Stonehenge: Facts & Theories About Mysterious Monument

By Owen Jarus, Live Science Contributor | September 15, 2014 12:59pm ET

A gloomy summer day at Stonehenge in southern England.

A gloomy summer day at Stonehenge in southern England

Stonehenge is an enigmatic prehistoric monument located on a chalky plain north of the modern-day city of Salisbury, England. It was started 5,000 years ago and modified by ancient Britons over a period of 1,000 years. Its purpose continues to be a mystery.

The biggest of its stones, known as sarsens, are up to 30 feet tall and weigh 25 tons on average. It is widely believed that they were brought from Marlborough Downs, a distance of 20 miles to the north. Smaller stones, referred to as “bluestones” (they have a bluish tinge when wet or freshly broken), weigh up to 4 tons and most of them appear to have come from the Preseli Hills in western Wales, a distance of 156 miles (250 km). It’s unknown how people in antiquity moved them that far; water transport was probably used for part of the journey. Scientists have raised the possibility that during the last ice age glaciers carried these bluestones closer to the Stonehenge area and the monument’s makers didn’t have to move them all the way from Wales.

Before Stonehenge:

Although construction of Stonehenge began about 5,000 years ago, the area appears to have been of symbolic importance for a much longer period of time.

As early as 10,500 years ago three large pine posts, which were totem poles of sorts, were erected at the site. Then around 5,500 years ago two earthworks known as Cursus monuments were erected, the longest of which ran for 1.8 miles. The purpose of these structures is unknown.

Construction of the monument:

No one knows why ancient people built Stonehenge, but it seems to have been arranged to face the midsummer sunrise and midwinter sunset.  Credit: Pete Strasser|

The building of Stonehenge started about 5,000 years ago with the creation of an earthwork enclosure. The presence of post holes suggests that either bluestones or upright timber posts were propped up on the site. In addition, archaeologists have found numerous cremation burials dating to this time and the centuries that followed. Recent research suggests that up to 240 people were buried in total, making Stonehenge the large Neolithic burial site in Britain.

Around 4,600 years ago construction ramped up with the erection of dozens of bluestones in a double circle at the site. This monument was not to last and by 4,400 years ago it had been replaced by something far grander.

The new structure had a series of sarsen stones erected in the shape of a horseshoe, with every pair of these huge stones having a stone lintel connecting them. In turn, a ring of sarsens surrounded this horseshoe, their tops connecting to each other, giving the appearance of a giant interconnected stone circle surrounding the horseshoe.

By 4,300 years ago this monument had been expanded to include the addition of two bluestone rings, one inside the horseshoe and another between the horseshoe and the outer layer of interconnected sarsen stones.

This would be the end of major construction at Stonehenge. As time went on the monument fell into neglect and disuse, some of its stones fell over while other were taken away.

A Walk Through Stonehenge

Significance to its makers:

Stonehenge at sunrise.  Credit: Simon Wyatt

There are numerous theories as to why Stonehenge was built. At the time it was made, people in the area were herders and farmers. They left no written records behind.

An “avenue” connecting Stonehenge with the River Aven is aligned with the solstice. In addition, research at the nearby ancient settlement of Durrington Walls, a site that also contains a series of wooden pillars, shows that pigs at the site were slaughtered in December and January, suggesting that the winter solstice was marked at Stonehenge.

The burials at Stonehenge offer another clue. Recent research indicates that the burials took place from its beginning, around 5,000 years ago, to its high point when the sarsen stones were set down. Among the burial goods is a mace head, an item historically associated with elite members of society. This discovery raises the question whether the people buried at the monument were local leaders and Stonehenge, in some way, commemorated them.

In 2014, scientists unveiled the results of a four-year survey of the landscape around Stonehenge. Using non-invasive techniques like ground-penetrating radar, the researchers detected signs of at least 17 previously unknown satellite shrines. People may have traveled considerable distances to come to Stonehenge, project leader Vincent Gaffney, an archaeologist at the University of Birmingham in the U.K., told Live Science. “It’s part of a much more complex landscape with processional and ritual activities that go around it.”

