Why A Henge?

There was an interesting event that happened about 5200 years ago. I’ve mentioned it before. Mostly in the context of Ötzi – the Iceman and a place in the Andes where a retreating glacier has uncovered plants that were suddenly covered with snow and preserved. Both of those events are dramatic proof that it was at least as warm then, as now. This is the first time in 5200 years that those two places have been free of snow and ice; yet they were free of ice then, as well. It is essential proof that nature gets to the present conditions all on its own.

OK there was another thing I’d been planning to ‘date match’, but not gotten ‘a round toit’… and “sabertoothed” gave me a nice rount toit in T8 ;-) with this article:


So h/t to Sapertoothed.

A professor of geological sciences at Ohio State and a researcher with the Byrd Polar Research Center, Thompson points to markers in numerous records suggesting that the climate was altered suddenly some 5,200 years ago with severe impacts

He points to perfectly preserved plants he discovered that recently emerged from the Quelccaya ice cap in the Peruvian Andes as that glacier retreats. This monstrous glacier, some 551 feet (168 meters) deep, has shown an exponentially increasing rate of retreat since his first observations in 1963.
Evidence shows that around 5,200 years ago, solar output first dropped precipitously and then surged over a short period. It is this huge solar energy oscillation that Thompson believes may have triggered the climate change he sees in all those records.
He points to perfectly preserved plants he discovered that recently emerged from the Quelccaya ice cap in the Peruvian Andes as that glacier retreats.
The plants were carbon-dated to determine their age and tests indicated they had been buried by the ice for perhaps 5,200 years. That suggests that somehow, the climate had shifted suddenly and severely to capture the plants and preserve them until now.

In 1991, hikers found the preserved body of a man trapped in an Alpine glacier and freed as it retreated. Later tests showed that the human – dubbed Oetzi – became trapped and died around 5,200 years ago.

Thompson points to a study of tree rings from Ireland and England that span a period of 7,000 years. The point in that record when the tree rings were narrowest – suggesting the driest period experienced by the trees – was approximately 5,200 years ago.

He points to ice core records showing the ratio of two oxygen isotopes retrieved from the ice fields atop Africa’s Mount Kilimanjaro. A proxy for atmospheric temperature at the time snow fell, the records are at their lowest 5,200 years before now.
Thompson believes that the 5,200-year old event may have been caused by a dramatic fluctuation in solar energy reaching the earth. Scientists know that a historic global cooling called the Little Ice Age, from 1450 to 1850 A.D., coincided with two periods of decreased solar activity.

Evidence shows that around 5,200 years ago, solar output first dropped precipitously and then surged over a short period. It is this huge solar energy oscillation that Thompson believes may have triggered the climate change he sees in all those records.

I’ve left out the obligatory bleat about the present day hazards and risks of “Climate Change” “greenhouse gases”…

On the page about lunar cycles and Taurid meteors, the linked paper found a hint of a 5,000 ish year cycle as well, but didn’t dwell on it.


has a link to this paper:


With this very long term graph:

Lunar Cycles

Lunar Cycles

A much larger version here:


Figure 3

Varying strength of the global tide raising forces (bottom plot), as in Figs. 1 and 2, together with parameters (top and middle plots) that reveal the basis for the 1,800- and 5,000-year tidal cycles, as described in the text. The plots are for a hypothetical 110-kyr sequence of tidal events beginning with the moon, sun, and earth in perfect alignment and closest approach (zero separation-intervals), producing a maximum γ of 17.165° per day never again attained. Tidal events occurring near peaks in the 5,000-year cycle (near zero crossings of top plot) are connected by straight lines to reveal their pattern (which includes a 23-kyr cycle not discussed in the text).

