Post by ammocarbsteve on Jan 15, 2014 16:43:06 GMT -5
Joe... Heres my jottings and fossils from this unrecorded site...
With coal mining operations in the north west of England brought to a halt during the 1980’s and 90’s as a consequence of ‘greener’ sources of energy being sought by the government in power at the time, It was presumed that the remaining coal fired power stations still online generating power to the national grid, would infact function almost entirely from the cheaper imported coal, cheaper , meaning cheaper to buy per tonne than what we could produce it for ourselves. Subsequently, the imported coal quality decreased and the cost increased once we had relinquished our ability to mine coal ourselves and even well into the new millenium, coal imports were greater than the volume we produced ourselves, even though the UK is well placed within Europe in having large reserves of coal both onshore and offshore in the southern North Sea. These reserves have the potential to provide security of future energy supplies long after oil and natural gas have been exhausted.
Recently, ‘green coal’ or to be more precise, a system that will allow the capture of carbon emissions from the burning of coal and subsequent safe storage, is being introduced, to carry us over until the new wave of nuclear energy is brought online in the near future. It was reported sites for new nuclear power stations have already been identified and are currently being considered, and it is thought that a combination of renewable energy, cleaner nuclear and green coal technology, will be used in the future to supply our growing energy needs.
Meanwhile, as a result of significant improvements in the performance of modern excavation machinery, it has become common practice and profitable to access the coal seams using open casting techniques, where the overburden is removed first, then the coal simply collected on mass, and the excavation hole then backfilled using the spoils. This has enabled for those interested the insitu collecting of fossils, giving a valuable insight into the landscape, flora and fauna, of the north west of England’s distant past.
The coal measures that are local to me are of upper carboniferous, Westphalian A age, approximately 300 million years old. This area at that time was covered by a vast carboniferous forest and river delta, and was positioned only a few degrees north of the equator and was a tropical environment that during times of monsoon or flood, laid down sediments and siltstones, that appear as the shale layers, formed in between the documented coal seams. It is these layers that contain fossils, in siderite nodules, creatures and plant material that were captured during a climatic event, carried in the mudflow then buried and fossilised for us to find today.
It is thought that it may take as long as 7000 years for sufficient plant material to be deposited to generate a one metre thick layer of coal, initially starting out as plant litter on the forest floor, then forming peat as it rots down, and finally being compacted over time by overlying sediments to create the coal, whereas the same thickness of sediment in between the coal may take as little as several years to deposit. Proof of this can be seen by the common occurance of insitu fossilised standing trees, where the tree has been buried quite quickly, still standing in a lot of cases, without having time to rot down, later after decay has taken place, leaving a perfect mould for sediments to fill creating the ‘tree cast’. These have been a relatively common occurance in the recent opencasts in the north west of England.
Doing the maths regarding deposition timescales it is considered that the area was forested for 95% of the time to enable the numerous coal layers to be created, and the sediments that are laid inbetween the seams, the result of climatatic events such as polar ice melting or monsoon floodwater, running off what was then a super continent. A wonderful example of a fossilised tree stump and root system can be seen at Manchester Museum,which is well worth a visit to see other examples of fossilised plant and animal material from the carboniferous period of this area.
The fossils of the west Lancashire coalfield have recently been very well documented, Bickershaw spoil heap, was collected and written up by (Anderson et al. 1997), and Westhoughton opencast ( Anderson, Dunlop & Horrocks et al. 1999) and most recently Crockhey , although the latter has not been written up; and, fossils from Lancashire coalfield have been collected and recorded over the past hundreds of years by coal miners and fossil enthusiasts alike. A visit to any of the local museums, will confirm this and you will find typical fossil material in all the collections, shale imprints and nodules, although for some reason not always on display. By prior arrangement it is possible to view this material which myself and a group of friends have done on many an occasion, to compare what we find today, from past exposures.
What makes open casting so exciting for the fossil enthusiast, is the difference in localised conditions each exposure will give. No two exposures seem to yield exactly the same type of material, and not only different species perdominate, but also the quality of preservation will differ as well. Sometimes uncommon material from one site is the most abundant at a new exposure, and the same goes for the inhabititants of that particular part of the forest or river delta.Each new exposure is a new glimpse into the past.
