Earth & Conservation

Stonehenge: Easier Done Than Said

How hard could it have been for prehistoric Britons to move stones the size of dump trucks?

How did prehistoric Britons manage to move Stonehenge's stones? Each rock weighed an average of 25 tons and stood as tall as 30 feet, and the first tractor was still five millennia away, so clearly they must have endured great pains to build the monument, right?

Much of the mystery around the site comes from the questions of how Stonehenge was built and why. A recent experiment by archaeologists at University College London provides a hint to that first part anyway.

As back-breaking a task as building a monument of dump truck-sized stones without the aid of modern machinery might seem, the demonstration held in London's Gordon Square suggests it wasn't that difficult at all.

Superhenge Found Buried Near Stonehenge: Photos

Last week, University College London doctoral candidate Barney Harris put out a call for volunteers to see how many people it would take to pull a stone about half the size as the smallest rock at Stonehenge, which is about one metric ton. Harris anticipated it would take a team of at least 15 people to move the stone, and as many as 40 to 50 to lift it.

Instead, 10 people were able to get the stone going at a rate of roughly 10 feet (3 meters) every five seconds, or around one mile (1.6 kilometers) per hour. A team twice the size would be able to move a small piece of Stonehenge.

Devoting the kind of human capital needed for what may appear to be a frivolous effort for a Neolithic society isn't all that far-fetched considering settlements in the area at the time numbered in the thousands, so there were plenty of other members of the society to carry on with the more life-sustaining activities, such as farming, hunting or child-rearing.

Video: Could a Bronze Age Skeleton Solve a Stonehenge Mystery?

Made of rope, a wooden track and a sycamore sled, the design of the rig used in the experiment mirrors others found throughout the ancient world. "We know that pre-industrialized societies like the Maram Naga in India still use this kind of sledge to construct huge stone monuments," Harris told The Telegraph. "And similar y-shaped sleighs have been found dating back to 2000 B.C. in Japan which we know were used to move megaliths."

Recreating even at a small scale how the rocks used at Stonehenge were transported can provide researchers an estimate of how long it took to complete the entire site.

Beginning around 5,000 years ago, the first stones were lain at Stonehenge. The monument was built in two phases with two different kinds of stones. The largest stones are called sarsens, a local sandstone, placed around 2400 B.C. The circle of rocks at the center, known as bluestones, were erected 500 years earlier, around 2900 B.C.

Giant Rock Sphere Linked to Mysterious Civilization?

Neolithic people quarried the slabs of bluestone in Preseli hills in Pembrokeshire, Wales. The builders then transported the rocks 140 miles (225 kilometers), through steep and uneven terrain, to the site of the monument in Wiltshire, England, reported a separate University College London study last year. The system devised in the most recent experiment works well over these rough patches and without the aid of livestock.

Knowing how ancient builders could have constructed Stonehenge does take a little mystery out of the site. But if nothing else, Stonehenge still stands as a marvel of ancient ingenuity, erected by people smart enough to make the effort as easy on themselves as possible at the time.

A row of huge stones stood some 4,000 years ago just two miles from Stonehenge, dwarfing the iconic stone circle. Dubbed "Superhenge," the site is five times bigger than the iconic stone circle and lies buried three feet beneath a thick, grassy bank at a Stone-Age enclosure known as Durrington Walls.

PHOTOS: Stonehenge Made to Glisten

"We're looking at one of the largest stone monuments in Europe and it has been under our noses for something like 4,000 years," Vince Gaffney, chair in Landscape Archaeology and Geomatics at the University of Birmingham, said. "We don't think there's anything quite like this anywhere else in the world. This is completely new and the scale is extraordinary," he said. Gaffney announced the finding at the opening of the ongoing British Science Festival.

Understanding Stonehenge: Two Explanations

Image: Artist reconstruction of the standing stones at Durrington Walls.

Lesser known than Stonehenge, Durrington Walls was the site of a large Neolithic settlement and later a henge enclosure measuring 1,600 feet in diameter. It is surrounded by a ditch up to 57 feet wide and an outer bank about 131 feet wide and three feet high. The henge, thought to have been built around 4,500 years ago, surrounds several smaller enclosures and timber circles, yet no one had imagined it concealed the massive stone structure, as shown by the yellow circles in the picture.

PHOTOS: Intricate Treasures From Stonehenge Burial

Image: The route of the stone row (yellow circles) at Durrington Walls.

The massive prehistoric site was identified by the Stonehenge Hidden Landscapes international team, led by Birmingham and Bradford Universities and Austria's Ludwig Boltzmann Institute. The five-year project, which is the largest geophysical survey ever undertaken, used advanced geophysical technologies such as powerful ground-penetrating radar, which can detect buried features to a depth of up to 13 feet.

Image: Running the radar near Stonehenge.

Stonehenge Was Once A Complete Circle

The remote sensing technologies revealed evidence of a row made up of 90 standing stones, some of which may have originally stood up to 15 feet high.

Image: Green circles show the position of the stone row.

Stonehenge 'Smiley Face,' Other Features Detected Underground

At some point, the stones were deliberately pushed over and covered with a huge bank of earth and chalk, under which they still lie. "In the east up to 30 stones, measuring up to size of 15 feet, have survived below the bank whereas elsewhere the stones are fragmentary or represented by massive foundation pits," co-director Wolfgang Neubauer of the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology, said.

Image: A rendition of the superhenge after the stones were pushed over and buried under a bank of earth and chalk.

The archaeologists concluded that the huge stones were part of a C-shaped Neolithic arena that faced directly towards the Avon River. The finding, according to co-director Gaffney, has significant implications for our understanding of Stonehenge and its landscape setting. "Not only does this new evidence demonstrate a completely unexpected phase of monumental architecture at one of the greatest ceremonial sites in prehistoric Europe, the new stone row could well be contemporary with the famous Stonehenge sarsen circle or even earlier," Gaffney said.

Image: A rendition of the Durrington Wall's horseshoe.

Photos: Intricate Treasures From Stonehenge Burial

It's not yet clear whether or not the buried stones will be excavated. "Archaeological excavations may play an important role in proving these findings. We will await any academic proposals and consider them," an English Heritage spokesman told The Guardian.

Image: The buried stones.

Swedish Stonehenge? Stone Structure Spurs Debate

Previous intensive study of the area around Stonehenge had led archaeologists to believe that only the enigmatic stone circle and a smaller henge at the end of the Stonehenge Avenue had significant stone structures. The new findings show Stonehenge wasn't standing in splendid isolation on the edge of Salisbury Plain. On the contrary, it was the center of a large and rich ceremonial landscape. "Everything written previously about the Stonehenge landscape and the ancient monuments within it will need to be re-written," Paul Garwood, the principal prehistorian on the project at the University of Birmingham, said.

Image: A close up of stone circle at Stonehenge.