Tuesday, 19 September 2017

Malawi Geothermal 2017

De-Risking the Geothermal Resource of Malawi

Earlier this year Dr Tim Raub, David Townsend (an ex-student and Founder of Townrock Energy) and myself made a reconnaissance field trip to Malawi to assess its geothermal potential.  We were joined in the field by ex-St Andy and lecturer in Geology at Chancellor College, Malawi, Dr Blackwell Manda. The trip covered the length and breadth of the country and finished with the delivery of a workshop on geothermal to university, government and industry. 
David Townsend and Blackwell Manda at the 

The project has grown out of our Department’s interests in geothermal in Scotland and abroad. It also continues a focus we have had on East Africa over the last 10years specifically with work in Ethiopia. 

So what geothermal interests do Africa and Scotland have in common you might well ask? Well both countries have a growing need for off-grid and end-of-grid energy solutions and both have some geothermal potential.

Global Challenge

The ubiquitous provision of clean, reliable energy represents one of our key Global Challenges that has both economic and well-being impacts throughout the developing world.  In so many countries, the current status where both heat and electrical power are supplied via erratic systems severely impacts economic growth.  In addition, the use of carbon-based (often charcoal) cooking systems has crippling health impacts, with associated deforestation causing further compounding of local environmental damage.

Over the last 10 years many developing nations have leap-frogged the Western world in telecom technology with a step change in thinking that is revolutionising daily lives (GSMA – The Mobile Economy, Africa, 2016).  In a similar mode, energy provision could also make a step change by not following a typical delivery system for energy through grid supply.  Rather, an off-grid model of energy provision (supply and storage) based on a scalable solution for small homesteads, through villages to townships could offer not only vital power to stimulate local industrial growth but could do so with major health benefits for the local populations. Furthermore, providing independence in energy at a local level would also address many of the issues caused by rural depopulation to cities and if the power is supplied by renewable, low to zero carbon means this would have wider global impact.
use of geothermal spring for washing

Addressing rural energy needs in the past have often failed as they have attempted to provide a singular energy solution to all settings.  Rather, the diversity of rural settings necessitates a flexible approach that offers a varied range of scalable solutions working together in an integrated network. Different physical settings require different combinations of technology. Renewable systems such as biomass, geothermal, solar, wind and hydro could provide the required mix of both electrical and heat base load together with peak demand when properly managed and backed-up with appropriate storage solutions.  The implementation of these solutions will require specialist teams of experts including resource scientist, engineers and social scientists. 

Malawi's needs

new pit being dug for using geothermal water for fish farming
Currently, Malawi produces 99.7% of electricity from hydro-power.  Supply cannot meet demand, and blackouts are regular in urbanising areas and normal in rural regions.  Most of the ~18 million population lives and works off-grid.  Assuring an energy future through carbon-based resources or nuclear comes with a price.  Further, as biomass burning is ubiquitous at a local level, this has large impacts on the environment and in particular the many unique forest ecosystems.  Biomass burning also contributes to soil erosion and hydro-power dam siltation, exacerbating Malawi’s energy crisis.
These power- and heat-generating challenges stunt development of industry, discourage tourism, frustrate personal ambition, and degrade Malawi’s cultural heritage. 

Solutions however are available.

Our initial funding from Global Impact and EPSRC funds allowed us to undertake an evaluation that consisted of three parts:
        Background desk-top review of geothermal potential including heat analysis of the country-wide geological database and recently acquired airborne geophysical survey
        Reconnaissance survey of known hot-spring sites
        Delivery of preliminary results plus geothermal methodologies and economics at a workshop to local stakeholders
Calculated heat production map and geothermal centres

Recommendations - a collaborative approach

stakeholder meeting 
It has been clear from the activities during Stage 1 of this project that there is not only a national geothermal resource for development in Malawi but that there is an appetite for development at both Government level and most importantly at a local level.  The latter is manifest by the high level of local interest we found during our field visit especially from young entrepreneurs.  They are clearly an important part of future developments as it is through local development that communities will benefit most. A course of action for us now includes the following:
Stage 2
        Later this year we will be hosting a visit by a team of Malawian engineers.  The visit will include meetings with Scotland-Malawi Partnership in Edinburgh; with collaborators at Strathclyde University in Glasgow; with industrial partners SASOL in St Andrews and ARUP in Edinburgh. A visit to the Netherlands geothermal operational plant is also planned
        Further field tests will be conducted at a few of the already visited sites in Malawi to better determine the resource potential.
        Working with socio-economic staff from University of Malawi an assessment of the social infrastructure for development and level of local (entrepreneurial) capacity for development will be made
Stage 3 longer term plans will then include:
        Drill to test the geothermal potential with two, 100m boreholes (testing the geothermal gradient and flow rates)
        Build energy and resource development partnerships – these will include key players both in Scotland and Malawi at academic institutes, government bodies and private companies 

        Delivery of integrated system to two test sites.

