Northward view over the environment in which the rocks of the Avon Group (Lower Limestone Shales) formed around 359 million years ago. Shallow shelf sea with low lying land to the north fringed by barrier islands enclosing clear shallow water lagoons.

The rocks of the Avon Group represent a time of marine transgression, when marine conditions gradually took over from the terrestrial conditions of the time represented by the Tintern Sandstone rocks of older age, below the Avon Group rocks. The rocks of the Avon Group consist of beds of limestone, mudstones and some thin sandstones and conglomerates. The mudstones would be deposited when and where the sea water was carrying more fine sediments, with the limestones forming during periods of clearer water.

Below a southward facing view over the shelf sea of the Avon Grouo time.

Aerial view of the typical setting in which the Avon Group rocks formed in the area of the Voyage around 359 million years ago.