Archaeology in the Red-Zone: post earthquake management in Christchurch, Canterbury, NZ

Working as an archaeologist following a natural disaster really makes you consider priorities in life as well as heritage management. I came to work at the New Zealand Historic Places Trust (NZHPT) following the Canterbury earthquakes. I work as the Assistant Archaeologist and Researcher in a fixed term role established to support earthquake recovery work.

I hadn’t been living in Christchurch long when the earthquakes struck – a 7.1 quake on 4 September 2010 which caused widespread damage and two serious injuries and a 6.3 quake which hit at 12:51pm on 22 February 2011 causing severe damage and the loss of 185 lives – and there have been over 10 000 aftershocks since. From my personal experience I would have to argue that natural disasters really do seem to result in a flight or fight response. However, despite not being a Christchurch resident long, I now feel an even stronger connection with this place and really want to contribute to the rebuilding of the city and people’s lives.

Looking down Manchester Street, Christchurch CBD after the February 22 earthquake [Dave Margetts, NZHPT, 2 March 2011]

Looking down Manchester Street, Christchurch CBD after the February 22 earthquake [Dave Margetts, NZHPT, 2 March 2011]

Damage to Odean Theatre (NZHPT Register No. 3140). This theatre was constructed in 1883 and is an archaeological site as defined by the Historic Places Act. It is the oldest masonry theatre in New Zealand. [Dave Margetts, NZHPT, 26 September 2012]

Damage to Odean Theatre (NZHPT Register No. 3140). This theatre was constructed in 1883 and is an archaeological site as defined by the Historic Places Act. It is the oldest masonry theatre in New Zealand. [Dave Margetts, NZHPT, 26 September 2012]

During the earthquakes widespread damage occurred to buildings and structures, with disruption to water, power and sewerage services. Many buildings are being demolished and earthworks are needed everywhere to remove building foundations, clear sites and repair infrastructure – over 300 kilometres of sewer pipes and 895 kilometres of road were damaged. The government is in the process of acquiring and clearing over 6000 residential properties in what is called the ‘Residential Red Zone’ in the worst hit areas so that residents have the option of moving on. Land in the Christchurch CBD, also one of the worst effected areas, is also being tagged for acquisition to redevelop the city centre. At the moment there are many empty parking spaces which will be rebuilt on in time.

As places of pre-1900 human activity some of these structures and properties, where damage occurred, are considered to be archaeological sites under New Zealand legislation. In New Zealand the Historic Places Act directs that an archaeological authority is required to destroy, damage or modify an archaeological site. As a Crown entity and as New Zealand’s leading historic heritage agency one of NZHPT’s jobs is to administer the archaeological authority process and carry out compliance to ensure that archaeological sites are protected or preserved via record. This has obviously proved challenging following a natural disaster where the priorities are rightly lives, safety and recovery. Funnily enough archaeology has not been the first thing on everyone’s minds. A streamlined authority process has been developed so that applicants can now expect decisions to destroy, damage or modify an archaeological site within 3 working days or 5 if the site is of Maori interest. Archaeological sites in Christchurch mostly relate to Maori (New Zealand’s indigenous population) occupation and the more recent European settlement of the area from the mid-nineteenth century. Shell middens, historic rubbish dumps, brick barrel drains and buildings, amongst other things, are all being recorded by archaeologists before they are destroyed.

A site visit to New Brighton with the Stronger Christchurch Infrastructure Rebuild Team (SCIRT) to understand the extent of excavations required for repairing sewer systems. NZHPT Regional Archaeologist and myself in yellow high vis.  [Huia Pacey, NZHPT, 9 July 2013]

A site visit to New Brighton with the Stronger Christchurch Infrastructure Rebuild Team (SCIRT) to understand the extent of excavations required for repairing sewer systems. NZHPT Regional Archaeologist and myself in yellow high vis. [Huia Pacey, NZHPT, 9 July 2013]

A large chunk of my job at the moment is to undertake desktop assessment and research of properties to ascertain whether an archaeological authority is required. Insurance companies, project managers, demolition companies and CERA (the Canterbury Earthquake Recovery Authority who have been set up by the Government to coordinate the ongoing recovery effort following the earthquakes) all send me lists of properties to check everyday resulting in about 200 a week to check. While we have a national database of recorded archaeological sites and a good understanding of where pre-1900 occupation occurred many of these areas have not been subject to archaeological assessments or investigation before. So my research is designed to fill this gap and identify unrecorded sites. The opportunity to research properties and find out more about patterns of settlement in Christchurch is fascinating. However every now and again reality hits that for each property that comes across my desk a family has lost their home or a business has lost their premises following the earthquakes.

