Limestone is a very ____ rock made of ____. There are many different types of limestones in the British Isles. Carboniferous ____ forms some of the highest upland areas in Britain such as the ____ and the ____ District. Carboniferous Limestone was formed about ____ million years ago at the bottom of shallow seas in the Carboniferous geological period. It is a ____ type of rock made up of ____ of skeletons and ____ from dead sea animals.

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