Specific Stonehenge quarries identified by new research

Findings from a team of British
archaeologists, announced this week in the journal Antiquity^[1], shed light on how some
of Stonehenge’s monoliths were extracted and
transported.

In an announcement Monday, the team said
it found extensive evidence of Neolithic stone quarrying at two
sites in Wales that supplied the distinctive ‘bluestones’ erected
at Stonehenge around 5,000 years ago. Forty-three bluestones
survive out of an estimated 80 that once stood at Stonehenge; they
form an inner horseshoe at the site, surrounded by the outer circle
of much larger giant sandstone monoliths. By dating and studying
artifacts from the quarries, the archaeologists have determined
when and how prehistoric people first extracted these
bluestones.

The Welsh quarries are located in the
Preseli hills in north Pembrokeshire, roughly 180 miles (290 km)
from Stonehenge by land. The bluestones weigh 1-2 tons and are up
to 8 feet tall.

The stones are volcanic and igneous rocks with precise
geological signatures that match the inner horseshoe of smaller
rocks at Stonehenge. Geologists have shown that this region of
Wales is the only part of the British Isles that contains a
particular type of rock—spotted dolerite—common in the
bluestones.

Archaeologists have uncovered stone tools, dirt ramps and
platforms, burnt charcoal and chestnuts, and an ancient sunken road
that was likely the exit route from the quarry.

“While we knew the locations where the rocks originated, the
really exciting thing was to find actual quarries,” says Michael Parker
Pearson^[2], director of the project
and a professor at University College London. “They built extensive
facilities here: platforms, ramps, a loading bay. You can see
chisel marks where they drove in wooden wedges at the recesses on
the outcrop.”

Radiocarbon dates from charcoal and burned hazelnuts at
prehistoric campfires show Neolithic activity at the quarries
between 5,400 and 5,200 years ago. Researchers believe that
Stonehenge was not built before 5000 BC. This raises a puzzling
question: where were the stones during those 400 years?

“It’s intriguing,” Parker Pearson says, “and while it could’ve
taken those Neolithic stone-draggers nearly 500 years to get them
to Stonehenge, that’s pretty improbable. It’s more likely that the
stones were first used in a local monument somewhere near the
quarries that was then dismantled and dragged off to
Wiltshire.”

Naturally forming rock pillars at the quarry sites made things
somewhat easier for the prehistoric workers. “They only had to
insert wooden wedges into the cracks between the pillars and then
let the Welsh rain do the rest by swelling the wood to ease each
pillar off the rock face,” says Dr. Josh Pollard of the University
of Southampton. “The quarry-workers then lowered the thin pillars
onto platforms of earth and stone, a sort of ‘loading bay’ from
where the huge stones could be dragged away along trackways leading
out of each quarry.”

Eighty of the bluestone monoliths were eventually transported to
Stonehenge. Moving two-ton monoliths across nearly 200 miles of
countryside is an extraordinary undertaking, but examples from
India show that stones this size can be carried on wooden lattices
by groups as small as 60 people.

Removing the stones from the quarries required a combination of
strength and ingenuity. The narrow width of the exit pathway—only 6
feet (1.8 m) across— is too small to accommodate the use of wooden
rollers. Archaeologists believe that workers used a combination of
ropes, levers, and a fulcrum to position the stones on top of
wooden sledges that were carried or slid downhill. “You need two
teams,” says Parker Pearson, “one on the top with a rope taking the
strain and lowering it slowly and another, standing roughly 3 feet
lower, ready to receive it.”

Though the workers at the site likely ate a diet of mostly meat,
no bones or antlers have survived because of the area’s highly
acidic soil. What does survive is evidence of snacks on roasted
chestnuts, a staple of the Neolithic diet. Parker Pearson thinks
that a group of at least 25 workers did the quarrying, probably
walking to the site each day from nearby settlements.