By Jack Pink
ACUA Graduate Student Associate Member, University of Southampton
The journey from Southampton to Stornoway takes two days. Loading the equipment for a month-long project into the backs of a hired van and pickup takes slightly longer. So, it is with some relief on the first day that we pull into our overnight stop near Penrith on the border of England’s Lake District National Park. Even amongst a travel-worn team the excitement is almost tangible, for the first time in years (for some of us) we are back in the field. The Islands of Stone project, created by Professors Fraser Sturt (University of Southampton) and Duncan Garrow (University of Reading), and Angela Gannon (Historic Environment Scotland), with Dr Stephanie Blankshein, sets out to investigate man-made stone islands—crannogs—in the lochs of the Outer Hebrides.
The equipment used to work underwater in the United Kingdom is governed by the Health and Safety Executive’s Professional SCUBA qualification we all hold. The kit is heavy and awkward. I am a tall man and swinging it up six feet off the ground is a challenging prospect no matter how long you spend in the gym. The offset bailout cylinder only makes things worse; on land you feel like you are being pulled down on your right side by an invisible snag. In the water if your weights aren’t trimmed—and on the first dive mine weren’t—you’ll roll and find yourself staring through the amber colored water to the surface. As I kit up, I miss my minimal 12 liter half-mask setup from recreational trips.
The OTS full-face system we use has through water communications, a fantastic tool, but this site is so shallow it is often easier to lift my face out of the water and talk round the mask instead. We dive from a pontoon assembled from plastic cubes, a giant industrial grey Lego set. A bright red water pump drives the dredge from one corner, long firehoses snaking into the whisky clear water of the loch towards the great dredge-heads waiting beside the excavation grid.
Left: Giant plastic ‘Lego’ blocks create a pontoon barge for the underwater team. Photo by Jack Pink.
Our enthusiasm is obvious even considering the awkwardness of an HSE setup. The site is more than I imagined it could possibly be. The majority of our work takes place in less than a meter of water. I could stand on our steel grid and the water wouldn’t reach my waist, but I don’t. Even before the dredges start running sinuous lengths of timber can be seen protruding from the loch bed. These things are impossibly old. I am used to timbers from the 19th century. This site is thought to date to the British Neolithic some 5000 years ago. It takes a few days for the team to get into our stride but rapidly the sediments are peeled back revealing an astonishing layer of cut timbers, coppice-like roundwood, and huge sections of tree as thick as my thigh. Amongst these timbers and in the sediment layer above are chunks of quartz and pieces of pottery. It is hard to tell if quartz has been worked—I can’t—so it all goes into a finds bag. Duncan will laugh at me later when I come up with a sack filled with the yellow lumps and flakes. One day I spend over an hour sharpening the section edges of the entire underwater trench, by then a four by two meter rectangle. I know Fraser is next in the water and an anxious voice whispers in my mind about messing this up and making it worse or causing a collapse, but I don’t.
The excavation on land runs in tandem with those of us working underwater. It is no small task. The entire crannog is covered in woodrush, like a lawn grass on steroids with a rough hairy mat of root anchored into the peat and stone.
Duncan’s team on land set about it with mattocks and spades, graduating rapidly to saws and knives, carving a trench across the middle of the island. It is physical work, each meter of trench won by hand. Woodrush and peat come out in blocks and are stacked into buckets and gravel-bags to be paddled across the loch in an inflatable boat, creating space to work on the island. Eventually we are rewarded by reaching the top of the crannog, an uneven surface of stone. The end of the underwater trench aligns with this one. Together they form a (mostly) straight line across the island and into the loch.
The land team now delve into the crannog itself. First boulders and stones are removed and stacked at the island’s periphery. Then the peat and following sediments are dealt with layer by layer until a deeper trench is cut in the southern half, right next to where we work underwater. This section runs all the way down to the point water starts to squeeze its way in. Now the first job of the morning is to bail the water from the trench on the island. From the pontoon it looks like a crew trying to keep some odd stone ship afloat. The line between our teams started blurred but is now perforated as the sediments each of us dig in start to align.
Left: Fraser and Duncan organize the land excavation. Photo by Jack Pink.
Underwater we try to erase that line by digging into the side of the crannog. We are fascinated and chase those winding lengths of timber as they run into and under the stones of the island. Those boulders are sometimes giants down here. Moving them is done extremely carefully. Divers in black drysuits and bright yellow harnesses stand on the edge of the crannog or float in snorkels. Choosing the rocks to move and clearing a place to dig whilst avoiding creating an archaeologist’s deadfall trap. The reward for this work is a wonderful matrix of timber, stone, sediment, pottery, and—of course—quartz. For something so old the sherds of pottery are beautiful things. Parallel lines and herringbone patterns abound.
We find an organic layer atop the timbers; it smudges and crumbles in our fingers as we work it. On land the team reaches an organic layer; dark and damp…heather. In both places we cut sections as sharp as we are able. It is possible we have found a layer that aligns the underwater and surface worlds.
We have other tools that help bridge the two. Chief amongst them is the use of photogrammetry. This produces models of both the underwater trench and the excavation on the crannog. Underwater the vast collection of images is handled expertly by Felix Pedrotti. Those images are then processed by Steph each evening before any of the rest of us have even had time to make tea.
On land, images are recorded using a drone, the kind that looks like it came off the back of an Air Force supply truck, black and menacing. Dr. Rose Ferraby names it “Tricia” and that sticks. Each morning as I put on my drysuit Tricia takes flight and circles the island recording our progress. Again, Steph has dealt with this material before we have sat down. The two pieces can be combined to create a full picture of the work we have done.
Left: Tricia the drone takes flight. Photo by Jack Pink.
Throughout the dig we have discussed ‘The Dropoff’, the point underwater that the gentle shallow slope of the crannog decides to plunge into the dark of the loch below. In the last week I get my chance to visit this mysterious place. I am diving with Fraser and now we kit up on the gentle sandy beach of the loch before maneuvering ourselves across the shallows. These are often less than a meter deep, but it is easier to swim to the site from here rather than trying to walk. Fraser doesn’t hang about and quickly we are floating at the edge. It is dark here like an English Channel wreck at thirty meters but looking at my gauge in the light of a powerful torch the needle points to six. The comms are filled with our excitement. We have found things here, huge sherds of pottery a third or quarter of a vessel covered in the herringbone and lines of the smaller pieces above. At the top of The Dropoff are more large timbers. We sample these with handsaws, wood that feels far fresher and takes much longer to cut than its expected age (thousands of years) would suggest.
Packing up takes far less time that loading everything to come up. It is so fast that I almost feel we have forgotten some complex thing on the shore of the loch. In no time at all we are waiting in Stornoway’s ferry terminal for the boat back to the mainland. I’ve learned a lot about how our crannog is built and joke it would be interesting to just dig a slice of the whole island out like pie. This is met with wry smiles and discussions of earth-moving equipment. As the ferry glides across The Minch (the strait between Lewis and the mainland) it is hard not to wonder at people crossing these same waters in a radically different vessel. I am excited to see what we find next.
Categorised in: Deep Thoughts