A Monument of Unification:

One new theory about Stonehenge, released in 2012 by members of the Stonehenge Riverside Project, is that Stonehenge marks the “unification of Britain,” a point when people across the island worked together and used a similar style of houses, pottery and other items.

It would explain why they were able to bring bluestones all the way from west Wales and how the labor and resources for the construction were marshaled.

In a news release, professor Mike Parker Pearson of the University of Sheffield said that “this was very different to the regionalism of previous centuries. Stonehenge itself was a massive undertaking, requiring the labour of thousands to move stones from as far away as west Wales, shaping them and erecting them. Just the work itself, requiring everyone literally to pull together, would have been an act of unification.”

Other work in acoustic archaeology, using Maryhill (which was built in the state of Washington to replicate Stonehenge) as a stand in for the now derelict Stonehenge, indicates the original structure created an environment similar to a lecture hall, with diffuse sound waves carrying sound throughout the monument and reverberation extending sounds by close to 1 second:

MysteryQuest – Stonehenge
Aired at 02:01 AM on Thursday, Dec 03, 2009 (12/3/2009)

A leading archaeologist and a research team traveled to Stonehenge to investigate the remains of humans buried there and also to investigate what the structure and arrangement of the ancient stonework reveals about prehistoric rituals at the site. Research, based on current technology, suggests that annual rituals conducted at Stonehenge would have been very effective in inducing trance among those who participated.

Research has shown that repetitive drumbeats can lower the brain wave frequencies. In these states, there may be a sense of presence associated with the awareness of spirits. Brain imaging research shows that sound alone can create altered states of consciousness.

What can make sound so powerful in a kind of ritualistic setting is that it can be very repetitious and rhythmic. The regularity of that helps to entrain the human mind so that we fall in sync with the music.

Ancient instruments have been re-created to replicate possible prehistoric rituals inside the circle, ceremonies that may have helped the ancient people believe dead spirits were present. People thousands of years ago lived in an oral culture, so oral from their mouths and aural from their ears. They didn’t live in a written culture and the culture rituals were passed on through speaking and listening.

Stonehenge is remarkable for the stones themselves: on one side, they’re quite rough. The other side is curved, and they’re curved in a way that seems only to have acoustic properties. And the circular arrangement creates a powerful echo that repeats and can actually change rhythms played inside the circle.

Here is a description of the research team in action:

