Thursday, April 16, 2009

Lesson 1: Earth Science. Ocean


Ocean


The word Ocean came from the Greek word Okeanos meaning river. Early Greeks thought a mighty river encircled the earth.

The Ocean is the world's largest natural habitat, covering more than 70 % of Earth's surface.


The water in the Ocean is the same water that has been on Earth since the Ocean was formed 4 billion years ago. So technically you are drinking the same water Dinosaurs drank!!


So how did the Ocean form? Billions of years ago, the surface of the earth was very hot and fiery red magma rolled on the surface of earth. Water ( from the volcanoes that were erupting and also from the comets that continued to strike the earth) evaporated to form a large cloud.

Eventually the earth started to cool down.

There have been a lot of speculation as to what made the earth cool down. ( there was a lull in comets and meteorites striking the earth, a large cloud blocked the sun for a very long period of time, the sun itself was a young star and was not very hot.etc etc)

It is difficult to analyze and find out what exactly happened that made the earth cool down because there is no specimen for us to look at..Remember, everything was burning.

The oldest rock formation found on earth is the four-billion-year-old Acasta gneiss in Canada's Northwest Territories. ( named after the Acasta river. The word Gneiss is an old German word meaning Bright or sparkling). We don't know what happened prior to 4 billion years.

Anyway, eventually the surface of the earth cooled. This eventually led to rain fall and water started to get collected, eventually forming oceans.

This process of evaporation, condensation and precipitation is called the water cycle. The sun's rays causes the water to evaporate, and as the evaporated water rises up the cooler temperature in the upper atmosphere causes the water to condense and form in to a cloud. As the cloud grows it eventually leads to rain fall ( or snow) The cycle repeats over and over.

Imagine what would happen if the sun decides to take a day off.

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