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survey

I have repeatedly failed to sort out the time to update the blog over the last week. However, on the plus side, this does mean there is lots to write about now. First, an update on the gradiometer survey on the north side of New Laund Hill. This has proved harder than we anticipated to process satisfactorily. We had a great deal of dificulty getting the gradiometer set up properly in the first place as there was so much variabilty in the background. The first survey we did last week was extremely noisy once we downloaded it and didn’t show anything at all. We have subsequently had three more goes at it, with gradually increasing success.

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This is that most recent survey after processing. North is at the top and the ditch features which John had pointed out to us are just outside the survey area to the east. It is still not ideal but I think I can see some circular arrangements of dark anomalies in the centre of the northern grid and a line of them running east to west just about where the two grids meet. It is all very speculative at the moment but they do look very similar to the circular feature in the centre of the New Laund Enclosure, which of course turned out to be an Iron Age roundhouse.

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Meanwhile, in the trench outside Dinkling Green Mine Cave we have successfully removed all the screes to expose the limestone bedrock over the whole area. Two things are now obvious. One, it is deeper than I had thought it would be. And two, there is evidence of quarrying or mining right down to the base of the trench. In particular there are three very clear drill holes for blasting charges.

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This is one of the ones in the main trench. Tony, Pete and Carol were back on site on Monday and Tuesday. They explored a lot more of the mine and discovered many more of these shot holes in every passage, even surprisingly deep underground. Beth also found a lot of small sherds of 18th century slipware at the north end of our trench, which gives a good idea of the general date of this mining.

The other thing that Carol, Tony and I did on Monday was explore some of the possible caves on the east bank of the Hodder. We followed a dry valley up the side of the main Hodder valley to look at three connected sites: Tip Wood; Whitewell Cave and Hell Hole. Tip Wood is a dry sink hole which is full of an implausibly vast amount of relatively modern junk (well there is a clue in the site name I suppose). There is no sign of either a cave or a rock shelter there now but I suppose if you could motivate yourself to shift all the corrugated asbestos, old freezers and plate glass you might get lucky.

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Whitewell Cave is relatively well known and has been explored by cavers without every producing any evidence of prehistoric occupation. It is the dark hole in the bottom right corner of this photo. However, what we are much more interested in is the long, low rockshelter which runs across the rock-face about one metre above the cave proper. This looks very similar to shelters in the Dales such as Sewell’s Cave, which did have prehistoric burials in them.

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This is Tony outside Hell Hole, which is smaller and more open and where the surface deposits at least look to be more recent. With these two sites, and the results of the geophysics, we are starting to get some  clear ideas about where we might do fieldwork in future.

Rick

 

 

An update from Tony on the conditions underground at Dinkling Green mine cave, after his and Pete’s exploration last week. He writes:

The lower entrance we explored had been worked quite extensively.  The slope from the top led to a small hole with a short drop into a high chamber which was actually a natural shaft going up and down.  It was probably 30 feet in total up and down.  To the right were very unstable  deads with a safer way down to the left which led to a very unstable mined area ending in a low choked phreatic arched tunnel with a shot hole to one side.   Just before this the bottom of the shaft was behind a very unstable barrier of wooden uprights and cross pieces holding back deads – black and rotten. Very dangerous and definitely not a place to ferret around.

Tony was back up on site yesterday, bringing Tom Lord with him, who I was delighted to meet again. He is one of the most knowledgeable people imaginable about Dales caves and their archaeology and geology and it was really useful to get his persepctive on our very different landscape.

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Outside the cave we have worked through a much greater depth of this scree, which is quite thick and very clayey (if that is even a word). We have found a few more pieces of worked stone in this layer as we have dug down through it towards the limestone bedrock beneath it.

