Cosmic clue to UK coastal erosion
By Jonathan Amos, BBC Science Correspondent
7 November 2016
Recent centuries have seen a big jump in the rates of erosion in the iconic chalk cliffs on England’s south coast. A new study finds that for thousands of years the rocks were being beaten back by the waves at perhaps 2-6cm a year. The past 150 years has seen this retreat accelerate 10-fold, to more than 20cm a year.
The speed-up was clocked with the aid of a smart technique that tracks changes induced in rocks when they are exposed to energetic space particles.
The research, led from the British Geological Survey and conducted by Martin Hurst and colleagues, is reported in the leading American journal, the Proceedings of the National Academy of Sciences.
The group believes the findings will help us understand some of the coming impacts of climate change. “Our coasts are going to change in the future as a result of sea-level rise and perhaps increased storminess, and we want this work to inform better forecasts of erosion,” Dr Hurst, currently affiliated to Glasgow University, told BBC News.
The research was centred on East Sussex and its towering cliffs at Beachy Head and Hope Gap.
Originally laid down 90 million years ago, these soft chalk faces are now being eaten away by the relentless pounding they get from the sea.Rood and Hurst on the platform. Image copyrightMARTIN HURST ET AL
Care is needed because the platform’s exposure can appear more recent than is really the case.
Dr Hurst’s team was able to estimate the pace of this reversal by examining the amount of beryllium-10 in nodules of flint embedded in the eroded platform in front of the cliffs. The radioactive element is produced when cosmic rays – that constantly shower the Earth – hit oxygen atoms in the flints’ quartz minerals. The longer the nodules have been exposed, the greater their build-up of beryllium-10.
At Beachy Head and Hope Gap, the gently sloping platform, which is only uncovered at low tide, extends seaward several hundred metres. It represents all that is left after millennia of cliff removal.
“The lower rates of erosion that we report – about 2.5cm at Hope Gap and around 6cm at Beachy Head – are averaged over that timeframe – through about the past 7,000 years of the Holocene,” explained Dr Hurst.
“But comparing that to observations based on topographic maps and aerial photography of the last 150 years – the difference is quite stark. These historical observations from 1870 to the present suggest erosion rates of 20-30cm a year at the two sites.”
Flint nodules. Image copyrightMARTIN HURST ET AL
The team removed flints for beryllium testing in a line perpendicular to the cliffs. The estimates of change in the deep past are tricky because the platform appears younger than it really is. This stems from the fact that its surface continues to erode downwards, removing its oldest exposed flints. The regular tidal covering of water also has to be considered because it will restrict the flux of cosmic rays reaching the platform, thus limiting the amount of beryllium that can be induced in the nodules.
But the team is confident in its analysis and puts forward some ideas to explain the recent big up-tick in erosion. These concern the available gravels at the foot of the cliffs that constitute the beach. Ordinarily, this material acts as a buffer, limiting the energy of crashing waves.
But there is good evidence that the beaches in this region of the south coast have got thinner through time and perhaps therefore offer less protection today than they once did. In the modern era, groynes and sea walls have been erected further down the coast and these may have interfered with the along-shore transport of gravels. And further back in time, several hundred years ago, it is possible also that there was a phase of more storms. These could have removed significant volumes of gravel and pushed the rates of erosion into a new, more aggressive regime that persists even now.
Co-author Dr Dylan Rood from Imperial College London told BBC News: “The coast is clearly eroding, and Britain has retreated fast. A nearly tenfold increase in retreat rates over a very short timescale, in geological terms, is remarkable.
“The UK cannot leave the issue of cliff erosion unresolved in the face of a warming world and rising sea levels. Cliff erosion is irreversible; once the cliffs retreat, they are gone for good.”
A couple of days ago I stopped-off at Birling Gap to have my lunch…
I noticed while standing at the top of the steps that go down to the beach, how grey and course the shingle appeared. Presumably this indicated that this material is of relatively newly exposed flint. There was a large cliff-fall mid-way along the Seven Sisters back in the summer which no doubt has contributed,it now completely dispersed by the sea. Shingle is in the main, of a brownish hue due to exposure over time to iron compounds in the seawater.
The land to the east of Birling Gap appears much improved from the now regular winter pony grazing. This week there were still a number of plants still in flower. Scrub clearance by National Trust staff and volunteers has also had a marked effect on this once un-managed area.
A herd of ponies were grazing on Eastbourne BC’s Belle Tout area, the first of the autumn/winter grazing of four sites within the Birling/Beachy Head area this season.
Extreme global warming of Cretaceous period punctuated with significant global cooling.
Date:May 28, 2015 Source:Goethe-Universität Frankfurt
Scientists at the Goethe University Frankfurt and at the Senckenberg Biodiversity and Climate Research Centre working together with their Canadian counterparts, have reconstructed the climatic development of the Arctic Ocean during the Cretaceous period, 145 to 66 million years ago. The research team comes to the conclusion that there was a severe cold snap during the geological age known for its extreme greenhouse climate. The study published in the professional journal Geology is also intended to help improve prognoses of future climate and environmental development and the assessment of human influence on climate change.
