Earth, the planet on which we live, is not a solid ball of rock. The Earth and its atmosphere provide everything needed to sustain life. The Earth consists of several layers, and the surface and atmosphere that we know today has changed a lot since it was first formed. For the GCSE, you need to know about the processes that build mountains, create oceans, eathquakes and volcanoes, how and why the atmosphere has changed naturally as well as how human activities have resulted in further changes in the atmosphere. This GCSE Chemistry quiz is all about the layers withing the Earth - the inner core, the outer core, the mantle and the crust.
Before the 1960s, ideas about the processes that changed the Earth were barely understood. There were various theories about the age of the Earth. The Romans believed it to be about 2000 years old; the ancient Egyptians believed it was about 40,000 years old; the Babylonian civilisation believed anywhere between 200,000 and 400,000 years old. In modern times, a seventeenth century Irish archbishop named James Ussher used the Bible to decide that the Earth was created at 6pm on the 22nd October, 4004 BC. Other dates from different versions of the Bible differ by up to 1,500 years.