 Today coal has lost the lead it once enjoyed among the fuels. First place has been taken by oil, the precious substance which gushes out of the depths of the Earth, bringing wealth and property to the countries where it is found.
In his search for oil, man has managed to make even the desert habitable, to build enormous platforms to float on the sea, to drill through rock strata down to depths of some 5,000 metres, and has spent enormous sums on doing so.
These are always handsomely repaid once an oil-field has been reached, however, for tons and ton of `black gold` stream out of the well. The oil is taken through pipelines to refineries or tankers.
Oil is generally younger than coal. Its formation dates back to a more recent period in the history of the Earth, to the Mesozoic Era, which lasted 225 million to 65 million years ago. This era saw the rise and fall of the great dinosaurs.
Even in the Mesozoic Era the folding and settling of the Earth's crust continued. Thick deposits of sea and lake sediment accumulated in different parts of the globe. The way in which these deposits are layered shows that the land and seas were successively rising and falling in this period.
The Cretaceous Period, from 130 million to 65 million years ago, take its name from the French Word craie, meaning chalk, which was actually formed in those distant times. This period is one of the longest in the history of the Earth. It lasted for over 65 million years, during which animal-life on land developed in profusion.
Some of the most important oil and natural gas fields discovered in Canada and the United States are to be found in the rocks of the Cretaceous Period. Because of the unsettled condition on Earth, enormous masses of organic substances, perhaps derived from decomposing animals, were imprisoned in the ground where they were gradually transformed until they became the mineral oils of today.
The rock strata of this period are very important, partly because they contain large deposits of copper, aluminium and other minerals but mostly because they also contain fossil traces of the first flower, a sign that great progress was being made in the plant kingdom.
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Updated On: 10/8/2007
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