Ordnance Survey Benchmarks at Stonehenge

18 11 2016

Amongst all the various carvings on the stones at Stonehenge, from the modern graffiti of the 17th to the 20th century and the ancient axe heads and daggers from about 1700BC, there are three that are not often noticed.

These are the Ordnance Survey (OS) benchmarks.

The OS website says: “Bench marks are the visible manifestation of Ordnance Datum Newlyn (ODN), which is the national height system for mainland Great Britain and forms the reference frame for heights above mean sea level.”

The original reference datum levelling survey was begun in Liverpool in 1840 using a benchmark on St. John’s Church, and in 1844 it was changed to the tidal pole in Victoria Dock. The reference Mean Sea Level (MSL) for the datum was established over a nine day period of tidal observations.

A second levelling survey was carried out in 1912-21 and the datum was changed to MSL at Newlyn in Cornwall. In the 1950s a third survey was performed, still making use of the Newlyn datum.

The OS benchmarks at Stonehenge are in the traditional form of three lines / | \ beneath a horizontal bar which is the indicator of the reference height above the datum’s MSL at that spot.

stone-16-annotatedCoincidentally, this is a similar form to that of the Druidic “Awen” emblem which also uses three lines / | \  but positioned below three dots rather than a horizontal bar. See https://en.wikipedia.org/wiki/Awen for the history and an explanation of this symbol.

At Stonehenge two of the benchmarks are on the Heel Stone and one is on Stone 16.

Stone 16 is the tooth-like stone at the southwest side of the monument directly behind the tallest stone on the site, and the benchmark is low down on the left of the southeast face.

 

This references the Newlyn datum, is 103.114m above MSL and was last verified in 1957.

The Heel Stone is the massive leaning stone some 80m northeast of the stone circle which famously (but only roughly) indicates the position where the sun appears on the horizon at the summer solstice as seen from the centre of the stone circle.

Its benchmarks are low down on the right hand side of the northeast faceheelstone-annotated

The upper one references the original Liverpool datum, is 101.346m above MSL and was last verified in 1900.

The lower one references the Newlyn datum, is 100.7m above MSL and was last verified in 1957.

From the Newlyn benchmarks, you can work out that there’s a drop of 2.414m from the one on Stone 16 to the one on the Heel Stone.

None of these benchmarks are visible from any of the visitor paths around the monument, although if the light is right (early morning or evening in summer) the upper one on the Heel Stone can just be made out from the National Trust field.

To see them properly you’ll need to come to one of the Managed Open Accesses at the solstices or equinoxes.

Alternatively, you can book a private Stone Circle Access visit which take place most days of the year before and after regular opening times.

STONE CIRCLE ACCESS

Stone Circle Access visits, give you a unique opportunity to experience up close this world famous monument. The visits take place outside of our normal general admission opening hours and are subject to very limited availability. Please note that this is not a guided tour, and touching of the stones is not permitted.  You can try Stonehenge Guided Tours for these special access tours

Article by guest blogger and local Stonehenge historian Simon Banton

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Biggest full moon for 60 years! At Stonehenge and in the UK #Supermoon

14 11 2016

STARGAZERS at Stonehenge and around the world are looking forward to catching a glimpse of the biggest supermoon in nearly 70 years.

Tonight’s supermoon will be particularly large because it is the first time that the full img_4552moon has come this close to Earth since 1948.

Make sure you look up to the night’s sky this evening because there will not be another supermoon as big and bright as this one until 2034.

The best time to see Monday’s supermoon in the UK will be at around 4.45pm – but a sighting will depend on the weather.

But the moon will actually be at its closest – 356,509km away – at 11.21am this morning.

NASA said that the biggest and brightest moon for American stargazers will be on Monday morning just before dawn.

A Met Office spokesman said: “Monday evening and overnight Monday night is the best chance to spot it in Europe.”

Although the sky may be cloudy in Wiltshire, he said that there are likely to be cloud breaks.

What is a supermoon?

Ever looked up at the night sky to see a full moon so close you could almost touch it? Well done, you’ve spotted a supermoon.

The impressive sight happens when a full moon is closest to Earth. It orbits our planet in an oval shape so sometimes it comes closer to us than at other times. To us Earth-lings, the moon appears 30 per cent brighter and 14 per cent bigger.