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The other thing we have been working on today is exploring another possible Iron Age enclosure on the west side of New Laund Hill. This is another small ditch which John pointed out to us last year and so we have been using the Gradiometer to survey the plateau behind it for signs of settlement. Here Nick, Nathan and Pauline are getting to grips with the kit as Chris gives them the benefit of his previous experience. This morning I couldn’t find my non-magnetic tracksuit bottoms anywhere and the only trousers with no metal in them I could lay my hands on were my cricket whites. Strangely, standing at the end of survey lines in a surprisingly chilly wind and waiting for the surveyor to get to you feels just like fielding at long leg in the late overs of a mid-week 20 over game. It’s dark and cold and you rather hope the action is going to go on somewhere else but you feel duty-bound to clap your hands and make encouraging noises anyway.

Thanks to everyone’s hard work on what was some quite difficult ground we completed the whole plateau in four 30 x 30 metre grids. We will have a go at downloading these tomorrow and as soon as we have comprehensible results I will post them here.

Rick

We started Wednesday morning with most of the Dinkling Green mine site down to the same level. This seems to be the bottom of a silty scree layer which extended all over the platform outside the now destroyed cave mouth. It looks as if the original cave would have opened about where Lewis is standing and pointing in this photo.

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The first job on Wednesday morning was a thorough clean of this surface so we could photograph it before doing any more digging. Archaeological photos are best taken in nice neutral light, a cloudy day is ideal. Consequently, we spent a fair bit of the middle of the morning with everything set up for the photo anxiously waiting for very small clouds to move in front of the sun.

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They turned up eventually. Here is the silty scree layer in section. Once this was removed we have found that there was another scree beneath this. Again this is entirely typical of the natural deposits we should expect to find outside a cave and makes me think that the early modern mining and limestone quarrying hasn’t done as much damage to the original deposits as we feared it might.

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As you can see, we have reinstated all the grid squares and their reference lines. With this sort of scree deposit any finds need to be recorded in 3 dimensions and so by digging in controlled spits and sieving all the deposit as we remove it we should have the best possible understanding of any archaeology which is on the site.

While everyone else got on with the task of exposing and excavating the new scree deposit, I took Josh, Bethany and Pauline up onto the northern part of New Laund Hill with the total station. This is an area where John had shown me another ditch curving around the hill. This is very like the one we dug in 2012, which subsequently turned out to be part of a Middle Iron Age enclosure. Next week we plan to do some geophysics up here so we spent the latter part of this afternoon setting out some survey grid in the area we want to work on. We have never gone wrong following John’s hunches before, after all he drives all over this landscape all day everyday, so I am quietly optomistic about this new site too.

Maranda brought not one but two cakes to work with her today, including a particularly fine lemon drizzle cake, so we celebrated the 4th of July in style. Wildlife of the day was a weasel/stoat (I can never remember which ones have the black tips to their tails¹) sprinting down the road away from us as we drove home.

Rick

¹I’ve just Googled it, it was a stoat, thank you Woodland Trust

 

We have started our fieldwork at Dinkling Green Mine Cave with many of the old favourites. There was a reprise of the ever-popular cattle/fence failure on Monday night. This year’s trench is inside an, admittedly quite venerable, barbed wire fence which we hoped would be enough to keep livestock and archaeology in two seperate places. As we left site on Monday night after a productive first day we were treated to the sight of frisky bullocks leaping over it in a ‘cow jumped over the moon’ style. This meant I spent the middle of Tuesday driving back to Preston to collect all the bits of the electric fence while everyone else cleaned up the mess in the rain.

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Chris admiring the neatly laid out grid squares on Monday afternoon before the bullocks got at them.

We’d had a bit of a slow start on Monday anyway. Normally I come out to site before a project starts with a couple of volunteers and we spend a day surveying and laying out the trenches so that the whole team doesn’t have to stand around watching two people arguing about who has done the maths wrong when the survey does go right first time. However, this year I decided that by doing that I was depriving everyone of a valuable learning experience by not letting them argue about who has done the maths wrong. This meant we all spent a happy morning setting and re-setting the total station before we got the trench in the right place about lunchtime. But hopefully everyone now has a much clearer idea about how you get from survey points in the GIS mapping to a trench in the right place on the ground.