00:03:56 He (the researcher) is using replicas of 4,500-year-old drums discovered by archaeologists in europe.
00:04:04 A highly sensitive multidirectional microphone and digital audio recorder will measure the response of the space.
00:04:11 >> These ones have decoration inside the foot, which would imply somehow someone has got to see it, maybe on a shoulder.
00:04:19 [drum beating] >> Very faint, but there’s an echo there.
00:04:25 >> It does sound different over there to over here, doesn’t it?
00:04:28 It’s astonishing.
00:04:29 Do you want to try it over here by what would have been the altar?
00:04:32 >> narrator: THE TEAM MOVES To where the main altar once stood.
00:04:36 [drum beating] >> Yeah.
00:04:43 >> There was a real patter echo off that.
00:04:45 We didn’t get that before.
00:04:46 >> You’ll keep going?
00:04:47 >> Yeah, absolutely.
00:04:48 >> You start. I’ll join in.
00:04:50 [drums pounding] There it is.
00:04:59 Can you hear it?
00:05:00 Stay there.
00:05:01 Try and play in time to it.
00:05:09 >> narrator: WHEN TILL AND WYATT Play at a certain speed, it sounds like the stones are playing the drumbeats back to the drummers.
00:05:17 >> It’s amazing, the echo.
00:05:19 You can hear the echo really clearly, can’t you?
00:05:20 Can you hear that pattering, that “taka-taka-taka”?
00:05:22 Once we started playing the repeated rhythm, the space seemed to interact with that and immediately build up.
00:05:30 >> narrator: THE TEAM MEASURES The frequency at which they are getting echoes from the stones.
00:05:35 >> We’re exciting this very low mode of vibration, this frequency, that you can’t hear unless you play it at the right speed.
00:05:42 So what happens is, once you start playing about the right speed, you start to hear these frequencies.
00:05:47 See, that’s about ten hertz.
00:05:49 That frequency is about the same frequency that alpha waves go at.
00:05:53 >> narrator: THE DRUMS ARE Playing at exactly the sound frequency needed to produce alpha waves in the human brain.
00:06:00 >> Alpha waves are one of the sorts of rhythms that the brain seems to fall into during times of relaxation.
00:06:10 Exposing people to rhythmic sounds can begin to put them into that kind of meditative state.
00:06:17 >> narrator: BY CREATING Alpha waves, repetitive drumbeats can actually create an altered state of mind.
00:06:24 >> Did you find yourself losing it?
00:06:25 I found myself drifting off, and then I started thinking, ” >> narrator: SOUND IS NOT The only clue to what went on at stonehenge.
00:06:39 Bones buried at the site may reveal a sinister story.
00:10:41 >> narrator:MYSTERY QUEST Is in england trying to unlock the secrets of one of the most famous mysteries in the world: Stonehenge.
00:10:55 Historians believe construction began at stonehenge as early as 3100 b.c.
00:11:02 But it continued for over 1,400 years as the monument was adapted and passed down from generation to generation.
00:11:14 It started off as a circular earthwork and ditch.
00:11:17 >> The first stones arrive– well, there’s a lot of argument about this at the moment– probably sometime around 2700 or 2600 b.c.
00:11:28 That’s the bluestones.
00:11:29 The bluestones are the first stones on-site.
00:11:33 >> narrator: STRANGELY, Bluestones originate more than 140 miles away at the preseli hills in Wales.
00:11:41 >> The people who built stonehenge must have been doing so for purposes that seemed very, very important to them at the time.
00:11:49 It was always a literally monumental undertaking.
00:11:53 A lot of the big stones come from wales, so transporting those for people who didn’t have the wheel has to have been an unbelievably difficult undertaking.
00:12:09 >> narrator: AROUND 2500 B.C., The bluestones were rearranged, and the larger sandstones were placed in a circle around them.
00:12:19 >> The really significant thing is that those stones are shaped.
00:12:22 They’re jointed together with these sort of mortise and tenon joints.
00:12:26 Each upright has protruding sort of knobs on the top of it that fit into hollows.
00:12:33 It looks like carpentry joints, but here they’ve done it in this very, very hard stone.
00:12:40 >> narrator: AMAZINGLY, 4,500 Years ago, the people who built stonehenge were applying carpentry skills to 40-ton boulders.
00:12:56 The monument appears to have been mysteriously abandoned sometime after 1000 b.c.
00:13:04 This prehistoric feat of engineering has baffled mankind for generations.
