Archive for November, 2009

Day Eight – Wednesday 9th September

November 27, 2009

Heard ourselves on Radio Scilly over breakfast – Jacqui describing OSL dating as ‘funky’!  Packed up and tidied up ourselves and our samples for the ferry journey home.   Helen set off for the plane back to Bristol in order to shorten her journey to Aberystwyth.  The rest of us went off the Quay in a taxi, dropping off various tools we had borrowed (and broken!) – thanks to everyone who helped out. 

We then went to visit Nornour and its prehistoric settlement and Romano-British shrine.   The island is tiny and provides a good example of rising sea levels – remains on this island indicate a mixed diet of domestic food animals and marine resources – presently the area of Nornour would be hard pressed to support a single sheep.  

On our return we bumped into Terry Perkins, of St Martin’s, who told us exactly where the peat deposits on Parr beach were located and that they are most visible in winter when the sand has been taken away by storms. We think we will need to return much earlier in the year to get good samples from these beach deposits.

After this we finally got to do shopping (buying a number of sets of ‘Scilly Gold’ the board game), lunch at Dibble and Grub (yumm!) and a swim from Porth Cressa prior to jumping on the ferry for our return journey. 

We picked up a hire car and then the team went their separate ways – Charlie staying in Cornwall, Dan (and all of our samples) to Plymouth and Steve, Jacqui and Rhiannon back to Cardiff.

Day Seven – Tuesday 8th September

November 27, 2009

Still no day off……

To Parr Beach St. Martins today – we love St Martins as we have spent more time camping on this island than the others it feels like home. Indeed our good friend Viv was there on the quay and made us feel most welcome.   We also had arrived in time to go to the Little Arthur café to for tea and cake whilst waiting for the tide to recede…….so discussed strategy over excellent carrot cake.

There are two known peat deposits on Parr Beach but they, and a stone row, were covered up by a good depth of sand. Cue lots of digging of pits down through the overlying sand across the whole beach on a large grid.  We located the ‘peats’ only towards the centre of the beach and as they were so deeply buried it was impossible to sample them – but at least we located them ready for a return trip next year.

We went out for our final team meal to celebrate the success of the project and the chance to rest our aching arms and weary feet.

Day Six – Monday 7th September

November 27, 2009

All the ‘T’s today – Tean and Tresco.   Tean first – a lovely island we spent two weeks on in 2007 (see the blog) and it was good to be back although it bought back sad memories of the loss of a local lad on the final day we were on the island.  The search parties came to Tean looking for him – but to no avail.

Anyhow, we set to looking for peat deposits, once again digging and coring across East Porth first, and then moving across to West Porth. We found peat on the latter associated with the two sets of walls that run up the beach, we are becoming expert submerged wall spotters although once you start to spot lines of stones it can be hard to stop.

After lunch we returned to the jetboat and went over to Tresco again – marching a way down the island to check out a couple of beaches with previously recorded inter-tidal ‘ground surfaces’. 

Digging through large pebbles is not much fun, and the holes tended to fill up with water as fast as we could dig – however we persevered and continued to core, eventually locating underlying clay deposits and one again  3D mapping the deposits.  This was followed by a long trek up the island to the quay – by now the survey equipment was becoming very, very heavy and techniques for carrying the dreaded yellow box included putting it on your head and clutching it in your arms.  All the long hauls included lively conversations on how to better move equipment – balloons, Sherpa’s, quad bikes, goat carts, golf carts – in fact anything. 

We were greeted by the CISMAS divers and more samples of underwater peat deposits.  It is hard to take samples under-water as the energy needed to swing a hammer to push in the coring equipment is dissipated by the resistance of the water and any attempts to push down results in the diver floating up!  However thanks to the persistence of the diving teams we now have a couple of great samples.

After a swift dinner Charlie gave a talk at the museum which helps the team and the visitors to get a good overview of the project and the islands due to some new aerial shots that have been taken.  We were excited to hear from Amanda Martin (museum curator) that there are local historical reports of the peat and she offered to track them down for us.  Then off to the pub to discuss island archaeology into the night.

Day Five – Sunday 6th September

November 20, 2009

Today has been a rather exciting day. We started with a trip over to Samson, marking our first beach landing with wet feet all round. The CISMAS divers joined us on their day off, meaning that we had extra people to help carry the equipment – always good. The tide was not out far enough to be useful, so Dan, our geographical expert, who was over here a few weeks ago on holiday, led us to an interesting rock, which he believed us archaeologists would surely know about due to the rather large carving on the rock face. However it turned out that not even the local archaeologists were aware of it, leading to quite a lot of excitement and numerous wellies of water (we didn’t have a bucket) being poured over to reveal the carving in all its glory.

As of yet we do not know how old the carving is or what it depicts, though suggestions have included a boat or some kind of cardinal marker, as it appears to be aligned North – South. We think Dan should ditch the geography and become an archaeologist instead.