Wednesday, 13 September 2017

Orkney 2017

Orkney 2017

This summer we (the Rising Tides team – Caroline Wickham-Jones, Martin Bates and Sue Dawson) undertook a number of field trips in Orkney to cover a growing number of projects with partners at the University of Highlands and Islands.

Bay of Ireland

Moving south from our work in the loch of Stenness we have begun a collaboration with Scott Timpany at UHI, Jane Bunting at Hull University and Michelle Farrell at Coventry University. This project aims to contextualise the findings that UHI have published on around the peat deposits where a large oak timber was discovered by Ted Pollard during a campaign of coastal walking (Timpany et al., 2017).  The Bay of Ireland opens into Scapa Flow, the infamous site of the scuttled German battle fleet from WWII. Our investigations however focus not on this rather on the very much older landscape during the early Neolithic when sealevel was still rising to that of today. This now submerged area is typical in that it has an infilling of both ancient and modern sediments.  Our first task was to map these and determine the depth to basement (rock and glacial till).  As with previous geophysical investigations it was also hoped that we might be able to see different layering within the sediments to discriminate packages that could be associated with different environmental conditions. We used the UHI Geoacoustic pinger for the initial survey.  Results gave us the required depth to basement but the quality of data was not sufficient to image sediment packages.  As can be seen by the map of basement depth the bay takes the form of a buried basin that deepens to the south.  

Map of depth to basement and example of sub-bottom profile, Bay of Ireland, Orkney 
The southern limit of the basin is marked by a submerged bank or barrier that stretches roughly east-west across the bay and separates it from the main part of Scapa Flow. Armed with this data we attempted to core through a thicker part of the sequence in the centre of the bay. The core penetrated over 2m of sediment that we now need to analyse.
At the same time as the marine work Scott also attempted to follow the peat layers offshore from the landside.  A rather gloomy, wet day saw him joined by Martin and Sue with hand augers. 


Following the geophysics and coring we were fortunate to be joined by Nat Hirst and Kerry Santander from SeasearchScotland.  Seasearch divers usually scour the bottom looking at biology but they were game for trying their hand at underwater archaeology in the form of hunt the peat!  Before diving Scott primed them on what sort of features we were after and we armed them with core tubes that could be inserted (bashed with a lump hammer!) into the seafloor.  Over the course of two days they dropped on a number of sites both here and in the Bay of Firth adding greatly to our understanding of the conditions.  Tough work but with the good weather a rewarding trip.  Hopefully they can be encouraged to return when we have more sites for diving.
hand coring on seafloor

Skaill and Skara Brae

In September we returned to the loch of Skaill as our previous attempts to core this site had been thwarted by strong winds. The objectives of this investigation are aimed at further understanding the role of coastal barriers in protecting heritage sites.  In particular we are trying to not only reconstruct the past environments around iconic settlements like Skara Brae but also to understand how the environment changed, and over what time periods it changed.  Once again, the changes are not only linked to climate fluctuations but also to sealevel rise.  It is likely that Skara Brae was first located some distance from the coast with a wetland between it and the sea. As the sea rose the coastal barrier was breeched and the land was flooded. Over the ensuing millennia the sea gradually eroded evidence for this land surface however the environmental conditions are still preserved beneath the site and in the surrounding landscape.  For example, during coastal protection work at the site in 2009 a significant peat layer was noted at the base of the revetment scheme.  Unfortunately, the works did not record this or sample for further environmental signatures.  Published work by de la Vega et al in 2000 does provide a broad environmental setting for the site however our investigation aims to put far more detail into the story. 
A series of cores both on the wetlands to the south of the site and in the loch of Skaill were taken and show a complex sequence of sand, peat and loch sediments. There will certainly be enough in here for environmental analysis over this winter.  Based on these results it is intended to return to the site with a range of environmental geophysical techniques in 2018.

Orkney International Science Festival

September also features Orkney International Science Festival, an event that we try to participate in on an annual basis.  This year we managed a great afternoon out with the P6 class at Dounby Primary School at loch of Skaill, a coring of the Peedie Sea with Scott Timpany at UHI as part of their project on Medieval Kirkwall, a joint exhibit of our palaeo-environmental reconstruction at the family day and a talk on the Borth fossil forest by Bates, Bates and Bates!! (my father, Denis and brother Martin giving the low down on joint work in mid-Wales). 