The Cretaceous, which occurred approximately 145 million to 66 million years ago, was one of the warmest periods in the history of Earth. The poles were devoid of ice and average temperatures of up to 35 degrees Celsius prevailed in the oceans. “A typical greenhouse climate; some even refer to it as a ‘super greenhouse’ ,” explains Professor Dr. Jens Herrle of the Goethe University and Senckenberg Biodiversity and Climate Research Centre, and adds: “We have now found indications in the Arctic that this warm era 112 to 118 million years ago was interrupted for a period of about 6 million years.”
In cooperation with his Canadian colleague Professor Claudia Schröder-Adams of the Carleton University in Ottawa, the Frankfurt palaeontologist sampled the Arctic Fjord Glacier and the Lost Hammer diapir locality on Axel Heiberg Island in 5 to 10 metre intervals. “In so doing, we also found so-called glendonites,” Herrle recounts. Glendonite refers to star-shaped calcite minerals, which have taken on the crystal shape of the mineral ikaite. “These so-called pseudomorphs from calcite to ikaite are formed because ikaite is stable only below 8 degrees Celsius and metamorphoses into calcite at warmer temperatures,” explains Herrle and adds: “Thus, our sedimentological analyses and age dating provide a concrete indication for the environmental conditions in the cretaceous Arctic and substantiate the assumption that there was an extended interruption of the interglacial period in the Arctic Ocean at that time.”
In two research expeditions to the Arctic undertaken in 2011 and 2014, Herrle brought 1700 rock samples back to Frankfurt, where he and his working group analysed them using geochemical and paleontological methods. But can the Cretaceous rocks from the polar region also help to get a better understanding of the current climate change? “Yes,” Herrle thinks, elaborating: “The polar regions are particularly sensitive to global climatic fluctuations. Looking into the geological past allows us to gain fundamental knowledge regarding the dynamics of climate change and oceanic circulation under extreme greenhouse conditions. To be capable of better assessing the current human-made climate change, we must, for example, understand what processes in an extreme greenhouse climate contribute significantly to climate change.” In the case of the Cretaceous cold snap, Herrle assumes that due to the opening of the Atlantic in conjunction with changes in oceanic circulation and marine productivity, more carbon was incorporated into the sediments. This resulted in a decrease in the carbon dioxide content in the atmosphere, which in turn produced global cooling.
The Frankfurt scientist’s newly acquired data from the Cretaceous period will now be correlated with results for this era derived from the Atlantic, “in order to achieve a more accurate stratigraphic classification of the Cretaceous period and to better understand the interrelationships between the polar regions and the subtropics,” is the outlook Herrle provides.
Jurassic shale of the Weald Basin: resource estimation report
The British Geological Survey (BGS) in association with the Department of Energy and Climate Change (DECC) has completed an estimate for the amount of shale oil and shale gas in the Weald Basin in south-east England [that is, Hampshire through to Kent and laying between the North and South Downs]; published 23 May 2014.
The estimate is in the form of a range to reflect geological uncertainty. The range of shale oil in place is estimated to be between 2.20 and 8.57 billion barrels (bbl) or 293 and 1143 million tonnes, but the central estimate for the resource is 4.4 billion bbl or 591 million tonnes.
No significant gas resource is recognised using the current geological model. This is mainly because the shale is not thought to have reached the geological maturity required to generate gas. The figure for oil represents the total amount of oil present in the rocks. It is not known what percentage of the oil present in the shale could be commercially extracted. In order to estimate the shale oil reserve, drilling and testing of new wells will be required to give a better idea of oil production rates. In addition, non-geological factors such as oil price, operating costs and the scale of development agreed by the local planning system will affect the amount of oil produced.
Shale oil clearly has potential in Britain but it will require geological and engineering expertise, investment and protection of the environment. It will also need organisations like the BGS to play their part in providing up to date and accurate information on resources and the environment to the public, industry and government.
But Professor Andrew Aplin, a shale expert at Durham University, says the heavy, viscous nature of the Weald oil and the tight, clay-rich rocks mean little oil may be extractable. “We might estimate that 1% of the Weald oil resource might be recoverable. This would equate to 0.05 billion barrels, which is about two months UK consumption. From a national perspective, this seems to be a rather small prize.” The same dashing of hopes has just occurred in the US, where the official government estimate for the nation’s largest shale oil prospect has just plummeted by 96%.
Tuesday, March 18.
ABSTRACT. The energy giant EDF has been accused of playing down the threat of flooding at Dungeness after it emerged that one of the nuclear power plant’s reactors was quietly shut down for five months last year after experts identified risk of a Fukushima-style disaster.