My workspace at the NZHPT Southern Regional Office. Our office was displaced from the CBD following the earthquakes and now operates from the outskirts of the city. [Frank van der Heijden, NZHPT, 29 July 2013]

My workspace at the NZHPT Southern Regional Office. Our office was displaced from the CBD following the earthquakes and now operates from the outskirts of the city. [Frank van der Heijden, NZHPT, 29 July 2013]

I also assist the Regional Archaeologist (also the Canterbury Archaeological Officer following the earthquakes) in processing authorities, assessing archaeological management plans, assessing archaeological reports and following up on site damage and compliance with the conditions of archaeological authorities. The volume of work post-quake means I don’t get much time outside anymore and when I do it is mostly to ensure that the conditions of our authorities are being complied with.

The things that keep me sane through all of this administration and earthquakes are opportunities to tell our stories – both past and present. I am interested in telling the stories of life in Christchurch through time and the story of managing archaeology following a disaster. One of my jobs is to catalogue and submit archaeological reports to the University of Canterbury’s CEISMIC Digital Archive called Quake Studies. My colleagues and I have also facilitated sharing of archaeological information and artefacts in public programmes such as Canterbury Museum’s Quake City exhibition and the CBD Rebuild tour. Hopefully we can learn from the settlement of our swampy city and previous building techniques to ensure that a disaster of this type doesn’t happen again. The scale of archaeological work in Christchurch is greater than it has ever been and the scale of earthworks required for redevelopment means in many areas this will be the last opportunity we have to examine the material remains of our past. It is important to keep talking about our past and remembering what was.

Sydney Observatory and Fort Phillip

Sydney Observatory, Fort Phillip, the missing Greenway magazine and Windmills

Fort Phillip used to send signals in the early 1800s.

Since the flag mast was reinstated in 2007, a flag decoder permits visitors to determine the daily astronomical, shipping, meteorological and ceremonial flags flown on Sydney’s highest hill in the CBD.

The significant heritage value of Sydney Observatory 1858 including the remains of Fort Phillip 1804 have been officially recognised at both local and state levels. The care and use of the site must protect the values that make it a significant part of the heritage of Sydney and NSW. 

The exceptional heritage aspects of the Sydney Observatory have been outlined in a ‘statement of significance’ in the Conservation Plan (Kerr). The statement forms a succinct summation of the particularly unique and significant aspects of the site and its values, and is used to guide decisions regarding the care of the site:

‘The Observatory is of exceptional significance in terms of European culture. Its dominant location beside and above the port town and, later, City of Sydney made it the site for a range of changing uses, all of which were important to, and reflected, stages in the development of the colony. These uses included: milling (the first windmill); defence (the first, and still extant, fort fabric); communications (the flagstaffs, first semaphore and first electric telegraph connection); astronomy, meteorology and time keeping ;

The surviving structures, both above and below ground, are themselves physical documentary evidence of 195 years changes of use, technical development and ways of living. As such they are a continuing resource for investigation and public interpretation;

The place has an association with an extensive array of historical figures most of whom have helped shape its fabric. These include: colonial Governors Hunter, Bligh, Macquarie & Denison; military officers and engineers Macarthur; Barrallier; Bellasis and Minchin; convicts: the as yet unnamed constructors of the mill and fort; architects: Greenway (also a convict), Lewis, Blacket, Weaver, Dawson and Barnet; signallers and telegraphists such as Jones and the family Moffitt; astronomers: particularly PP King, Scott, Smalley, Russell, Cooke and Wood;

The elevation of the site, with its harbour and city views and vistas framed by mature Moreton Bay fig (Ficus macrophylla) trees of the surrounding park, make it one of the most pleasant and spectacular locations in Sydney;

The picturesque Italianate character and stylistic interest of the Observatory and residence building, together with the high level of competence of the masonry (brick and stone) of all major structures on the site, combine to create a precinct of unusual quality;

