Open University Geological Society (London Branch)
At each event we ask for a volunteer to record their experiences and impressions. These articles are published in our newsletter and eventually appear here as an archive of our activities. Note that these are only provided for reference, and are not endorsed by Event Leaders. Interpretations can change often and rapidly in Geology, any information stated should be verified from appropriate sources before being quoted.
Carbonate platforms of the Early Cretaceous • Shale Oil and Gas Success • The Building Stones of Lincoln’s Inn • Lusi: the origin, evolution and future of a mud Volcano in Java • Mapping Day in Kent • West Norwood Cemetery • Etna: How does a volcano work? • Conservation Day at Gilbert’s Pit • The Devil’s Punchbowl • Crustal melting in the Himalayas • Geology in Space: Meteorites and Cosmic Dust • Sarsens in the Medway Valley • Summer Long Weekend Torbay • LOUGS and WSGS Bicentennial William Smith Sussex Field Trip • Oceanography Experience 2015 • Day Trip: Fossils and Geology on the Isle of Sheppey • The oceanic-driven decay of the Breidamerkurjokull glacier into Jokulsárlón lagoon, Iceland. • Joint Day Trip to Stour and Wrabness with East Anglia branch • Tectonic Evolution of the Alps • Hands-on at Herne Bay for S209 Students • The Scarplands of Lincolnshire: From the Lincoln Edge to the Wolds • Members Evening Talks • Fossil Fakes & Deceptions
Lecture: Carbonate platforms of the Early Cretaceous – 'miner's canaries' for perturbations of the global carbon cycle - by Peter Skelton
31 January 2015
We were delighted to welcome Dr Peter Skelton, retired Reader in Palaeobiology at the OU, and for many of us a major influence in our Earth Sciences courses, in particular as the author of ‘The Cretaceous World’ (2003), as the speaker after our AGM.
He began by comparing the last Glacial Maximum at 22my with its low sea levels, with the situation in the Cretaceous: ice-free poles in a much warmer climate, forests as far north as Alaska, and sea covering much of the shelf areas, when there were periods of anoxia etc. It is estimated that 60% of oil reserves date from that period. There was a complete oceanic ‘girdle’ round the Earth, sea levels were much higher and at Mediterranean latitudes, massive carbonate platforms populated by rudists flourished during the Aptian (123- 112ma). The ocean floor was characterised by huge plateaux and superplume volcanism in addition to Mid-Ocean Ridge-building, producing large amounts of CO2.
Peter then concentrated on rudists, major reef-builders during the Cretaceous, with their three ecological morphotypes, all sessile: elevators grew upright in more sheltered zones; clingers stuck down on a hard surface; recumbents were suited to more energetic conditions. The shells grew very fast, so they quickly ran out of room because of the low amplitude sea level change at the time. The repeated cyclicity of recumbents with porous aragonite shells provided ideal conditions for a reservoir. In the Lower Aptian these recumbents were dominant, whereas in the Upper Aptian calcite rudists with much thicker shells dominated.
There followed a discussion of the differences between the aragonite recumbents in the Bedoulian, attached to the substrate and therefore not needing a calcitic outer shell, and the Upper Aptian with elevators or clingers. At the boundary is a Carbon Isotope Excursion. This can be found in many places round the world: at Resolution Guyot in the mid-Pacific, in southern Oman, and in Sicily. The map shows a geographic distinction with aragonite rudists in the more northerly Tethyan area and calcite in the centre and south.
The cause is the subject of ongoing research. For more information read: Skelton and Gili: ‘Rudists and Carbonate Platforms in the Aptian’, Sedimentology, Vol. 59, issue 1 (2012).
Lecture: Shale Oil and Gas Success: It all begins with the rocks! - by Tony Grindrod
19 February 2015
With more than forty years’ experience in the international oil and gas industry, Tony is well- placed to give us an unbiased account of the controversial attempts to develop the exploitation of shale oil and gas in Europe, and specifically the UK.
He compared the US situation with its relatively simple geology and light population density and its desire to decrease reliance on imports, with the situation in Europe with high population density and heavily faulted terrain.
Within the progression: Exploration -> Appraisal -> Exploitation, the UK is at an early stage with at present only two onshore wells, with seven other possibilities since 2010. Shale is a fine- grained sedimentary rock, fissile, including silts and clays, and with some organic content. It has very low porosity and permeability, often important as a source rock, it may also act as a seal.
The main sources of shale gas are the Scottish Central Belt, the Bowland Shale and the Weald basin. In practice only a fraction is available for extraction: the UK shale gas reservoirs are much thicker than in the US, therefore more difficult to extract and there are significant practical issues of land ownership, legislation, and the limited availability of fractioning equipment and trained staff in Europe as a whole. Below ground there are problems of where to place the laterals in the thick deposits.
A time to panic? Or a time to invest? According to the BP energy forecast of consumption by fuel, in 2035 coal is still substantial, along with oil and gas, renewables are growing, while nuclear power is past its peak.
A lively question session followed, covering politics, the possibility of explosions, earth tremors, and the complex geology of Britain compared to the US. We were left with a much clearer appreciation of the current state of play on the issue.