In the bottom row you can see a series of “spikes” to the lunar angular velocity. If you count from one ‘peak’ of the envelope line connecting the tops to the next, it’s about 13 ‘spikes’ of the lunar angular velocity spikes between major peaks and the following major peak and about 10 ‘spikes’ between that first bottom drop and the next peak. Then notice that “now” is 10 peaks from the last bottom and 13 from the last top…

Also notice that 5.2k years ago was just about at the fall from the top of one of those peaks. (It has a 2kyr interval, so some ‘visual interpolation’ needed…) You will also notice that the immediately prior to ‘now’ peak is on top of the Roman Warm Period about 2000 years ago. That was when Romans were building villas with open airy form in places where you need a heater today. Romans knew how to build central heat, but didn’t. It was warm then.

What about the prior cycle? Closer to that 5.2 kyr, but just before ‘the event’?

Proposed dates for Mid-Holocene Warm Period straddle 6 kya, but range from 5 to 7 kya.

Mid-Holocene Warm Period – About 6,000 Years Ago
Paleoclimatologists have long suspected that the “middle Holocene” or a period roughly from 7,000 to 5,000 years ago, was warmer than the present day. Terms like the Alti-thermal or Hypsi-thermal or Climatic Optimum have all been used to refer to this warm period that marked the middle of the current interglacial period.
The paleoclimatic data for the mid-Holocene shows these expected changes, however, there is no evidence to show that the average annual mid-Holocene temperature was warmer than today’s temperatures. We also now know from both data and “astronomical” (or “Milankovitch”) theory that the period of above modern summer temperatures did not occur at the same time around the northern hemisphere, or in the southern hemisphere at all.

In summary, the mid-Holocene, roughly 6,000 years ago, was generally warmer than today, but only in summer and only in the northern hemisphere. More over, we clearly know the cause of this natural warming, and know without doubt that this proven “astronomical” climate forcing mechanism cannot be responsible for the warming over the last 100 years.
For larger viewing version of the graph, please click here or on graph. Graph courtesy of Kerwin et al., 1999, complete scientific reference located here.

Don’t you just love how CERTAIN they are that the same thing that made it warmer then, could not possibly be the reason now?

OK, why mention it? Look again at the peaks at the bottom of the prior graph. One is at about 5800 – 5900 years ago. Just about where that Holocene Warm Period lands. Hmmmm….

That leaves that peak at about 3900 ya or 1900 BC to sort out.


says that just before that time, the Egyptians were having a great time, building pyramids and living the good life, but the Sumerians while they had it good then, later on had a bit of drought:

2650 BC Sumerian epic of Gilgamesh describes vast tracts of cedar forests in what is now southern Iraq. Gilgamesh defies the gods and cuts down the forest, and in return the gods say they will curse Sumer with fire (or possibly drought). By 2100 BC, soil erosion and salt buildup have devastated agriculture. One Sumerian wrote that the “earth turned white.” Civilization moved north to Babylonia and Assyria. Again, deforestation becomes a factor in the rise and subsequent fall of these civilizations.

Some of the first laws protecting the remaining forests decreed in Ur.

c. 2630 BC 1815 BC Construction of the Egyptian pyramids

then it turns from drought to floods:

2200 BC Beginning of a severe centennial-scale drought in northern Africa, southwestern Asia and midcontinental North America, which very likely caused the collapse of the Old Kingdom in Egypt as well as the Akkadian Empire in Mesopotamia. This coincides with the transition from the Subboreal period to the subatlantic period.
21st century BC construction of the Ziggurat of Ur

2nd millennium BCYear(s) Event(s)
Start End
1900 BC The Atra-Hasis Epic describes Babylonian flood, with warnings of the consequences of human overpopulation.
1600 BC Minoan eruption destroys much of Santorini island, and decimates the Minoan civilization on Crete. This may have inspired the legend of Atlantis.

Hmmm…. floods and volcanoes following an era of warmth and “overpopulation”…

We’ve see that 4.2 Kiloyear event before. It is “Bond Event 3”.

A phase of intense aridity in ≈4.2 ka BP is well recorded across North Africa, the Middle East, the Red Sea, the Arabian peninsula, the Indian subcontinent, and midcontinental North America. Glaciers throughout the mountain ranges of western Canada advanced at about this time. Evidence has also been found in an Italian cave flowstone, and in Andean glacier ice.

