Why was Stonehenge constructed with those woodwork joints (mortise and tenon; tongue in groove)?

Notice anything unusual about that upright?

Here is the first real post on this, my new Stonehenge/Silbury site – not counting the Hello World preliminary supplied by the WordPress host. It takes a close look at a detail regarding Stonehenge – one that is both at first sight practical and mundane,  yet baffling at the same time. I then use that detail to prise open what I believe to be the answer to the Stonehenge/Silbury enigmas – why were they built? Why go to so much trouble when, 5000 years later, archaeologists and historians are still asking what they were for?

Look first at the picture below.

It shows one of the upright sarsen stones which originally supported a lintel (the latter now next to it on the ground).  Notice the hump on top.

It is in fact the tenon of a mortise and tenon joint, the mortise being in the fallen lintel. Someone has handily provided a diagram to show the location of the two components of the joint – designed to locate one on the other to ‘tie’ the two together.

The two red circles show the position of the mortise (lower left) and tenon (top) respectively

But that’s not all. In addition to a mortise and tenon joint, the upright and lintel were interlocked by a second tongue in groove joint. Here’s a diagram showing this remarkable belt-and-braces arrangement, looking for all the world like something out of a woodwork class, yet laboriously fashioned using stone tools in the late Neolithic (pre-Bronze age).

Two mortise and tenon joints AND a tongue in groove (just to be on the safe side)…

The purpose of such joints is obvious where furniture is concerned. They allow a chair, table etc to support a weight without collapsing. But why the need to interlock the components of a heavy self-supporting structure like Stonehenge? Would not the force of gravity alone be sufficient to keep the arch-like trilithon arrangement of two uprights and a lintel crosspiece intact? Not even a hurricane could blow it down, surely?  Or even an infrequent earth tremor? What could possibly dislodge that mighty lintel, given that it is several metres high, towering above its builders, and weighing some tens of tons?

Answer? The doubly-secured lintel was to prevent it being detached by the ever-present  Enemy, who, arriving in large numbers, maybe at the dead of night, might come equipped with ropes, levers etc and attempt to dislodge those lintels, to send them crashing to the ground.

Why would the Enemy be so determined it its mission to destroy the crosspieces of Stonehenge?  Could it be that the circle of standing stones that we call Stonehenge came to represent a symbol of the awesome power of its builders over the nearby Enemy. Where the latter was concerned, did that circle of stones, looking somewhat sinister even to modern eyes,  represent something else – like summary execution, and a humiliating and highly visible fate to follow – one in which those lintel crosspieces played a key role?

So who was the Enemy? And why was Stonehenge a prime target for raiding parties, and accordingly designed to resist being torn down? Those questions will be the subject of my next posting

Further reading on those mortise and tenon joints

 Update April 22, 2016 (4 years on!)

I think I’ve sussed it out. Shame that all my text (imprudently composed online) disappeared when I hit the Publish button! Just as well that a picture is worth a 1000 words. Here’s the schematic I made to accompany the posting:

new trilithon 1 aligned plus mound penultimate for blog

See the new posting for a longer-than-usual caption to the above, essentially a Band-Aid operation. I’ll try restoring the full posting in easy stages, though that may take a few days.

 

 

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About Colin Berry

Retired science bod, previous research interests: phototherapy of neonatal jaundice, membrane influences on microsomal UDP-glucuronyltransferase, defective bilirubin and xenobiotic conjugation and hepatic excretion, dietary fibre and resistant starch.
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2 Responses to Why was Stonehenge constructed with those woodwork joints (mortise and tenon; tongue in groove)?

  1. Pingback: Mortise and Tenon (Week 3) | A Year at College of the Redwoods Fine Woodworking

  2. Ben says:

    Have you been to Peru or other megalithic sites? They often use similar stone tricks https://upload.wikimedia.org/wikipedia/commons/8/86/Peru_Sillustani_Grave_Tower_Chullpa.jpg (although terrible reconstruction/restoration job attempt)

    Interestingly enough, these towers all collapsed on the same sides and rocks are strewn far from the towers themselves (they are heavy). Requires explosive forces to do that kind of damage. Strategically placed Dynamite? Strategically placed thunder strikes? Comet breakdown/strike (in the region) causing a deluge or air pressure wave?… http://m.phys.org/news/2014-08-year-old-nanodiamonds-multiple-continents.html

    …and the last thing they are, are tombs (at least for their original designed purpose).

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