Ancient mapmakers labeled dry land terra firma (firm earth), but in reality the land beneath us is moving. The continents are adrift, gliding about the globe. The speeds at which the continents move may seem modest, for they rarely exceed six inches a year. But over millions of years, the results have been dramatic. If one only looks at a map of the globe, one can see that the eastern coast of South America neatly fits (almost like a jigsaw puzzle) into the western coast of Africa. Wegener suggested that all the continents had been joined together in a single land mass a very long time ago.
The
earth is a water planet – more than two thirds submerged by water or covered by ice. There is a thin veil of water vapor in our atmosphere. Born in the mountain snows, running water flows in the
form of rivers. And our lakes provide us with most of the fresh water we use. Water is essential to life as we know it because it moderates extremes of temperature and maintains a comfortable
environment for life forms to flourish. Its oceans, lakes and
rivers support an abundance of life.
Rocks belong to one of three basic types – igneous, sedimentary and metamorphic. Rocks preserve the memory of the time in which they were made. Igneous rocks (formed from fire)
began as hot magma that rose from the earth’s interior. Sedimentary rocks (that have settled) are
formed from beds of small particles. Metamorphic rock (whose form has changed) are formed when rocks are subjected to heat and pressure.
The ocean currents are the arteries of the living earth. They bring vast amounts of warmth from the tropics into colder latitudes that would be uninhabitable without them. Without them, the tropics would grow hotter and the higher latitudes would freeze. The Gulf Stream alone carries more than fifty times the amount of water carried by all the world’s rivers combined. The ocean currents help in balancing the differences in temperature across the earth.
Without the gases that make up the atmosphere, there would be no air to breathe or to absorb the sun’s harmful rays. Nothing is more capricious than the weather – for the weather changes from day to day. A drop in gobal temperatures of only two degrees centrigrade could start a new ice age.
Life began in the oceans long ago. Each life form is unique, and there is an amazing variety in the genetic pool. The environment selects those organisms best suited to life in a particular niche, and roots out those that cannot make optimum use of the earth’s natural resources. The story of mankind began in the tropical forests millenia ago.
We share many characteristics with other intelligent primates such as chimpanzees, gorillas and orang-utans. Our bodies may bear the stamp of our lowly origin, but how we have arrived at our present state remains a mystery.
Today, nearly half of the world’s population is urbanized, with many of them living in cities over half a million people. Today, the earth grows enough food to support its population. Today, there is a new understanding of the earth and our place on it. From being a place to be used and abused, the earth’s environment needs to be managed and sustained. Our future as a species depends upon it.
More abstracts about the Article: A World of Wonders