The onset of the aridification in Mesopotamia near 4100 B.P also coincided with a cooling event in the North Atlantic, known as Bond event 3

Gee… Drought in the middle of the USA and a cooling ocean. And what do we have right now? Oh, a drought in the middle of the USA and a cooling ocean… (Though, I suspect, we may be just at the start of this). So IF things are following the prior pattern, who gets screwed?


Ancient Egypt

In ca. 2150 BC the Old Kingdom was hit by a series of exceptionally low Nile floods, which was instrumental in the sudden collapse of centralized government in ancient Egypt. Famines, social disorder, and fragmentation during a period of approximately 40 years were followed by a phase of rehabilitation and restoration of order in various provinces. Egypt was eventually reunified within a new paradigm of kingship. The process of recovery depended on capable provincial administrators, the deployment of the idea of justice, irrigation projects, and an administrative reform.


The aridification of Mesopotamia may have been related to the onset of cooler sea surface temperatures in the North Atlantic (Bond event 3), as analysis of the modern instrumental record shows that large (50%) interannual reductions in Mesopotamian water supply result when subpolar northwest Atlantic sea surface temperatures are anomalously cool. The headwaters of the Tigris and Euphrates Rivers are fed by elevation-induced capture of winter Mediterranean rainfall.

The Akkadian Empire—which in 2300 B.C. was the second civilization to subsume independent societies into a single state (the first being ancient Egypt at around 3100 BC) —was brought low by a wide-ranging, centuries-long drought. Archaeological evidence documents widespread abandonment of the agricultural plains of northern Mesopotamia and dramatic influxes of refugees into southern Mesopotamia around 2170 BC. A 180-km-long wall, the “Repeller of the Amorites,” was built across central Mesopotamia to stem nomadic incursions to the south. Around 2150 BC, the Guti, who originally inhabited the Zagros Mountains, defeated the demoralized Akkadian army, took Akkad, and destroyed it around 2115 BC. Widespread agricultural change in the Near East is visible at the end of the third millennium BC.

Resettlement of the northern plains by smaller, sedentary populations occurred near 1900 BC, three centuries after the collapse.

Arabian peninsula

In the Persian Gulf region, there is a sudden change in settlement pattern, style of pottery and tombs at this time. The 22nd century BC drought marks the end of the Umm al-Nar period and the change to the Wadi Suq period.


The drought may have caused the collapse of Neolithic Cultures around Central China during the late third millennium BC.
At the same time, the middle reaches of the Yellow River saw a series of extraordinary floods. In the Yishu River Basin, the flourishing Longshan culture was hit by a cooling that made the paddies shortfall in output or even no seeds were gathered. The scarcity in natural resource led to substantial decrease in population and subsequent drop in archaeological sites. About 4000 cal. yr BP Longshan culture was displaced by Yueshi culture which was relatively underdeveloped, simple and unsophisticated.

So, the big question is: Will this time be more like the 4.2 Kyr Event, or The Dark Ages (right after the Roman Optimum)? Hell of a choice…

Look again at “now” on that graph. We’re at one of the very high peaks that tends to be followed by a very deep drop.

We have no idea how that one ‘works out’ as the last one was during a glacial period.

As noted in the caption to that graph, we are nearing the ‘zero crossing’ of the top graph that marks a 5 ky cycle event. We are also at one of the 23 ky nodes. I think “this will be interesting”…

But I Thought you Said Henge?

Yes, I did. One of the persistent questions about Stonehenge, and all the Henges to some extent, is “Why?”

IMHO, “why” is answered by “when”.

Most of the time, when talking about the date of Stonehenge, folks focus on the Stones.

Not that surprising, really, since they are the big thing that stands out. Turns out, they were a relatively later addition.


Stonehenge 3 II (2600 BC to 2400 BC)

During the next major phase of activity, 30 enormous Oligocene-Miocene sarsen stones (shown grey on the plan) were brought to the site.

