Promotional Video – Ancient Prehistoric Canals (Dykes) – Wansdyke (Prehistoric Canals – Wansdyke 2)
Chapter 1 – Dykes, Ditches and Earthworks……. Book Extract
The modern word dike or Dyke most likely derives from the Dutch word “dijk”, with the construction of dikes in the Netherlands well attested as early as the 12th century. The 126 kilometres (78 mi) long Westfriese Omringdijk was completed by 1250 and was formed by connecting existing older dikes. The Roman chronicler Tacitus even mentions that the rebellious Batavi pierced dikes to flood their land and protect their retreat (AD 70). The word dijk initially indicated both the trench and the bank.– Wikipedia
If you study archaeology at university or even on an ordinance survey map at length, you will notice strange earthworks on the sides of hills of Britain, with no rational explanation as to why they are there and for what reason. These features are mostly ignored at university, or an excuse is made for their construction. The reality is that these features do not make any sense unless there are other factors in operation which have been ignored.
The first thing to notice is that the word ‘Dyke’ is associated with water. It does seem strange you would call an earthwork on top of a hill a Dyke, unless there was some history passed down through the years to its actual use. If we look at the most famous Dyke in Britain, ‘Offa’, we notice that it is attributed to a Saxon King and, therefore, could not be prehistoric. Or is this a clear indication of how archaeologists find excuses for these features rather than factual, empirical evidence?
“Offa’s Dyke (Welsh: Clawdd Offa) is a massive linear earthwork, roughly followed by some of the current borders between England and Wales. In places, it is up to 65 feet (19.8 m) wide (including its flanking ditch) and 8 feet (2.4 m) in height. In the 8th century, it formed some kind of delineation between the Anglian kingdom of Mercia and the Welsh kingdom of Powys.” – Wikipedia
At face value, this explanation seems to answer all the questions about Dykes (except the water connection). But suppose you delve further down to look at the evidence, such as findings from the Dyke and any written history. In that case, you get a different version for the Roman historian Eutropius in his book, Historiae Romanae Breviarium, written around 369 AD, mentions the Wall of Severus, a structure built by Septimius Severus who was Roman Emperor between 193 AD and 211 AD:
“He had his most recent war in Britain, and to fortify the conquered provinces with all security; he built a wall for 133 miles from sea to sea. He died at York, a reasonably old man, in the sixteenth year and third month of his reign.” – Eutropius (369 AD)
This ‘wall’ need not be made of stone as we know from their Scottish endeavours that the first structure as a defence was usually a bank and a ditch – just like a Dyke!!
The problem with this account is that none of the known Roman defences are 133 miles long – Harridan’s Wall is only 70 miles, so are they talking about Offa’s Dyke, which is much longer?
Chapter 2 – The Post-Glacial Flooding Hypothesis.………… Book Extract (Prehistoric Canals – Wansdyke 2)
Before we show you what these ‘Linear Earthworks‘ were used for in prehistoric times. We need to give you an idea of how the environment was at the time of construction and why it is so different today.
In ‘The Post-Glacial Flooding Hypothesis,’ we looked at the new mathematical models that allowed us to calculate the amount of water released during and after the Last Glacial Maximum just over ten thousand years ago.
If the Dykes of Britain are canals (and not markers or defensive ditches), we must prove that the water table was higher in the past than today (otherwise, they would still be flooded).
The models contained in the PGFH showed us that a minimum of 8.42 quadrillion tonnes of water was released on the UK at the end of the last ice age. This is equivalent to 98425.2 inches of rain falling on every square inch of Britain’s landmass or the same as – One Inch of rain steadily falling every day for the next 270 years
The worst known flooding in British history occurred in 1947 when just six inches of rain (149mm) fell on up to 12″ of snow (so a maximum of 15″ of rain if melted) over three months. The flooding, which inundated nearly all the main rivers in the South, Midlands, and the Northeast of England, was notable for its origins, geographical extent, and duration.
It impacted thirty out of the forty English counties over two weeks, when around 700,000 acres of land flooded. As a result, tens of thousands of people were temporarily displaced from their homes, and thousands of acres of crops were lost; and this was just 15 of the estimated equivalent of 98,425 inches of water that was shed on the British landscape after the last Ice Age.
Raised Water Table
According to William Donn (Donn et al., 1962). The Fennoscandian and Great Britain ice sheet covered 4.7 106 km2, which is equivalent to:
• 8.42 106 Gigatonnes of water / 4.7 106 km2, which gives us 1.79 Gt per km2
• 1.79 Gt of water at a penetration rate of 43%, give us 0.77 Gt of water per km2
• 0.77 Gigatonnes of water by UK landmass 242,495 km² give us 186,804 Gt of groundwater
This water will be released at a rate of 1 – 12mm per annum and possibly at a depth of 75km. Therefore, to release groundwater at a depth of 75km at an average rate of 6mm per annum would take 12,500 years – not the 1,200 years previously believed, which is just the surface water from the last stages of the meltwater ice.