EDF closed the reactor on the Kent coast on 22 May to allow work on a new flood protection wall, after alerting the Office of Nuclear Regulation that without urgent work the site was at risk of being inundated by sea water.
The reactor – which should provide power for about 750,000 homes – did not reopen again until 15 October. The closure of the 550-megawatt reactor – one of two at Dungeness – followed an internal EDF report which found that the shingle bank sea defences were “not as robust as previously thought”, raising fears that they could be overwhelmed in extreme weather, according to the ClickGreen website, which first reported the closure.
EDF marked the closure of the reactor with a short statement to local media saying: “Unit 22 at Dungeness station was taken offline on 20 May for maintenance work which includes completing improvements to flood defences for extreme events.” Five months later, the company said: “Unit 22 at Dungeness B power station resynchronised to the Grid at 0.522am on Tuesday 15 October.”
There was no clear explanation of the remarkable length of the outage, which was not widely reported. Stephen Thomas, professor of energy policy at the University of Greenwich, said: “EDF should have made more of an announcement. If a plant closes for five months it is not just fiddling about, it is something serious and EDF can’t pretend it’s not.
“I think there is a bad attitude in this country that we must not frighten the horses. But playing it down is the wrong way – we need to be told the truth,” Professor Thomas added. He calculates that the five-month closure could have cost EDF around £100m in lost electricity revenue, while the group would have saved very little in the way of expenses, still having to pay wages and maintain the reactor.
The EDF review that led to the flooding work was carried out with the Environment Agency and meteorological experts based on new modelling in the wake of the Fukushima disaster, which involved assessments of extreme still-water levels, wave heights and historical tsunamis. EDF notified the Office for Nuclear Regulation (ONR) in December 2012 that it “no longer had confidence” in its primary sea defence. It committed to boosting flood protection by “taking due cognisance of the need for a margin against more severe events”, ONR documents show.
This involved upgrading the defence from one that could protect against a one in 1,000-year weather event to one that occurs every 10,000 years.
According to a briefing to local community representatives by the station director, EDF originally boosted the shingle flood defences early last year. However, a further review of the site in May concluded that “the flood protection work already completed needed to be extended… to further enhance the plant resilience to this extreme hazard”, the station director said. The defence consists of “a permanent flood protection wall around the site” and is expected to be finished by the end of this month.
Dungeness is one of eight operational nuclear power plants in the UK and the Government has plans to build 12 new reactors as it looks to switch to lower-carbon energy. But none of the proposed projects has been finalised.
The spokesman said the closure was part of its “response to events in Japan which caused serious damage to Fukushima Daiichi [while] an extensive programme of analysis, modelling and physical testing has been carried out to review and update the assessments of potential flooding around our sites. We are continuously updating and improving the plant to ensure it is operating safely.”
Martin Pearson, station manager at Dungeness B, said: “The recent adverse weather has had no impact on existing infrastructure and the power station has operated normally in recent high tides and stormy weather.” A spokesperson for the Department for Energy and Climate Change declined to comment.
[It has always seemed incredulous to me that nuclear power plants were ever allowed to built on the tip of Dungeness, in view of its landscape significance and more importantly, that the ‘after life’ of these facilities is of thousands of years and the location – at the end of shingle promontory – not the most stable of geological landforms!]
Thursday, March 13.
Enjoyable walk along the coast at Hastings Country Park… Warm sunshine, little breeze, sleeves rolled up. Saw the first sinister growing-tips of bracken appearing above the dry, brittle litter of last year’s growth. Ants active and plenty of small tortoiseshell butterflies engrossed in courtship flights and of course, queen bumblebees on the wing. Much evidence of landslips and also large pools of ‘set porridge’ of downwash at a number of locations below the dishevelled sandstone cliffs. Early pm, and a sea fog crept in over the lower portions of the coast.
Abstract. ‘October 1, 2013. Drilling cores from Switzerland have revealed the oldest known fossils of the direct ancestors of flowering plants. These beautifully preserved 240-million-year-old pollen grains are evidence that flowering plants evolved 100 million years earlier than previously thought, according to a new study in the open-access journal ‘Frontiers in Plant Science.’ The oldest known fossils from flowering plants are pollen grains. These are small, robust and numerous and therefore fossilize more easily than leaves and flowers. An uninterrupted sequence of fossilized pollen from flowers begins in the Early Cretaceous, approximately 140 million years ago, and it is generally assumed that flowering plants first evolved around that time. But the present study documents flowering plant-like pollen that is 100 million years older, implying that flowering plants may have originated in the Early Triassic (between 252 to 247 million years ago) or even earlier.’
Peter Hochuli and Susanne Feist-Burkhardt from Paleontological Institute and Museum, University of Zurich, studied two drilling cores from Weiach and Leuggern, northern Switzerland, and found pollen grains that resemble fossil pollen from the earliest known flowering plants. The pollen’s structure suggests that the plants were pollinated by insects: most likely beetles, as bees would not evolve for another 100 million years.