Tuesday, 23 October 2012

South Downs and more conclusive evidence of Post Glacial Flooding

By Robert John Langdon

If you study any British Geological Society (BGS) geological map of Britain you will notice it shows a series of bedrock, sedimentary and superficial deposits.  At a scale of 1:50,000 km and below these deposits start to form labyrinth of material that look like canals and gigantic waterways which lay under the surface on top of the bed rock. This lays testament to how the landscape must have looked at some stage in of our natural history and this is particularly prevalent in the Stonehenge area as well as other chalk bedrock outcrops.


Stonehenge - BGS Geological Map showing superficial deposits
Stonehenge - BGS Geological Map showing superficial deposits
These superficial deposits that resemble ancient rivers can clearly be seen on the surface and are known to the archaeologists, geologists and the general public as ‘Dry River Valleys’ -  because the river valleys are currently dry.

But this was not always the case!

Until recently geologists believed that the contours of these chalk hills and valleys were cut during a ‘Periglacial Phases’ of the ‘Quaternary Period’, which is the current geological period that started about 2.6 million years ago - although there is no real evidence of their exact date of their formation.
Recent theories (and in Geology these new ideas are occurring on a regular basis) suggest that these dry river valleys are the result of water flooding, washing away the top soils and rounding the chalk sub-soil, during the melting period after an Ice Age. 

The problem for archaeologists and geologists is - which one?  - For there has been several during the quaternary period.
Devils Dyke - a 'dry river valley' on the South Downs
Devils Dyke - a 'dry river valley' on the South Downs
Geologists seem content to give rough estimations on the construction date of geological objects such as dry river valleys, which for the archaeologist can become misleading.  For although the origin of these objects is of interest, the actual dates when they could have been used my man is even more important, if we are to understand  the anthropological implications and through this process, any archaeological findings in relation to their location.  
So we must best try to understand not WHEN the dry river valleys were formed, but when LAST did they have water running within them?
Geological maps clearly indicate that great rivers once flowed through Britain and we know that the greatest deluge of water that has ever affected the landscape is at the end of an ice age, when the gigantic ice caps finally melt.  In the end of the last ice age some 17,000 years ago, geologist have estimated that the ice was over two miles thick in some places. This substantial level of ice MUST have created huge flooding all over the Mesolithic landscape including the Valleys of the South Downs, even thought they were over 100 miles away from the main ice sheet.
South Downs -BGS Geology map showing SALTDEAN
South Downs -BGS Geology map showing SALTDEAN
Modern geologists now accept that the dry river valleys are the product of water (not ice as previously believed) and looking at some extreme examples of the soil eroded and valleys cut, we are not talking about just frozen tundra slowly melting in the summer season - but millions of gallons of fast flowing water cutting away at the top-soil and sedimentary deposits, all the way down to the bedrock in some instances. 

Saltdean - showing the chalk face with the remains of the sandy post glacial river bed
Saltdean - showing the chalk face with the remains of the sandy post glacial river bed

This geological evidence can clearly be seen in the cliffs and valleys of the South Downs.  Just like the Stonehenge region, this area has the same chalk sedimentary bedrock and ancient post-glacial rivers.  Evidence for these rivers are found by the sandy subsoil consisting of sand, silt and clay.  This subsoil can be seen in the valleys (known as deans) of the South Downs and most graphically in the exposed face of the white chalky cliffs that have been eroded  by the sea giving us a perfect ‘dissection’ of a typical prehistoric waterway.  Modern geologists have yet to identify these huge concave sections as being the remains of the ice melt from the last glaciations that had filled with water leaving the sandy sediments embedded in the chalky sedimentary rock face just after the great melt, some 15,000 years ago, instead they claim they are 'wind blown' loess or wash from the valley walls.
What they can't explain is the relatively short distance from the sandy soil to today's top soil and the exact date of this sandy sediment.  As you can see the sandy remains of the river is touching the top soil.  If this dry river valley was as old as some archaeologists and geologists suggest - where is the rest of the top soil? 
If the top soil erodes as quickly as some 'experts' also suggest - why is there 18 inches of top soil on top of the chalk today, there should be none?
Bottom of the prehistoric riverbed - showing how close to the top soil is the sand
Bottom of the prehistoric riverbed - showing how close to the top soil is the sand
Are we expecting some massive climatic event to wipe away the top soil in the near future or is the dating of the prehistoric river beds and consequently dry river valleys totally incorrect?  
As a matter of practice, archaeologist investigating Stonehenge have always ignored the obvious dry river valleys that surround the site, as they are incorrectly perceived that this area looked as it does today at the time of Stonehenge's construction and therefore, the River Valleys were dry in the Mesolithic/Neolithic Periods.   
Our case studies (in my book - The Stonehenge Enigma) of the South Down's, the River Ouse gave us  radiocarbon dates of 6290 BC +/- 180 for this same sediment.  Combine this with our other case study of the Thames (shown on an earlier blog) showing it was cut in the early Mesolithic and at that time, ten times larger than it is today - we have proven beyond reasonable doubt these rivers actually existed from the start of the Mesolithic, just after the ice age great melt late into our prehistory in the Neolithic period and in some instances the medieval period as in the river Ouse
RJL
(by Robert John Langdon)

18 comments:

  1. Robert

    Looking forward to the second edition.

