Monday, 17 February 2014

The Secret our ancient ancestors knew about Britain's floodplains

By Robert John Langdon

In recent weeks, our news has been dominated by stories and pictures of the devastating effects of high winds and rain on our environment.  These areas of devastation are shown as flooding on a vast scale over the normally dry countryside and villages of our land.  This latest obsession with the weather is highlighted by commentator’s quoting statistics and facts such as ‘highest rainfall since records began.

But are they correct?

The reality is that the current records actually go back another one hundred and fifty years prior to the ‘official’ figures and show that rainfall was much greater in the past.  The evidence of written history also indicated that coastal flooding was once so great that tens of thousands of people drowned in ‘tidal storms’ of the past.  Waters of the last age just ten thousand years ago (a mere moment in human history) led to the land flooding for thousands of years, which laid down the original sediments which are now causing the flooding of farmland away from the rivers.

Moreover, our ancient ancestors wisely built their settlements and monuments, such as Barrows on high ground not prone to flooding and constructed subterranean shelters in there thousands to provide shelter from these storms, some of which still survive.  This bears testament to the fact that the weather conditions we experience today are not unusual but possibly the norm for these islands and that over the last two thousand years, we have benefited from a period of mild clement weather, which is probably coming to a dramatic end.

This is the Environmental Agencies map of Chippenham showing the current flood areas.

Environmental Agency Flood Map
Live flood data 17/02/2014 (© Environment Agency 2014)

Prehistoric Map of Chippenham
Langdon's Bronze Age Map - 1000BC
This map shows what has happened after about just 6" of rain fell on this area over the last two months.  It looks remarkably like my map of this area showing the raised groundwater levels in the Bronze/Iron Age period about 3,000 years ago.


Prehistoric Chippenham
Langdon's Neolithic Age Map including Bronze Age rivers (dark blue) - 4000 BC


If the rain kept falling the flooding will increase and my map series can predict the extract extent of the flooding as it will follow the same prehistoric floodplains of the past as the sand and silt sediments are currently below the top soil.
Prehistoric Chippenham
Langdon's Mesolithic Age Map - 10,000 BC
It is unlikely that the landscape will return to this level of flooding as this was how Chippenham looked six thousand years after the last ice age melted which was the single greatest water event in our history depositing the equivalent of 126,000 inches of rain creating massive complete flooding as seen on this Mesolithic map of Chippenham.


So how would Chippenham have looked during these flooded phases in the past?


Ordnance Survey Map Cheltenham
Chippenham Today (© Ordnance Survey 2013)

But three thousand years ago the flood waters had receded from there maximum ten thousand years ago and would look like the flooded the rivers we have seen recently.


Ordnance Survey Map Cheltenham
Today's Flood levels and Bronze/Iron Age floodplains (© Ordnance Survey 2013)
By Robert John Langdon


Six thousand years ago the rivers were so swollen it immersed the low lands.


Ordnance Survey Map Cheltenham
Neolithic Water levels (© Ordnance Survey 2013)

But directly after the last Ice Age the equiverlent of 126,000 inches of rain fell flooding everything apart from the highest of hills.

Ordnance Survey Map Cheltenham
Mesolithic Period shows most land were islands!(© Ordnance Survey 2013)
Not only did the ice caps melt flooding the landscape but the release of water led to a change in direction of the gulf stream and massive storms and even hurricanes hit the West Coast of Britain, so the residence protected themselves by building subterranean shelters by the thousand.

The settlement of Carn Euny in Cornwall is best known for the well-preserved state of the large fogou, an underground passageway roofed with massive stone slabs that is more than 65 feet long and runs below the surface of the ground leading to a side passage that leads to an unusual circular stone-walled chamber. Excavations on this site have shown that there was activity at Carn Euny as early as the Neolithic period.


Fogou
In Cornwall subterranean shelters are called 'Fogou'
Fogou
Diagram showing the size of the 'Fogou'
RJL

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