By the way, supermoon is not an astrological term. It’s scientific name is perigee-syzygy, but supermoon is more catchy, and is used by the media to describe our celestial neighbour when it gets up close.

Astrologer Richard Nolle first came up with the term and he defined it as “… a new or full moon which occurs with the moon at or near (within 90 per cent of) its closest approach to Earth in a given orbit”, according to earthsky.org.

How can I see it? 

The best time to view it in the UK will be when the sun is setting in the late afternoon. The closer to the horizon it is, the bigger it will appear.

Pick a place with the least light pollution. Paul Thomsett, chairman of the South East Kent Astronomical Society said: “As long as the skies are clear and you have a good view to the south you will have no trouble seeing our nearest celestial neighbour blazing in the night sky.”

The Stonehenge Guided Tour Company offer Stonehenge ‘Full Moon’ walking tours with a local astronomer and Stonehenge expert

Full Moon (SuperMoon) Links Links:
What is a supermoon, when can I see the largest moon in 69 years and will it be cloudy where I live? (Telegraph)
Watch the Moon rise at Stonehenge with local astronomer tour guide (The Stonehenge Guided Tour Company)
‘Supermoon’ viewers to get closest glimpse since 1948 (BBC)
Catch a glimpse of the biggest supermoon for 70 years in the UK TONIGHT (Express)Full Moon Rise at Stonehenge:  (Silent Earth Blog)

“Weather permitting it will be visible without the need for a telescope in Wilsthire.”

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Celebrating 30 Years of World Heritage at Stonehenge and Avebury on 19th November 2016 #WHS30

12 11 2016

This year Stonehenge and Avebury World Heritage Site is celebrating 30 years since its inscription on to the World Heritage list in 1986.  A number of events are taking place throughout this year.

whs-s

The Stonehenge and Avebury WHS Coordination Unit, with the support of their partners, is holding a 30th anniversary conference on 19 and 20 November 2016 to celebrate the many aspects of the World Heritage Site and the gains made over the past 30 years.

On Saturday 19 November in the Ceres Hall, the Corn Exchange, Devizes, a number of speakers including Dr Serge Cassen (University of Nantes), Dr Alison Sheridan (National Museums of Scotland), Dr Heather Sebire (English Heritage), Prof Tim Darvill (University of Bournemouth), Dr Josh Pollard (University of Southampton), Prof Vince Gaffney (University of Bradford) will be joining us to examine developments in conservation, changes in our knowledge through research and archaeology, the impact on culture and how Stonehenge fits into the European and British culture at that time.

CONFERENCE FINAL PROGRAMME

There will be a panel discussion to think about what advances in our knowledge there might be in the next 30 years as well as opportunities to find out about the work of the key partners in helping to manage the World Heritage Site.

On Sunday 20 November there will be limited opportunities for delegates to attend exclusive expert led tours to both Stonehenge and Avebury and to The Salisbury Museum and Wiltshire Museum to explore their related collections.

Tickets are open to all and must be booked in advance through Eventbrite.

This event is supported by Historic England and Wiltshire Council

There’s still time to book your tickets for the conference on 19th November.

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The Stonehenge Bluestones.

7 11 2016

The bluestones at Stonehenge are the smaller rocks you can see standing inside the huge sarsens that form the outer circle and the inner trilithons.

Stone 62.jpgThey range in size from stumps barely visible in the turf through to slender pillars standing nearly 2.5m tall (plus another metre or more below gound) with the largest weighing between 2 and 3 tonnes.

These rocks definitely come from the Preseli Mountains in southwest Wales, 150 miles from Stonehenge as the crow flies. Their place of origin was first established in 1923 by the geologist H. H. Thomas and has been confirmed by modern geochemical analysis. They used to be known as the “foreign stones” because it was recognised that they weren’t local to the Stonehenge area.

The name bluestone is a collective term and there are two main types – spotted dolerite and rhyolite.

It’s not obvious why they’re called bluestones to most people since at first glance, and especially from a distance, they look more greyish green in colour. But a freshly broken piece of the dolerite type reveals that the unweathered interior is a striking blue-green colour with white spots.

