(a) ‘Dynamic’ means changing.

(b) Our environment is never static.

(c) The earth is constantly undergoing a change, ever since it has come into existence.

(d) Changes may take place either slowly or suddenly, e.g., mountains like Urals and the Aravalies have been eroded gradually to low heights. The change may be sudden due to earth movements which results in upliftment of land, e.g., the formation of the Himalayas or separation of land masses.

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(e) Due to change in temperature, pressure. There is circulation of air and water which brings about climatic changes, which is slow.

(f) When there are long-term changes in physical environment, there is extinction of certain species of plants and animals.

(g) When there is mass extinction of species, new species evolve. Thus, any change in the physical environment leads to changes in the biological environment.

(h) The distribution of continents and oceans are an indication of the changes that have taken place ever since the earth has come into being. Initially there was a single continent called Pangeae. The continents have drifted from their original position to the present position. All these facts suggest that the environment is dynamic.