Wednesday, 14 July 2010

Minnie's Quarry


Minnie’s Quarry (name changed) is a very similar quarry to the Devil’s Hole and is, indeed, quarried for the same materials, i.e. the sand and gravels laid down during the Pleistocene period, although older at around 125 thousand years. And again, as in the Devil’s Hole, the upper levels of the Oxford clay are soon reached, whereupon the excavation stops.

However, this is where the two quarries differ slightly. Whilst the north end of the quarry is exactly as above, the southern end has been quarried for its clay as far down as bed 10, the same range of clays as Quarry 4. And this is where I intended to concentrate my efforts, not only for vertebrate fossils, but also to see if I could find one of those very elusive three dimensional Oxford clay ammonites that are so rare.

A small group of us arrived at the quarry after a trek of about a mile and the conditions were good. There had been substantial rainfall in mid-week and a drying wind had made the clay reasonable underfoot. We gathered at the head of the quarry to review safety procedures and then proceeded to prospect for fossils.

I could hardly believe it when, after only five minutes, Cliff Nicklin found a super little tooth. About 25mm long, it looked initially like an ichthyosaur tooth but both Cliff and I were inclined to think that it was from a marine crocodile. All in all a great find and a super start to the day.

Galvanised by that find I went down to the Bed 10 level and started to look in earnest. I found it hard to differentiate objects, primarily because the volume of belemnites in view at any one time made it difficult to concentrate on anything else, and I found my eyes constantly tuning into the symmetry of the belemnites!

As I moved down the quarry I could see that the group had broken into two distinct groups, with some concentrating on the Pleistocene gravels and the rest of us on the Oxford clay. I moved further into the quarry, crossed over to the other side and started to look through some very fine shales. They were full of ammonite impressions; some were startlingly beautiful in their clarity but you could hardly touch them without fear of breaking them and, unfortunately, there were no three dimensional fossils at all.

I pushed on further into the quarry and after a little bit of scrambling reached a section that looked really promising, the fine layers of clays and shales glistening wet in the newly arrived sunshine. But still nothing of note appeared before me. I then arrived at a flat section of the quarry, the deepest part as it turned out, and found myself walking on Bed 10. Shaped like an amphitheatre, the flat area shelved into water and was surrounded by the aforementioned clays.

I spent some time scrutinising Bed 10 but continued to struggle. After a while I moved out of the area and started to sift through the spoil heaps further along, but again I was to find that continually moving on isn’t always the best policy.


I had moved on about 200 metres when I decided to climb the spoil to my right and head up a bank to an area that looked as if it had been untouched for some time, and decided to walk back to Bed 10 along this route. This was a great area for well preserved belemnites but I ignored these and continued to look for other fossils of note.

After about 45 minutes I reached the Bed 10 area and was surprised to see four or five of the others on their knees carefully removing spoil near the back of the amphitheatre. This was the only area I hadn’t checked and again I had that sinking feeling that I had missed something important.

Sure enough, as I reached the others, I saw the remains of some fossil bone weathering out of the clay and more had been carefully exposed. These were fish bones, and Cliff tentatively assigned them to Leedsichthys but this would need to be verified.

As the others continued to carefully remove the clay around the bone, I decided to help and proceeded to prospect in the immediate area. However, it soon became apparent that there were no further bones to be exposed in the bed and it was a case of carefully removing the existing bone and preparing it for travel.

At this point I moved on more or less back to where we had entered the quarry and eventually arrived at the spot where Cliff had found his tooth. But still there was nothing of any significance to be found. After a drink and a bite to eat I decided to head to the Pleistocene gravels at the other end of the quarry.


I was struck by its similarity to the Devil’s Hole and remembering how I located the rhinoceros vertebra previously, I felt that had a reasonable chance of finding some bone. Gradually I worked my way through the spoil heaps and started to find derived fossils out of the Oxford clay, but eventually found a couple of pieces of badly exposed bone.

At last I noticed a block of clay that was situated between two spoil heaps and was pleased to find a small section of well preserved rib bone that had obviously only just been exposed. An expert would be able to identify it but, in my opinion, it was not a particularly diagnostic rib. The later consensus was that it may be bison but more likely deer.

At this point I met up with Cliff and a couple of others and we headed back to the end of the quarry, more or less in a line, continuing to prospect. Nothing else turned up and we eventually returned to the cars and discussed the day. Fossils that had been recovered included a plesiosaur tooth, a nice section of proximal femur from a big mammal, maybe rhino or mammoth, and a partial lower leg bone from a similar sized animal.

Incidentally, the guy who found the plesiosaur tooth was also the “lucky” chap who had those excellent bones and tooth finds from Quarry 4. His name is Carl Harrington and he’s much more experienced in Oxford clay fossils than I am, and I’ve also met him at the Bluff. I’ll chat with him soon and ask him how he does it. Cliff says it’s definition – he looks for shapes but this is difficult when there is so much material in view at any one time and all I focus on are belemnites because they are simply everywhere but I will keep trying. I’ll get there in the end.


Whatever his advice may be I hope to be able to use it soon! Minnie’s Quarry was a good site overall and I’d like to think a return trip may be possible for the future.

Footnote
Earlier this year I got word that both Minnie’s Quarry and the Devil’s Hole had been closed – permanently. I never got that chance to go back to the former and am bitterly disappointed at the news. These two quarries, as mentioned previously, were quarried for their sand and gravels and demand over the last two years has collapsed.

I have to say that I have no idea what has happened to both sites and I hope to have more detail soon. The only sand and gravel extraction in recent months has come from Quarry 5 but they are only removing this to get to the clay so you would assume that there is some form of action plan in place that will enable a ready supply of sand and gravel to be extracted quickly should demand reoccur.

And I hope there will be better news soon. Having spoken only the other day to the guys at Quarries 4 and 5 (yes, 4 is still being worked!), there has been a marked increase in demand for bricks and thus clay. The works were described as “hectic”. I only hope that this is an upturn for all concerned, not yet another false dawn, and that this is the beginning of the recovery and that it spreads to the quarries in the south as well. Keep your fingers crossed..........

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