it would have formed 390 million years ago during the caledonian orogeny, when the mantle crust would melt after an eruption, which may have measured a height of 3,000 meters (10,000 feet) almost the same height as mount etna in italy, and a diameter of 37 miles. during its last eruptions they could have been explosive and violent and the lava could have flowed up to branxton and flodden ridge while the pyroclastics flows up to coquetdale and ingram.