One exposure I have previously been collecting is called Sandyforth Opencast near to Winstanley in the Wigan area, although the last mining operator went bankrupt, leaving the site open for a good number of years, which allowed a longer than usual period of time to find fossil material from there. Recent research suggests the area encompassed by the recent exposure has been opencast mined on four occasions previously, the first instance called Ryecroft, completed in 1948, removing coal from the Wigan 9 feet, Wigan 4 feet and Wigan 2 feet coal seams, the second exposure being called Gladdon Hey 1953, removing coal from the Wigan 9 feet, Wigan 2 feet, Wigan 4 feet and Wigan 5 feet coal seams, then Sandyforth Farm 1988, removing coal from the Sir John and Flaggy Delph coal seams, and finally Sandyforth Opencast accessing the King and Queen, Flaggy Delph, Sir John, Wigan 9 feet, Wigan 2 feet, Wigan 4 feet and Wigan 5 feet coal seams. The area is crossed by a number of geological faults, one being named the crows nest fault, which throws the seams out of alignment approximately 40m bringing differing seams closer to the surface within the boundaries of the opencast.
Over the last six months the excavated material has gone back in the hole, and is currently being covered in subsoil. The subcontractor undertaking the backfilling, would not allow fossil collecting, as I was informed it was almost impossible and very expensive to insure against accident, for non employees to be present on the site. It’s a shame, health and safety has become so stringent over the last decade, as collecting is usually more rewarding during the movement of the spoil heaps. Im sure a lot more material could have been found here if it had been permitted.
On this exposure, my recent experience’s at Crockhey opencast had me initially looking for siderite nodules, but for some reason at Sandyforth, although not completely devoid, these seemed very few and far between. At Crockhey, most of the fossil bearing nodules came from above the Wigan 2 foot seam, although here, that seam had been extensively worked previously, and it was possible that some nodules would be present in the form of previous opencast backfill, but what sparse nodules were actually present, seemed to be relatively fresh from the most recent excavations. It was quite puzzling to be honest, how sufficient material was deposited to create the coal seams, but not a lot of plant got fossilised, and what there was, seemed to be smallish fragments. Presumably, in between times of heavy forestation, when the coal layer was being created, it must have been a low lying area of the delta, where water currents were more powerful, so material didn’t settle easily to enable them to be fossilised. Due to the lack of nodules I started to determine other possible sources for fossil material from the site, looking at for example the mudstone shale’s, and a very dark siltstone band, that would possibly contain fish remains if laid down as a silt sediment during periods when the area was under water. It had already produced a number of small fish related fragments although the bulk of this material was buried, and what was exposed, quite weathered and breaking down. The shale’s that was accessible contained numerous lepidodendron branches, and rootlets, although these were very poorly preserved and not really worth collecting, as well as a consistent layer of non marine bivalves.
Some examples of what nodular plant material I found aty the site are, a small example of neuropteris and mariopteris, beautiful florets of Lepidostrobophyllum alatum sporophylls: of various types, Bothrodendron, Lepidostrobophyllum seed cone ‘husk’, although this nodule is weathered from a previous opencast exposure and Cyclopteris, with Alethopteris visible through the leaf fossilised underneath it, calamites and various woody stem remains with spirorbis worm casts attached, a genus of very small worm usually with a white shell ranging in size from 2 to 5 mm in size, along with a single Asterophylites equisetiformis.
The alternative, to concentrate on a dark silt layer, that was different to the one containing the bivalves, started to prove successful. Sections of this I found up to 300 millimetres thick, where at a previous exposure, I have only observed similar material up to 50 mm thick, further evidence it must have been a lower lying area, obviously remaining underwater longer than the other exposure to enable the deposition of this thickness of silty sediment. The silt was very fine as well, so I presumed the area must have been very slow moving water way if not a lagoon, for such fine particles to settle. It became quite frequent in this layer to discover individual fish scales and teeth, nice finds, that was until I found a lower jaw bone, which had the teeth still embedded within it. This was attributed to a juvenile Rhizodont, a species of fish which are an extinct group of predatory lobe-finned fishes. The fossils are found in many areas of the world with the earliest known being about 377 Ma, the latest around 310 Ma. Rhizodont’s lived in tropical rivers and freshwater lakes and were the dominant predators of their age. They reached huge sizes, the largest known from Europe and North America, were an estimated 7 metres in length, making it the largest freshwater fish known. The large tusk like front tooth was used to grasp their slippery prey which was thought most probably other fishes, until they were able to position the prey ready to be swallowed as a whole. In addition to the normal type of scale, I came across a grouping of scale type attributed to Strepsodus anculonamensis sp.