This is why rivers (like the Thames) still flow even after months of drought, as the groundwater is constantly leaking into the river, which was at its highest rate at the start of the Mesolithic, just after the great meltwater floods.
If this model is correct, we should be able to get verification via other empirical evidence, as shown in sea level water rises, to see if it has been constant over the last 12,500 years.
Most geologists and paleoclimatologists, when talking about the end of the last ice age, refer people to the phenomenon called the ‘Meltwater Pulse’ – which is the rapid rise in sea level (20m) between 13,500 and 14,700 years before present, over a 400 – 500 year period. Although it is a tremendous value, it should be recognised that this ‘pulse’ as only 16% of the total sea rise since the end of the last ice age.
Chapter 3 – Hydrology 101………….. Book Extract (Prehistoric Canals – Wansdyke 2)
When it comes to the use of ‘linear earthworks’ (we call ‘Dykes’), there is massive confusion amongst both professionals and amateur archaeologists about how such structures could function when they are dry today?
The incorrect perception of these ‘Dykes’ is either they are ‘rivers’ (like the Thames) that flow uphill or Victorian Canals with locks and wooden gates regulating the flow of the water – which are equally nonsensical as a prehistoric structures. Basic Hydrology that most people (should be but not necessarily ALL) learnt at school is that water is under the ground – not just a little water but 30% of all the fresh water on the planet.
This abundance of ‘groundwater’ is evident as it is the source of ALL rivers and supplies the Wells that have been dug since the beginning of time when rivers were absent. Even today, if you go into your garden and dig a hole, it will eventually fill with groundwater, whether in a valley or on top of a hill or mountain.
How and why water is on hills is very challenging for individuals as most people have a simplistic view of water being flat and sitting at ground level – but the earth is a far more complicated structure as this is the reason that it took centuries for people to recognise that we lived on a sphere and not a ‘flat-earth’ as such complex concepts such as gravity are hard to comprehend.
The reality is that ‘streams’ of water are encapsulated within the bedrock allowing ‘springs’ to start rivers at a great height as the groundwater is under pressure and erupts to the surface from BELOW and does not flow up or down the hill internally – but can flow downhill AFTER it escapes from the soil, because at the point of escape gravity then becomes the greater force overcoming the water pressure when within the bedrock – which stops it flowing down the landscape and can push it up to the top of hills and mountains.
Consequently, wells work even on hills as the groundwater is encapsulated in the bedrock and soil. The above illustration shows that if wells are dug halfway up a hill where there is a groundwater pocket, they will fill – if we join up these wells, the entire ditch will also fill with water – sourced from the ground.
The central aspect that must be remembered when considering the reasons behind the construction and maintenance of these earthworks (Dykes) is that the environment was so much different in the Mesolithic Period, which changed rapidly when entering the Neolithic and then even more changes in the Bronze and Iron Ages.
Once the ice sheets had melted and the climate began to warm, the landscape gradually changed from open tundra to dense woodland. By around 8000 BC, pine and birch dominated the woodland cover. These were slowly replaced by lime, elm and oak with some hazel. By 6500 BC, pine and birch woodland would only have been found on the thinner limestone soils of the uplands.
Case Study Wansdyke – Morgan’s Hill West………. Book Extract (Prehistoric Canals – Wansdyke 2)
The steepest aspect of Wansdyke is the rise over Morgan’s Hill, which is an incline from 182m OD to 252m OD.
If we are correct with our assumption, we need to show that you can transverse this massive incline using natural springs and basic wooden weirs. If we split the gradient into four parts, we can see better the profile and problems our ancestors faced.
Section A – 0 to 300 downhill
Length is 300m, and the inclination lowers from 251m OD to 242m OD at a ratio of 3% or 1:33 – If we accept that within this section, we had four cat A ‘springs’ that would release 11.2 cu. metres of water PER SECOND (11,200 litres per second) would fill a 10m ditch that is 1.5 deep by one-metre width of the Dyke’s ditch every SECOND.
According to the mathematical formula (v = k * C * R0.63 * S0.54 ), water at the end of section A would be travelling at 5 MPH – the speed of the Thames at Henley (so quite navigable) and, therefore, no need for any Weirs to reduce the water flow.
Section B – 300 to 800m downhill
This section would receive water at one metre per second from Section A, travelling at 5 MPH – The length of this section is 500m in length, and the inclination lowers from 242m OD to 200m at a ratio of 8% or 1:12 this would accelerate the water to 15 mph which is too fast the navigate uphill. Therefore, a series of weirs would have been placed either under the water or, as the early Victorians achieved, by a paddle weir or both.