How and – more importantly – when and why they were brought to Stonehenge is a matter of lively debate.raw-bluestone

Being comparatively lightweight, the transportation from Preseli to Stonehenge may have been accomplished fairly simply despite the distance involved. In the 1950s a team of a few dozen teenage schoolchildren was easily able to drag a replica bluestone using rollers and a sledge, and half a dozen were able to pilot one on a raft up and down a small river with no trouble.

One theory of when they arrived at Stonehenge suggests that it was around 3000BC and that they were placed in a circle just inside the earthwork bank in the 56 sockets that are known as the Aubrey Holes. This was 500 years before the large sarsens were put up. Subsequently, this theory says, they were moved to within the sarsen monument and re-arranged at least twice.

carn-goedogThe question of why anyone would go to the bother of transporting up to 80 rocks from Wales to Wiltshire is unanswerable. It may be that they formed an existing monument that was dismantled as the spoils of war, they might represent the ancestors of a group of people who migrated eastwards or they may even have been a gift from one population to another.

They clearly had some great significance, perhaps because of their striking position in easily quarried outcrops on the top of the Preseli Mountains.

Curiously, a number of the Stonehenge bluestones were once the components of two bluestone trilithons that must have stood about 2.5m tall. The evidence is in the form of two half-buried bluestone lintels that have mortise holes worked into them and several other standing bluestones that have the remains of tenons on their tops.

These individual components are now placed remotely from each other at Stonehenge but perhaps these small trilithons were the inspiration for the enormous sarsen versions that still stand at the monument.

There are only about 30 visible bluestones remaining at Stonehenge and it is likely that the others have been chipped to pieces for souvenirs and talismen or stolen away for use elsewhere in the last 5000 years. Local rumours of bluestone doorsteps, bridge footings and magnificent fireplaces crop up every so often and fragments have been found in many of the nearby Bronze Age burial mounds.  Stonehenge special access tours allow you to enter the inner circle of Stonehenge and get close to the blusestones.

Article by guest blogger and local Stonehenge historian Simon Banton

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Solar Astronomy at Stonehenge

4 11 2016

Most people are aware that Stonehenge is somehow aligned to the annual movements of the Sun.

Each year thousands of pilgrims, druids and party-goers gather in celebration, hoping to Stonehenge Avenue.jpgwitness the most famous of these – the Summer Solstice Sunrise on June 21st.

At this time of year, as seen from the centre of the monument, the Sun rises in the same direction as the centre-line of the Avenue – the ancient processional approach to Stonehenge – towards the northeast.

The Stonehenge Avenue alignment was first pointed out by William Stukeley in 1740.

Even though almost everyone believes the Heel Stone was put up by the builders to exactly mark the summer solstice sunrise position, this can’t be true because it stands off to the right hand side of the alignment.

Today the Sun seems to rise out of the top of the Heel Stone due to the modern trees that are on the horizon.

heel-stone-sunrise

Walking up the Avenue they would have seen the Sun setting exactly into the middle of the stones between the uprights of the tallest trilithon in the southwest. We can still experience this today, even though only one upright of that trilithon – Stone 56, the tallest stone on the site – remains in place.

There’s a secondary alignment too – from Winter Solstice Sunrise to Summer Solstice Sunset.

This was first described by Prof. Gordon Freeman in 1997 and it makes use of a “notch” in the edge of Stone 58 of the western trilithon to give a clear sightline across the stone circle.

Viewed through this notch, Winter Solstice Sunrise is seen over Coneybury Hill to the southeast…

winter-solstice-sunrise

If they weren’t there, sunrise would be almost a Sun’s width to the left – and 4,500 years ago the Sun would have risen a whole degree further over to the left.

Even though the Heel Stone wasn’t intended as the solstice sunrise marker, the sight is still magnificent – when the weather cooperates.

Along the same alignment, but exactly in the opposite direction, lies the Winter Solstice Sunset point.

… and Summer Solstice Sunset is seen over Fargo Wood to the northwest.

What’s remarkable about these alignments through the circle is that they intersect over the centre of the Altar Stone (shown as Stone 80 in the plan below). The Altar Stone is not perpendicular to the main alignment but is offset so that it lies exactly along the secondary one.

image description

The intersection angle of 80° between summer and winter solstice sunrises at this latitude is echoed in the large gold lozenge discovered in 1808 when the Bronze Age “shamanic” burial from Bush Barrow, just south of Stonehenge, was excavated.

