Tuesday, 7 October 2014

From the Toarcian to the Callovian Pt.4


 
The following morning I headed off to the final venue for the week. By reputation it was difficult to reach and, for me, this reason alone was why it would be worth the attempt since it would follow that those spots that are hard to get to are probably more likely to throw up some nice specimens. The most direct route was to scale a more or less vertical cliff with the help of only a rope that is permanently in situ there.
Well I cannot speak for others but I actually don’t fancy risking my neck to find a fossil. Sure, it saved time, was very direct and dropped directly onto the fossil beds but, in my opinion, it was not worth the risk. Trying to manoeuvre down a cliff face by using a rope that is constantly exposed to sea salt and the elements does not imbue you with confidence. Add to that you have at least a shoulder bag or rucksack on your back to make things even more imbalanced as you climb down which will probably become quite heavy with any amount of fossils you may find and make the ascent back even harder. And if the rope breaks and the tide comes in – you are going to drown.
Having quickly decided that I was not going to do that I set off on the reputedly long walk to the fossil grounds. I double checked the tides and the weather and, going by the information I had researched, nothing would be left to chance. It was a beautiful morning and I made goodtime as I circumnavigated the main cove which was all sand and then, as I approached a large stretch of boulder strewn coastline, I was pleased to be able to negotiate this stretch without too much trouble.
I rounded the headland and was gobsmacked to see that I had already reached my destination. At first I doubted myself that I could not have possibly been able to reach this spot in such a short time – but I had. It took me thirty minutes to get here and I could just make out the rope from the top of the cliff coming down the face to reach the shoreline and, right in front of me, the very well-known small cave with a delightful waterfall falling behind it.
 
Just why this trip has been made out to be such a tough and long walk to partake is anyone’s guess but perhaps it is perpetuated by local fossil hunters to dissuade people from visiting the site. This may seem harsh but I can think of no other reason. Thirty minutes from car park to site walking at a reasonable rate - but not over the top. The terrain is a little awkward in only one or two spots but the rest is easily negotiated. However, I would reinforce that it is still essential to plan the trip knowing the tides and weather – it is still easy to get cut off unless you take extra care and pay attention to the time. Never take chances.
As I approached the beds I was delighted to be, yet again, the only person around and it was such a beautiful day. The tide was going out, the sun was pleasantly warm and there was a gentle breeze – I could not believe my luck. I quickly found the fossil bearing spot and began to search and soon found one or two odd bits of ammonite. This area was very similar to my other regular haunt and was also not that big an area.
It consisted of boulders, rocks and gravel and these were intermingled with large dislodged sections of shale that had broken off from the wave cut platform and were slowly being eroded away by the ceaseless tides of the North Sea. Amongst this there was a lot of seaweed that had taken hold in the nooks and crannies and, all in all, this seemed to represent quite a challenge to locate fossils.
I need not have worried and continued to find bits of ammonite but I only kept a couple of fragments since I had loads from the other coastal spots I had been frequenting. Pretty soon, however, I found my first nodule which seemed likely to hold a reasonable ammonite and then found another one in quick succession. As I got my eye in, the fossils came in little hot spots where I would find two or three fairly close to each other and then nothing for quite a while. The same issues here were the same as at the other stretches – namely there was lots of cracked nodules where other fossil hunters had been here before me and, again, there were a couple of nice specimens that had been completely destroyed by reckless hammering.
 
As the tide moved out I checked the platform but this was extremely difficult to walk on and there was copious amounts of seaweed in place that covered the shales in vast swathes of green. I persevered for a while for I knew that vertebrate fossils were not too uncommon here but I could find only flattened ammonites and a few belemnites. Ichthyosaurs are the most common reptiles found here and a fairly complete skull had been removed only a few years prior.
After I gave up the search on the shales (mainly because I did not want to slip and break something!), I returned to the foreshore and continued the search there. The fossil bearing stretch slowly widened out and became more difficult to search but it was apparent that it was not rich at all and I returned to the more constrained area to look for more nodules.
Despite not being as rich as I first imagined I still managed to find some nice pieces that are likely to yield one or two nice specimens and I felt quite happy with my finds. I also looked further up shore and had a tentative look in the cliff face but I could find very little. That weather was still wonderful and I decided to call it a day and begin the walk back. Again I reiterate that the walk is not as long or as tough as is made out by others – just be sensible and pay attention to the tides and weather. I soon found a pub and enjoyed the view for today was my last day in the north east but although this week was ending, tomorrow I would be heading south to an undisclosed and disused quarry to look in the clays of the Callovian seas.
I left the north very early and headed south down the A1. After I has stopped for a much needed breakfast I arrived at the quarry around nine o’clock and met up with a few colleagues from our research group to see what we could find. Conditions were fine – blue sky, not too hot and a gentle breeze but there had been no rain here for many a day and the terrain looked harsh. Compared to what I had been experiencing over the last week with the ever encroaching tides revealing new treasures each day, this looked very likely to be a hard day. A dry arid basin swept before us with the ancient clay sea glistening white amongst the copious amount of vegetation that was now growing rapidly.
 