Finally, the continued use of the observatory for astronomical observations and the survival of astronomical instruments, equipment and some early furniture, although temporarily dispersed, and the retention of most interior spaces, joinery, plasterwork, fireplaces, and supports ensure that the observatory can remain the most intact and longest serving early scientific building in the State (Kerr 1991: 39)

Also of significance for relationship of Commonwealth and State powers. Site of the first inter-colonial conference on meteorology and astronomy. (Pearson et al 1999)

An excellent example of a Colonial building erected for scientific purposes and continuing to perform its function at the present time. The structure makes an imposing composition atop the historic hill originally known as Flagstaff Hill and occupies the historic Fort Phillip site (1804-45). Designed by the colonial architect Alexander Dawson and built in 1858.

After completion of recent restoration from 2008  to 2011 the remains of Fort Phillip are now used for Australian historical archaeology workshops. Two of which are being set up today, June 29 for the school holiday period commencing tomorrow. They are Time Detectives and Dig It! Both workshops are being used as school holiday programs with the intent to run them on a regular basis for school and community tours.

Dig it! Archaeologists in training workshops run several times each holiday period and last just under two hours. They are always sold out and we use the following ad online and in our collateral:

“Become a hands-on archaeological detective and investigate the history of Fort Phillip and the site of Sydney Observatory. Experience a simulated archaeology dig, find out what happens to artefacts after they are ‘dug’ out of the ground. In wet weather, the dig is replaced by a fabulous 3-D Space Theatre session. Suitable for: ages 6–10 years”

Budding young archaeologists learning the trade in the Signal Master’s Cottage atop Fort Phillip.


More “Dig It!” archaeologists with one of our very own archaeologists, Anthea.

Our second workshop is Time detectives: a science and archaeology game. “Treat your child to a fabulous day of science investigation at historic Fort Phillip, part of Sydney Observatory. This workshop includes a simulated archaeology dig, investigating finds, making an electronics analysis device which they then use to solve a mystery dating back 200 years. Participants get to view through binoculars and telescopes and experience the 3-D Space Theatre. Suitable for: ages 8–12 years.” This workshop lasts 6.5 hours and again is always sold out.

The third archaeology program is offered to Vacation Care groups. In a typical 2 week holiday period we may have up to 10 groups attend and it is this one we have been preparing today in particular by cleaning the “dig pit” and planting our artifacts. Vacation care groups: dig it! And map it!A fun, hands-on simulated archaeology dig. In the program for primary and infants school age children participants dress up and take part in a simulated dig with our resident archaeologist and record their findings. Binoculars are used to view South Head and the children decode Sydney Observatory flags. For high school children measurement is made using instruments and participants map a section of the site, recording their archaeology finds. Participants safely view the Sun through a telescope (weather permitting) and record their measurements of solar activity. This workshop caters for up to 60 children at a time and is suitable for ages 5–9 years and 10–14 years.

As we continue to develop our programs and target schools and community groups it is expected that archaeology will continue to expand at Sydney Observatory.


Work on Fort Phillip commenced in 1804 but ceased in 1806.


Sydney Observatory and Fort Phillip ground plan circa 1870s. Note no mention of the magazine.


One of the many relics found at the site.

Geoffrey Wyatt

Education Officer

Sydney Observatory and Fort Phillip

Moving a dune, eroding archaeology on Scotland’s north east coast.

The sand dunes at Brora, Sutherland, on Scotland’s north east coast, are over four metres high. Buried within them are the remains of the late 16th / early 17th century saltpans. Over the centuries, the wind had blown sand over the site, completely covering it until it became forgotten about.

Sand dune at Brora

Sand dune at Brora

In recent years, coastal erosion had exposed part of the front wall of one of the buildings, and on the Day of Archaeology, we finished machining and started cleaning up the site.

We knew that masonry remained buried in the dunes as we had uncovered half of a building in 201. Although we had seen the front wall of the buried portion, we did not know how much would survive.

In order to uncover the site, we had to remove hundreds of tons of sand and had spent the previous two days landscaping the dune. Removing the sand would allow us to work safely , but we had to make sure that the wind would not blow away the reshaped dune, so were replacing the turf on the remodelled dune as quickly as possible.

