The origin of the Earth

... Sonja Radmilovic Earths History 17/4/02 The origin of the Earth The age of the Earth was once, and still is, a matter great debate. In 1650 Archbishop Usher used the Bible to calculate that the Earth was created in 4004BC. Later on in the mid-nineteenth century Charles Darwin believed that the Earth must be extremely old because he recognized that natural selection and evolution required vast amounts of time. It wasn't until the discovery of radioactivity that scientists began to put a timescale on the history of the Earth. Rocks often contain heavy radioactive elements which decay over long periods of time, the decay is unaffected by the physical and chemical conditions and different elements decay at different rates (These rates are slow and half-life's of several hundred million years are not uncommon) Throughout this century the race has been on to discover the oldest rocks in the world. The oldest volcanic

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