And while 2600 BC is an interesting time, it’s not a catastrophic wake up and smell the coffee time. The Egyptians are building their pyramids, and generally “life is good”. So a reasonable time to be doing ‘big stone works’. Gilgamesh is having a good time in the Cedar forests of Sumer about then too, and it’s before the 2200 BC “Aw Shit”.

But what folks usually don’t think about is that this was an “upgrade”. The earlier work was done much earlier.


Original from here.

The “original” henge, and what IMHO determines the primary purpose, was those rings of holes around the outside of the stones. And when was that dug / built?

Stonehenge 1 (ca. 3100 BC)

The first monument consisted of a circular bank and ditch enclosure made of Late Cretaceous (Santonian Age) Seaford Chalk, measuring about 110 metres (360 ft) in diameter, with a large entrance to the north east and a smaller one to the south. It stood in open grassland on a slightly sloping spot. The builders placed the bones of deer and oxen in the bottom of the ditch, as well as some worked flint tools. The bones were considerably older than the antler picks used to dig the ditch, and the people who buried them had looked after them for some time prior to burial. The ditch was continuous but had been dug in sections, like the ditches of the earlier causewayed enclosures in the area. The chalk dug from the ditch was piled up to form the bank. This first stage is dated to around 3100 BC, after which the ditch began to silt up naturally. Within the outer edge of the enclosed area is a circle of 56 pits, each about a metre (3’3″) in diameter, known as the Aubrey holes after John Aubrey, the 17th-century antiquarian who was thought to have first identified them. The pits may have contained standing timbers creating a timber circle, although there is no excavated evidence of them. A recent excavation has suggested that the Aubrey Holes may have originally been used to erect a bluestone circle. If this were the case, it would advance the earliest known stone structure at the monument by some 500 years. A small outer bank beyond the ditch could also date to this period.

Gee, that 3100 BC date is looking kind of familiar. Just AFTER that 5.2 kyr ago “event” changed everything…

IMHO, what happened was a major shift of ocean currents, rains, and flood / drought patterns. Probably some impact on the wind patterns too. Folks, then, were very much ‘in tune’ with nature and with the celestial ties. IMHO, they noticed, and noticed a connection to long duration lunar patterns. The movement of the moon during these long duration cycles traces out a pattern on the earth, and folks here watching the movements might well have noticed an ‘inflection’ in the direction of drift. We know that, at that time, calendars were often lunar based. (Hebrew and Muslim calendars continue that tradition) and that key folks were assigned to keep track of the lunar dates.

We have found conical copper ‘hats’ with the 19 year lunar cycle marked on them, and other indications that they knew of, and paid attention to, the longer lunar cycles.

So lets say all of a sudden, things change, and the moon is being a bit ‘different’ from what you learned in the last couple of generations. What to do? I’d say “Build a world class lunar / solar observatory” and try to figure out ‘what changed’ and what are the cycles. (They were much more in tune with natural cycles then, too.)

Old folks and those who like old gear know that for an analog device or computer (like a circular slide rule) the precision scales with the instrument size. So if you want to make a really accurate and precise lunar dial, you need a big one. If you want to avoid the horizon and ‘junk’ messing up your viewing, you put it on a mountain top (hard to do) or you pick a big flat plain. (easier to do). Then you flatten the dirt around it (there are ‘curcus’ flat areas heading in particular directions) and you make a constant ‘horizon’ (so they dug a trench, leveled and raised a berm, and potentially put in ‘sight poles’ to raise it above even distant clutter).

Now you can make sightings, mark them with stones or poles, measure, calculate, think, (and accept offerings to the “priests” from the local yokels…)

Over time, various changes are made to the instrument. The central stone works are added with demarcated sight lines, and with a very nice, stable, and elevated flat platform ring for high of clutter sightings. There are some horseshoe small holes that look to be usable for counting out the 19 year lunar cycle (harder to forget what the last ‘count’ was when you have a 100 lb stone in the hole..) and the outer ring can have both solar and lunar stones, moved as an eclipse predictor ( I won’t go into how here unless folks want me to).

In short, you have great big observatory to try and figure out how all those bits ‘up there’ move.