Thursday, 23 March 2017

The Mysteries of Gilmerton Cove

The Mysteries of Gilmerton Cove

Back in the mid-80s I lived in Edinburgh while studying geology at the University of Edinburgh (happy days!).  I would like to think that during that time I got to know the city quite well and I certainly made sure investigate many dimly lit, subterranean hangouts (Bannermans comes to mind as a place frequently visited but full of hazy memories), however I never heard of the Mystery of Gilmerton Cove. 
Gilmerton is a suburb on the south side of the city and is home to a series of caves or tunnels that are not on the main tourist route.  The tunnels were for long assumed to have been the work of an 18th century blacksmith, George Paterson.  After having been caught selling liqueur from them on a Sabbath (he blamed this on his wife) he claimed that he had dug the labyrinth over a five year period as an underground dwelling for his family.  There are a number of “rooms” in the tunnels with stone tables, benches and even some that look like stone beds. In the walls there are markings suggesting that some of the rooms were separated by, presumably wooden, doors and curiously there are various skylights at strategic places.

The Cove was well known in the late 1700s with local historian Rev. Thomas Whyte noting their unusual construction. Various recordings have been made since with the first investigation undertaken by F. R. Coles, Assistant Keeper of the Museum in Edinburgh in 1867.  He described the construction of the caves in an article in the Scotsman in 1906 as having been dug using pointed chisels and further commented that it would have been unlikely for Paterson to have been able to create them by himself in just 5 years.

If not Paterson, then who had constructed the tunnels?  The area is one that has long been associated with mining and as far back as the 16th C there would have been ample and adequate labour to have dug them but for what purpose? 

The walls today are without marks of soot and with virtually no inscriptions apart from one small cross it is hard to imagine what went on in them.  Dating structures like these is notoriously difficult and so all we can do is compare them to similar structures elsewhere and better understand the layout of the caves themselves. 
sketch plan of caves
In the 1970s excavations revealed blocked passageways suggesting that the tunnels extend beyond the current layout.  So finally this is where the geophysics comes in.  About a year ago Dr Simon Shackley and Prof Stuart Haszeldine at the University of Edinburgh asked if I thought any geophysical technique might be appropriate for exploring the extensions to the caves and I suggested that ground penetrating radar would be our best bet in this very noisy urban situation.  The main problems for the site are that to the west is built up with housing, to the north three shops have been constructed over the tunnels and to the east is a very busy main road. Combined with this the pavement and road areas are riddled with drains, pipes and buried cables.  Not ideal for high quality geophysics!

The NERC Geophysics Equipment Pool provided a Sensors and Software Radar and we used this with 500Mhz antenna.  A station spacing of 10cm along lines was used and we placed lines at 30cm apart down the pavement and as far into the road as we could safely do. The results somewhat surprised me, especially those on the pavements either side of the main road.  Here reflections were recorded in the radar data that are consistent with a void-like structure at 2-3m in the subsurface.   

These seem to align across the road, however the significant gap in data where we could not survey still means that we do not really know what the extension might look like.  At the other end of the tunnels the picture is not so clear as the ground is very uneven and to achieve better quality data would require a significant amount of ground preparation.  So a little bit further with the mystery but certainly no great Scottish enlightenment yet – just like the old days coming out of Bannermans.

We hope to be back and continue the work but as with most projects, funding is now needed plus cooperation with the council to get a few hours of road closure would help greatly.

Friday, 24 February 2017

Searching for evidence of WW I German occupation in Namibia

Searching for WW I German armaments in Namibia, 2017

So I have had a few unusual survey proposals over the years, Yagan’s head comes to mind for example, but a call back in October led to a trip at the end of the year to Namibia.  At first I thought the request a little bizarre and one in which I would be of limited help but on talking the problem through I saw that perhaps geophysics might be able to add to the investigation.  

So what was the request? Well it started with a story surrounding the retreat of German troops from Namibia during WW I.  The story goes that as the German Schutztruppe ("protection force") left the country they disposed of various armaments in the sinkholes around the town of Tsumeb. In particular the lakes of Ojikoto and Guinas were suspected to contain field guns, rifles, carriages, ordnance and even (as always in these cases) a safe full of gold!  
German WW I field gun in Ojikoto Museum

This was too much to resist!!

