes requires • Wind of high velocity • Abundant sand • Obstacles such as trees , bushes , forests , rock outcrops , walls against , which dunes may settle • Ideal places i.e. dune complex , dune colony or dune chain . Dunes formed due to obstacles like hushes , walls etc. are called nebkhas , where dune formed besides desert depressions are called lunettes. Dunes are classified on the basis of morphology , structure , orientation , location , internal structure , ground pattern and number of slip faces . These are the various types of sand dunes a) Transverse Dunes are dunes deposited transverse to the prevailing winds direct...
In this Geoshortqa we are going to know about types of Sand Dunes.
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| Types of Sand Dunes, Geoshortqa |
Sand Dunes Sand dunes are heaps of sand found in deserts . Generally , their heights vary from a few metres to 20m , but in some cases dunes are several hundred metres high and 5 to 8 km long .
The formation of sand dunes requires
• Wind of high velocity
• Abundant sand
• Obstacles such as trees , bushes , forests , rock outcrops , walls against , which dunes may settle
• Ideal places i.e. dune complex , dune colony or dune chain . Dunes formed due to obstacles like hushes , walls etc. are called nebkhas , where dune formed besides desert depressions are called lunettes.
Dunes are classified on the basis of morphology , structure , orientation , location , internal structure , ground pattern and number of slip faces .
These are the various types of sand dunes
a) Transverse Dunes are dunes deposited transverse to the prevailing winds direction . They are formed due to ineffective winds blowing along the coast and margins of deserts .
b) Parabolic Dunes are generally developed in partially stable sandy deserts . They are U - shaped and are much longer and narrower than barchans .
c) LongitudinalDunes are formed parallel to the wind movement . The windward slope of the dune is gentle whereas , the leeward side is steep . These dunes are commonly found at the heart of trade wind deserts like the Sahara , Australian , Libyan , South African and Thar deserts .
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| Longitudinal Dunes, Geoshortqa |
Longitudinal dunes are separated by reg or hamada which are sand free bare surfaces . The corridors so formed are called caravans.
d) Barchan: Crescent -shaped dune whose long axis is transverse to the dominant wind action
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| Barchan, Geoshortqa |
e) Star dune: • Large pyramidal or star- shaped dune.
• Has three or more slip- faces.
• Does not migrate along the ground, but grows vertically.
f) ) Dome: Mound of sand that is circular or elliptical in shape. Has no slipfaces.
g) Reversing: • Dunes that are intermediate between star and transverse dunes.
• Ridge is asymmetrical and has two slip-face.
h) Coastal dunes: • Forms when there is a large supply of beach sand and strong winds blowing from sea to shore.
• Beach area must be wide.
• Dissimilar from desert dunes in their form and shape and in the fact that they do not migrate.
Coastal dunes, Geoshortqa
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