Machine stripping of dune

Machine stripping of dune

We were finished with the machine by 9:00am (the machine driver had another job to go to so started early, one of the benefits of long summer days up in the north!). The machine had taken out the bulk of the sand while we dug close to the walls to ensure that the machine bucket didn’t damage the masonry.

Cleaning site by hand

Cleaning site by hand

When the machine had gone, the walls plotted with the EDM, and loose of unsafe masonry was drawn, photographed and then removed.

Using an EDM for survey

Using an EDM for survey

There was also much collapsed masonry within the building, and once the machine had left, this had to be removed by hand.

Heavy work, moving stones

Heavy work, moving stones

We also spent time videoing Calum, a young volunteer who helped us out last year also, and had been inspired to use the Brora dig for a school project.

By the end of the day, we had cleared enough sand to reveal a small room, roughly 4 m x 4.5m, with a doorway facing the sea and a fireplace in one wall. While machining we had seen the lintel of the fireplace and it seemed to have initials carved into it. As we removed more sand from around it, we could see that there were further initials on one of the jambs; the other had nicks etched into its edge, perhaps where people had sharpened their knives.



The project had been initiated due to Jacqueline Aitken’s passion for, and concerns about, the archaeology of Brora. Jacquie remembers playing on eroding masonry (now long gone) when she was a child and was worried that Brora’s industrial heritage was being washed away by the sea. A member of the Clyne Heritage Society, she contacted SCAPE (Scottish Coastal Archaeology and the Problem of Erosion) and a joint project, (also involving the University of St Andrews where Jo and I are based), was established. Thanks to funding from Historic Scotland, a small bit of Brora’s past is being recorded before it is lost forever.

Clyne Heritage group members

Clyne Heritage group members

Medieval water management, some experimental archaeology Part II – What happened?

Well, what a day!

I am aching, my hands are full of cuts & splinters and my body has practically seized up. Wading through 100’s of metres of water that is over two feet deep does that to you at my age. I enjoyed it though. The experimental side of things was just that, experimental. Not all is lost though, the lessons learned are that I either get the fire brigade or Territorial Army in to supply me with a serious body of water, or, I wait until the rainy season in Wales (this could be at anytime of the year) and use the drain tracing dye then.

When the soil has been battered by relentless rain I have witnessed the water systems working in full flow. The water erodes any soil build over the dams drain outlet and literally pours straight down it. As you can see from the film, we had to spray the water directly onto the soil hoping that the tracing dye would not be filtered out. As it was the ground was that dry, and the system that long, that nothing came through. Of course, my theory of the dam and drain being of one system could be incorrect but future experiments will prove that either way.  Many thanks go to Neil of  WelshDrainage who not only provided the water for the experiment but also provided the drain dye free of charge. More people running business’ like that are worth their weight in gold to people like us. You can see a very short video of what we did here. That has been edited right down but we will produce a more polished effort when the time is right and we have more time to organise things.

WelshDrainage. What a service in the name of experimental archaeology!

WelshDrainage. What a service in the name of experimental archaeology!

The cleaning of the possible wharf  went well and it sprang up a few surprises. I had only seen it once or twice before and that was at a distance, but as I approached it I realised that it was a larger than I had previously thought.

As you can see, there was a lot of vegetation to clear

The Sisters at the Abbey had kindly invited me for lunch but after lunch at the abbey the only thing you really want to do is sleep. I had around one and half hours to get as much cleared as possible.

The size of the remaining structure really started to show just before lunch

After fish for lunch (well it was a Friday) I started clearing the remaining vegetation which thankfully was mainly ivy rather than brambles, thorns and stinging nettles.  After I had cleared it all away it was possible to start getting some dimensions. Its length was just over fifteen metres with a height of one point eight metres. Interestingly the walls were constructed so they curved back into the banks at either end, probably to enable  the bank to take weight and also to stop the structure being washed away. They also curved towards the bank away from the perpendicular. This feature may have been incorporated to  make berthing easier. It is the direct opposite shape of a curved  hull.

The structure curving away from the perpendicular

That was not all. Spending the amount of time that I had in this area gave me the opportunity to take a good look at the surrounding landscape. As you may have noticed in the above picture the bottom of the Dowlais Brook also contained surviving masonry. Not only that I had noticed that there were walls buried on  the opposite bank. So I cleared all of the vegetation away to get a better view.