An underwater weir (blocking 50% of the water but allowing boats to move over the top without hindrance) would reduce the flow by 50% – so if placed at the End of Section A (at 5 MPH) would reduce the water flow to 2.5 MPH and down to 12.5 MPH at the End of Section B. Consequently, if we place one of these 50% reduction weirs at 100m intervals the water flow would not go over the 5-mph mark and would probably be in the region of 3 – 5 MPH which again is easily navigable.
Chapter 4 – Wansdyke……………. Book Extract
According to Wikipedia, “Wansdyke consists of two sections of 14 and 19 kilometres (9 and 12 mi) long with some gaps in between. East Wansdyke is an impressive linear earthwork, consisting of a ditch and bank running approximately east-west, between Savernake Forest and Morgan’s Hill. West Wansdyke is also a linear earthwork, running from Monkton Combe south of Bath to Maes Knoll south of Bristol, but less impressive than its eastern counterpart. The middle section, 22 kilometres (14 mi) long, is sometimes referred to as ‘Mid Wansdyke’ but is formed by the remains of the London to Bath Roman road. It used to be thought that these sections were all part of one continuous undertaking, especially during the Middle Ages when the pagan name Wansdyke was applied to all three parts.
East Wansdyke in Wiltshire, on the south of the Marlborough Downs, has been less disturbed by later agriculture and building and remains more clearly traceable on the ground than the western part. Here the bank is up to 4 m (13 ft) high with a ditch up to 2.5 m (8.2 ft) deep. Wansdyke’s origins are unclear, but archaeological data shows that the eastern part was probably built during the 5th or 6th century. That is after the withdrawal of the Romans and before the takeover by Anglo-Saxons. The ditch is on the north side, so presumably it was used by the British as a defence against West Saxons encroaching from the upper Thames Valley westward into what is now the West Country.
West Wansdyke, although the antiquarians like John Collinson considered West Wansdyke to stretch from south East of Bath to the west of Maes Knoll, a review in 1960 considered that there was no evidence of its existence to the west of Maes Knoll. Keith Gardner refuted this with newly discovered documentary evidence. In 2007 a series of sections were dug across the earthwork which showed that it had existed where there are no longer visible surface remains.
It was shown that the earthwork had a consistent design, with stone or timber revetment. There was little dating evidence, but it was consistent with either a late Roman or post-Roman date. A paper in “The Last of the Britons” conference in 2007 suggests that the West Wansdyke continues from Maes Knoll to the hill forts above the Avon Gorge and controls the crossings of the river at Saltford and Bristol as well as at Bath.
As there is little archaeological evidence to date the western Wansdyke, it may have marked a division between British Celtic kingdoms or have been a boundary with the Saxons. The evidence for its western extension is earthworks along the north side of Dundry Hill, its mention in a charter and a road name.
Section 1 – HE:1003784 Wansdyke: section 610yds (560m) NW of Wernham Farm to 250yds (230m) SW of New Buildings (560m = 1680 working days – 20 men taking 84 days to complete)
No, HE Historic Details or Excavations Registered
1800 OS Map
LiDAR (with Mesolithic water levels)
A feature called ‘firs’ is a gap on the OS Map – there is a strange quarry pit (no relevant substances under the surface to quarry?) – this pit is two metres deep and probably built later to the original ditch.
Are we looking for a hole to find the groundwater to keep the canal working with fresh water? As we will discover, this is not the first pit cut deep on the line of Wansdyke.
The Mesolithic water levels certainly explain the strange start of Wansdyke and the unexplained gaps (if it’s not a canal) in the Dyke.
Notice on the LiDAR maps the extensive ‘pits’ surrounding the Dyke, which are not below the Mesolithic river shoreline and are 14m in diameter.
These features seem to be connected to even larger quarry holes (some under the Mesolithic shoreline), indicating that minerals have been extracted here for thousands of years and may be the reason for the Dykes construction to take minerals away – as have also found these pits in other mineral-rich areas of Britain such as Hadrian’s Wall.
The pits are about 20m in diameter and up to 5m deep, as revealed by further geophysical surveys using ground-penetrating radar and mechanical coring around Durrington Walls. Small quantities of struck flint, shell, and animal bone have been recovered from them, with the bone providing radiocarbon dates from about 2500 BC to 1200 BC.
What we see is that this type of quarrying was commonplace in the past and has confused archaeologists – but as this was a trading nation, the solution is evident and straightforward.
Gap in the Dyke route
At the end of Section 1, we find the first gap (if you exclude the massive gap at the start of the Dyke) – this gap appears as the Dyke dips into a paleochannel. The obvious conclusion for the break in Wansdyke is that it must have been full of water at the construction time.
This was an extracts from the NEW Book Ancient Prehistoric Canals (Dykes) – Wansdyke available on Amazon as a FULL COLOUR HARD BACK (£19.95) or a ECONOMY (£4.99) SOFTBACK black and white VERSION – it is also available as a KINDLE (£1.99) book. For further information about our work on Prehistoric Britain visit our WEBSITE or VIDEO CHANNEL.