    Teri Holliday

    ReplyDelete
  2. Teri

    Yes as I have mentioned before, the second edition (which includes a fuller explanation of this post and the evidence found on the South Coast) will be available in December 2012 - sorry for the delay as I did originally expect it to be out in September.

    RJL

    ReplyDelete
  3. What does the pink colour signify on the BGS maps?

    Dr Stuart Love

    ReplyDelete
  4. Stuart

    According to the Stonehenge map key the pink colour found on the BGS 1:50,000 geology maps - Head: variable deposits of sandy, silty clay, local gravely chalky and flinty in dry valleys.

    Wiki def of head: Head describes deposits at the very top of the geological succession, that could not be classified more accurately. The term has been used by British geologists since the middle of the 19th century. Areas identified as head include deposits of aeolian origin such as blown sand and loess, slope deposits such as gelifluctates and solifluctates, and recently eroded soil material, called colluvium. With geologists becoming more interested in studying the near-surface environment and its related processes, the term head is becoming obsolete.

    So as you can see - clear as mud!!

    After spending too much time reading different interpretations, I have found a common theme - sand! If there is sand there was once water and the borehole data around Stonehenge shows a huge amount of sandy head!

    RJL

    ReplyDelete
  5. Robert,

    Sorry you stopped posting in Brian's blog! I was looking forward to some lively discussions … But I understand your frustrations being intermittently blocked! Went through that with Brian myself. But now he seems a little more considerate of my contributions. The same may happen with you. So don't give up yet! And your contributions will add to the discussions, I know. We do agree on a number of key important views. And disagree on many others. But that's normal!

    In one of your last posts in Brian's blog you mentioned “Open the BGS viewer for Castell Mawr” . Can you detail how to do this? I am interested looking further into this.

    Kostas

    ReplyDelete
    Replies
    1. Kostas

      As you well aware happy to have a debate, but Brian has become more 'stubborn' in recent months and has from time to time deleted my comments that show flaws in his theories. The reason I look his web site from time to time, as some of my theories are based on geological assessments i.e. riverbeds.

      If he is unwilling or does not have the geological knowledge of sub-deposits to have a positive debate, checking my assumptions, then its not worth my time commenting. He has recently stated (when cornered) that is only a geomorphist and not a geologist - but Geomorphology is about rivers and groundwater, which clearly he has little to no knowledge.

      You will like this link as it looks under the surface to show you the bedrock and sub-deposits around Stonehenge and sadly to say ;-( you first piece of tangible evidence for your theory??

      http://mapapps.bgs.ac.uk/geologyofbritain/home.html

      RJL

      Delete
    2. Robert,
      I see lots of yellow with some narrow brownish strips. What am I seeing?

      Kostas

      Delete
    3. Kostas

      The button on the bottom right of the Viewer will show you the key to the maps - To my best memory Yellow is alluvium (what is left after a river has run dry - sand & silt) Brown is either another more clay type of alluvium or 'Head' which is sand again and pebbles, geologists do not associately link this to rivers - but if their is sand there was a river once.

      RJL

      Delete
    4. Kostas you are right and I did a blog some time ago showing the extent of the flooding and how the site would have looked - you will approve i'm sure as it backs your hypothesis..

      http://robertjohnlangdon.blogspot.co.uk/2011/09/craig-rhosyfelin.html

      Good luck trying to persuade Brian!!

      RJD

      Delete
  6. Robert,

    In a comment in Brian's blog you say, “the discredited Darvill”. How so? Can you elaborate?

    Kostas

    ReplyDelete
  7. MPP and others do not like Darvill's 'monument for the sick' theory of Stonehenge or the methods used in the excavation and recording - its all academic twaddle Kostas. All archaeologists are trying to discredit the other as the money for excavations and more royalties for books have dried up - so if their is money to be spent they are trying to make sure they are 'perceived' as the 'current' expert in the field.

