
Basalt, the Edinburgh volcano

This was one of many active volcanoes in the central Scotland Rift Valley during the Devonian and Carboniferous periods (around 300 to 400 million years ago), whose remains now form hills along the edges of the Scottish Lowlands.
The Edinburgh Volcano

1. Salisbury Crag - an ancient sill
2. Arthur’s Seat - core of the volcano
3. Castle Hill - a volcanic plug, once the vent of a parasitic cone