Directly opposite the large visible structure, more clues started to appear

I think I shall leave it at that for now. Obviously I have a lot more investigation to carry out and that is on this one structure alone. The day was a success in that I now have more information to work with. What I have suggested may change in time as more and more evidence comes to light although at least I have enabled myself to tighten my research for a  comparable Cistercian structure.

An archaeobureaucrat writes…

A day or so in my life as an archaeologist working for English Heritage.

Started off by working at home at Haslemere in Surrey, eating toast with tea while dealing with e-mails with Radio 4 providing the background noise.  As usual, was mildly distracted by Frankly the cat who views my attempts to sit down and work at a laptop as his cue to demand food with menaces and then attention, generally in that order. 

A demanding cat. Frankly.


E-mails give me a few things to deal with before I do anything else. There are corrections to check on a chapter I helped to write for the forthcoming book on the Elizabethan Garden reconstruction at Kenilworth Castle. I was involved in organising the programme of archaeological and architectural research that contributed to the project, and I’ve co-written the archaeological chapter with Joe Prentice of Northamptonshire Archaeology, who directed the excavations, and Brian Dix, garden archaeologist extraordinaire, who advised throughout. Not much left to do – just checking that the photographs are in the right order, have the right numbers and captions, and are available in the right format for reproduction.

That done, I moved on to deal with some work on our forthcoming organisational restructuring. It’s no secret that English Heritage took a huge hit in last year’s government Comprehensive Spending Review. The organisation is having to deal with the impact of a net 35% cut in our grant from government. I can’t say a great deal about what is currently going on, but it will come as no surprise to learn that many jobs are being lost, and that I and many of my colleagues will be put formally ‘at risk’ in the autumn, and will have to apply for a smaller number of jobs in the restructured National Heritage Protection group.  We’ve been through such reorganisations before, and I know the stress that this puts my colleagues through, but the scale and scope of these changes is greater than anything we’ve seen so far. A lot of colleagues are having to consider other career options and paths; an unsettling time for us all.

After a couple of hours, time to trek to the station to catch the 11am to Waterloo. I’ve been taking a few pictures to illustrate this blog, and drew pitying looks from fellow travellers as I took a photograph of the train as it came into Haslemere station.  I’m a blogger, not a trainspotter….


My train arriving at Haslemere station


The train was fairly full, but got a seat and used the time to write up the blog of the day so far. Also did a little more on the draft publication strategy and synopsis for the Windsor Castle updated project design.  I worked at Windsor from 1989 to 1995. We started off in the Round Tower, the shell keep that stands on top of the 11th-century motte, excavating and recording the structures as part of a major engineering project.

Round Tower team, 1989, with the blogger looking much younger.


We’d just finished that project and evacuated our site office in November 1992 when fire broke out in the Upper Ward. That was the start of a huge programme of salvage and architectural analysis, with some excavation involved too.

Archaeological salvage of fire debris starting in the Grand Reception Room, Windsor Castle, 1993

The assessment of these large project archives was largely complete by the end of 1998, but work has been on hold then for a number of reasons.  I’ve been in deep discussion with my colleague and good friend Dr Steven Brindle over the last few months, and the next stage is to get in touch with all the project specialists to let them know that the analysis may finally be about to happen. Hence the publication strategy, so they can see what we’re asking them to do.  By Guildford my seat was surrounded by loud and excitable children, and I was bitterly regretting having left my i-pod in my bag, which was overhead and thus inaccessible.


English Heritage offices at Waterhouse Square, Holborn

By bus to our Waterhouse Square offices in Holborn, where I find a seat among friends in London Region. Here I dealt with a variety of business by e-mail, including mundane admin tasks such as approving invoices and expenses.  Fortunately we have quite good electronic systems for dealing with such things, so they were finished very quickly. The online press summary included a link to a Telegraph opinion piece on the listing of London tube stations. I tweeted the link with my own comments, and was later gratified to learn that my comment “Entertainingly daft Torygraph rant” appeared on the relevant page of the Telegraph website.  A small but pleasing result. At this point I lost the use of the camera; my chum Dr Jane Sidell was off to give a walking tour of Roman London, and borrowed the camera to record the event.