    RJL

    ReplyDelete
    Replies
    1. Robert,

      The BGS maps are very interesting. Know of any similar maps detailing the superficial deposits of Stonehenge proper, the Avenue, and the surrounding areas to these? Or any other studies (bore holes, etc.) describing such deposits?
      I totally agree with your assessment of archeologists! More interesting in funding than in truth.

      Kostas

      Delete
    2. Kostas

      Borehole data is now available FREE although you can not print or download it without a fee - if your patient enough you can compare the maps with the borehole data and the findings are 'ambiguous' enough to be re-interpreted if you are 'open minded'. But if you believe that sand in the superficial deposits are due to wind rather than water - then the maps are relatively accurate.

      http://mapapps.bgs.ac.uk/boreholescans/boreholescans.html

      RJL

      Delete
    3. Robert,

      Thanks for the borehole info. Sorry to see your continued struggles with Brian getting your ideas accepted. It has occurred to me this may be because both of you are right and wrong! While my theory reconciles both in between. Brian is right in expecting much greater sand/gravel deposits found at Stonehenge if inundated by water. And you are right in arguing for flooding after the glaciers melted.

      The reason there are scant sand deposits is because Salisbury Plain was covered by a local ice sheet (possibly a frozen glacier lake) which protected the land from such deposits. As all such were flushed into the sea as the ice sheet gradually melted and drained into the sea. It's also the reason why we don't find many glacier erratics at Salisbury Plain. As these also were flushed into the sea. Where they can in fact be found buried underwater along the shore.

      Merry Christmas!

      Kostas

      Delete
    4. Kostas

      The pictures in this blog show you these 'scant' deposits first hand - as you see these rivers were not small and the deposits are huge (the brown is colour is your scant deposits!!)- the BGS maps I have proven to be deceptive. This was the reason for my move so that I have empirical evidence which I can compare against the maps - even bore hole samples can not compare to the level of detail. As Stonehenge (less than 100 miles away) has the same ancient waterways as shown in the BGS maps - there is no reason to believe they are any smaller than the South Down's ancient rivers.

      As for glacier ice, it has now been show that only a small percentage goes into the sea - the sea level maps (http://en.wikipedia.org/wiki/File:Post-Glacial_Sea_Level.png) show that that the melt water surge lasted 1000 years and when it was over the sea level was still 80m lower than today. This is because 90% of all meltwater goes into the ground as groundwater and takes up to 20,000 years to make it's way to the sea.

      This is the main reason for rising sea levels not melting glaciers such as the north pole - in fact frozen ice displaces more cubic capacity than water so if the north pole melts the sea level would in fact drop, but the release of groundwater through wells to be used in domestic/industrial use - the waste is pumped out to sea directly or via rivers.

      RJL

      Delete
    5. Robert,

      The pictures are compelling. I agree these show prehistoric river beds. My puzzle is why we don't see such extensive alluvial deposits at Salisbury Plain. If the Avon River was at one time lapping Stonehenge stones in the Mesolithic, shouldn't we have similar vast sand/gravel deposits at the Stonehenge landscape? I ask, though I have an answer: ice covered the landscape and protected it from such alluvial deposits.

      Kostas

      Delete
    6. Kostas

      What makes you believe that the same same kinds of beds are not on Salisbury Plain? To quote from my book:

      "And what of the other borehole SU14SW56 at 14m below the surface we still do not find the bedrock but “weak to very weak thinly bedded light brown to brown silty fine to medium grained sandstone. Silt of chalk, sand is subrounded in filled with brown silty sand”. Again this shows that groundwater was on this spot in prehistoric times. In fact if we go to the extremes of the borehole area SU14SW76 some 500m to the west of the maps centre we even find the return of both topsoil, head and structureless chalk, down to 1.1m. Clearly the prehistoric river was not just 80m wide but more like 1000m wide, better known as a kilometre. So armed with this proof of evidence we can move forward to show how these rivers affected our prehistoric past, putting aside the idea of ‘hill wash’ as more ‘eye wash’ than substance."

      The boreholes show the river at Stonehenge Bottom was at least 1 km wide and left deposits 14 metres (45 feet deep) - the same scale as the South Downs river beds - seeing is believing!!

      RJL

      Delete
    7. Robert,

      Interesting info. It's not hard to believe prehistoric rivers, with vast glacier meltwater making up their volume, were much bigger and wider than today. Have you been following my posts in Brian's blog on Crag Rhosyfelin? I am also arguing the river there was much wider during prehistoric times, placing MPP's “quarry” in water!
      ( http://brian-mountainman.blogspot.com/2012/12/castell-mawr-rome-and-mecca.html )

      Every time I recall your chance meeting with MPP at Stonehenge Bottom, suggesting to him this area was under water, I LOL with his reaction running away!

      Kostas

      Delete