00:13:11 In the early middle ages, it was believed that the legendary wizard merlin built stonehenge with the help of giants.
00:13:20 In the 17th century, it was thought to be a roman temple dedicated to the gods of the sky.
00:13:29 But the first concrete clue was discovered in the 20th century when archaeologists realized the position of the sun dictated the monument’s orientation.
00:13:40 >> It clearly is aligned on the midsummer solstice and the midwinter solstice, the longest and the shortest days of the year.
00:13:52 >> narrator: WHEN STONEHENGE Was built, the ancient people of britain were beginning to live in larger communities, farming the land.
00:14:01 They relied on the seasons and marked their passing at stonehenge.
00:14:11 In 2005, an archaeologist named mike parker pearson made an astounding find a short distance from the site, one that shed further light on ancient seasonal rituals here.
00:14:22 >> At a village site that was in operation about the same time that one of the big building phases was going on at stonehenge, they found masses and masses of pig bones.
00:14:35 >> narrator: ANALYSIS OF The bones showed that they date to approximately 2600 b.c.
00:14:41 All the pigs were of a similar age and killed at the same time of year: Around the time of the winter solstice, a few days before our modern-day christmas.
00:14:54 >> It’s just the sheer quantity of pig bones that have been found there.
00:14:59 It looks like feasting.
00:15:06 >> narrator: AT THE STONE CIRCLE Itself, even more sinister clues were unearthed: Human bones, hundreds of them, primitively burned and buried.
00:15:18 >> The first analysis of all the cremated bones that were found at stonehenge suggests that it’s mainly adult males, adult men, that were buried there.
00:15:30 So it’s quite a distinctive group of people, and only probably very important people came there to be buried.
00:15:37 >> narrator: THE BONES WERE Dated across 1,000 years of prehistory, leading some experts to suggest that rituals here may have been organized to honor the dead of an ancient ruling dynasty.
00:15:50 But what were these rituals?
00:15:56 One full skeleton discovered at the site could provide clues.
00:16:01 >> There is a burial in the ditch: The man who’s known as the stonehenge archer.
00:16:07 This man was found at stonehenge quite close to the entrance.
00:16:11 He was buried with his stone wrist guard and a quiver of arrows.
00:16:16 The assumption was that he was an archer, but then somebody looked very closely at the arrowheads and realized that a lot have got their tips missing, and some of the tips are actually embedded in his bones.
00:16:31 So the arrows weren’t something that was put in his grave as grave goods.
00:16:35 They were actually the cause of his death.
00:16:40 >> narrator: THE ARCHER WAS SHOT With at least five arrows and buried in the most sacred monument of his time.
00:16:47 >> To me, the most informative of the bones in this person’s body is this one.
00:16:53 And this has got damage from a flint-tipped arrow, but it’s not on the outside.
00:16:58 It’s from the other side.
00:17:00 So what this means, this little tiny mark here, is that this man was shot from behind with an arrow that went right through his body cavity and lodged in the back of his breastbone.
00:17:12 >> narrator: THE EVIDENCE POINTS To the possibility of human sacrifice.
00:17:17 >> I can’t believe that he was simply a murder victim, because you would not bury somebody in the ditch at stonehenge if you just happened to kill them.
00:17:24 So he must have been somebody important.
00:17:28 >> narrator: THE SCIENCE TEAM Has devised a test that could reveal the archer’s true fate.
00:17:39 Barry keegan is a primitive technologies expert.
00:17:42 He makes prehistoric and ancient bows and flint-tipped arrows and is also an accomplished archer.
00:17:50 >> In prehistoric or ancient times, bows and arrows were certainly a part of daily life, an extension of oneself.
00:17:57 >> narrator: IF THE STONEHENGE Archer was a sacrifice, he would have been shot at close range.
00:18:03 For his test, keegan will fire at this bone from progressively closer distances and try to replicate the scarring found on the stonehenge archer’s breastbone.
00:18:17 The first shot is from 50 feet.
00:18:20 >> Doubt that it’s going to do much damage to the bone at this point.
00:18:35 [bow snaps] Hey, I think I hit it.
00:18:38 >> narrator: AND KEEGAN IS Right.