As the tide receded we got down to the business of peat. Unlike previous days we did not set up a grid, as the area we would have had to have covered was huge so we focused on the fieldwalls.

Finally we went off to check on the standing monuments, the houses we had so lovingly cleared and recorded prior to minor repairs two years ago. They were beginning to become overgrown again and some had been subject to rather obvious recent repairs and rebuilding. 

On our return to the quay we were greeted by the local IMAG divers who, lead by Todd Stevens, had re-visited the peat exposure he had identified and taken some samples for us. This included a core through the peat and a tree trunk about 20cm in diameter; the reddish colour of the trunk led Dan to suggest that it was probably alder.

Day Four – Saturday 5th September

November 20, 2009

Today we walked to site as it was only at Port Mellon.  Here are some of the best reported peats and lowest peats. We arrived early and had to wait for the sea to retreat and the peats to emerge from underwater.  We followed the tide down using our augur to establish the extent of the peats, using spades, ranging poles, beach litter and students to mark out a grid, until someone thoughtfully bought a bundle of bamboo canes! Using this grid, we managed to auger across a large amount of the beach, but as the tide reached its lowest, it was clear that the peats extended much further out into the water, leading to two members of the team getting rather wet in order to plot the edges using the GPS. The peats appeared to be quite deep and rich in organic material so we decided to take a sample, again by using a monolith tin. This was much easier to accomplish on this site, as the peat was very soft and so a tin could be knocked in from the top using the rubber mallet, which was lucky, as the hole was full of water almost as soon as it had been dug. This would have made taking the sample rather difficult. We also took a core using what is essentially half a metal drainpipe with a handle. This was pushed into the deeper sediments under the initial sample to see what exists beneath.  Once again we raced the tide to fill the hole – this appears to be becoming a recurrent theme.

We had a number of visitors towards the end of the day, including Todd Stevens, the local diver who came to discuss taking samples from deeper under the water in an area where he has seen submerged tree trunks and roots – perhaps evidence of a submerged forest? We were also visited by Eleanor Breen, the island archaeologist, and her family.  We finished relatively early, as the tide started to come in, covering most of the peat. While most of the team packed up and took the equipment back to base, Charlie and Jacqui went to be interviewed on Radio Scilly – to be broadcast on Monday. Unfortunately we managed to misplace an auger, so if anyone is in the local area and finds it let us know!

As we finished so early, half the team walked across the island to Old Town, to investigate some reported peats in the area. These were found about half a metre under the sand, though the excitement of finding  the peat was nothing compared to that conjured by the sighting of a basking shark just outside the bay. The team also visited Porth Hellick, but by this point the tide had come in too far.

Day Three

November 20, 2009

Tresco – a bright and breezy day with another bouncy boat trip followed by a long haul from our drop off point to the sampling locations. We first of all checked out a potential sample site at Bathing House Porth – but to no avail – we could see no peat – although there were some walls.

We then moved to the larger peat deposits that had been previously mapped and sampled by English Heritage in the 1990s. Here there are a series of wall running down the beach from the land into the sea and the peat deposits were recorded as lying close to these walls.

We marched along the beach and quickly located extensive peat deposits that were indeed near to the walls.

The deposits were visible as a large area of peat running along the shoreline, just as the finer lower sands became covered up by an upper band of stones.  We mapped the visible peat and also used our augur to sample down through the lower sands to see if the peat was lying below.  We covered an area that centered on the peat and moved out from the centre along and down the shore.   At the top of the shore the peat ran under the stones, we discovered this by digging along the surface of the peat up slope until the stones became too deep to excavate.   Wherever we found peat we mapped its location in 3D, keeping a record of what it was covered by or lay over, in this way we can create 3D maps that will show slices through the beach.

Once we located the deepest depth of peat we sampled, once again we used monolith tins.

We had a little trouble with water running into our pit, but this was solved by digging a series of gullies around the perimeter to divert the water away.  The upper one had preserved plant material and distinct banding visible in the organic part of the sequence.

We also took a core from a second, much shallower, peaty deposit lower down the beach.  We have been finding that, in some locations, the peat lies over clay (as can be seen in our monolith section), whilst in others it lies over the ramm (the reddish material visible in every section in Scilly – laid down at the end of the last glaciation).     The clay can be very deep and sometimes shows banding which suggests very still water, possibly when the island first became inundated with fresh water?

We were racing against the tide to finish the samples and ended up backfilling both pits just ahead of the sea.

We then had to carry back our rather heavy samples to Carn Quay to catch the boat.  We very nearly had to walk to Old Grimsby with all the stuff but luckily Bryher Boats managed to pluck us away.   We met our landlords on their way off the island, and they told us that our surveying equipment had made it onto the Scilly webcam – stood proudly alone on Bryher beach whilst we nipped off for a quick cup of tea.

