This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
The Quarterly journal of the Geological Society of London . PROCEEDINGS OP THE GEOLOGICAL SOCIETY June whatever but it was found to be quite poor nearly barren under neath the granite though pretty rich above it and the horse dividing the reef gradually widened again in depth whilst for good height above towards the second