Trying to persuade Dr Jane Sidell, Inspector of Ancient Monuments for London, to point the camera somewhere else.

I also had to draft a response to a member of the public who had written to say that she was disappointed to learn that we aren’t running the Fort Cumberland Festival of British Archaeology event this year. I explained that this was as disappointing to us as it was to her; our free FOBA weekend event has been very popular, usually attracting c. 2000 people over a weekend to enjoy a range of archaeological and related activities. We enjoy it as much as the visitors do. We had to take the difficult decision not to hold the event this year in late 2010; by then it was already clear that we would be in the middle of a major reorganisation, and in that context it seemed unfair to ask colleagues to commit their time and energies to planning the event at a time when they were likely to be severely distracted by other events. We hope to be able to reinstate the event next year, resources permitting…

At 2pm, I took part in a Portico project team  meeting. Portico is a project that aims to provide up-to-date research content on the English Heritage website for our historic properties. Enhanced content is already online for all of the free sites, and the first sets of pages for 12 of the pay sites are now available. An introduction to the project with links to the available content is available at (insert link).  We were updated on progress, which remains good; the first batch of site information is now online, and all of it has been or is being updated with links to online resources. Another batch of sites is nearly ready to go online, including Susan Greaney’s excellent Stonehenge pages.  The next stage of the project is currently being planned; I may have volunteered to write up one or two sites myself.  A day conference is being planned for London next April to promote the project. The introductory page on the EH site shows the content that’s available so far –

Following the meeting I had a very useful discussion with Christopher Catling about the National Planning Policy Framework, which is currently out for consultation.  I think we agreed that it’s a huge improvement on the earlier practioners’ draft, preserving more of PPS5, but there are still some concerns, including the assumption in favour of development that permeates the document.

After that, there was time to check e-mails and deal with a few more bits of business before catching the train home. This included correspondence relating to one of last year’s fieldwork projects, on the Romano-British settlement around Silbury Hill, and the forthcoming excavation at Wrest Park in Bedfordshire, where we’ll be digging up parts of the French Parterre to assist in its restoration.

That was Thursday 28th July – I decided to write it up for Day of Archaeology as I was taking today off.  In the event, I took a trip to Corfe Castle, which I haven’t been to for far too long.  Despite the long queues of holiday traffic, it was a useful and hugely enjoyable visit. I always particularly enjoy the path up to the keep, which passes through the tumbled remains of the demolished sections of the keep. It’s very evocative of the sheer scale of destruction on this site.

The degree of destruction caused by slighting varies from site to site; this would appear to be off the vindictive end of the scale. The site is looking very good, but I was very disappointed by the new interpretation panels, full of rubbishy unhistorical cliches. The panel about ‘oubliettes’ was the worst example. It went on about the agonies of the poor prisoners abandoned in deep pit prisons. The work of Peter Brears has, of course, demonstrated beyond reasonable doubt that such structures are strong-rooms, for the safe storage of documents, money and other valuables. The reason that they often have well-lit chambers with fireplaces above them is not to provide accommodation for the better-off prisoners, but to provide a room for the clerk or steward to work in. Worst of all, having conjured up imaginary sufferings  in imaginary oubliettes, the panel finished by admitting that no such chamber survived at Corfe. So the point of this rubbish was…..?  Rant over.

The effects of undermining - the tower has slid down the slope, and the curtain wall has fallen over.

I took some time looking at the evidence for the destruction of the site, which is a particular interest of mine. This was the subject of the thesis of a friend of mine, Dr Lila Rakoczy, and since reading her work I’ve become more interested in looking at the evidence for how buildings were demolished. The walls at Corfe have certainly been undermined, but there’s no clear evidence for the use of gunpowder, despite the claims on a number of panels that the site was ‘blown up’. The surviving unused sap at the base of the keep’s latrine tower is a simple horizontal rectangular slot, which I think argues for the use of the ‘burnt timber prop’ method of undermining – i.e. using timbers to prop up the wall as the sap is excavated, and then burning them out to bring down the mass of masonry above. Drawings of near-contemporary saps used for explosive undermining, e.g. in Vauban’s work, show that these saps tend to be hollowed out behind a small opening in the outer face of the wall, to contain the blast and thus maximise the effect of the explosion on the masonry.  A bit anorakish, but it keeps me happy.