The architecture of the caves and even their depths were in dispute despite a long history of local divers testing their prowess at exploration. Descriptions by local divers Chris Steenkamp and Johan le Roux (who provided incredible support throughout the trip - thanks guys) talked of overhanging caves extending unknown distances with jagged roofs and a very soft sediment on the lake floors.  The region is one of limestone and dolomite with a regional fracture pattern that shows linear trends to the lakes.  Along the weakened trend the lakes open up as sink holes and thus have steep to vertical sides.  These were going to necessitate some unusual access means and a very portable geophysical survey platform. 

Lake Ojikoto
To survey the lake floor and also to stand a chance of seeing something of the lake sides would require a sonar with a wide beam pattern so I took with me both a 468kHz and a 234kHz SwathPlusMotion reference and positioning was provided by a TSS DMS205, a Vector Cresent and Topcon HiperPro.  

The steep sides of Lake Guinas Lake meant that we had to abseil the inflatable boat into the sinkhole before setting up the equipment.  However, once on the lake the sonar produced fantastic maps of the underground structure showing the bell-like form of the sinkholes and also providing a series of targets for the dive operations. 

In Lake Ojikoto these were at 30-40m depth and proved to be a carriage gun and boxes of shells however in Lake Guinas the depth of over 100m was way beyond my comfort dive range and so remains to be investigated with remotely operated vehicles (ROVs) and cameras.  

The sonar produced a really great map of the underside or roof of the sinkholes even where the angle was very small compared to the water surface but the data set did require some significant manual filtering as the geometries of the structure was anything but typical for sonar data. Still, it just goes to prove that often you really do not know what you will get with geophysics until you try!
"outer" walls of cave

point cloud view of cave walls

The “expedition” was in part sponsored by a US Travel channel so watch out for Josh Gates and Expedition Unknown to be broadcast on March 6th in the US on the Travel Channel. 
Check out to view. 

Unfortunately, no gold yet but we will continue our hunt for the means to support the Schools future………

Sunday, 16 October 2016

Geophysics at the Gorgan Wall, Iran

Hunting the Red Snake – part II

Back in Iran, this time with my brother, Martin, to continue the hunt for the remainder of the Gorgan Wall.  Last year I was here with marine geophysical equipment to try and find the remains of both the Gorgan Wall and the Tammisheh Wall as they enter the Caspian Sea as part of a project with the University of Edinburgh and the National Museum, Iran.  From a previous blog (GorganWall I) I showed the results for the Tammisheh Wall extending well over 2km from the southern shores of the Caspian into a large lagoon behind the Miyankale Peninsula.  The sidescan sonar survey and sub-bottom profiling showed the remains of the brick wall with its accompanying ditch/canal.  Unfortunately we so no manifestation of the Gorgan Wall extension – so back to try again.

The Gorgan wall projection to the west towards the Caspian Sea
The Gorgan Wall (the Red Snake) extends from the Alborz Mountains in the east across the Gorgan Plains and was built from the 4th C AD as a defensive structure to keep out the marauding Turks from the north.  The wall was constructed of bricks fired from local clay in kilns spaced 40-80m apart along the length of the wall. It was at least 2m wide and tall expanding to a more substantial feature at numerous towers and where defensive forts occurred.  In front, to the north, of the wall was a 10-30m wide, up to 3m deep, canal.  The remains of the wall and canal are relatively well documented to the east. H,owever to the west, evidence of it remains elusive with historical writings describing the wall splitting into different parts and extending down to long-lost towns.

Despite being of similar age to the Tammisheh wall and being relatively close to each other the geomorphological setting for both is somewhat different.  The Tammisheh wall extends into the Caspian at a place where the sea is relatively sheltered with fairly benign sedimentation gently silting up the almost closed lagoon.  The projection of the Gorgan Wall however is across an area of coast where there have been highly dynamic changes due to the interplay between the Gorgan Ricer discharge and longshore drift bringing sediment onshore from the Caspian.  The present day shoreline demonstrates these active processes where the waves can reach impressive magnitudes due to a fetch stretching the length of the Caspian.

CMD Mini-explorer and Explorer ground conductivity meters
This year we have returned to attack the challenge of finding the remaining western part of the Gorgan wall as it progresses towards the Caspian Sea. We come armed with electromagnetic instruments, the GFInstruments CMD Explorer and Min-explorer.  Both are frequency domain ground conductivity meters, each with three coil spacings, in order to look to a range of depths.  We have a Leica dGPS for positioning control and for ground truth work a more traditional shovel and trowel.