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This was the trench this afternoon, taken from the top of the limestone outcrop that the cave sits in. As you can see we are well on with digging off the upper layers of the rubble and scree left by the mining. I am hoping that this will include evidence for what was in the cave mouth before it was mined away.

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The sun came out this afternoon too, reminding me to take some photos which show what an excellent view the cave would have had.

Tony and Carol from the caving club were also on site on Monday and we had an explore of the many current entrances to the cave system. Most of these are vertical shafts of varying degrees of scariness. Tony was involved in the original mapping of the cave and they are going to come back later on in the project with a team and explore these further.

Hares continue to be the wildlife we see most of. There were a pair of males boxing in the pasture below us on Monday afternoon. However, wildlife of the day on Tuesday was a mole, swimming along in the long grass on New Laund Hill when we went for a tour of the previous excavations. I didn’t realise that they moved above ground like this.

Rick

It is getting very close to the start of the fieldwork at Dinkling Green Mine Cave. The other Uclan projects on Anglesey, Ribchester and out in California are already going full tilt and now it is our turn. I have spent most of this week sorting out all the equipment we need, and, in some cases, buying more. Hard hats, it turns out, go out of date. Who knew? Well me, if I thought about it. Also if I thought about it I would have realised that helmets I bought in 2005 to work at Goldsland might be approaching the end of their working life. Anyway, I digress. With a lot of help from Eleanor, I have turned out the stores and packed up all the kit we needed.

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Today we drove up to Whitewell to load a lot of it into the farm buildings we are going to be using as a toolshed. We are working in a different part of the landscape so we have moved from the old shed on New Laund Farm. It looks like we are going to be disputing the tenency of this new one with the hens. I had meant to ring John this morning to check that today was a good day to bring all the gear out. However, I had a minor computer glich this morning which meant that I ended up spending a lot of the early morning on the phone to Leica customer support. This meant I missed the time when I can normally be sure of contacting someone at the farm, while they are having their mid-morning break and the rest of us are just about thinking about starting work. We headed up there anyway and caught Daniel in the middle of shearing many sheep, so we went round the back way and tried to keep out of the way.

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Once the tools were safely stored we headed up to site to see how overgrown it had become since my last visit in May. Generally not too bad, although there are a few more nettles than there were. Just as we were walking up to site a big male hare sprinted across the track in front of us and headed off up the hill to be the wildlife of the day.

Rick

 

I was back out to Whitewell on Tuesday afternoon this week to meet up with John and plot and scheme. This summer, for the first time since 2015, we are going to do a full four week excavation season on the project. The plan this year is to spend our time looking for evidence of prehistoric activity on Whitmore Knott and Long Knott. These two hills form a similar limestone ridge to New Laund Hill, which we worked on between 2011 and 2015, but are about one kilometre further west.

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We are going to start by looking in and around two cave sites. This is the first of them, Dinkling Green Mine Cave. As the name suggests, it was heavily mined in the early modern period. the whole of the front of the limestone escarpment here was removed by miners looking for zinc ores. What I am hoping is that we will be able to pick up evidence of any prehsitoric activity in this cave by sampling the extensive spoil tip which you can see in front of the current cave entrances in this photo.

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What this will also do is give us a rapid idea of whether it is worth exploring further into the cave. As you can see from this photo, the passages shoot off steeply into the hill, so this is not something we will undertake lightly. In any case, Neolithic and Bronze Age activty in caves tended to be most concentrated in the areas around the cave mouth so if there is nothing in the spoil heap it is a good bet there is nothing in the cave at all. There are other 18th and 19th century lime and lead mining remains all over the two hills, so we won’t be short of archaeology to record, but the main aim of this season is to map where any prehistoric activity was.