A further discovery from within the same slity sediment proved to be the spine of a xenacanthida, which is a prehistoric freshwater shark, that appeared during the Lower carboniferous period. At two exposures previously,I have previously found fossil shark eggcases, and its nice to finally find part of the shark that produced them. It is thought some xenacanthida grew up to 4 metres in length. The spine I found was from a species that had a large serrated spine extending backwards from behind the head, possibly Anodontacanthus triangular is, im not exactly sure on the identification at this stage of writing this. As for what purpose the spine served, maybe to prevent being swallowed by the larger predators, a backward pointing serrated barb could possibly hinder this.
All these fossil specimens appear to come from juveniles of the species, which for carboniferous fish is very rare indeed, so I think it can be determined that this area during the upper carboniferous period was not possibly a section through a constant river channel, but more than likely marginal section of a levee, as predominantly marginal shallow areas are used as sanctuary by smaller fish to prevent predation from their larger relatives, as they still do today. Its also possible if the area was a contained Levee, that the fish are adults and possibly stunted. Another clue to this was the discovery of some ripple marks contained within a mudstone, suggesting the area’s could have been shallow marginal edges, where water rises and falls slowly creating the ripples. Im pretty sure that wind, shallow water and a gentle gradient plays a factor in allowing these to form.
From the same area two quite poorly preserved Bellinurus trilobitoides horse shoe crabs were also discovered.These were the only ones we found, which was confusing, as I would of expected this environment to be an ideal home for these creatures to flourish.
Insects, they are present usually with an abundance of well preserved fossil plant material, which wasn’t the case at Sandyforth, so what I have found are more likely to be Syncarid, crustacean’s, Synacarid meaning, without a carapace, although one could be a small type of millipede. There was very little sign of anything of this nature until I discovered a small area that had some promising nodules contained within the characteristic light blue mudstone. It was only after it has rained that this material stood out from the rest and appeared to be worth further investigation and following contacting my collecting friend we managed to find 5 examples of this crustacean, uncovering and breaking down shale blocks, from a very small localised area in less than a day. Two individual examples came from one shale block in one instance. A section of an insect wing was found fossilised as well, with the condition of the nodule suggesting it to be from a previous exposure at the site. Some larger individual fish scales up to 25 mm in size were also collected in siderite nodules as well from this material, difficult to pin down an ID as the nodule split’s the scale into two, along with the occasional Lepidostrobophyllum alatum sporophyll.
To summerise, not all temporary exposures will produce vast amounts of fossil material, or necessarily very high quality fossils, but each will hopefully have there very own treasures. Temporary exposures near you could be new road works, foundations for new buldings, excavating for pipelines etc, and the collecting and recording of this important fossil record is essential from all these temporary exposures if all the pieces of the jigsaw are to come together at some point in the future to form the bigger picture of your area. I think it is therefore scientifically important to collect and record the faunal differences of each site, for this comparison to be made. I wish I could have collected at this site as it was being initially excavated, but modern health and safety laws are increasingly restricting access to these exposures, as well as an obvious reluctance from some quarry owners, as some collectors in the past have blatantly exploited these resources for their own individual financial gain, having little regard of their actions in how it may affect access for other collectors in the future.
References
Anderson, L I., Dunlop, J. A., Horrocks, C. A., Winkelmann, H. M. & Eagar, R. M. C. 1997. Exceptionally preserved fossils from bickershaw, Lancashire, Uk (Upper Carboniferous, Westphalian A. Geological Journal 32, 197-210.
Anderson, L. I., Dunlop, J. A., Eagar, R. M. C., Horrocks, C. A. & Wilson H. M.