The western limit of the wall is manifest by a series of “robber” pits that were used by locals to mine the decaying bricks for use in other projects.  The wall and remains of the canal that ran along the north side of the wall run in a straight course here for at least 20km.  Our first geophysical grids were laid over the robber pits and known wall/ditch locations in order to characterise their geophysical signature. The figure below shows this mapped on the satellite images.  Note that the background satellite images clearly define the agricultural system of 200x200m fields and also parts of the old natural landscape with its river channels and back barrier bars with sloughs.
EM Conductivity over robbed-out portion of wall
We continued to map the wall to the west and after approximately 1km a large modern drainage ditch was encountered and gave us the opportunity to ground truth the geophysics.  A 2D interpretation of the geophysics together with the surface mapping suggested that wall and ditch might exist here.  Excavation proved this to be true and samples have now been taken for analysis.

Using this characteristic signature mapping was continued a further 5km to the west with a complex pattern developing of linear features mixed with sinuous features.  Our current thinking has an interpretation based on a landscape evolution of shorelines behind which the old Gorgan River fights its way to the sea and through which the wall and canal/ditch is cut.  It is likely that the dynamic natural landscape was always an issue for maintaining the wall and canal here and a much larger geophysical and ground truth investigation is going to be necessary before a clearer picture of the history is revealed.
New geophysical results showing extension to the west from last known position

So, more geophysics to come hopefully in 2017. 

During the trip we also tried making maps with and AUV operated by Georgian colleagues.  While the purpose was to make maps along the wall projection we also took time to investigate some of the more interesting geological features.
Dormant mud volcano,Gorgan, Iran

This was way too short a trip as usual but a highly enjoyable one.  Our biggest issue this time was getting the equipment through customs – lessons for the next trip.  Our biggest hazard encountered (apart from the driving)  ........... watch out for those camels!


Monday, 30 May 2016

AUV hits Orkney

In the week of large scale remembrances of the Battle of Jutland that will include amassing parts of the British Naval Fleet, the German Fleet and possibly parts of the Danish fleet we made our own bit of history by testing for the first time one of the new generation of survey vehicles the Gavia AUV in the waters of Orkney.  The Gavia (Teledyn, Iceland) Autonomous Underwater Vehicle is a type of propelled platform designed to deploy geophysical instruments for survey beneath sea.  The vehicle looks like a small torpedo and in our configuration has onboard a complex navigation system, sidescan-bathymetric sonar and a high resolution camera.  The sonar is used to map the seafloor and to obtain backscatter images of the features on the seafloor.  The camera can likewise be used to identify seafloor features and to mosaic complete maps of what is there. There are two big advantages of using AUVs over conventional surface-based survey methods.  The first is that by flying an AUV beneath the surface it will not be affected by the noise and motion of waves and thus be able to “fly” in a steadier manner.  The second is that it can be pre-programmed for the survey and launched from either a boat or the shore.  With a forward looking sonar onbaord for collision avoidance the AUV does all the work while you sit back and have a cup of coffee – at least that is what should happen in theory!

The AUV (named “Freya”) was brought to the site by a team from the Scottish Association for Marine Science out of Dunstaffnage (SAMS) and was part of a small grant awarded to us by the Marine Alliance for Science and Technology Scotland (MASTS).  For John Howe, Karen Wilson and Colin Abernethy it was a first for not only visiting Orkney but also for using the AUV on an archaeological project.   Time was split between surveying the loch of Harray, near to the Ring of Brodgar and Ness of Brodgar archaeological sites and surveying in the Bay of Firth close to areas where we have previously mapped and reported unusual features on the sea floor.

The Rising Tides project has been investigating the area around the Ring of Brodgar for a number of years.  Most recently we have completed a full bathymetry and sub-bottom sonar survey of the loch of Stenness to the west.  The purpose of this work was to reconstruct the palaeo-landscapes and environments when the Ring of Brodgar and Ness of Brodgar were being built and used. What our work demonstrates is that the loch was smaller at that time and further that there was a complex history of sealevel rise associated with the infilling of sediments with a step change in sediment input coincident with changes in vegetation in the catchment at about 6ka BP. For more details on this see our publication “The environmentalcontext of the Neolithic monuments on the Brodgar Isthmus, Mainland, Orkney

Caroline and I have also been experimenting with digital reconstructions for the area that can be seen on our test site "Ancient Lands