Add to this I knew that this venue had been visited only recently by another group and without a change in the weather, I felt our chances of finding things were low to say the least. As we began searching we immediately came across a vast plain of mud cracks, many of which were already desiccating and others were curling up and were now loose on the surface. Everything looked grim.
We found a spot that looked like it may be promising and a couple of us dropped down onto our hands and knees for a closer inspection of the exposed surface. The clay looked completely bereft of fossils and I was just about to move on when I spied a tiny black fragment pushing through the clay. I carefully cleared the sediment from this speck of black and was amazed to find a partial tooth from the hybodont shark Asteracanthus. Considering the conditions this was completely unexpected.
We gradually looked around the same spot gently sifting through the clay and were rewarded with two further partial fragments of teeth from the same shark. Associated remains? Possibly but considering this quarry had not been worked for some years now it is hard to be sure.
After this brief moment of interest we spread out to see what else we could find. It had really turned out to be yet another nice day but it was proving difficult to find anything. A lot of the old spoil now was like concrete and had formed almost a solid crust on the surface. As you broke into it, the old shales simply disintegrated - everything was so dusty.
Eventually, one of the crew found an unusual, what appeared to be, compressed mollusc. We had seen these on occasion but only rarely and the general consensus is that they are actually the compressed remains of a nautiloid – perhaps Paracenoceras. In any event this turned out to be quite a rare fossil and now resides in the collections at the NHM in London.
Unfortunately this find turned out to be the exception rather than the rule. The ever increasing amount of vegetation (you could almost describe it as scrub) was making things really difficult and, for all our prospecting abilities we could only muster up a couple of scrappy bits of bone and couple of fish scales although there was one more interesting fossil that turned up.
From L - R Two bits of bone, three fish scales with the Asteracanthus tooth above and the coprolite at the far right.
Coprolites are extremely abundant in the Oxford Clay. Most are from fish which are small, generally a pasty off white colour and of little interest. Large ones from animals such as the marine reptiles are much rarer but these too, apart from their size, are also of little consequence.
But every now and then one turns up with inclusions which are normally representative of the animals most recent meal – and these are very interesting indeed. They normally show up as black and shiny against the pasty background of the coprolite and represent various food sources that would have passed through the food chain.
Many of these inclusions are unrecognisable but some can be readily identified. One of the more common elements found are the remains of belemnites and some of the hooklets appear as pristine today as they may have been over 160 million years ago. But, on occasion, a coprolite can reveal something extraordinary and I was fortunate enough to find just such a fossil today.
This coprolite reveals, remarkably, several pieces of fish bone including a perfect little vertebra. A couple of inclusions looked like small teeth but were revealed to be a scale and a small bone. There were other indistinguishable inclusions as well and this coprolite is the first one of its kind that I have found – maybe not as spectacular as big teeth or bones but no less of equal fascination.
In the end we decided to call it day and headed home – for me the first time I had been home in a week. All in all it had been a great week that I had spent with friends, both old and new, and I was very lucky with the weather which had been very spring-like. I had also found a good quantity of ammonites in the north east although vertebrate fossils had eluded me on this occasion but I had managed to find a nice shark tooth and coprolite on the very last day so you cannot complain about that.
Most of all I loved the fact that I had begun the week searching for fossils in the Toarcian seas of 180 million years ago and finished up looking for the creatures of the Tethys Ocean, in sediments  around 16 million years younger than where I had first started prospecting simply by driving a few miles in my car. Ancient worlds brought to life by the tools of the modern world.

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