This period represents over 4,500 million years of the Earth's history from the point of its formation to the appearance of the first animals with shells, roughly 600 million years ago.
Warwickshire's oldest rocks belong to the latest part of this period and provide evidence for volcanic eruptions along the edge of an ancient ocean. The rocks originated as sheets of molten material injected under pressure into earlier rocks and layers of ash thrown out of volcanoes to fall into the surrounding seas. Today, the rocks are amongst the toughest to be found in the county and have been quarried for aggregate.
Rocks of this type are found only along the Nuneaton Ridge. |