Was Neolithic Silbury Hill Designed as a Welcoming Home for Omnivorous, Upwardly-Mobile Earthworms?
Silbury Hill, said to be the largest prehistoric man-made mound in Europe, looms over the landscape. Yet so little is understood about this enigmatic British site. However, surprising as it may seem, evidence supports the idea that it was intended to be a specialized funereal mound, a veritable processing plant, intending to free souls trapped within their mortal bodies.
Let’s start our story on what, for the writer, was a breezy elevated ridge on southern England’s North Wiltshire Downs at the West Kennet Long Barrow in March 2016.
Fig. 1: Entrance to the West Kennet Long Barrow. ( CC BY-SA 3.0 )
Fig. 2: From inside the West Kennet Long Barrow looking towards entrance. (Photograph courtesy writer).
Neolithic Defleshing Released Trapped Souls
The barrow, south of Avebury in Wiltshire, England, with its chambered tombs constructed of megaliths, was reckoned to be in use as a repository for bones and largely disarticulated skeletons up until about 2400 BC.
West Kennet Long Barrow (Ben Cremin, Flickr/ CC BY 2.0 )
The underlying belief seems to have been that upon death of a human, the soul was trapped with the mortal body. Any process – natural or assisted – that consumed the flesh served to release the soul.
Thus we have the ‘difficult,’ not to mention repellent (to modern eyes) literature on “excarnation” – or the defleshing of the newly deceased, which could either be passive (e.g. by primary burial assisted by soil microorganisms and earthworms, or scavenger-assisted, as with birds in sky burial) or by active excarnation (separate harvesting of bone from soft tissue using sharp implements).
Barrows only tell us that the bones were revered. But was soft tissue (heart and other vital organs especially) so appreciated?
- Stone Age bones found in Irish cave may reveal prehistoric practice of excarnation
- Archaeologist finds defleshed human bones in ancient religious complex in Bolivia
Swing around from the Long Barrow and another iconic site greets one, a mere half mile away. It’s Silbury Hill, claimed to be the largest man-made mound in Europe.
Fig. 3: The iconic Silbury Hill, as seen from the West Kennet Long Barrow. (Photograph courtesy writer).
Despite its impressive size (31 meters or 101 feet high) it’s reckoned that Silbury Hill was constructed in a relatively short time, variously estimated at between a decade and a century. It’s believed that Silbury began when the nearby Long Barrow was finally abandoned and the entrance sealed up. Was this a change in mind-set and funereal practice? Maybe. Let’s take a closer look at what’s inside Silbury Hill.
Silbury Hill, Enigmatic Mound
First let’s join our fellow tourists near the visitor car park, where one is greeted by a helpful, open air display board.
Fig. 4: Silbury Hill: visitors’ observation area with display board, summarizing results of centuries of archaeological investigation. (Photograph courtesy writer).
Fig. 5: Close up of display board artwork (Judith Dobie).
The three panels above show the initial stages in the Silbury construction, as inferred from the various tunneling and excavation operations, starting with the first (vertical) shaft in 1776, ending in most recent 2007 probing by English Heritage archaeologist Jim Leary and archaeological investigator David Field and their fellow researchers.
It may help to consult this writer’s own schematic cross-sectional diagrams. Beware: they are based on interpretation of sentences from archaeologists Leary and Field and are not to scale regarding relative dimensions, precise ordering of soil layers etc.
“Silbury 1” is the name of the first small mound made of layers of gravel and dark layers of turf and soil. “Silbury 2” was built up over this first mound, and was composed of chalk rubble and soil. “Silbury 3” was the final phase, wherein ditches were filled in, others were created, and the mound was finished off, creating a 60-degree sloping, pyramidal structure.
Fig. 6: Left: initial site with topsoil. Center: removal of topsoil. Right: Silbury 1 - adding heap of gravel. (Image courtesy writer)
The third diagram on the right corresponds with the first on the display board, showing the initial gravel mound. Note that the gravel was NOT deposited on original soil and turf, which had first been removed (see below for later use). Many questions stem from this revelation.
Why bother to remove the topsoil if one is building a mound, even if planning only a modest-size one initially?
Fig.7: The seemingly ever-more perplexing steps. Mounds upon mounds, and then pits dug in and backfilled. (Image courtesy writer)
In Figure 7 we see at left that the top soil has now been added back, together with turves—turf or sod — (some still green after 4,500 years!) and residents such as ants and other insects (as well still visible after 4,500 years!)
The center stage shows several more layers of diverse origin have been added on top, amongst which is a mysterious black addition (a dense black band shown above the grey topsoil, not necessarily its exact location among the new additions).
The end result is what the distinguished late British archaeologist Richard Atkinson, leader of the 1967 BBC investigation, described as a “layer cake” and other more colorful descriptions, and which Leary and Field refer to as the “organic mound”, a term replete with various associations and connotations, whether intended by the authors or not.
