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Susivuori, Karijoki and Kristinestad, Finland

Susiluola

Perhaps the Eemian, about 130,000 to 100,000 years (stones in a cave, read as tools and as natural breakage)

Inside Susiluola in July 2008. The walkway and the mesh are modern. The disputed stones are not labelled in this frame. Roquai, Public domain. Shown unedited.

In 1996 a plan to empty a gravel-filled crack on Susivuori, for visitors, turned up stones that looked worked. Excavation from 1997 to 2000 found them in layers the diggers date to the Eemian, the warm interval before the last ice, roughly 130,000 to 100,000 years ago. If the stones are tools, they are the only Neanderthal artefacts in the Nordic countries. If they are natural, Finland’s ice-age archaeology is still empty.

Why this is extraordinary

Susiluola, the Wolf Cave, is a crack in the north side of Susivuori, on the border of Karijoki and Kristinestad. In 1996 the plan was to empty it for visitors. The gravel held stones that looked struck, and the emptying stopped. From 1997 to 2000 the dig opened about 25 square metres near the mouth and described seven layers of gravel. The four lower layers held the pieces in dispute. Ground radar made the crack about 30 metres deep and about 26 metres wide at the entrance. You duck in. The entrance is 1.4 metres high, at 116.5 metres above the sea.

How old is the floor? Feldspar from layers IV and V gave thermoluminescence and infrared dates around or just above 100,000 years. The excavators prefer the Eemian, the warm stage before the last ice, isotope stage 5e, because the sea rose over this hill and a soil formed in the way Eemian soils do elsewhere in Ostrobothnia. They also say the clock’s weak point is whether the sand saw daylight before it was buried. A grain that was not bleached looks older than it is. The top of the fill is much younger, shore gravel from the Ancylus lake, about 8,500 to 8,000 years ago. That is not the layer anyone is fighting about.

Are the stones tools? The dig report describes more than one way of breaking them, and it says red siltstone and a fine quartzite are not the ordinary local pebbles. Carrying rock is a human habit. The same report says layer V was put down by the sea, the pieces in it are water-worn, and they could be wash from activity beside the cave rather than a workshop on this floor. The patch they trust is a small old surface near the mouth, with burned stones at the rim. Critics say the scars are what frost and waves do, that the cave was a bad camp and perhaps underwater, and that without bone there is no person to name. The gravel is acid, so bone of that age was never likely. Absence is explained. It is still absence. The excavators list the natural ways a pebble gets a scar. They think the pattern, taken together, is still Mousterian. There is no instrument that ends that sentence.

No sunrise is published for the low mouth. The photograph is the interior in 2008, a boardwalk and wire mesh over the ceiling, pale rock on either side. None of those stones is captioned as a tool. What this changes: if the pieces are artefacts, people stood in western Finland before the last ice, and almost every other trace was planed away. If they are gravel, the Wolf Cave is a sediment trap, the scars are the shore’s, and the country’s ice-age human story still starts after the ice.

Why it matters

People in Finland before the last glaciation would push the human map onto ground that the ice later scoured clean. Stones cracked by waves and frost would leave that map where it was.

The cave is a crack in granodiorite. Ground radar gave about 30 metres of depth and about 26 metres of width at the entrance. The mouth is at 116.5 metres above the sea, and the entrance height is 1.4 metres. Seven gravel layers were described. The four lower ones held what the excavators call archaeological finds. Luminescence dates on feldspar from layers IV and V came out around or just above 100,000 years, the infrared signal a little younger than the thermoluminescence. The excavators still prefer the Eemian, isotope stage 5e, because a sea rose over the site and a soil formed, even though the glow dates sit nearer a later stage, 5c. They also say the zeroing of that glow, when sand is bleached by daylight, is the weak point of the clock. No Pleistocene bone survives. The bedrock and the gravel are acid. No sky alignment of the low mouth is published. The dispute is whether a stone was struck by a person.

Photo tour

1 photograph, unedited. On a phone, swipe the row. Choose one to look closely.

Inside Susiluola in July 2008. The walkway and the mesh are modern. The disputed stones are not labelled in this frame. Roquai, Public domain

What is still unexplained

These sit beside the consensus account, with the same visual weight. None of them is marked solved.

Open Tools, or beach gravel The excavators describe several ways of breaking stone, including a simple anvil technique on vein quartz, and they say red siltstone and fine quartzite do not occur as local pebbles the way ordinary quartzite does. A stone carried in is a clue that someone chose it. The same paper says layer V was laid by the sea and that its stones are abraded, so those pieces were washed in from activity somewhere near the cave, not necessarily knapped on this floor. Layer IV2, a patch of old ground near the mouth, is the horizon they call in place, with burned stones at its edge. Critics answer that the “tools” are geofacts, broken by waves, ice, and sediment movement, and that a rounded siltstone with chipped edges is what a beach does. The excavators themselves list frost, glacial water, and the shore as ways a pebble gains a fake scar. There is no machine that separates those scars from a hammerstone. The argument is the pattern, and the pattern is what the two sides do not share.
Open A cave under the ice, and no bones If the floor is Eemian, the cave then sat under a warmer climate than the ice age that followed, and a low passage could have been used. Critics have said the passage was a poor dwelling and that the shore may have stood over it at the time in question. The luminescence result near 100,000 years and the Eemian preference are not the same sentence. A date “around or just above 100,000” can be late Eemian or the cooler stage after it. Burned stones are evidence of fire if they were heated here. Fire in a cave can be a hearth or a forest burn washed in. No human bone, and no animal bone of that age, exists to name the visitor. Acid soil explains the absence. It does not replace a skeleton.