00:18:41 The arrow causes little damage from 50 feet.
00:18:44 >> The closer we get, the more damage it’s going to do.
00:18:48 >> narrator: THE NEXT SHOT ..
00:18:54 [bow snaps] >> That definitely hit.
00:19:05 >> narrator: 30 FEET…
00:19:08 [bow snaps] >> It looks like it broke in a couple of places.
00:19:14 >> narrator: AND FINALLY, At 20 feet.
00:19:17 [bow snaps] >> Wow, there is nothing left of that tip.
00:19:26 Wow, yeah, there’s a nice deep mark right there.
00:19:29 Yeah, right there.
00:19:30 This nick looks very much like the nick in the stonehenge archer’s sternum.
00:19:34 This is the shot from 40 feet, and this is the shot from 20 feet.
00:19:38 The flint arrowhead was probably better than anything else that was used.
00:19:42 It had the cutting ability.
00:19:43 It slices very much like a steak knife.
00:19:46 At 20 feet, the power of the arrow is certainly enough to do the kill.
00:19:50 Definitely not an accident.
00:19:52 >> narrator: THAT IS ABOUT The same distance between shooter and victim in a modern-day firing squad.
00:19:59 And there is further evidence to suggest this was an intentional killing.
00:20:04 >> If you look very carefully at the bones themselves and also the angle that some of the arrows have gone into them, what you realize is that he must have been lying almost flat on the ground.
00:20:16 If somebody’s standing upright, you cannot shoot an arrow into them at that angle.
00:20:21 It just doesn’t work.
00:20:28 >> narrator: THE EXPEDITION TEAM Has been investigating the theory that stonehenge was a temple used to commune with the dead.
00:20:36 But only around 40% of the original stones are still standing.
00:20:41 >> The difficulty with the stones being down is, it’s like trying to measure a cathedral’s acoustics when you’ve knocked the thing down.
00:20:49 There should be some of the same effects, but it’s not the same.
00:20:54 >> narrator: THE TEAM NEEDS TO Test the sound in stonehenge as if the site was still intact.
00:21:03 And there is a place to do this.
00:21:07 >> You could hear them starting to resonate one at a time.
00:24:40 >> narrator:MYSTERY QUEST Is investigating whether stonehenge could have been a temple for communicating with the dead.
00:24:50 The circle is missing many of its stones, but there is a full-size reproduction of the original intact monument.
00:25:01 It stands next to the columbia river in maryhill, washington.
00:25:08 Native son sam hill built it as his monument to the war dead from world war i.
00:25:14 It is the best approximation of what stonehenge would have looked like 4,500 years ago.
00:25:23 The team’s theory is that ceremonial drumming at stonehenge could have induced a trance in ancient humans, one that could have helped them believe dead spirits were present.
00:25:38 In many cultures, trance is used for the same purpose.
00:25:44 Voodoo rituals in haiti and parts of africa rely heavily on repetitive drumming to induce a trance.
00:25:51 In this state, participants believe that they become possessed by gods and can talk to the dead.
00:25:59 Experts now believe that drums are key in creating a mind-altered state.
00:26:05 >> The reason for that seems to be this general phenomenon of what is called entrainment.
00:26:10 When people are exposed to certain rhythmic stimuli, their brains drop into sync with that pattern.
00:26:18 That seems to be one of the reasons why they help people drop into meditative states.
00:26:24 If stonehenge really is a place where you’re getting the right kind of acoustic boosting, the echoes might have taken on a very unusual property.
00:26:38 >> narrator: THE TEAM BELIEVES That stonehenge may have amplified the drum rhythms, enhancing their effect on the human brain.
00:26:45 >> No one’s heard what stonehenge really sounded like for at least 3,000 years because it’s not been complete.
00:26:50 So we can hear what it sounded like and know how it would have felt to be in there.
00:27:00 So this is our dodie.
00:27:02 It’s a dodecahedron, a special speaker for acoustic measurements.
00:27:06 It’s got 12 sides, 12 speakers.
00:27:09 It sends sound in every direction.
00:27:14 This is the sound card.
00:27:15 This is going to communicate with the computer.
00:27:17 That then gets sent to the low-frequency speaker, and the high frequency gets sent to the dodie.
00:27:25 >> We’re going to play one sound at a time– one frequency, one note– and try and find the frequencies where things resonate and see if we can make the place ring like a wine glass.
