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 know about some important Ecology and environmental terms
i) 1869, German biologist Ernest Haeckel first coin the term ecology.
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| Ecology and environmental terms, geoshortqa |
ii) The word niche was first used in biology by naturalist Roswell Johnson, but in 1917 Joseph Grinnell was the first to use it in a research program, in his paper "The niche relationships of the California Thrasher".
iii) The term "ecosystem" was first used in 1935 in a publication by British ecologist Arthur Tansley. Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment.
iv) Food chains were first introduced by the Arab scientist and philosopher Al-Jahiz in the 10th century and later popularized in a book published in 1927 by Charles Elton, which also introduced the food web concept.
v) Charles Elton pioneered the concept of food cycles, food chains, and food size in his classical 1927 book "Animal Ecology"; Elton's 'food cycle' was replaced by 'food web' in a subsequent ecological text.
vi) The concept of pyramid of numbers ("Eltonian pyramid") was developed by Charles Elton (1927). Later, it would also be expressed in terms of biomass by Bodenheimer (1938). The idea of pyramid of productivity or energy relies on works of G. Evelyn Hutchinson and Raymond Lindeman (1942).
vii) The term ecological succession was first given by Ragnar Hult in 1885. Ecological succession is the process of change in the structure of different species of an ecological community or ecosystem over time.
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