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OSL Chronicles: Questioning Time in the Geological Tale of the Avon Valley


In delving into the Quaternary deposits of the Avon Valley, a rich tapestry of geological history unfolds, challenging conventional perceptions and demanding a nuanced understanding. Among the varied deposits, including clay-with-flints, head, gravelly head, river terrace deposits, brickearth, and occasional peat, the clay-with-flint stands out as a residual deposit shaped by the modification of Palaeogene sediments and the dissolution of the underlying chalk. (OSL Chronicles: Questioning Time in the Geological Tale of the Avon Valley)

The age of these deposits remains a subject of uncertainty, though there’s a prevailing notion that clay-with-flint deposits in southwest England likely date back to the Pleistocene era. Perched atop hilltop flats, these deposits, alongside older head deposits formed through solifluction and the solution of underlying layers, paint a dynamic picture of geological evolution. The landscape tells tales of hillsides shaped by natural processes, offering glimpses into the Earth’s ancient transformations.

As we descend into the valley, encountering ‘head gravel,’ ‘gravelly head,’ and ‘head,’ the remnants of fluvial transport, hill wash, hill creep, and solifluction emerge. Each layer tells a story of a landscape molded by the forces of water, a testament to the intricate dance between terrain and river dynamics. The river terraces, a flight of 14, exhibit a remarkable geological history, spreading wide and standing tall above the Avon valley floor, pointing to the draped deposition of terraces over the landscape.

(OSL Chronicles: Questioning Time in the Geological Tale of the Avon Valley)
OSL Dating of the Sediments on the River Avon

The constant thickness of these terraces along the valley signifies a system influenced by sediment overloading from upstream and contributions from tributaries. The mechanisms involved, including lateral erosion and redeposition of fluvial sediments, paint a vivid picture of the intricate dance of geological processes. This dynamic interaction between rivers and their surroundings challenges simplistic narratives tied to Milankovitch cycles, urging a more nuanced understanding of terrace formation in the Avon Valley.

River Terraces

Diving deeper into the historical context, the discussion extends to pre-Quaternary geology, with terraces labeled T5 to T10 in the Hampshire basin, indicating the complexity of the geological narrative. The dating of these terraces, often obscured by a lack of comprehensive research, unveils a need for a more thorough investigation into the ancient past. Organic remains found within the terraces, assigned to different interglacial periods, offer glimpses into ancient climates and environments.

(OSL Chronicles: Questioning Time in the Geological Tale of the Avon Valley)
River Avon River Terraces showing the size of the River in the Past

However, the narrative takes a twist with a recent publication challenging previous dating methods. The application of Optical Stimulated Luminescence (OSL) dating brings forth results that question traditional interpretations. The inconsistency and seemingly random nature of the OSL ages for different terraces raise doubts about the accuracy of the method. The debate around the accuracy of OSL, akin to the historical debates around radiocarbon dating, emphasises the evolving nature of scientific methods.

The complexity of dating terraces is further underscored by discrepancies between OSL and carbon dating, revealing potential anomalies in age estimates. Questions emerge about the accuracy of the OSL method and the need for ongoing refinement and validation. The recognition of discrepancies between upper and lower catchments adds layers of intricacy to the geological narrative, emphasizing the need for a more nuanced understanding.

(OSL Chronicles: Questioning Time in the Geological Tale of the Avon Valley)
Macklin’s Model of the extsent of the River Flooding in the Past

In conclusion, the exploration of the Avon Valley’s Quaternary deposits reveals a dynamic interplay of geological forces, challenging simplistic narratives and inviting a deeper understanding. From the intricacies of clay-with-flint formations to the geological dance shaping river terraces, each layer tells a story of Earth’s evolution. The uncertainties in dating methods, highlighted by the OSL results, beckon for continuous refinement and scrutiny. The Avon Valley’s geological narrative, like an open book, invites scientists to read between the lines and uncover the hidden stories of our planet’s past.

But there is on thing that we now understand is that the River Terraces of the Avon we flooded in ‘recent times’ and this would have a profound effect on the peoples of this area and a clue to the construction of the sites that were on the shorelines of these raised rivers of the past. (OSL Chronicles: Questioning Time in the Geological Tale of the Avon Valley)

More information on the River Avon can be found at:

Further Reading

For information about British Prehistory, visit for the most extensive archaeology blogs and investigations collection, including modern LiDAR reports.  This site also includes extracts and articles from the Robert John Langdon Trilogy about Britain in the Prehistoric period, including titles such as The Stonehenge EnigmaDawn of the Lost Civilisation and the ultimate proof of Post Glacial Flooding and the landscape we see today.

Robert John Langdon has also created a YouTube web channel with over 100 investigations and video documentaries to support his classic trilogy (Prehistoric Britain). He has also released a collection of strange coincidences that he calls ‘13 Things that Don’t Make Sense in History’ and his recent discovery of a lost Stone Avenue at Avebury in Wiltshire called ‘Silbury Avenue – the Lost Stone Avenue’.

Langdon has also produced a series of ‘shorts’, which are extracts from his main body of books:

The Ancient Mariners

Stonehenge Built 8300 BCE

Old Sarum

Prehistoric Rivers

Dykes ditches and Earthworks

Echoes of Atlantis

Homo Superior

For active discussions on the findings of the TRILOGY and recent LiDAR investigations that are published on our WEBSITE, you can join our and leave a message or join the debate on our Facebook Group.

(OSL Chronicles: Questioning Time in the Geological Tale of the Avon Valley)

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