AUV in the Loch of Harray
In order to match the work in the loch of Stenness we brought the AUV to the loch of Harray.  This loch is a shallow, freshwater loch to the east of the Brodgar isthmus.  Previous surveying with the sub-bottom profiler showed it to not only very shallow at the southern end (less than 4m water depth), but also that the sediments were gas saturated for the most part.  Because of the very shallow water the AUV was not able to “fly” beneath the water and had to be operated as a surface vehicle.  This, combined with the fresh water challenged both the vehicle and the operations team to come up with novel ways of ensuring the AUV did not either crash into the bottom or into any of the small fishing vessels on site! Unfortunately, the weather also proved problematic with strong winds.  The vehicle was able to survey a few lines of data but the automated tracking features did not work correctly and so the vehicle did not manage to stay on course in order to survey a complete grid of data.

AUV in Bay of Firth
Following the tests in Harray (also useful because it was a confined loch and so there was no chance of the AUV being lost out to sea!) we took Freya to the Bay of Firth.  Here she was much more at home back in saltwater and also with a greater depth range to work in (up to 9m water depth).  A survey grid was programmed in the centre of the bay over areas where we have previously recorded and dived on unusual stone features.  Freya was deployed from a small rib and perfectly performed her planned mission of bathymetry mapping, sidescan sonar imaging and photography.  The preliminary results, processed within minutes of return to shore (another huge advantage over old methods of survey) showed a resolution that we had not seen before.  Fantastic new images of the seafloor which we will now ponder over before our return to dive on them in August.  Look out for results in a later post.
The AUV opens up a new era for us with archaeological survey.  There are so many sites that could benefit from this type of survey and many new and exciting discoveries to be made.
The AUV team with Richard and Caroline in Orkney - check out the renewable power sources!

 PS – on a historic note, the Gavia is approximately half the size (half the length and diameter) of the original WW I torpedoes and weighs about the same as the explosive head that these carried

Friday, 11 March 2016

Recon on Lewis

Recon Survey to the Outer Hebrides

to see this in 3D go to GoogleSpheres here

Over the last 10yrs or so I have made a number of visits to the Outer Hebrides for both work and holidays. Most of the research trips have focused on marine biological habitat mapping and assessment of the impacts of storm activity on the coast lines. However, as with most of the Scottish landscape, the archaeology of the islands tells a compelling story, especially in comparison to the work we are currently doing up in Orkney.  So when Donald Herd, a colleague and native of Lewis, mentioned the possibility of a trip to visit his ancestral stomping grounds with the possibility of building collaborations for some future work on the islands I readily agreed to go even if it is sometimes dodgy weather in March!

Donald hails from the village of Suainebost in the far north of Lewis where there is a fantastic community historical society – Comunn Eachdraidh Nis.  This group is working to preserve island history, language and culture for both local community now and in the future as well as providing a resource for visitors to the area. This north part of the island has a diverse range of heritage on offer from some of our most ancient rocks in the Lewisian Gneiss to the heritage of the people. A great example of this is the recently completed investigations published in two books by Chris and Rachel Barrowman on the archaeology and heritage of Ness and an investigation on the unusual 16C-17C remains on the sea stack of Dun Eistean.  Hopefully we will be able to find funding to work on some of this in the future.  

The island of Lewis is justifiably famous for its archaeology, the centre piece of which are the iconic standing stones of Calanais (Callanish).  The best estimate of when the stones at Calanais were raised is about 3000BC, nearly at the time that farming began during the Neolithic here. However it is incredibly difficult to date the actual erection of stone circles, especially when almost no other structures, either houses or burial chambers have been discovered in the surrounding environment. We visited this site in order to check out the wider landscape as a potential place to conduct palaeo-landscape studies.  Since it was a quiet time of year with no visitors, Donald also took the opportunity to fly the site for aerial photography.  The results were quite stunning and fit nicely into the quick 360 image that we took at the centre.

We experimented with photographing a number of the stones as the structure displayed in the Lewisian Gneiss that the Neolithic people used is quite stunning!

As the day was such a good one we visited a much later broch on our way back to the north of the island.  Dun Carloway is a remarkably well preserved Iron Age broch (a type of fortification found throughout Scotland) likely constructed between 100BC to 100AD. It is of typical double wall construction which can be seen in the east side. The remains were in use, laterally as a kiln until at least 1000AD.  Folklaw has it that the clan Morrisons of Ness (Donald’s ancestors) used to hide in it while they went on cattle raids of their rival clan, the MacAulays! 

Now looking forward to a trip back, if for no other reason than to try some of the island's famous product - Black Pudding!  trouble is there are so many to try .......