Soft - bodied fossils from the roof shales of the Wigan Four Foot coal seam, Westhoughton, Lancashire, UK.
With coal mining operations in the north west of England brought to a halt during the 1980’s and 90’s as a consequence of ‘greener’ sources of energy being sought by the government in power at the time, It was presumed that the remaining coal fired power stations still online generating power to the national grid, would infact function almost entirely from the cheaper imported coal, cheaper , meaning cheaper to buy per tonne than what we could produce it for ourselves. Subsequently, the imported coal quality decreased and the cost increased once we had relinquished our ability to mine coal ourselves and even well into the new millenium, coal imports were greater than the volume we produced ourselves, even though the UK is well placed within Europe in having large reserves of coal both onshore and offshore in the southern North Sea. These reserves have the potential to provide security of future energy supplies long after oil and natural gas have been exhausted.
Recently, ‘green coal’ or to be more precise, a system that will allow the capture of carbon emissions from the burning of coal and subsequent safe storage, is being introduced, to carry us over until the new wave of nuclear energy is brought online in the near future. It was reported sites for new nuclear power stations have already been identified and are currently being considered, and it is thought that a combination of renewable energy, cleaner nuclear and green coal technology, will be used in the future to supply our growing energy needs.
Meanwhile, as a result of significant improvements in the performance of modern excavation machinery, it has become common practice and profitable to access the coal seams using open casting techniques, where the overburden is removed first, then the coal simply collected on mass, and the excavation hole then backfilled using the spoils. This has enabled for those interested the insitu collecting of fossils, giving a valuable insight into the landscape, flora and fauna, of the north west of England’s distant past.
The coal measures that are local to me are of upper carboniferous, Westphalian A age, approximately 300 million years old. This area at that time was covered by a vast carboniferous forest and river delta, and was positioned only a few degrees north of the equator and was a tropical environment that during times of monsoon or flood, laid down sediments and siltstones, that appear as the shale layers, formed in between the documented coal seams. It is these layers that contain fossils, in siderite nodules, creatures and plant material that were captured during a climatic event, carried in the mudflow then buried and fossilised for us to find today.
It is thought that it may take as long as 7000 years for sufficient plant material to be deposited to generate a one metre thick layer of coal, initially starting out as plant litter on the forest floor, then forming peat as it rots down, and finally being compacted over time by overlying sediments to create the coal, whereas the same thickness of sediment in between the coal may take as little as several years to deposit. Proof of this can be seen by the common occurance of insitu fossilised standing trees, where the tree has been buried quite quickly, still standing in a lot of cases, without having time to rot down, later after decay has taken place, leaving a perfect mould for sediments to fill creating the ‘tree cast’. These have been a relatively common occurance in the recent opencasts in the north west of England.
Doing the maths regarding deposition timescales it is considered that the area was forested for 95% of the time to enable the numerous coal layers to be created, and the sediments that are laid inbetween the seams, the result of climatatic events such as polar ice melting or monsoon floodwater, running off what was then a super continent. A wonderful example of a fossilised tree stump and root system can be seen at Manchester Museum,which is well worth a visit to see other examples of fossilised plant and animal material from the carboniferous period of this area.
The fossils of the west Lancashire coalfield have recently been very well documented, Bickershaw spoil heap, was collected and written up by (Anderson et al. 1997), and Westhoughton opencast ( Anderson, Dunlop & Horrocks et al. 1999) and most recently Crockhey , although the latter has not been written up; and, fossils from Lancashire coalfield have been collected and recorded over the past hundreds of years by coal miners and fossil enthusiasts alike. A visit to any of the local museums, will confirm this and you will find typical fossil material in all the collections, shale imprints and nodules, although for some reason not always on display. By prior arrangement it is possible to view this material which myself and a group of friends have done on many an occasion, to compare what we find today, from past exposures.
What makes open casting so exciting for the fossil enthusiast, is the difference in localised conditions each exposure will give. No two exposures seem to yield exactly the same type of material, and not only different species perdominate, but also the quality of preservation will differ as well. Sometimes uncommon material from one site is the most abundant at a new exposure, and the same goes for the inhabititants of that particular part of the forest or river delta.Each new exposure is a new glimpse into the past.