Possible sap at the base of the Keep's latrine tower, The masonry at the right hand corner is, I think, relatively-modern underpinning.

After that, I enjoyed a much faster and prettier drive home by avoiding the main roads. So there you have it – two days for the price of one, and I got to see some archaeology on one of them.

Brian Kerr, Head of Archaeological Projects, English Heritage


Musketballs, Mortars and Matchlocks

What do you think of when you think of archaeology? For the majority of people the answer is simple- ‘musketballs’. If that wasn’t the first thing in your head, there’s no need to fret; ‘fragmented portion of a 17th century grenade’ is also a perfectly acceptable answer. Ok, none of the above is true. But for me it is objects such as these that make up my Day of Archaeology.

I work as Operations Manager for a commercial company, Headland Archaeology (Ireland) Ltd. The majority of my work involves overseeing all the projects we undertake and making sure they run smoothly, are carried out to a high standard and progress as efficiently as possible.  However, I also specialise in ‘Conflict Archaeology’, a field of study which explores evidence for the forms and effects of conflict on past populations. Today is a ‘Conflict Archaeology’ day.

The material I work with the most relates to conflict in 16th and 17th century Ireland. This was an exceptionally bloody period in Irish history. The Elizabethan Conquest of Ireland took place in the second half of the 16th century, while the 1640s witnessed eleven years of war, culminating in the Cromwellian intervention on the island. Later still the War of the Two Kings was fought between William III and James II’s forces. The conflict artefacts and conflict architecture left behind on sites from this period can tell us much about the personal experience of individuals during these troubled times. What was it like to be a soldier in one of these armies? How did they operate? What affect did the wars have on the civilian populace?

Today I am working on an assemblage of military artefacts from a Castle site which was besieged in 1653, when Parliamentarian forces bombarded the site and forced the Irish defenders’ surrender. Although there are some historical accounts of the siege, many details of the engagement remain unknown. This is where the artefacts come in. It becomes quickly apparent to me as I trawl through nearly 200 iron ball fragments that the castle was extremely heavily bombarded. The sheer number of fragments is unusual in Irish archaeology- it is the highest concentration of artillery projectiles from a conflict site I have yet come across in the country.

What can they tell us? They are all heavily damaged, with only one complete spherical ball surviving. This suggests that the projectiles shattered as they struck masonry, or split into deadly shrapnel as they exploded. Their form tells us that the Parliamentarians used at least two main types of projectile; solid iron balls and mortars. The solid shot was intended to break down the walls of the castle, while the mortars (hollow iron spheres filled with powder) would explode and fragment as they rained down on the defenders.

I am currently analysing the size of the fragments to try and tell what type of artillery piece fired them. Although most iron balls are today usually called ‘cannonballs’, in the 17th century a ‘Cannon’ was a specific type of gun which fired a particular size of ball. Many other types existed, with names like ‘Culverins’ ‘Sakers’ and ‘Falcons’. These fired different sizes of ball over varying distances. Identifying the type of gun can help us identify how far away the besiegers may have been from the castle, and also tell us how difficult it was to get them into position. For example, some of these guns required dozens of oxen to haul them around the countryside.

'17th century grenade and lead shot'

And what of the defenders? The majority survived this siege and were able to surrender, but the castle was destroyed in the bombardment. Among the military artefacts that relate to them are lead musketballs (also called lead shot) and weapon fragments recovered from the rubble. The size, shape and weight of the musketballs can tell us what types of gun they were used in, provide information about how they were manufactured and also suggest if they have been fired or not. The examples from this site appear unfired, so they may have been dropped or lost by the defenders. This site is unusual in that it has also produced part of the firing mechanisms from some of the defender’s weapons, most likely destroyed during the bombardment. These fragments are from matchlock muskets, a type of gun that used a lit piece of cord to fire the musketball.

When I have finished the technical analysis of the material (a process which will take a few days) it will be possible to build a picture of the siege. I will be addressing what types of artillery the Parliamentarians brought with them, how this was used and transported and where it might have been fired from. From the defenders viewpoint it should be possible to suggest how the bombardment was experienced by the men within the castle, as well as talk about how they were prepared to meet the onslaught. This is all in the future, however, and for now I am immersed in the technical analysis of each of the artefacts.