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The second cave site we are going to look at it this one, Whitemore Pot, which is only about 200 metres to the north-east of Dinkling Green Mine. The cave entrance, which is another vertical shaft, is at the bottom of this wild garlic covered hollow. As I was gingerly edging my way down the slope to explore the entrance (and it seemd a lot steeper in real life than it looks in this picture) I disturbed a barn owl. This was presumably roosting somewhere in the crevice which leads to the cave mouth or amongst the trees. It sped away huffily, looking exactly like an offended cat (assuming cats could fly), as I slipped about beneath it. I was much too slow to get a photo of it, as I always am in these situations, but I am still going to count it as the wildlife of the day.

We will be starting work at Dinkling Green from 24th June and will be on site until the 19th of July. As we get nearer the fieldwork season I will, hopefully, be posting more regularly.

Rick

Heaning Wood Bone Cave in West Cumbria is a prehistoric burial cave with a long history of research. Ian Smith has recently shown that the human bone from the site was Early Bronze Age while the large assemblage of different species of animal remains were Early Neolithic.

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Cave explorers in the mid 20th century got into the Cave this way through an extremely tight squeeze further along this horizontal passage but, by the time Ian was carrying out his research, improvements in the average British diet meant that no one was capable of entering the cave that way.

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This was probably the prehistoric entrance to the cave. It was discovered in the 1970s by the landowner and has been cleared and explored by Martin Stables. This shows that the cave was more of a vertical shaft than previous suspected, which fits well with the pattern I identified in my upcoming book for Late Neolithic and Early Bronze Age cave burials to be in vertical shafts like this. I have been helping Martin with the survey and recording of the cave. As you can imagine, producing a measured drawing of a constricted and irregular shape like a cave can be quite challenging. In the past I have used a total station to do this kind of thing, which involves a lot of time underground but is relatively quick on the computer afterwards.

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For more on site speed and accuracy of survey I did the Heaning Wood survey with our Faro Focus laser scanner. This shot shows the machine set up at the choke point in the vertical shaft where most of the human and animal bone built up. Behind the tripod you can see the shaft heading off down into the bowels of the earth. This also gives a good sense of how tight the space is, this was taken from the ladder on the way back up the entrance shaft. The scanner works by bouncing its laser off the cave wall and logging the position of many millions of points to build up a 3d model of the cave. To do this it has to spend about 30 minutes spinning around on the tripod and while it is doing this you can’t be in sight of the scanner (otherwise a ghostly blurred image of the surveyor turns up in the final computer model). When you set the machine off it gives you about 30 seconds to get out of range, this is fine if you are scanning a room (we also use this scanner in crime scenes) but scrambling out through a narrow vertical tube in this time is more of a challenge.

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Even so, the survey is the easy part. I did three overlapping scans of the cave interior to cover any blank spots. Clare and I then spent about three hours in the imaging lab trying to make sense of the data. When you get the numbers out of the scanner these different scans have to be registered and linked together to create the 3d model of the cave. This is what the raw scan data looks like. Within the two scans on screen here you can see various control objects that I added into the cave to help the scanner link the different scans together. These include white plastic globes and checkerboard patterns. The software compares the measured distances between these points to build up a grid of similar distances. This view shows how Clare and I made sure that the software was linking the right control points together. It normally does this automatically but some times, and this was one of them, its gets confused. The issue this time was that two of the globes were close together and only one showed in each scan. The software decided they were the same point but, of course, they weren’t.

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Once this little issue was fixed these two scans snapped together nicely. This view shows the merged model with the first scan highlighted to show which bits of data came from where. We are now at the stage where we have a nice 3d model of the main bit of the cave we can rotate and examine.

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This view shows the width of the chamber quite nicely, while also giving a sense of the depth of the vertical shaft.

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On the other hand, this view clearly shows up the depth of the deep fissure beyond the point where most of the bone was found. This really shows well how a 3d scan like this can give you a much more nuanced understanding of a cave than even the most accurate plan.

Rick