Cardigan Bay Mesolithic Landscapes Re-visited

Combining work with fun is a common theme on many of these pages and so my latest travels are once again in that vein.  A few years ago we undertook a small seismic sub-bottom survey in Cardigan Bay to see what the potential was for mapping buried and submerged land surfaces.   In a similar situation to Doggerland, the west coast of the UK also hides secrets of past landscapes that our early ancestors used.  Mapping these however has been at a slower pace than in the North Sea mainly due to the lack of hydrocarbon exploration data and more recently the slower uptake of offshore wind.  Research undertaken by Aberystwyth University (Rob Wittington et al) and the BGS does give us some clues to the situation through sub-bottom records and some deep boreholes.

Our data from 2018 With the Irish Marine Institute and the Celtic Explorer identified a complex landscape from which I was able to speculate on a series of possible geographical models for the time periods from early Mesolithic to today (in press, Europe’s Lost Frontiers: Vol II).

Coastal geographies and positions of major river and associated archaeological sites. A: Early Mesolithic, 10,000 cal yrs BP. Sites 0: Aberdaron; 1: Pencilan Head; 2: Y Bryn;  3: Afon Wen; 4: Aberystwyth; 5: New Quay; 6: Newport; 7: Pencaer.  

These models were based on the limited seismic data that we had acquired, the old seismic data and some limited boreholes. Using the boreholes I created a function to adjust the present day bathymetry with the seismic mapped river/estuaries and a different function for the land that fell between them.  Sarah Boyd provided palaeo-sealevels from PhD research and tidal regimes were derived from the work of James Scourse.  Armed with these we now needed to test against new seismic and ground truth data.

Teaming together with Dei Huws from Bangor Uni we used a sub-bottom profiler to acquire new data during a particularly calm period in late May.  We used the 13m ketch Ivilia for the survey and she proved a stable platform for 24hr ops.

 

New survey lines were acquired north of Aberdovey down to NewQuay.  The fidelity of the sub-bottom data was far higher than the earlier information from the Celtic Explorer but the major horizons match nicely. The major palaeo-channels that parallel the coast offshore were confirmed and showed more complexity than we had originally been able to see.  As always, the more you look, the more complex the history becomes. Tying these to the onshore story is going to be quite a challenge.

Bully (Prof Martin Bates) has been working the onshore side of this paleo-reconstruction game on the West coast of Wales for many years with a particular focus on the forest site at Borth. Here many finds, including some impressive antlers record very different environments back through hundreds to thousands of years.

The new data will allow us now to better target key locations with the palaeo-geography and to acquire higher density seismic and ground truth data. Out there somewhere will be sites with key evidence of what the people were doing.  Just got to keep looking for them.

Sunrise over Cardigan Bay - a sight that I have rarely seen

Hunting Pyramids in Sudan

 Hunting Pyramids in Sudan

Over the past few years I have worked with a number of TV companies on shows that have highlighted the use of geophysics for archaeological investigation.  One of the most fun teams that has presented me with some of the greatest challenges to the use of both land and marine geophysics is led by Josh Gates at ExpeditionUnknown.  In his long-running series that airs on the Discovery Channel he has allowed me to run various geophysics in Dwarka (India), Namibia, and at various sites around the UK.

Early this year Josh asked if I would join him for a project in Sudan trying to find a lost pyramid.  Now you would think that it would be pretty hard to lose a pyramid, but it turns out that this might not be the case.  Pyramids are sometimes only partially completed or sometimes never really get beyond the foundations. They are often robbed of material to build other structures, let alone that they weather over time in the harsh desert environments where they are typically found.

The Nubian pyramids in Sudan were built by rulers of the Kushite kingdom from 1000BCE to 300AD.  While they have similar forms to those of Egypt the Sudan ones tend to be steeper sided and are constructed mainly out of the local coarse sandstone bedrock. The focus of this research project was the site of Nuri where it is thought that once over 80 pyramids may have stood marking the tombs of the royals from around 670BCE to 310BCE. The oldest, that of Taharqa (690-664BCE), a pharaoh of the 25^th Dynasty of Egypt and King of the Kingdom of Kush stands 50m tall and appears to contain a pyramid within a pyramid as seen from the stones eroding from the summit.  

One of the most interesting projects running at the site currently is led by Dr Pearce Paul Creasman who has an intrepid team of divers who are excavating the tomb of Nastasen.  Diving you may well ask?! Yes, because the nearby waters of the Nile and recent dam projects have caused the ground water level to increase to the point of flooding the tombs.  While I resisted the temptation of joining them (Josh did not) in zero visibility water that contains bits of old pharaoh my task was to find evidence for both the pyramid within a pyramid for Taharqa and also to search for a pyramid of a known king which could not be accounted for. 

