Hallmundarhraun, Borgarbyggð, Iceland
Surtshellir
Late 9th century into the 10th (bone piles after the lava cooled, read as rite or as shelter)
Surtshellir is a lava tube in western Iceland, named for Surtr, the fire-being the poems put at the world’s end. A 2021 study of 22 radiocarbon dates puts the eruption that opened the cave in the late 9th century, just after settlement, and reads piles of animal bone deep inside as repeated offerings until the conversion.
Why this is extraordinary
The lava of Hallmundarhraun is young enough that the first people in Iceland may have watched it burn. Surtshellir is one of the tubes it left. A 2021 model of 22 radiocarbon dates, set against the ash, puts the eruption in the late 9th century and the use of the cave in the decades after. The deposit is not at the mouth. It is nearly 300 metres in, more than 10 metres below the surface, where bone piles run for about 120 metres. The same model reads the activity as lasting at least 60 to 80 years and ending around the time the island converted. An earlier account of the dig had said 80 to 100 years. Both are published. They are not the same sentence.
Inside a stone enclosure the dig found burned bone, glass beads, and flecks of a yellow arsenic pigment that does not come from Iceland. Beside it, a larger pile of bone had been smashed and not burned. Sheep, cattle, horses, and pigs are in the fragments. Little soot on the ceiling, no latrine, and no ordinary cooking hearth were reported. That is a poor description of a house and a fair description of a place people visited on purpose. Lead pieces were read as a set of weights. A weight can close a legal act. It can also be lost.
The cave’s medieval name is Surtr’s cave. In the poems Surtr is the one who brings fire when the gods fall. A rite in a fresh lava tube, kept up until Christianity, is a reading that uses that name. The catch is that the poems were written down later than the oldest bone. People may have walked into the dark because they already feared Surtr. Later writers may have given Surtr a cave that herders or outlaws already knew. From the 18th century the place was told as a robbers’ cavern. Smashed bone can be marrow. It does not have to be a gift.
No measurement in these sources aims the mouth at a solstice. The sky in this room is the being in the name, not a notch on the lintel. The photograph is the collapse where you climb down into the tube, moss on the lava, a mountain behind. The bones are in the black beyond the frame. What this changes: if the offerings reading holds, settlement in Iceland included a long answer to a volcano, stopped at the conversion. If the shelter reading holds, the giant’s name is medieval literature on top of a hiding place, and the beads are the part still to explain.
Why it matters
If the bones are offerings, the first generations in Iceland answered a new volcano with a rite in the dark. If they are meals, the same cave is the hideout later writers already called it, and the poems were set on top of a shelter.
The lava field is given as about 240 square kilometres. The Viking Age deposit sits nearly 300 metres from the entrance and more than 10 metres under the surface. Bone piles run for about 120 metres. The statistical reading is that deposition lasted at least 60 to 80 years and stopped around the conversion to Christianity. An earlier account of the same dig spoke of 80 to 100 years. Beads, a yellow arsenic pigment matched to eastern sources, and lead pieces read as a weight set were found with burned bone inside a stone enclosure, while a larger pile of smashed, unburned bone lay beside it. Little soot, no latrine, and no ordinary hearth were reported. The medieval name is the sky reading that exists: Surtr, fire, and the end of the world in the poems. No azimuth from the mouth to a sunrise is published. The mouth in the photograph faces the open lava. The activity is in the dark beyond it.
Photo tour
1 photograph, unedited. On a phone, swipe the row. Choose one to look closely.
- The stone enclosure and the bone are not in the photograph. The frame is the collapse entrance and the lava.
What is still unexplained
These sit beside the consensus account, with the same visual weight. None of them is marked solved.
Location and dating
- Location
- Surtshellir, in the Hallmundarhraun lava field, Borgarbyggð, western Iceland. The pin is the cave, 64.782 north, 20.724 west. The deposit is inside, not at the collapse in the photograph.
- Period label
- Current consensus — open to revision The eruption is placed in the late 9th century. Bone deposition is read as the decades after that, ending around the conversion near the year 1000. The two published spans are at least 60 to 80 years, and 80 to 100.
- How this dating was done
- Radiocarbon on the bone, 22 dates in the 2021 model, with the volcanic ash as a second clock. The outlaw story is the cave’s reputation from the 18th century back into medieval writing.
