Thursday, 31 May 2012

Return to Minnie's Quarry

A couple of weeks ago I embarked on the latest field trip of the new season. This was a welcome return to Minnie’s Quarry – somewhere I had not been able to get back to for about three years. After that first visit the quarry owners, like so many nowadays, heavily curtailed access and I am unaware of any visitations taking place during the time period after we had visited. And then the quarry itself was closed for a time, apparently on a temporary basis, during the worst of the economic downturn.

Fortunately, this appeared to be fairly short term and the quarry was reopened some months later. But still the same problems persisted and there was no access permitted. There were rumours that the quarry was being poached by illegal collectors and that at least one person had been caught but, whatever the truth may have been, access was still denied.

We were, therefore, pleasantly surprised when the quarry appeared on the list of venues available for a field visit. It had, apparently, taken a lot of coaxing and negotiating to gain access and we were both surprised and delighted at the outcome. I was curious. I knew the site was being considered for major redevelopment and was unsure where we would be allowed  to prospect since the site covers a massive area and small quarries are continually opened to strip away the economically viable glacial sand and gravels. And, of course, below these lies the Oxford Clay and yet more opportunity for finding ammonites and the highly prized reptile remains.

So it was with great eagerness that we drove to the quarry ready for our day in the field. The event was well attended and the conditions looked good. Despite a lot of recent heavy rain, the quarry had been drying out well and the quarry manager confirmed that the trip could take place. We made our way to the quarry and I expected to traverse a field, climb down a ladder and make my way eastwards to the quarry, about a quarter of a mile distant.

Imagine my surprise when, after we had barely entered the field, we turned right and headed westward. On reflection, this should not have been so surprising since, as I mentioned, the site is massive and different quarries were being opened on a fairly regular basis. This time we crossed another field before paralleling a drainage ditch and then heading down toward what was obviously an old exhausted quarry.

This was filled somewhat with water but the old spoil heaps kept the water in check and the site looked interesting – especially as there were obviously large areas of clay to check out. Unfortunately we were told that this quarry was strictly off limits and we were a little disappointed to say the least. As we skirted around the quarry we made our way through a gap in a hedge and then made our way up a ditch and finally reached the quarry we were to be allowed to prospect in.

At first glance, it looked much like any of these glacial quarries do – a series of drainage ditches criss-cross the quarry floor interspersed by spoil heaps and plateaus of the prized sand and gravels. However, the much prized Oxford Clay was conspicuous by its absence and although there were a few small isolated patches of clay that were readily apparent it was obvious that there were no significant exposures of clay to prospect.

Disappointed we asked the quarry manager why this was the case and was told that new directives  dictated that the clay was no longer to be excavated unless it was needed to shore up the sides of the quarry and help with stabilising the drainage ditches. This was hugely disappointing and I felt a little sadness that this particular deposit of the Oxford Clay was unlikely to be exposed at any point in the immediate future.

Undaunted we still had the Pleistocene deposits to prospect and these had proven to be quite productive in the past. However a further restriction placed upon us meant we only had a couple of hours to search for fossils before we had to withdraw – things were a little disappointing to say the least. However, we were finally unleashed and started to prospect in the quarry and I made my way to the clay deposits for a quick search just in case something may have been uncovered. 

I need not have bothered since the clay was only surface deep really and it was obvious that there was nothing to find – not even a belemnite. So it was onto the glacial exposures to see what could be found. The answer was not much really. I found nothing at this point but there were a couple of bits of mammoth tusk found although these were quite rough really and the only bones of note looked to be a bison tibia and a nice rhinoceros toe bone. Apart from that there were only scraps.

No sooner had we gone in then it was time to come out and this, since there was still a lot of the quarry to be searched, compounded my frustration. We took the opportunity for a spot of lunch at which point only seven of us remained at the quarry and the others returned to their vehicles – including the organiser and quarry manager. It was at that point my luck took a turn for the better.

Where we were having lunch was at the top of the quarry on a gravel plateau that had been levelled off some time in the past and since there was lots of vegetation and bushes that were well established it was largely ignored. After I had finished lunch I decided to take a look around and see if anything may have washed out over the previous months (years?).

Mammoth toe bone

I had only walked a few yards when I noticed something protruding from a bank of gravel. I was not sure what it was at first since there was some vegetation obscuring the view but as I pulled the plants out of the way I was rewarded with a strange looking bone that I was, frankly, unsure of its identification (if it’s not dinosaur or other reptile I’m in trouble). Fortunately I had Carl with me and he excitedly exclaimed that I had found a mammoth toe bone! That was a real bonus and I was very pleased.  

There were now four of us prospecting on this plateau and then, within about ten minutes, I found another super specimen completely exposed on the gravel surface. It was lying on its side and as I picked it up I could see that I had found a substantially rooted tooth which, I was reliably informed, was almost certainly from a horse although there was a slight chance it may be from a bison as well. Needless to say I was delighted with the finds and although we spent a little longer picking over the plateau there was nothing more forth coming.   Still I was more than pleased.

Then we got word that, because of our truncated visited into the quarry, we were to be taken into the works itself and be able to root through what is known as the rejects pile. When the gravel is removed from the quarry, it is transported to the works for sorting where it is graded by size and stored accordingly. The reject pile contains any rock or gravel that is 10mm in size and over and, of course, this contains rock that is very much bigger than that which got picked up in the excavation process. And naturally enough this includes some fossil material.

A rooted horse tooth

When we arrived at the works, we were promptly shown the reject heaps and were allowed to get stuck into them straight away without any rules or regulations other than common sense. The heaps did not disappoint and there were some nice specimens recovered including a mammoth tooth and many other odd bones. The find of the day was a beautifully preserved lower jaw complete with several teeth in situ from what was probably a deer. How this managed to get through the excavating and sorting and survive is something of a mystery but it really was an exquisite piece.

For my part I found a few bits which included a distal end off a small metatarsal from something or other and a segment from a hippopotamus tusk which is quite rare by all accounts so I had to be happy with that.  Eventually, I called it a day during the late afternoon sun and started the long journey home. I wonder how long it will be before we can get back into the quarry again this time. I’m really not so sure anymore and all we can do is hope that we are given the opportunity to search in this interesting quarry again at some point in the future.

A section of hippopotamus tusk


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