For the task at hand in such dry conditions then ground penetrating radar was the tool of choice but since those who know me will also know I never trust just one technique, and especially if that is GPR. So, I also took along the trusty CMD Explorer electromagnetic ground conductivity meter as well.

The GPR was a Mala system with a 250MHz antenna.  Normally this should have been adequate in a dry, sandy environment to penetrate to at least a few meters.  I surveyed lines with a spacing of no more than 1m between lines and for most of the site a spacing of 0.5m between lines to form dense grids. An example of the results for a grid in front of the most northerly pyramid is shown below.  

Here you can see the sides of the tunnel stairway to the burial tomb close to the surface where it begins to descend.  While the edge is visible  the data shows the relatively limited penetration of the radar. This was curious and all I can think is that the wind-derived sand from the local coarse bedrock has winnowed the grains to leave a large proportion of the heavy metal minerals thus inhibiting the radar signal.

The results of the EM across the site showed much more promise.  The tomb entrances stand out clearly in the conductivity and magnetic susceptibility signatures against the backdrop area.  Interesting results were also obtained over a large flat and open area between the upstanding pyramids. The data here was consistent with there being a tomb entrance and foundations for a pyramid but clearly one does not exist – it is postulated that the missing pyramid was never built beyond the tomb and foundations. I hope that the dig team on site under the direction of Dr Pearce Paul Creasman will open up some test trenches to prove this in the near future.  

A cross section walked over the top of Taharqua’s pyramid also revealed the encased structure within the pyramid and now all that needs to happen is to extend this survey over the whole structure.

The survey, and especially the diving will be fully featured by Josh later this summer so watch out for the next program as part of Expeditions Unknown and pay careful attention to my new survey vehicle with its 1dp (donkey power) engine!

Croatia 2023

 The drowned landscapes off Croatia

I visited Croatia a number of years ago after diving on some of the submerged Roman sites in Greece and seeing the Temple of Serapis in Naples (https://upload.wikimedia.org/wikipedia/commons/9/9e/Charles_Lyell_-_Pillars_of_Pozzuoli.jpg) . The temple is geologically infamous as the front piece to Charles Lyell’s seminal work The Principals of Geology where he notes the mark of marine boring organisms at some height up the columns thus indicating that they were once submerged.  He correctly interprets this as representing tectonic movements that have caused both a submergence and subsequent re-emergence of the temple since its construction in the late first to early second century AD. Contemplating the potential for drowned landscape reconstructions around the Mediterranean and Adriatic seas I briefly looked for papers describing sea level changes.  These were almost entirely absent from the academic literature.  Fast-forward to 2023 and I am here on the invite of Dr Simon Fitch (Bradford University) as part of his Future Leaders project. The idea is to map paleo-landscape surfaces in the many rias (drowned river valleys) along the Adriatic eastern shore. 

Split, Croatia

The project in Croatia is partnered with Dr Vedran Barbarić at the Faculty of Humanities and Social Sciences, University of Split and the first trial survey was undertaken on board the Pram, expertly skippered by the enthusiastic and knowledgeable captain Jerko Macura . For the acquisition we had chosen to use an Innomar Quattro parametric sonar (https://www.innomar.com/products/multi-transducer/quattro-sbp).  This hull-mounted sonar is configurable as either a line of four transducers emitting separate signals for high-resolution 3D type survey or as a block of four transducers working together for greater power and thus sea floor penetration.  The unit was side-mounted together with a Novatel IMU GNSS unit to provide heave corrections.  

Innomar Quatro with Novatel dual antenna motion reference unit

Over the course of 5 days we surveyed a number of small bays, outlets to the main large bays, channel crossings and both large and small deltas.

The weather cooperated for the most part until the Bora winds (a sever katabatic northerly wind from the shore) stopped play on our last day. The survey exceeded our expectations with penetration to greater than 15m sub-bottom in water depths up to 70m deep.  The seismic reflectors and character demonstrated sequences that could be interpreted as eroded bedrock, basin sediment infill, channel cuts, deltaic progression with periods of both regression and transgression. 

Channel entrance to the old harbour of Split

The potential for mapping multiple palaeo-landscapes and associated environments is huge. We now need a program to accomplish this that has ground truth from coring and careful modelling.  The project has only just begun so here is looking forward to returning and working with a great team.