The Building Stones of Lincoln’s Inn - with Diana Smith and Richard Trounson
19 February and 19 March 2015
An intrepid group from LOUGS gathered for a perishingly cold afternoon walk on which Richard Trounson explained the fascinating history of Lincoln’s Inn, and Diana Smith explained the surprising variety of building stones there and around the Strand.
We started at the war memorial within Lincoln’s Inn, its Portland Stone being unique as a white limestone (as it was not overlain by marine sediments or the iron oxidised). Christopher Wren had popularised the use of Portland as a building stone, inspired by the white stone churches seen on his travels. We then sheltered from the weather in the chapel undercroft, where Richard outlined the origins of the Inns of Court. They were established following a Papal Bull in the thirteenth century that prohibited the clergy from teaching secular law. In England and Wales practicing barristers must belong to one of these, Lincoln’s Inn being the largest.
The Inn is modelled on an Oxbridge college, with a mix of building styles, the hall being by Philip Hardwick, designer of the Euston Arch, but styled to match the adjacent Tudor buildings. These are near the chapel and have impressive diaper work, patterned with blue brick headers in red brick. The exterior of the old chapel is Ancaster Stone, with it’s the characteristic streaky bacon appearance.
Then into the New Court, with the modern concrete Hardwick Building being roofed with green Borrowdale slate, though the court is predominantly brick, and it can be seen that the upper story was added later.
We then went down Carey Street past Ede and Ravenscroft (where Richard explained the different styles and grades of legal wigs) to look at the Royal Courts of Justice, designed by G.E. Street after a competition in 1868, who designed all the details and used 35M million red bricks and 62,000t of Portland Stone. This is described as “blood and bandages”, with more stone at the judges’ end of the building.
Then a brief look at LSE and the modem sculptures, along St Clements passage, and onto the Strand, to examine the stucco and gabbro columns on the Strand face of the Royal Courts of Justice, and along to look at Kings College with its modern use of Portland Stone, to finish outside the first purpose built business premises at 187 Fleet Street, opposite the only remaining private bank in England, Hoare’s Bank.
From here it was a short tube ride to South Kensington for the evening talk, preceded, for some of us, by hot chocolate (to warm up) and the pre-talk Lebanese meal organised by Gina.
Lusi: the origin, evolution and future of a mud Volcano in Java - by David Shilston
19 March 2015
David Shilston introduced us to the mud volcano LUSI, pronounced “Lucy”, or in full ‘Lumpur Sidoarjo’, a large mud volcano in the Sidoarjo area of Eastern Java.
The mud volcano began to erupt in 2006, and initially produced flows in the order of 180,000 m3 of mud per day, accompanied by plumes of steam. Since then, the rate of flow has much reduced, but still produces about 10,000 m3 per day. It is thought to be the biggest active mud volcano in the world. There is no ‘cone’: the area is a flood plain and the mud spreads out evenly across the area like a huge muddy pond. The flows are now largely controlled by levees, but the area covered is around 6 Km2. Overspills and levee failures can occur, allowing the mud to enter neighbouring rivers causing further environmental damage.
The effects of the mud volcano are severe. The area was densely populated, and mud has covered roads, villages and farmlands. Thousands of people have been displaced. The mud, containing complex hydrocarbons, is toxic and cannot currently support vegetation. While compensation for those dispossessed is available, many people cannot access this as the legal documentation required is either lost in the mud or non-existent.
David explained the geological setting for LUSI. The lower level of rock is a water-bearing limestone covered by mud beds. On top of these mud beds is a layer of volcanic and alluvial deposits. Deposits above the limestone are some 3 Km thick. The overburden has over-pressured the fluids in the limestone. Once the limestone is broken or breached, the water forces its way towards the surface, entraining some of the mud on its way, and depositing the resulting sludge on the surface where it flows and spreads out.
David has served as President of the Geological Society and is currently Technical Director of Engineering Geology at Atkins, a design, engineering and project management consultancy. It is in this latter role that he is involved with LUSI, monitoring the mud-flows and subsidence of the surface using the remote techniques of satellite imaging and satellite radar, as well as site visits.
Subsidence is a major risk in the area of the volcano. As mud is removed from below the volcano and emplaced on the surface, a cavity, or more likely an area of lower pressure, opens up in the ground, and this can lead to caldera style collapse in a way analogous to that sometimes seen in the case of conventional volcanoes. The measured subsidence so far is in the order of 40m near the vent, down to 0.2m near the edges of the mud flow, although this is covered up by the mud.
David provided us with an insight, not only to LUCI and mud volcanoes generally, but to the role of consulting geologists in disaster situations, and also to the plight of those people who are caught up in the long-term results of such eruptions. It was a very interesting and thought provoking talk.
Mapping Day in Kent with Barbara Cumbers
21 March 2015
This was my first field trip and although my studying of S276 is going quite well, my grasp of the subject is rather tentative and so I was somewhat daunted about what the day would involve. Fortunately my fears were allayed by the friendly welcome from everyone and it was soon established that my lack of knowledge was just an opportunity to quiz everyone else!Barbara introduced us to the Dryhill site, a ragstone quarry which had closed in the 1930s and since been landscaped as a picnic site. At the entrance to the site we discussed the features of the first outcrop and how to describe it. We examined fragments of one of the beds with the hand lens and were able to identify some of the minerals present – carrying a bottle of acid proves handy for this!