The intersection angle of 80° between summer and winter solstice sunrises at this latitude is echoed in the large gold lozenge discovered in 1808 when the Bronze Age “shamanic” burial from Bush Barrow, just south of Stonehenge, was excavated.bush-barrow-lozenge
Some see this as coincidence. Others believe the lozenge shows that the knowledge of this important astronomical angle was passed down the generations for at least 600 years.

The lozenge and the other astonishing Bush Barrow finds are on display at Wiltshire Museum in Devizes.

There are Stonehenge lunar alignments too, but that will be the subject of a different article.

Article by guest blogger and local Stonehenge historian Simon Banton

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Massive 25 ton stones of Stonehenge may have come from further afield

29 10 2016

The builders of Stonehenge are known to have sourced the smaller bluestones used in the 5000-year-old monument from Wales.

But a new theory suggests that the entire monument might have come from elsewhere, even the huge 25 ton Sarsen stones which make up the large circle of the Wiltshire megalith.

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The huge sarsens at Stonehenge could have come from elsewhere

Katy Whitaker, of the University of Reading, will present a new paper at symposium at University College London next month suggesting that the sarsens could have come from sites as far away as Ken.

“Most people are aware that some of Stonehenge’s stones came all the way from south-west Wales,” she said.

“The really huge sarsen stones at Stonehenge are assumed to have come from sources on the Marlborough Downs in Wiltshire, about 30km to the north of Stonehenge. Sarsen stone, however, is found in other locations across southern England.

“There are sarsens in Dorset, spread about dry chalk valleys similar to the locations on the Marlborough Downs in Wiltshire, and as well as locations in Berkshire, Oxfordshire, Hampshire and Sussex, there are even sarsens in Kent.

“The distribution is quite broad, there are sarsens in Buckinghamshire and even across to Norfolk.”

People in the Neolithic are known for trading stone across large areas, including from the Lake District to the East of England.

Huge Sarsen boulders from outside of Wiltshire are known to have been used in other prehistoric monuments including Kits Coty House in Kent, and Wayland’s Smithy, a burial mound, in Oxfordshire.

“People were clearly aware of, and using, these stones in prehistory.” said Miss Whitaker. “Why not think about the possibility that sarsens came from further-afield too?”

The idea could also challenge that Stonehenge represents a peak of monument construction which could only have been achieved through organisation by a hierarchical leadership.

Instead, it may show that smaller groups had banded together to bring meaningful stones to a central area.

“Maybe it wasn’t a large group of people under the control of a tribal leader ‘cracking the whip’ to move all the rocks from one location down to Stonehenge as has been suggested before,” added Miss Whitaker.

“What about groups of people related in different ways, working collaboratively to move a special stone from one area to another? “

The source of the Stonehenge stones was first determined in the early 1920s by H.H. Thomas, an officer with the Geological Survey of England and Wales.

He determined that the so-called ‘spotted dolerites’ matched a small number of outcrops in the Mynydd Preseli district in south-west Wales

Latest theories about Stonehenge also suggest it was once an impressive Welsh tomb which was dismantled and shipped to Wiltshire.

An experiment this summer by University College London found that mounting huge stones on a sycamore sleigh and dragging it along timbers required far less effort than was expected.

They discovered that a  one tonne stone could be pulled on a raft by just 10 people at around one mile per hour, far faster than experts believed.

MS Whitaker is presenting her work at the Neolithic and Early Bronze Age Research Student Symposium at University College London from 18th to 19th of November.

Full article (source) The Telegraph:

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Ever wondered where the builders of Stonehenge lived? Discover Durrington Walls with a landscape guide.

25 10 2016

Discover Durrington Walls.  Join the National Trust landscape guides to explore the secrets of Durrington Walls – once home to the builders of Stonehenge – and discover 6,000 years of hidden history (2.5 – 3 mile walk).

16th November 2016 at 1pm

Event ticket prices
Adult £8.00
Child £0.00

Booking details
Call National Trust Direct: 0844 249 1895
More details on the National Trust website

Why did the builders of Stonehenge choose Salisbury Plain?

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