Then something even more unexpected, indeed extraordinary, took place.
On the right of Figure 7 are seen modest-size (approximately on meter or 3 feet in diameter) holes or pits which were made in the center and sides of the organic mound. They were then backfilled with what seems to be the same material!
Not content with having created one central mound studded with excavated pits, we then learn that numerous ‘satellite’ mounds were created around the central one. They too have excavated/refilled pits we’re told. Again, WHY?
Aerial view of Silbury Hill and the A4 road. ( CC BY-SA 2.0 )
Silbury 1 is described as the very heart of Silbury Hill.
The tricky part came when scouring Leary and Field’s book The Story of Silbury Hill for every scrap of information regarding those “darker” contributions to the “organic mound” that comprise Silbury 1 (not counting relocated turves).
Leary and Field make references to pits and mounds being sealed under dumps of different material that had been tipped on top. The soil had apparently been brought in from some distance, since the underlying material was chalk, not clay-with-flints. Next came more chalk, clay, gravel and more turves. However, the only theory for the enigmatic pits was that they were the “result of ceremonial activity on or around the mound.”
What Lies Beneath, Waiting for the Dead
Can we assume that dark bands necessarily represent imported “dark soil” or “mud” or “silt” from the nearby river bed? Or might they include something else?
What else can make soil darker, indeed blacker, but also finely particulate and silt-like? Gardeners have a ready answer, at least those who maintain a compost heap, fed with grass and cuttings from the garden or food waste from the kitchen: earthworms.
Black, agreeable-smelling humus can be the end-product of natural decay processes, initiated by soil microorganisms (bacteria and fungi) and terminated by those obliging earthworms that feed on the decaying organic matter, usually but not always plant-based, finally producing worm casts (“poo”) that are essentially new growth-promoting plant fertilizers (“compost”, “manure” etc.).
Might we now have an explanation for the rigmarole with gravel and relocated topsoil, pits and backfilling?
It makes sense to propose that Silbury 1, the “organic mound” was designed deliberately to make a home, (or open prison), for earthworms, supplied with whatever was placed into those pits before back-filling. It may not have been an earthworm’s preferred diet of decaying PLANT matter. Fussy feeders might have been tempted to ‘turn tail’ so to speak and exit from Silbury 1. But they would then come up against a man-made barrier—that unwelcoming gravel and sterile subsoil, with no interesting aromas from below. So they would have to be content with what was on offer—a little slowly decaying turf, but a lot of something else. Can we infer human remains?
- Not a Great Place to Pass at Night: Haunted Mounds from Prehistoric Times
- First evidence of defleshing of human bones in Neolithic Europe found in Italy cave
To stay alive and reproduce, the first generation earthworms deep in Silbury 1 would have needed to become “upwardly mobile”.
So what was incorporated into the pits of the primary mound and probably subsequent tiers of new satellite mounds, new tiers, further new mounds?
Readers who have persevered thus far are now left to figure that out largely for themselves, but a clue was given at the start: think through the realities of “excarnation”, positive excarnation especially.
It seems very plausible that the ancient builders of Silbury Hill introduced earthworms to their mound so as to ensure decomposition of any earthly remains buried therein. Indeed, research from 2013 points to soil samples from Silbury Hill which are chock full of earthworm feces, and are being used to measure past temperatures. It’s appearing more and more that the dark base layer of Silbury Hill was produced by earthworms (which may have been placed there purposefully).
In all, it could be that the mound was designed as a barrier to keep a starter population of captive earthworms within a biodegrading series of compost heaps, forcing the little critters off their regular, plant-based diet onto something else—something definitely more exotic. As this process went on, the compost heaps gradually melded to become one.
This hypothesis does not take away from the sacred nature of the site and the possible intentions of the Neolithic builders. Complicating the issue and raising other questions is that no human remains have yet been recovered at Silbury Hill.
It’s said that “home is where the heart is”. Might Silbury Hill represent a communal home for communal hearts (literally, and maybe more besides)? Was Silbury Hill conceived as a finessing of Neolithic hitherto bone-recovery funereal practice, an alternative way of earthworm-assisted release of the soul from its prison of flesh and blood, as described some 4,000 years later by a certain celebrated playwright living a mere 70 or so English miles from Silbury in the memorable words: “to shuffle off this mortal coil”?
By Colin Berry
J. Leary and D. Field, 2010. “The Story of Silbury Hill” Published by English Heritage (December 17, 2010)
Emma A.A. Versteegh et al. 2013 “ Earthworm-produced calcite granules: A new terrestrial palaeothermometer?” Geochimica et Cosmochimica Acta. ScienceDirect.com doi:10.1016/j.gca.2013.06.020