Fossil fuels are made up of____ that sank to the bottom of oceans or ____ over 300 million years ago. The organic matter was ____ by layers of material e.g. sand. Over time, these layers built up putting ____ on the fossils. A mix of the pressure and the ____ turned the fossil fuels into the oil, gas and coal we use today. Oil and ____ were formed under oceans whereas ____ was formed under swamps.

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