I have been trying to find a way of posting this blog – but it is proving rather difficult.  I asked at the tourist office and it seems that the entire harbour is Wi-Fi enabled courtesy of the Duchy – so I could blog on my yacht (if I had one) or just perch on the harbour wall.  I did ask ‘what about when it rains?’ and the quick reply was to ‘wear waterproofs’.  Hmmm – I wonder can I get Harbour Wi-Fi from the Mermaid?

Day Two – Thursday 3rd September

November 20, 2009

Up early and down to the Quay where we met the other (marine) half of the team for a catch up just before they headed off to sea.  They have been here for just under a week already and, despite the weather have managed make good progress. They have located and mapped the submerged peat deposits at about 8m, estimating an oval area of about 300m by 75m.  Their remote sensing equipment maps changes in the ocean floor which they identify as particular types of deposit based on ‘ground-truthing’ i.e. diving down and seeing what it is.

They have been off on Bryher Boats, Lightening, for a bumpy ride to Bryher.  Fieldwork on Scilly always involves a lot of handing equipment on and off boats and then trudging along to your fieldwork location weighed down by all manner of tools none of which seem to be designed to be carried any distance.

We attempted to locate the peats recorded on the English Heritage Peat database, we first looked for those on Town Beach, but failed to locate any true peats.

Then we went to Tresco Flats where we mapped the visible sediments. The ‘peat’ exposure did not appear to be a true peat but could be described more as an organic sand (sand with bits of decayed vegetation) – however we sampled it using a monolith tin (we dig a pit through the deposits and then knock a 50cm long metal box about 20cm wide and deep  into the section to grab a large vertical slice of deposits).   (see tomorrows entry for an image).

The most entertaining part of the day involved our involuntary capture of a Scilly shrew. Whilst scurrying along the shore line it fell into one of our pits.   When we helped it out of the pit were it promptly headed for the nearest hiding place – up my trousers, after clasping my leg to ensure it did not climb up further up my leg – I checked its location and found it perched on my socks.  We then encouraged it to leave its temporary shelter, which it did in such a hurry that it ran headlong back into the hole and had to be rescued all over again….

We were visited by English Heritage Historic Environment Enabling Program staff, Charlie took them off to see the site of the Bryher burial and Shipman’s head Cliff Castle and a range of Bryher folk many of which we knew.

In the evening we meet up with the folk from EH and our marine team members and s in the Old Town Inn to discuss strategies and successes.

Day One – Wednesday 2nd September

November 20, 2009

Three of the team, Jacqui, Steve and Rhiannon, travelled down to Scilly from Cardiff – leaving very  late Tuesday night and arriving at 24 hours Tesco’s in Penzance around 4.30 am.  After a couple of hours dozing to the sound of radio three we were joined, at the quay, by our fellow team members from Cornwall, Charlie and from Exeter, Dan. 

The weather was hellish and the resultant rocking caused the majority of the passengers – many only going over for a day trip – to be very seasick.  Luckily our team was impervious and by taking advantage of the fabulous quiet lounge on the boat, complete with  long benches, pillows and blankets  we caught up with our sleep – spending so long asleep that we awoke to find the cafe ws n o longer serving breakfast – curses.  Our arrival on the island was heralded by driving rain – 18mm had fallen in a couple of hours – so the proposed trip to Nornour with the English Heritage team was called off.  Instead we settled ourselves in and planned our strategy.  An attempt to locate the second, marine, part of the team (CISMAS) failed so we wait to catch up with them on the morrow.

And just what are we doing here?  The isles of Scilly were originally made up of a much larger landmass, known as Ennor but over time the low lying inner area eventually became covered by the sea.  We are trying to find out when, how and at what rate the Isles of Scilly become inundate d by the sea.  To do this we will be examining deposits and structures that indicate changes in sea level: mostly we are looking for peat – material formed under wet conditions, both freshwater and marine – that provides a great record of changes in vegetation (from pollen and plant remains), in water quality (from diatoms and foraminifera) and can be dated using radiocarbon techniques. So we can tell when the land first became soggy (freshwater peats), was washed over by the sea (saltwater peats) and become fully submerged (peat formation stops). 

There are a number of peat deposits that have been indentified across the Isles of Scilly over the years and we will be visiting all of these.  A number have been investigated previously, some have not, but we will be sampling all that we can and applying some more recently developed techniques to help us understand them.

The peats we are seeking are found in the inter-tidal zone (between low and high water) or are fully submerged by the sea.  To sample the inter-tidal peats we need low tides when the reported exposure are visible, but the fully submerged peats can only be located and sampled by boat – hence our marine team who will be using geophysics to map and characterise the sea bed, looking for peat, which we will then sample.  Thanks to local diver Todd Stevens we already know that there are peat beds, visible tree stumps lying under about 8m of water so we will be mapping and sampling these peats as well as hoping to find new peats.