00:27:39 >> narrator: IF THE TEAM Can find the point at which the space begins to vibrate with sound, or resonate, they will be able to create a drum track that may induce trance.
00:27:49 >> So this is the first mode.
00:27:51 [low-pitched frequency] >> narrator: THEY SWEEP THROUGH The different sound frequencies, called modes.
00:28:06 The first three modes do not produce the effect they are looking for.
00:28:13 >> That should be mode number four.
00:28:17 >> narrator: BUT AT MODE Number four, there is something different.
00:28:24 >> Volume at the center?
00:28:28 >> 92.5.
00:28:30 >> All right, just move on to the next one.
00:28:37 It’s just amazing.
00:28:39 So that’s 4.3 meters away.
00:28:42 61.
00:28:43 >> Okay.
00:28:47 >> So here I’ve moved maybe a meter away, and we’re at 75 decibels.
00:28:54 So it’s doubled in volume just by moving a meter.
00:28:56 Instead of getting quieter, it’s getting louder.
00:29:01 ..
00:29:05 >> narrator: THE SOUND DOESN’T Seem to decrease in volume the further you get from the speakers.
00:29:12 This is a sectional look at how this sound is traveling from the center of the circle to the edge.
00:29:18 The peaks show where sound is loudest and the valleys where the sound is distinctly quieter.
00:29:25 >> The sound seems almost magically to be carried across the space.
00:29:29 It moves around the space in a really unusual way.
00:29:37 [dramatic music] ♪ ♪
00:29:42 >> narrator: TO UNDERSTAND HOW Sound at stonehenge can affect the human brain, the science team will conduct an experiment using a brain imaging system , magnetoencephalography.
00:29:54 It measures the magnetic fields produced by electrical activity in the brain.
00:30:04 David poeppel a neuroscientist and one of the leading experts on how the brain processes sound.
00:30:10 >> Magnetoencephalography is particularly exciting because it’s so well suited to study hearing.
00:30:16 This is a machine that has 160 sensors placed all around your head, and then we play you auditory materials or visual materials, and we record your brain activity while you’re in there lying on your back surrounded by 160 tiny little sensors recording from your brain.
00:30:35 >> narrator: POEPPEL WILL PLAY Two sets of sounds to a 42-year-old male subject.
00:30:41 >> One kind of sound is crafted to simulate what may have been heard at stonehenge.
00:30:49 The hypothesis is that this particular kind of rhythm– that’s timing– and that reverberation will have a special effect.
00:30:58 >> narrator: FOR COMPARISON, The other sound is generic traffic noise.
00:31:02 [horns honking] >> All rightso we’re ready to play the sounds.
00:31:16 First the stonehenge reverb sound.
00:31:20 [percussive knocking] Okay.
00:31:29 And the traffic noise for comparison.
00:31:35 [horns honking] >> Okay, wayne, were you able to hear those sounds okay?
00:31:41 >> I can hear them fine, yes.
00:31:46 >> narrator: POEPPEL PLAYS The subject each sound 50 times.
00:31:51 He uses a map of the brain and an activity response graph to measure the reaction.
00:31:58 >> As soon as he hears the first traffic beep or the first stonehenge boom, the brain response is being recorded almost with no delays, about 1/10 of a second.
00:32:08 That’s roughly the speed of the brain as it responds to sounds.
00:32:12 And the top panel are the stonehenge sounds; bottom panel, street sounds.
00:32:17 You see these three waves of activation to the street sounds: Big and then down and big and then down and big and then down.
00:32:25 You don’t see that to the stonehenge sounds.
00:32:28 In the stonehenge sound, you have this regularity, right?
00:32:31 So you have the boom, boom, boom, the rhythm, so that regularity is in fact reflected in the brain response.
00:32:39 >> narrator: THE TRAFFIC NOISES Cause the subject to work hard to interpret the varied sounds.
00:32:45 They produce more brain activity.
00:32:51 When the subject listens to the stonehenge sounds, his brain adjusts its own rhythms to mirror the drumbeats.
00:33:01 >> That regularity is in fact reflected in the brain response.
00:33:04 This is the entrainment.
00:33:05 It suggests why the stonehenge type of sound makes you more relaxed or is more inducing to trance.
00:33:17 >> narrator: AT THE EXPEDITION Site, the team is about to re-create the ancient sounds of stonehenge.
00:33:23 [low rumbling tone] >> Can you hear the effect?
00:33:31 >> Yeah, absolutely.
00:33:32 It’s pretty amazing, really.