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Stonehenge‘s Bluestones: Enduring Mysteries of Megalithic Mastery

The towering sarsen trilithons of Stonehenge are an iconic and awe-inspiring sight – but some of this stone circle‘s most intriguing features are its smaller, unassuming megaliths known as "bluestones". Clustered within the heart of the monument among the giant sarsens, these stones have a remarkable story that speaks to the ambitions, skills and cultural significance of Stonehenge to Neolithic people.

Blueprints of the Bluestones

Stonehenge‘s bluestones are a collection of around 43 igneous rocks, including 27 spotted dolerites, 2 different types of rhyolite, a single example of calcareous ash, and 13 sandstones. Estimates suggest there may have originally been closer to 80 or more bluestones erected at the site.

The term "bluestone" comes from the stones‘ bluish tinge when wet or freshly broken. It‘s most often used to refer to the spotted dolerites, but has become a catch-all name for all of Stonehenge‘s non-sarsen stones. These range in size from just a couple feet to over 8 feet long and 4 feet wide, weighing between 2 to 4 tons each.

What‘s most remarkable about the bluestones is where they came from. In the 1920s, geologist Herbert Henry Thomas recognized the spotted dolerites as a close match to rock found in the Preseli Hills of Wales‘ Pembrokeshire peninsula, over 140 miles away. This was a staggering distance to transport megaliths in the Neolithic era some 5,000 years ago.

Preseli Provenances

Subsequent studies have confirmed a number of specific quarry sites or "provenances" for the bluestones within the Preseli Hills and surrounding area:

Stone Type Quarry Site Location
Spotted Dolerite Carn Goedog Preseli Hills
Spotted Dolerite Carn Gyfrwy Preseli Hills
Spotted Dolerite Cerrig Marchogion Preseli Hills
Rhyolite Craig Rhos-y-felin Near Pont Saeson
Volcanic ash Carn Breseb Preseli Hills

The famous "Altar Stone", a green sandstone slab lying flat within the circle, has been suggested to come from the Senni Beds formation near the Brecon Beacons, even farther east.

Archaeological excavations at quarries like Carn Goedog and Craig Rhos-y-felin have uncovered evidence of Neolithic stone-working, such as wedges, platforms, and discarded stone flakes and chips. Some partially-worked monoliths were found that seem to have been left behind. Dating of charcoal and burnt hazelnuts at the sites indicates activity around 3000 BCE, suggesting that initial quarrying and transport of the bluestones to Stonehenge likely began around this time.

Monumental Undertaking

So how did Neolithic Britons transport these multi-ton stones nearly 200 miles from Wales to Salisbury Plain? There are a few possible scenarios:

  1. Overland all the way, a journey of 140 miles as the crow flies (but longer with real terrain)
  2. By sea, a voyage of 250+ miles involving the treacherous waters around Land‘s End
  3. A combination of overland and sea legs utilizing river valleys and short sea crossings

The third option is considered most likely given the rugged terrain. Archaeologist Mike Pitts has proposed a route involving hauling the stones on sledges down the Taf and Tywi river valleys to the Bristol Channel, crossing the channel by raft or boat, then continuing up the River Avon and overland to Salisbury Plain.

Other theories for the final overland leg in Wiltshire suggest the stones may have come up the River Wylye or followed an ancient trackway marked by the current path of "The Avenue", remnants of parallel banks leading to Stonehenge.

Whichever exact route, it would have been a monumental undertaking. Experimental archaeology has demonstrated how sledges, rollers, ramps and levers may have been used to transport the stones.

In one experiment, a 4-ton bluestone was hauled on a wooden sledge by a team of 60 people. They used log rollers to slide the sledge over, with extra people to retrieve and replace the rollers as the sledge passed. Smaller teams pulled ropes on each side to steer. Progress was slow – just 1.5 miles per day on flat ground, less on hills. From this, the experimenters estimated a single stone‘s journey could have taken nearly a year with over 200 people working in relays.

Given the distances and challenges involved, the bluestones were likely transported and erected in multiple phases over centuries, not all at once. Still, it would have been an immense coordinated effort requiring great planning, engineering and social organization.

Meaningful Megaliths

What would drive Neolithic people to undertake such a difficult, dangerous and time-consuming venture? The bluestones must have been imbued with profound meaning and significance to Stonehenge‘s builders.

One theory suggests they were believed to have magical or healing properties, as Preseli means "place of the dead" and local folklore attaches mystical powers to the region‘s springs. Geoffrey of Monmouth wrote in the 12th century that Merlin magically transported the stones from Ireland for their healing powers. Perhaps a similar belief drew the Neolithic builders to the distant Preseli Hills.

Another idea is that the stones represent the ancestors of different groups, brought together as a symbol of unity. The act of transporting them would have required many people cooperating across a wide area, fostering social cohesion.

Some researchers believe the bluestones originally formed an earlier stone circle in Wales that was dismantled and moved to Salisbury Plain to be incorporated into Stonehenge. This could have represented a literal and symbolic relocation of a sacred site.

Whatever the reason, the bluestones were clearly essential to Stonehenge‘s design and purpose. They are placed most prominently within the monument and its earliest phase, known as Bluestonehenge or Stonehenge I, consisted of a ring of 56 bluestones.

Ever-Evolving Enigma

Over a span of 1500 years, through the efforts of many generations, Stonehenge was continually expanded and modified into an increasingly sophisticated complex. By 2500 BCE, the sarsen trilithons and outer sarsen circle had been erected, with the remaining bluestones rearranged within them.

Further changes included the digging of surrounding ditches and pits, the raising of an earthen avenue, and the construction of a slaughter stone, altar stone and heel stone. Hundreds more stones were added at Durrington Walls and Bluestonehenge, other monuments in the Stonehenge sacred landscape.

What ultimately inspired and guided this incredible cumulative work is largely lost to time. Despite extensive archaeological investigation and research, there are limitations to what we can ever know for certain about Stonehenge‘s deepest-held secrets and the intentions of its Neolithic architects.

Like the cultures that built them, the actual purposes and meanings attached to the stone circles very likely shifted and evolved over their many centuries of use and alteration. How they were understood and used by later generations may have been quite different from the original conceptions.

Still, the enduring power and magnetism of this magnificent and perplexing monument is a testament to the remarkable vision, skills and convictions of our Neolithic ancestors. In their precise placement and alignment of each stone, their incredible feats of engineering and transport, and their sheer dedication to a project spanning lifetimes, we see an civilization capable of complex cooperation and abstract thinking, with a rich sense of shared identity, cosmic wonder and connection to their environment.

The mysteries of the bluestones and Stonehenge may forever inspire more questions than answers, but the stones themselves stand as an eternal tribute to the exceptional abilities and aspirations of their builders – a civilization dreaming in stone, building for the ages.