Wednesday, 7 April 2010
Wonderworld is the name given to what can only be described as a very interesting quarry. This site in Northampton has been earmarked for a housing development of some 5000 houses and part of it is situated where there were ironstone quarries many years ago. Logically enough, the building authority has decided to reopen the quarries to use the many hundreds of tons of Upper Lincolnshire limestone as the foundation stones for the new houses.
Fortunately this has also uncovered fossiliferous rocks, not only the limestone, but also Oxford clay and Lower Jurassic boulder clay has also been exposed. Naturally enough, being a working site, access is very restricted but some of us were lucky enough to visit the site in May 2008. Interestingly enough, however, there is a public footpath that runs right through the site so it is a bit of a losing battle to keep people out.
Fossils from the boulder clay include many species of ammonoids and nautiloids, Pinna Sp, Gryphaea Sp, belemnites, crinoids and gastropods. There are also ichthyosaur elements and teeth to be found. Fossils from the Lincolnshire limestone include gastropods, echinoids, bivalves, brachiopods and also ammonites, but these are extremely rare.
The first thing that strikes you about the site is the sheer scale of the project. We knew we would be walking through a square kilometre of land at various elevations and despite the exposed beds, fossils would not necessarily give themselves up easily. Sometimes a site can be too big, especially without any clearly defined fossiliferous exposures to work in.
After walking into the site and on into a central position, we all split up and started to prospect for fossils. The first pile of spoil that was of interest contained big lumps of Oxford clay and there were some small belemnites and a few good examples of Gryphea recovered.
The next spoil heap of interest was comprised mainly of Lincolnshire limestone. Although not very fossiliferous, the fossils that are found are often well preserved and/or unique and we knew any ammonoid that might be found was to be left in situ for documentational and scientific purposes.
This first heap of limestone produced nothing but I nearly hit pay dirt at the next site a hundred yards further on. I noticed that there were some big chunks of limestone at the top of one particular heap and decided to look closer. Almost immediately I spotted the distinctive cast of an ammonite in one of these blocks. It was only half an impression but it looked fresh and I started to look in the immediate vicinity for the owner of the cast.
After a while though it became apparent that the ammonite was nowhere to be found. It was, after all, just as likely to be buried under several tons of spoil as it was to be exposed at the surface. I decided to move on.
The further I walked the more I realised I was walking along the public footpath mentioned earlier. Strangely though I picked up a few more nice Gryphea examples as well as a rough specimen of Pinna, my first three dimensional example as opposed to the delicate impressions in the clay that we are all familiar with.
I looked to my right and could see a proper little limestone quarry in a dip and headed down to explore. After a bit of scrambling I found myself there and had a look around but it appeared most unfossiliferous and I didn’t want to waste too much time there. I did take a couple of photos to show the bedding planes however.
Looking out and up from the quarry I could see more exposures of clay that had been scraped by bulldozers recently and started to ascend the hillside. As I climbed I noticed more Gryphea and belemnites and I also recovered some wonderful selenite. There was, in fact, loads of this mineral exposed and it is very attractive.
Selenite is an evaporate that is formed when sea water becomes trapped and evaporates, and the salt crystals that are left behind gradually form into this unique form of gypsum. Some pieces are almost clear, others have inclusions which affect the colouration but they are all attractive.
As I reached the top of the hill I looked down and saw the most wonderful sun baked gulley. It was just like being back in the badlands of Canada, but on a much smaller scale of course. I walked into the gulley and started to prospect. This area felt right. The clay hadn’t been disturbed for some time and there were many fossils and loads of selenite exposed.
The deeper I walked into the gulley, the hotter it became and I was convinced that I was sure to find something significant. Eventually the gulley became narrower and narrower and although there were lots of partial fossils there was still nothing of any significance and I eventually bumped into a few of the others who were prospecting there.
One of these was Cliff Nicklin, one of the nicest men I’ve met over the last couple of years. Cliff is a recognised expert in all aspects of the Oxford clay and what he doesn’t know about ammonites isn’t worth knowing. He showed me a wonderful crushing tooth from some species of shark that he found on top of a spoil heap. I think I would have dismissed it as a shiny stone – another lesson learnt.
I spent the rest of the day in Cliff’s company, prospecting other areas but unfortunately still not finding anything of any significance. But I didn’t mind. Chatting to Cliff was a really nice diversion in the day and you just cannot fail to learn from the guy.
We made our way back to the cars for some refreshment before leaving for the day. There were a few others already there and it became apparent that we had all struggled to find anything. Just as we were about to go news came to us that a couple of the others, who were at least a mile away from where we were, had recovered a couple of nice ammonites and an ichthyosaur vertebrae.
Wonderworld wouldn’t be my first choice of venue in the future, but it proved interesting none the less. At least the housing estate destined for this site has opened up some nice fossiliferous beds for prospecting in the immediate future which would never have seen the light of day otherwise. On the down side, of course, is that in a few years, when the estate is finished, all of this site will be lost to science forever.