That’s basically it. Other than to point out that Orion Rising was a key constellation then, and we find Orion shaped layout of circles / henges in the UK; and that Stonehenge looks to have been abandoned just about the time that the 25,000 ish year precession cycle would have made the “works” no longer in alignment with things. That’s the problem with a massive multi-ton rocks in dirt instrument… it’s hard to ‘adjust’ it. ;-) There is some evidence for ‘pole holes’ out near the ‘heel stone’, as though they were either measurement markers for short term lunar position changes, or potentially an attempt to do a ‘life cycle extension’ that did not involve moving a giant stone.

But in the end, I think it just became technologically obsolete. The Builders learned what the wanted to learn, figured out the relevant cycles, and then didn’t need it anymore. So why build a new one, knowing it, too, will get ‘out of adjustment’? They moved on to more adjustable methods.

In Conclusion

That’s my thesis of “why a henge”. It was driven by unexpected shifts of weather and tides, likely with a lunar nodal change, and folks needed to ‘figure it out’. If you are marking the Winter Solstice and calling the weather and lunar calendar to come, you can’t be too wrong or folks get grumpy…

Then there were a few thousand years of tuning, expansion, and party time; until the eventual demise.

One wonders what will be built after our cycle turns. And just exactly WHEN that turning comes…

As a sidebar: It is suspicious that there are solar changes that sync with the lunar tidal cycle. Almost certainly due to “Orbital Resonance”. That our current solar state has shifted from ‘very active’ to ‘nearly inactive’ is not encouraging. That we’re at the 5 kyr AND 23 kyr inflection points is intriguing. One can only hope that they move in opposition to dampen each other and not in synchrony to make this one worse. One could also hope that it takes 40 or 60 years to have ‘onset’ and we can enjoy the present state for just a lifetime more ;-)

“But hope is not a strategy. -E.M.Smith”…

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
This entry was posted in AGW Climate Perspective, History, Science Bits, Stonehenge and tagged , , , , , , , , , , , . Bookmark the permalink.

11 Responses to Why A Henge?

  1. agimarc says:

    The YD guys over at the Cosmic Tusk are also looking at events around the same time period in context with some spikes in ice cores of ammonia thought to be related to impact events. Discussion makes an attempt to tie it to Mayan calendar rollovers. Interesting stuff at the links. One of the things we humans do wonderfully is pattern recognition. Problem is matching patterns where none exist – especially in a complex system like climate where drought can be caused by anything from a simple change in ocean temperature (El Nino / La Nina) to catastrophic cooling events like eruptions and impact events, not to mention solar activity. Fun stuff, though. Link to the Tusk follows:


  2. E.M.Smith says:


    The major “problem” with this particular “look” at things is the scale. At this 5k – 23k year scale, the graph just doesn’t have enough resolution to say “this one” or “in 200 years on the next one”. (Or even “200 years ago in the LIA was it”…)

    On a closer look (at a faster chart) it looks like “next 200 to 300 years” after some drop now. Then again, as a 23 kyr overlay, it might be “5 kyr event now” then the double-tap in 200-300 years to “That 23 kyr wopper”… Just no way to know. Like you said: Seeing patterns… be there or not…

    (But I think at least one of them is there…)

    Per impacts:

    In theory we are out of the middle most dense part of the Taurid stream right now. Got a ways to go to be in the main target area. ( a few hundred years at least ). So an impactor “now” would likely be from a different source… or not ;-)

    Ammonia can also come from decay of proteins, so “quantity” would matter…

    I’ll take a look at the “Tusk” guys. They have interesting stuff…

  3. John F. Hultquist says:

    And when was that dug / built? Stonehenge 1 (ca. 3100 BC)

    I put the following in the Christmas note my spouse is sending to relatives and friends. The date or 3,114 almost matches the above.

