Article | Iceland

Born of Fire, Home of Trolls

Iceland is often called the land of fire and ice, but what exactly does that mean? The country contains many unique geographical features. Learn more about how lava, glaciers, tectonic plates, and weather all combine to shape Iceland’s geology.
Troll shaped rock Iceland

© Jon Dudley

“When one’s life is conditioned by a landscape dominated by rocks twisted by volcanic action, wind, and water into ferocious and alarming shapes…the imagination fastens on these natural phenomena.” —B. S. Benedikz, "Basic Themes in Icelandic Folklore"

My imagination became fastened on Iceland’s natural phenomena when first I travelled there in 1986 to attend a geological conference, and then again many years later with Adventure Canada. As a geologist, I am excited by the stories of Iceland’s ongoing creation and the influence on its people. As a traveller, I am overwhelmed by the wondrous shapes and smells of lava and geothermal fields, interspersed with magnificent waterfalls and glaciers. Let me share some of this geologic story of Iceland, in hopes it may inspire you to experience some of it for yourself.

Iceland unknown bureaucrat sculpture

© Jon Dudley

Unknown Bureaucrat (1993), sculpture by Magnús Tómasson at Reykjavík's City Hall

As Charles Dickens once wrote in A Christmas Carol, let’s start with the big picture, which, “… must be distinctly understood or nothing wonderful can come of the story I am going to relate.”

Iceland was born of fire sixteen million years ago, at a place where tectonic plates diverge in the Atlantic Ocean.

World tectonic plate map

© Fathimahazara / Wikimedia Commons CC BY 4.0, arrows added

The earth’s crust is comprised of tectonic plates that are in constant motion. Iceland is located where the North American and Eurasian plates diverge, at a place called the Mid-Atlantic Ridge.

Lava creates the Mid-Atlantic Ridge which, for most of its length, is underwater. Iceland continues to grow as molten magma comes to the surface of the ocean floor.

Iceland magma diagram

© Domdomegg / Wikimedia Commons CC BY 4.0, labels added

One source of lava for the volcanic activity that builds Iceland comes from the diverging plates at the Mid-Atlantic Ridge.

So, you may be wondering, why is Iceland an island? The reason is that there is a hotspot centred under the island that provides an additional source of molten magma, fuelling Iceland's volcanic activity so that it can build itself above sea level.

Iceland hotspot 3 D diagram

© Cecily J. Wolfe / Nature

A hotspot related to a plume of heat from the mantle provides a second source of magma, helping build Iceland into an island. The plume is currently fuelling a new zone of volcanic activity in south-central Iceland.

The island of Heimaey is one example of Iceland’s new volcanic activity. In 1973, over 400 homes were destroyed by a lava flow, and it is a poignant place to visit.

Heimaey Iceland home filled with volcanic rock

© Jon Dudley

Heimaey, Iceland

The volcanic action on Iceland creates its many amazing features that so strongly influence Icelandic life and lore. (This is similarly true of the Faroe Islands, which were previously joined to Iceland and Greenland by a land bridge created by the same mantle plume. )

Lava, cooled into geometries of basaltic columns, are an inspiration to Icelandic architecture, including those of faith—perhaps a nod to the spirit of Earth’s underworld sweeping to the heavens?

Basalt columns and Reykjavic church

© Jon Dudley

Basalt columns at Reynisfjara black sand beach, and Hallgrímskirkja Lutheran Church of Iceland in Reykjavík

In the presence of glacial meltwater and rainy seasons, the many layers of lava flows create resistant ledges spawning magnificent waterfalls.

Iceland waterfalls godafoss

© Jon Dudley

Goðafoss Waterfall

Geothermal fields created from volcanically heated groundwater provide Iceland with all of its power and heating needs. Where the heated water comes to the surface, it creates otherworldly landscapes of vivid colour and acrid air from dissolved sulphur.

Iceland geothermal fields

© Jon Dudley

Námafjall Hverir Geothermal Area, near Lake Myvatn

In special places such as Dimmuborgir (whose name translates to “dark castles”), a lava lake boiled water in the marshy soil below, creating steam vents. After the lava lake drained, these became pillars and caves in the "ferocious and alarming shapes” referred to by B.S. Benedikz, which have inspired much Icelandic folklore. There are trolls frozen in place and living in the caves. Some of these tales once played an important role in deterring children from venturing into areas where they may become easily lost.

Iceland lava pillar

© Jon Dudley

Dimmuborgir, Lake Myvatn

I have loved my times in Iceland and with each visit feel a deeper appreciation for its earthly creations, its people, and its mystical souls born of fire. I invite you to see, smell, and hear it for yourself. The trolls are calling.

About the Author

Jon Dudley

Jon Dudley


Jon has been sharing stories of the land, as read from the rocks, as a career and passion for over forty-five years. He was for many years a member of the Adventure Canada expedition team, interpreting geology and providing a tune or two on Arctic trips. His degrees in geology (B.Sc. University of Toronto; Ph.D. University of Calgary) started a career as a professional geologist, which included fieldwork across Canada as well international locations such as Brazil and Iceland.

He is currently a Research Associate with the Arctic Institute of North America at the University of Calgary and an honorary member of the educational Burgess Shale Geoscience Foundation in recognition of his past service as a guide and Board Chair.