- What could change it
- A published plan that ties each bone pile to one of the 22 dates would show whether the decades are continuous or a few visits. A chemical match of the yellow pigment, printed with the sample, would hold or drop the distant origin.
What is actually there
- The cave formed in an eruption placed in the late 9th century.
- The deposit is nearly 300 metres in and more than 10 metres down.
- Bone piles stretch about 120 metres.
- Burned bone and unburned smashed bone were kept apart.
- Beads and a yellow pigment from outside Iceland were in the enclosure.
- No sunrise azimuth of the mouth is published.
Open questions
| Question | Status |
|---|---|
| Were the bones offerings to stop a volcano, or food in a refuge? | Open. Distance, darkness, and exotic beads favour a rite. Smashed bone also favours eating. |
| Does the name Surtr date the belief to the first visitors? | Open. The name is medieval. The poems are later than the oldest bone. |
The current narrative
Where publication stands today. It is the best-supported reading, and it is open to revision. It is not a verdict.
The current narrative — open to revision
Repeated offerings in Surtr’s cave
After the eruption, people brought animals and valued objects into the dark for decades, a rite linked to Surtr, and stopped near the conversion.
What supports this
- Twenty-two radiocarbon dates and the ash put the activity after the lava cooled and before it fades near the conversion.
- The spot is far inside, with two ways of treating bone and with beads and pigment that travelled.
- The medieval name already gives the cave to a fire-being. A new lava tube is a literal fire-place.
What pushes back
- The poems were written down later. A name can be applied after the fact.
- Smashed unburned bone is also what a camp looks like when people want marrow.
- An earlier write-up of the dig used 80 to 100 years, and the 2021 model says at least 60 to 80. The length is still a model.
What would settle it
It is the centre because the place is a bad kitchen and a good setting for a repeated deposit, and the dates cluster before the conversion. It moves if the exotic objects are shown to be stray.
Emerging narratives
Other published readings. Each may be right. None is adopted here unless the evidence carries it.
An emerging narrative
A shelter that later received a giant’s name
People hid or camped in the new cave, ate the animals, and left. Surtr is the story medieval writers attached to a dangerous hole.
What supports this
- The cave’s reputation as a robbers’ cavern is old, and the mouth is a real refuge from weather.
- Marrow-smashed bone does not need a theology.
- A weight set can be property, not an offering that ended a cult.
What pushes back
- No latrine, little soot, and no ordinary living floor were reported, which is a thin outlaw camp for 60 years.
- Beads and imported pigment are a strange cache for a hideout and a familiar one for display.
- The activity’s end near the conversion is a coincidence if the cave was only a shelter. It is a date if the practice was religious.
What would settle it
It stays because the outlaw reading is the historical one and the bone really is smashed. It is not the centre while the cave shows so little sign of anyone living there.
Should the current view be reevaluated?
Open to revision
A new lava cave, bone for decades in the dark, and a medieval fire-being are a strong ritual case. The poems are later, the duration has two published spans, and the mouth is not a measured sunrise. Open keeps the rite and the shelter.
What drives this
- Twenty-two dates after a late 9th-century eruption, ending near the conversion.
- A deposit 300 metres inside, with exotic beads and two treatments of bone.
- A name, Surtr, whose poems are younger than the first bone.
This is the museum’s own weighing of the evidence. It is not a visitor vote, and it is separate from the slider.
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If the contested reading is right
What would follow if a reading that is not the consensus turned out to be true, and what could settle it. This explains the stakes. It does not adopt the reading.
The deposits were offerings while the volcano was still a living fear
The first century of settlement included a repeated rite in a lava tube, aimed at fire under the island, and the conversion cut it off.
Why it is still worth a test
The pigment’s source, published as a match, and a plan of which piles belong to which of the 22 dates.
Sources
- Ritual responses to catastrophic volcanism in Viking Age Iceland Journal of Archaeological Science, 2021, the radiocarbon model
- New publication on Surtshellir The museum note of the same study, for the 22 dates, the 240 square kilometres, and the 60 to 80 years
Image credits
- The collapse mouth of Surtshellir in the Hallmundarhraun lava. The bone piles are hundreds of metres inside, in the dark, not in this frame. . Rémih, CC BY-SA 4.0. Shown unedited.