The Organ Pipes, dark brown intrusive dolerite, near the Burnt Mountain, Kunene region, Namibia, Africa

Basaltic cliffs facing onto Raasay Sound, east coast of Skye, Trotternish, Isle of Skye, Inner Hebrides, Scotland, United Kingdom, Europe

Quiver tree forest (Aloe dichotoma) at sunset, Gariganus farm, Keetmanshoop, Namibia, Africa

Quiver tree forest (Aloe dichotoma) at sunset, Gariganus farm, Keetmanshoop, Namibia, Africa

Bamburgh Castle, a medieval fortress, Grade I Listed Building constructed on top of a craggy outcrop of volcanic dolerite, overlooking a cricket ground, Bamburgh, Northumberland, England, United Kingdom, Europe

Bamburgh Castle, a medieval fortress, Grade I Listed Building constructed on top of a craggy outcrop of volcanic dolerite, overlooking a cricket ground, Bamburgh, Northumberland, England, United Kingdom, Europe

Bamburgh Castle, a fortress constructed on top of a craggy outcrop of volcanic dolerite in the Middle Ages, now a Grade I Listed Building, Bamburgh, Northumberland, England, United Kingdom, Europe

Bamburgh Castle, a hilltop fortress constructed on top of a craggy outcrop of volcanic dolerite, Grade I Listed Building, Bamburgh, Northumberland, England, United Kingdom, Europe

Jacob's Ladder, Ben Lomond, Ben Lomond National Park, Tasmania, Australia, Pacific

Quiver tree forest (Aloe dichotoma) at sunset, Gariganus farm, Keetmanshoop, Namibia, Africa

Unusual rock formations, Giant's Playground, Keetmanshoop, Namibia, Africa

Quiver tree forest (Aloe dichotoma) at sunset, Gariganus farm, Keetmanshoop, Namibia, Africa

Unusual rock formations, Giants Playground, Keetmanshoop, Namibia, Africa

Dolerite cliffs near Rowallan that typify the glacially scoured landscape of The Walls of Jerusalem National Park, the north, Tasmania, Australia, Pacific

Gerduberg basalt columns in Snaefellsnes; Iceland