Continental drift and mountain building

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Continental drift and mountain building

Under the process of plate TECTONICS, the continental plates of the earth slowly drift as they respond to the drag of molten rock circulating in the deep parts of the earth's crust below. Where plates collide over millions of years, rocks very slowly crumple—some get pushed into deep layers of the crust, and others buckle upwards to form mountain chains. The high mountains of Papua New Guinea are continuing to grow as the Australian Plate moves north and pushes into the western section of the Pacific Plate; and the Himalayas have formed from the collision of the Indian and Eurasian Plates.

As land masses move and mountains grow or are eroded away over geological time, they cause very slow and long-term changes in climatic patterns. For example, the location and size of land masses influence the distribution and intensity of surface heat absorption and reflection, which cause high and low pressure systems and give rise to wind movement. The location, orientation and height of mountains affect air circulation and cloud formation, and rainfall distribution patterns.

It must be remembered that the rate of these geological processes is very slow, and measured in millions of years. Continental plates drift at between 1 and 10 centimetres per year; the Himalayas are growing at around 5 millimetres per year.

Further reading:

W. J. Kious and R. I. Tilling, This dynamic earth—the story of plate tectonics, US Geological Survey, 1996.

15 November, 2010