Written by Matthew Butler, Work Experience Student
Anticipation was high when cars rolled into the quarry car park. The group grew steadily. There was a buzz of noise as we all became acquainted, preparing for the day’s adventure. Present was a wonderful mix of people at varying stages of their careers, palaeontological or otherwise. We all gathered around for a safety briefing from the Quarry Manager and the Geological Curators Group.
Instructors for the day were GCG Chair, Dr Emma Nicholls and GCG Journal Editor, Dr Duncan Murdock, both of whom are Collections Managers at Oxford University Museum of Natural History which supported the Dinosaur Trackways Field Workshop. The third instructor was GCG’s Web Coordinator Simon Harris, from the British Geological Survey. Before we got our hands dirty, we were treated to an introduction to the site and the geology of the local area by Phil Powell, Honorary Associate at the OUMNH, and author of The Geology of Oxfordshire as well as multiple articles on the trackways.
We all piled into our transport down to the quarry floor, not yet knowing the amazing experience we would have today. The trackways themselves were breathtaking, there really is no other feeling like literally following in the footsteps of great beasts like sauropods. For me, trace fossils like these are so magical and really help to bring the bones in museums to life. There were two tracks that intersected each other (labelled A and B). Trackway A seemed to belong to a much larger individual, whereas trackway B consisted of considerably smaller (though still big!) footprints. One of the things that was interesting about the tracks for me, was that it seemed like there were only two feet making the tracks. But what was actually happening was the hind feet were going in the same place as the fore feet, making it almost seem as if the sauropod was walking bipedally!
Each footprint was made up of what is called a ‘bruise’, the raised ridge surrounding the print; and a bowl, where the foot was placed. Most of the bowls were filled in with mud from the overlying layer, which meant our first job of the day was to get digging.
We broke off into small teams to get our hands dirty working on a footprint. Two teams worked on track A, and two teams, including myself, worked on track B. We found a footprint that looked promising and spent a bit of time familiarising ourselves with our equipment. With a lot of excitement, we started to use our trowels to carefully clear out as much mud and dirt as we could, taking great care not to dig too deep and scratch or damage the surface of the footprint.
Unbeknownst to us, GCG and the Quarry Manager had organised a very special experience. After we had been working for a while, they asked us to retreat to a safe distance and we watched the quarry staff use a digger to excavate a further section of track B. We were the first humans to ever see these footprints that had remained buried for millions of years. Watching these prints being exposed was a feeling like no other, to be one of the first things ever to see these prints was so special, and definitely one of the highlights of the day. All of us walked over to them, staring in awe at the prints. When we had all soaked them in, we returned to our chosen prints and resumed delicately removing what we could with our trowels.
We were so absorbed in our work and chatter that it was lunch before we knew it, so we all reluctantly said goodbye to our footprints and hoped the fair weather would continue into the afternoon. We all tried our best to de-mud as we climbed into cars to make our way to a lovely lunch in a nearby pub.
Unfortunately, as we were leaving the pub after lunch, we felt the first few drops of rain for the day, but none of us minded, we were all just eager to get back to what would be a very exciting afternoon. The rain had picked up a bit by the time we arrived back at the quarry but no matter how wet we got our spirits were never dampened. We resumed our trowelling until just a few centimetres of mud was left coating the footprint, at which point we switched to using a combination of a stiff and soft brush to try and clear out the final layers, without risking any damage to the trace beneath. The most important lesson of the day was to use the gentlest tools as was practicable at any given point in the excavation. So, although there was a pressure washer on site for us to use and get experience with, the instructors made it clear that this should only be used on the lowest possible setting, and on trackways preserved in hard rock, so as not to damage them. Whilst the teams on track A got to work with the pressure washer, us on track B learnt all about “string theory”, which was Emma and Duncan’s term for the method of using string to measure trackways!
Whilst the phrase “string theory” may make you think of complex physics, at the field workshop it just meant using a ball of string and a tape measure to measure a trackway site. Using a piece of string, as the name suggests, in a straight line we can measure the footprints against it. We had to try our best to keep it close to the middle of the track, but on a straight bearing. After a bit of fiddling and adjusting, we were all happy that we had got it straight and central. With a tape measure, we measured the distance along the string between each print, and then the distance to a specific point of the print (the apex of the crescent in this case) with the tape measure held perpendicular to the string to create a map of the trackway. It was essential we were as accurate as possible because we were the first people to map certain parts of both tracks. All of these measurements were carefully recorded in our field notebooks. An additional way of locating the footprints is with GPS, where we put the GPS at each end of the trackway to record the longitude and latitude.
When it was finally our turn with the pressure washer, it was as much fun as I was expecting it to be. We took turns testing the pressure off to one side to ensure it was as low as was reasonable and then carefully used it on appropriate areas of our print. Finally, we used some sponges to soak out the mini lake that had formed in the bowl and gently cleaned up the footprint as much as possible. Finally, we could see our footprint unobstructed by layers of ancient mud. It was very rewarding to see the fruits of our labour, and to see all we had learnt pay off.
As the day was nearing an end, Simon Harris taught us how to do photogrammetry. Essentially we took lots of pictures from all over the print, keeping the camera the same distance away. These images are then put into a computer that turns all of the pictures into one 3D model. Photogrammetry is quite a new practice and ensures that the trackway remains undamaged. More traditionally, moulds were taken of footprints, but this can sometimes damage the track so is a practice that should be used with great caution, if at all.
The Dinosaur Trackways Field Workshop taught me so much about fieldwork, and about the practices and conditions I could be working with in the future. This day solidified my love of working in the field, and I can’t wait to put the skills I learned into practice again.
Geological Curators' Group Blog 
Dear Sir/Madam, Can you please explain how I can attend future field trips with the group and play an active part? Yours sincerely, Alasdair Farquharson.