Location and dating

Location
Susiluola, on the north slope of Susivuori, at the border of Karijoki and Kristinestad, Ostrobothnia. The pin is the cave, 62.303 north, 21.661 east. Two more cracks nearby were still full of sediment when the main cave was dug.
Period label
Current consensus — open to revision The occupation is read as Eemian, with luminescence near 100,000 years and a geological preference for stage 5e. The topmost gravel is from the Ancylus lake phase, about 8,500 to 8,000 years ago, and is not the disputed layer.
How this dating was done
Thermoluminescence and infrared stimulated luminescence on feldspar, plus the sea level and a buried soil compared with other Eemian soils. Not radiocarbon. The tools are argued from scars, raw material, and context.
What could change it
A luminescence series that agrees with one isotope stage, on sand shown to have been fully bleached, would tighten the year. A blind test of the stones against beach gravel from the same hill would test the geofact reading without a new date.
Published ranges, drawn as bars. A bar is a claim about a span, not a point.
Luminescence, layers IV and VContested
130000 BCE115000 BCE100000 BCE
  • Luminescence, layers IV and V. Glow dates around or just above 100,000 years, and the excavators’ Eemian preference, which is older. One bar for a disagreement, not a single laboratory mean.

What is actually there

Open questions

Question Status
Are the stones tools? Open. Scars, burned pieces, and non-local rock favour hands. Beach gravel produces scars too.
Is the floor Eemian or nearer 100,000 years? Open. Geology prefers stage 5e. The glow dates sit younger, and bleaching is admitted as a problem.

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

Natural stones in a sediment trap

The crack collected beach and glacial gravel. The scars are natural. Nobody has to have lived here before the last ice.

What supports this

  • The excavators list frost, glacial streams, and the shore as processes that mimic tools, and they say layer V is secondary.
  • Critics find the pieces unlike convincing Neanderthal tools elsewhere, and they doubt the cave was even dry.
  • No human fossil exists. The absence is explained by acid, and it is still an absence.

What pushes back

  • A non-local siltstone is a fact about transport. Waves do not select a rock that the hill does not have, unless the pebble came from farther than the paper allows.
  • Burned stones on an in-situ patch are an odd kind of geofact.
  • “Natural” has to explain why the lower layers have the pieces and the upper shore gravels, in most of the cave, do not.

What would settle it

It is the centre because extraordinary arrivals need a stone that cannot be a pebble, and this cave is a pebble trap under an ice sheet. It moves if a scar pattern survives a comparison with the sterile gravel.

Emerging narratives

Other published readings. Each may be right. None is adopted here unless the evidence carries it.

An emerging narrative

A Middle Palaeolithic visit before the last ice

People, most plausibly Neanderthals, used the cave or its doorstep in the Eemian, and the stones are their tools.

What supports this

  • The excavators describe reduction methods that match early Mousterian habits, varied by the quality of the rock.
  • Some raw materials are not the local pebbles, so a person is the simplest way for them to arrive.
  • Burned stones sit at the edge of the one patch they call an undisturbed floor.

What pushes back

  • Layer V was deposited by the sea. Its artefacts, if they are artefacts, were washed in.
  • Luminescence is around 100,000 years and may be poorly bleached. The Eemian label is an interpretation on top of that.
  • Independent critics read the same pieces as geofacts, and there is no bone.

What would settle it

It is not the centre, because a cave full of gravel under an ice sheet has many ways to break a pebble, and the year is split. It stays because non-local rock and a burned floor are not what every beach produces.

Should the current view be reevaluated?

Open to revision

Susiluola is either the first human site in Finland before the last ice or a lesson in how shores break stone. The glow dates and the Eemian label disagree, the bone is gone, and both sides have published the difficulty. Open is the honest stance.

What drives this

  • Stones in layers IV and V, some of them non-local, some of them burned.
  • Luminescence near 100,000 years against an Eemian geological reading.
  • A geofact critique, and no Pleistocene bone.

This is the museum’s own weighing of the evidence. It is not a visitor vote, and it is separate from the slider.

Weigh it yourself

Anonymous. Nothing here is stored except on this browser. Your lean does not change the assessment beside it.

A Middle Palaeolithic visit before the last ice Unsure Natural stones in a sediment trap

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 stones are Middle Palaeolithic tools

Neanderthals, or some other pre-ice people, reached the eastern shore of the Gulf of Bothnia in a warm interval, and the ice afterwards erased almost every other trace.

Why it is still worth a test

A published comparison of the pieces with natural gravel from the same slopes, and a luminescence run whose bleaching is demonstrated.

Sources

  1. The lithic industry from layers IV–V, Susiluola Cave The excavation account of 1997–2000, luminescence and the Eemian reading
  2. Susiluola geology Karijoki municipality, eight layers described and fire in layer IV
  3. Artefact-geofact analysis of the Susiluola lithic material Fennoscandia archaeologica, the continuing argument over the stones

Image credits

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