One exposure I have previously been collecting is called Sandyforth Opencast near to Winstanley in the Wigan area, although the last mining operator went bankrupt, leaving the site open for a good number of years, which allowed a longer than usual period of time to find fossil material from there. Recent research suggests the area encompassed by the recent exposure has been opencast mined on four occasions previously, the first instance called Ryecroft, completed in 1948, removing coal from the Wigan 9 feet, Wigan 4 feet and Wigan 2 feet coal seams, the second exposure being called Gladdon Hey 1953, removing coal from the Wigan 9 feet, Wigan 2 feet, Wigan 4 feet and Wigan 5 feet coal seams, then Sandyforth Farm 1988, removing coal from the Sir John and Flaggy Delph coal seams, and finally Sandyforth Opencast accessing the King and Queen, Flaggy Delph, Sir John, Wigan 9 feet, Wigan 2 feet, Wigan 4 feet and Wigan 5 feet coal seams. The area is crossed by a number of geological faults, one being named the crows nest fault, which throws the seams out of alignment approximately 40m bringing differing seams closer to the surface within the boundaries of the opencast.
Over the last six months the excavated material has gone back in the hole, and is currently being covered in subsoil. The subcontractor undertaking the backfilling, would not allow fossil collecting, as I was informed it was almost impossible and very expensive to insure against accident, for non employees to be present on the site. It’s a shame, health and safety has become so stringent over the last decade, as collecting is usually more rewarding during the movement of the spoil heaps. Im sure a lot more material could have been found here if it had been permitted.
On this exposure, my recent experience’s at Crockhey opencast had me initially looking for siderite nodules, but for some reason at Sandyforth, although not completely devoid, these seemed very few and far between. At Crockhey, most of the fossil bearing nodules came from above the Wigan 2 foot seam, although here, that seam had been extensively worked previously, and it was possible that some nodules would be present in the form of previous opencast backfill, but what sparse nodules were actually present, seemed to be relatively fresh from the most recent excavations. It was quite puzzling to be honest, how sufficient material was deposited to create the coal seams, but not a lot of plant got fossilised, and what there was, seemed to be smallish fragments. Presumably, in between times of heavy forestation, when the coal layer was being created, it must have been a low lying area of the delta, where water currents were more powerful, so material didn’t settle easily to enable them to be fossilised. Due to the lack of nodules I started to determine other possible sources for fossil material from the site, looking at for example the mudstone shale’s, and a very dark siltstone band, that would possibly contain fish remains if laid down as a silt sediment during periods when the area was under water. It had already produced a number of small fish related fragments although the bulk of this material was buried, and what was exposed, quite weathered and breaking down. The shale’s that was accessible contained numerous lepidodendron branches, and rootlets, although these were very poorly preserved and not really worth collecting, as well as a consistent layer of non marine bivalves.
Some examples of what nodular plant material I found aty the site are, a small example of neuropteris and mariopteris, beautiful florets of Lepidostrobophyllum alatum sporophylls: of various types, Bothrodendron, Lepidostrobophyllum seed cone ‘husk’, although this nodule is weathered from a previous opencast exposure and Cyclopteris, with Alethopteris visible through the leaf fossilised underneath it, calamites and various woody stem remains with spirorbis worm casts attached, a genus of very small worm usually with a white shell ranging in size from 2 to 5 mm in size, along with a single Asterophylites equisetiformis.
The alternative, to concentrate on a dark silt layer, that was different to the one containing the bivalves, started to prove successful. Sections of this I found up to 300 millimetres thick, where at a previous exposure, I have only observed similar material up to 50 mm thick, further evidence it must have been a lower lying area, obviously remaining underwater longer than the other exposure to enable the deposition of this thickness of silty sediment. The silt was very fine as well, so I presumed the area must have been very slow moving water way if not a lagoon, for such fine particles to settle. It became quite frequent in this layer to discover individual fish scales and teeth, nice finds, that was until I found a lower jaw bone, which had the teeth still embedded within it. This was attributed to a juvenile Rhizodont, a species of fish which are an extinct group of predatory lobe-finned fishes. The fossils are found in many areas of the world with the earliest known being about 377 Ma, the latest around 310 Ma. Rhizodont’s lived in tropical rivers and freshwater lakes and were the dominant predators of their age. They reached huge sizes, the largest known from Europe and North America, were an estimated 7 metres in length, making it the largest freshwater fish known. The large tusk like front tooth was used to grasp their slippery prey which was thought most probably other fishes, until they were able to position the prey ready to be swallowed as a whole. In addition to the normal type of scale, I came across a grouping of scale type attributed to Strepsodus anculonamensis sp.