So, this is how I am spending my Day of Archaeology, 29th July 2011! Every object I am handling was deposited over a handful of days 358 years ago, in what must have been an extremely dramatic and traumatic event in the lives of all those who were present. For some these objects represent their final moments.  It is an honour and privilege to deal with these artefacts, as by doing so you are literally ‘touching history’; the results of the analysis itself helps bring this history to life. It is certainly one of the most fascinating ways to spend a day that I can think of!

Ancient concrete? Really?

Yes, really.  I first fell in love with old buildings in Pompeii, where I spent summers working as an excavator from 2002-2008. Every day it struck me that I was in a place that still looked and felt like a real city. To my mind, this was down to the fact that the buildings are still standing. After more than 2000 years. Someone did something very, very right when making those buildings and I want to know more.

For my D.Phil research, I have landed in an opportunity to study structures in Ostia, Italy, which is also a preserved city-sized site.  The structures I’m investigating are all brick and mortar masonry, with concrete filling up the center wall core. This is what Vitruvius called opus caementicium. To be honest, I’m most interested in the people who made it: the builders who developed this wonderful, magical material that is still performing successfully more than 2000 years after it was first installed. Where did they get their materials? Why were certain materials preferred over others? How were the materials processed and mixed together? How did builders’ choices affect the concrete and its performance? Were the same mix types used for both public and private structures? Why is this stuff still standing? These are the questions driving my research, and I am looking to answer them by investigating the material itself.

To give a quick overview, the mortar and concrete I am analyzing was made of lime, volcanic sand aggregate, and water. Sounds rather simple, however, the combination of materials they were using produced complex chemical reactions, known to modern concrete scientists as pozzolanic reactions, which resulted in a sophisticated, high quality material. My sample collection was collected from a series of structures in Ostia from the 2nd century CE, by which time – at least in Rome – concrete was well-developed and had been employed in large-scale Imperial building projects. My task now is to analyze the Ostian structures to determine how well-developed their concrete industry had become by that time. The benefit of a site like Ostia is that the ancient city is left largely in tact without modern development. This means that unlike in Rome, where centuries of modern development has destroyed all but the most protected monumental structures, it will be possible to evaluate the buildings within their original cultural context.

The analytical techniques employed for my research are borrowed from geology and concrete science, which makes this a truly interdisciplinary project. My samples are essentially synthetic composites of natural materials that can be investigated with traditional petrography. I’m using light microscopy of thin sections to identify and quantify the aggregate, to describe the cementitious matrix, and to identify any  obvious degradation features or alteration products. Today I’m working on point counting one of the samples, which is pretty straight forward. I move across the sample in 1 mm steps, and at each location I record what I see in the cross hairs of the eyepiece. Besides the obvious benefit of quantifying each of the different components, I’m also getting to the know the sample really well. As I go, I’m recording information about the state of degradation or alteration, the shape and fillings of any cracks or holes, particle size and shape, and any other details that may give me a clue about what the builders were doing when they made the concrete.

I am also using scanning electron microscopy (SEM) to collect high-resolution, high-magnification backscatter images of the samples. At this scale I can get a better look at the binder-aggregate interface to see how well-bonded these components are. It is also possible to see any microscopic cements that have formed in pores, cracks, and the vesicles of aggregate clasts that would otherwise not be visible. The SEM also detects the atomic weights of everything in the sample, which show up as differences in the greyscale colour of the image. It  also can calculate the chemical composition of the different components, so using a combination of chemical data and backscatter images, I can determine what types of cements have formed (strengthening) and how much leaching has occurred across the matrix (degradation). The ratio of calcium to silica is key in both cases.

X-ray diffraction is also on the menu, assuming I can find the funding to pay for it. This technique is incredibly useful for identifying the mineral assemblage in rocks and materials. In this case, I will use it to confirm the original petrographic identification of minerals in the aggregate and to find any other alteration minerals that could not be seen in thin section. The presence of certain minerals like gypsum or ettringite usually indicate alteration of the mortar itself, but minerals such as stratlingite and calcium-aluminum-silicate-hydrates suggest the mortar was rather well-formed in the first place.

So today, I’ll be giving an account of what it’s like for me in the lab. I realize that being stuck in the lab sounds like a death sentence to some people, but for me, it’s where the magic happens.