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|
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.
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|
|South Downs -BGS Geology map showing SALTDEAN|
|Bottom of the prehistoric riverbed - showing how close to the top soil is the sand|