    “Consider the end of the world next Friday. The impetus for this world shattering (or not) event is the Mayan Long Count Calendar. All that will happen, so it seems, much like the odometer on an auto when it reads all 9s, is that the numbers all switch to zero and it starts over. So, not a problem. Move on. Then in an idle moment or at night when you wake – there it is again. What’s that calendar all about. So, you work your way back. It is not called the Long Count Calendar for nothing. This will be the 13th time for the passage of 144,000 days which takes us to 1,872,000 days ago for the calendar start date. That would be 3,114 BC – using today’s Julian calendar. But the Maya civilization established the calendar in about 500 BC, roughly 2,600 years after — — –. After what? No one knows. If the world ends next Friday we will die, never knowing. Perchance to dream. Ay, there’s the rub. ”

  4. Graeme No.3 says:

    See also the remains being discovered in the Orkneys e.g. the Ness of Brodgar. Near Skara Brae and the Ring of Brodgar ( a stone henge). The village had stone walls, inside running water, live food saving and writing before Stonhenge.

  5. adolfogiurfa says:

    @E.M.Smith: Would you be so kind of getting for us, the updated maps of the geomagnetic fields? and where is it now the magnetic equator?. It seems there are no publications since 2010.
    During 1957, the so called “geophysical year”, it was found marked changes in these fields. There is a lot of fun to be found in these data.

  6. Tim Clark says:

    { Two intervals of elevated stalagmite δ13C values occur at
    3.4–2.6 and 1.2–1.0 ka at Devil’s Icebox Cave. The exact
    mechanism driving these changes in stalagmite δ13C values is
    unclear, but it appears likely associated with increased aridity,
    either through increases in C4 abundance or the proportion of
    bedrock carbon in infiltrating solutions. The limited impact of
    temperature change during these elevated δ13C episodes is
    supported by the absence of concomitant increases in stalagmite
    δ18O values. The observation that the timing of these more arid
    periods at Devil’s Icebox Cave are similar but not identical to
    the timing of more arid intervals across the eastern Great Plains
    may be explained by (1) different response rates to climate
    change among caves, dunes and pollen/macrofossil records; (2)
    errors and uncertainties among the distinct chronologies ( Page break) }

    Looks like I’m good to go in Arkansas for 1000 years or so, water wise.

  7. E.M.Smith says:


    These folks claim “real time” maps. Are they not?

    @Tim Clark:

    Good one!

    FWIW, it looks like California gets a modest drought from what I’ve found so far. As we get through droughts OK as is, I’m not real worried. Worst case is that we stop shipping food to the rest of you ;-)

    ( something like 95% of the water is used for agriculture most of which is exported so that is what will get whacked. I can always go pickup a bucket of water from the local river…)

  8. Tim Clark says:

    Worst case is that we stop shipping food to the rest of you ;-)

    Damn, I’ll have to raise my own veggies!

  9. Dave says:

    Funny after reading this today, I’m wasting away on the couch trying to beat a cold watching H2 and a show comparing modern NYC to ancient wonders mentions this:


    in relation to the need to tell time. Was not aware of this example. Who knows how many others have been lost to the plow over the centuries?

    In relation to the previous post regarding European roots of Native Americans, another show is scheduled called “America Unearthed” that purports to locate a pre-columbian “Englishman’s Grave” located in North America. You have to be careful with H2, but some good shows if you can filter out the obvious trash. This show could be another example of the Inca Island show that was total crap, but sounds interesting.

    Considering we know so little about the mound building people ( http://en.wikipedia.org/wiki/Mound_builder_(people) ), who knows. They seemed to have a “more” structured society as it relates to buildings and other sturctures. They always get overlooked because of the fact that early Spanish contact descimated them due lack of disease resistance. Also when you look at North/South American archeology people were IMHO too widely dispersed to have only come over the Bering Land Bridge. Then again people can accomplish a lot in a few thousand years so who knows?

  10. sabretoothed says:

    Guess what, deforestation caused warming last time but not this time (and we had Little Ice Age in between) LOL http://www.jsonline.com/news/education/36279759.html

  11. p.g.sharrow says:

    Possible new timeline of construction of Stonehenge;
    Also archeologists discover more of “avenue” to Stonehenge.
    just adding more to the list of interesting bits of Stonehenge information. ;-) pg

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