A further discovery from within the same slity sediment proved to be the spine of a xenacanthida, which is a prehistoric freshwater shark, that appeared during the Lower carboniferous period. At two exposures previously,I have previously found fossil shark eggcases, and its nice to finally find part of the shark that produced them. It is thought some xenacanthida grew up to 4 metres in length. The spine I found was from a species that had a large serrated spine extending backwards from behind the head, possibly Anodontacanthus triangular is, im not exactly sure on the identification at this stage of writing this. As for what purpose the spine served, maybe to prevent being swallowed by the larger predators, a backward pointing serrated barb could possibly hinder this.
All these fossil specimens appear to come from juveniles of the species, which for carboniferous fish is very rare indeed, so I think it can be determined that this area during the upper carboniferous period was not possibly a section through a constant river channel, but more than likely marginal section of a levee, as predominantly marginal shallow areas are used as sanctuary by smaller fish to prevent predation from their larger relatives, as they still do today. Its also possible if the area was a contained Levee, that the fish are adults and possibly stunted. Another clue to this was the discovery of some ripple marks contained within a mudstone, suggesting the area’s could have been shallow marginal edges, where water rises and falls slowly creating the ripples. Im pretty sure that wind, shallow water and a gentle gradient plays a factor in allowing these to form.
From the same area two quite poorly preserved Bellinurus trilobitoides horse shoe crabs were also discovered.These were the only ones we found, which was confusing, as I would of expected this environment to be an ideal home for these creatures to flourish.
Insects, they are present usually with an abundance of well preserved fossil plant material, which wasn’t the case at Sandyforth, so what I have found are more likely to be Syncarid, crustacean’s, Synacarid meaning, without a carapace, although one could be a small type of millipede. There was very little sign of anything of this nature until I discovered a small area that had some promising nodules contained within the characteristic light blue mudstone. It was only after it has rained that this material stood out from the rest and appeared to be worth further investigation and following contacting my collecting friend we managed to find 5 examples of this crustacean, uncovering and breaking down shale blocks, from a very small localised area in less than a day. Two individual examples came from one shale block in one instance. A section of an insect wing was found fossilised as well, with the condition of the nodule suggesting it to be from a previous exposure at the site. Some larger individual fish scales up to 25 mm in size were also collected in siderite nodules as well from this material, difficult to pin down an ID as the nodule split’s the scale into two, along with the occasional Lepidostrobophyllum alatum sporophyll.
To summerise, not all temporary exposures will produce vast amounts of fossil material, or necessarily very high quality fossils, but each will hopefully have there very own treasures. Temporary exposures near you could be new road works, foundations for new buldings, excavating for pipelines etc, and the collecting and recording of this important fossil record is essential from all these temporary exposures if all the pieces of the jigsaw are to come together at some point in the future to form the bigger picture of your area. I think it is therefore scientifically important to collect and record the faunal differences of each site, for this comparison to be made. I wish I could have collected at this site as it was being initially excavated, but modern health and safety laws are increasingly restricting access to these exposures, as well as an obvious reluctance from some quarry owners, as some collectors in the past have blatantly exploited these resources for their own individual financial gain, having little regard of their actions in how it may affect access for other collectors in the future.
References
Anderson, L I., Dunlop, J. A., Horrocks, C. A., Winkelmann, H. M. & Eagar, R. M. C. 1997. Exceptionally preserved fossils from bickershaw, Lancashire, Uk (Upper Carboniferous, Westphalian A. Geological Journal 32, 197-210.
Anderson, L. I., Dunlop, J. A., Eagar, R. M. C., Horrocks, C. A. & Wilson H. M.
Soft - bodied fossils from the roof shales of the Wigan Four Foot coal seam, Westhoughton, Lancashire, UK.