We then learnt how to use a compass clinometer to establish the strike and dip of a bed. Moving onto the next outcrop gave us an opportunity to practice this. It took me a couple of attempts to understand the technique, but thanks to the patience of several more experienced people, eventually it clicked. We were able to plot our measurements on a map and established that there was evidence of anticline and syncline folding. Determining on the map where the anticlinal axis would be, we then found rocks with horizontal dip to support this.
The afternoon took us to Moorhouse Sand Pit, a working quarry, where the exposed cliff faces prompted discussion about methods of deposition. We looked at examples of cross stratification and discussed how the strength of the current transporting the sediment would have influenced the angle at which the beds were laid down. A closer look at one of the faces showed beds of pebbles and sand at an angle, with horizontal red bands showing later deposition of iron by groundwater.
Above the Folkestone Bed sand is Gault Clay. Having been advised of the dangers of the wet clay and potential for boot loss we searched for fossils. Apparently the clay usually yields these in a greater abundance than it did this day, but between us we managed to find a range of specimens. Some of the examples were tiny and I don’t know how people spotted these, but I was excited to find an ammonite and bivalve! Eventually the cold weather brought an end to our search and we concluded by trying to identify our finds with the aid of a textbook (and expert help).
The trip was a great opportunity to reinforce my study and experience Geology in context. In particular, mapping the outcrops at Dryhill has helped my understanding of the relationship between 2D maps and the 3D landscape – it was very satisfying to plot the anticlinal axis and then find evidence to support the location of this. It was also useful to learn that a clipboard is an essential piece of equipment when measuring dip and strike! Searching for fossils was also a highlight (as this is where my interest in the subject is focussed) and I can see how collecting could become something of an addiction!
Overall I now understand how important fieldwork is when it comes to studying Geology, both as part of the learning but also as a motivator to keep doing so, as it seems that there are always new questions to try to answer. Many thanks to Barbara, John and everyone else!
West Norwood Cemetery - with Diana Smith and Colin Fenn
28 March 2015
Colin Fenn, Vice-Chairman of the Friends of West Norwood Cemetery (FOWNC) and Diana Smith of LOUGS co-led. Our thanks to both & my personal thanks to Anna Saich for sharing her photos.
Opened in 1837, WNC was the second of the ‘Magnificent Seven’ commercial cemeteries founded between 1833 & 1841. The site was a remnant of The Great North Wood (hence Norwood) in the headwaters of the River Effra in South London now mostly covered over: http://www.londonslostrivers.com/river-effra.html.
In 1965 Lambeth Council compulsorily purchased WNC for £6,000, then destroyed 10,000 graves by ‘grass conversion’ between 1978–1991, including listed monuments, and keeping no records. Nearly 1000 plots were resold for new burials, which was declared illegal in 1994 by the Consistory Court.
We touched an almost black rough-hewn Millstone Grit monolith, reminiscent of the film ‘2001’ (Fig 1). The indurated (well-cemented) poorly sorted sandstone with pebbles had been blackened by soot from air pollution. Diana said its absence of lichen growth was due to Millstone Grit being mostly composed of quartz grains cemented with more silica. Sand was deposited in Carboniferous deltas, which were prograding (building seaward) southwards in the Namurian (326-313 MA = million years ago). Colin told us that the deceased, John Britton, had written the 26 book series “The Beauties of England & Wales“, describing topography – in some detail, one assumes!
William Knight emigrated to South Africa and prospected for diamonds at Kimberley. He alone realised that the gems were coming from a buried in situ deposit, began deep digging and discovered the kimberlite pipes. He established mines and sold them to De Beers. Knight next founded gold mines at Witwatersrand, returning to London very rich with a pet baboon.
William Knight’s cross had pale yellow ochre carved lilies (Fig 2). Diana explained this was Carrara-type Italian marble, pure limestone metamorphosed in the Alpine Orogeny. The cross originally would have been starkly white and polished but is now discoloured and roughened by acid rain again from past air pollution. Carrara shows ‘saccharoidal’ fracture resembling white sugar crystals when broken
Diana showed us a small gravestone with 2cm Larvikite crystals (Fig 3). Larvikite is from one huge quarry in Norway at Larvik south of Oslo. It is a 298Ma Permian igneous intrusion, one of a series of plutonic intrusions, some of which produce rocks of a similar mineralogy, but differing in colour, on the edge of the Baltic Shield, a Precambrian craton. The stone trade calls this common decorative building and memorial stone ‘Blue Pearl’; other parts of the same pluton produce greenish ‘Emerald Pearl’ and grey ‘Imperial Pearl’. They all have the same composition: a quartz-free rock with two intergrown feldspars which have tiny flecks of opaque minerals on the cleavage planes. These refract light, which generates the blue sparkle called ‘Schiller’. http://www.ngu.no/upload/Publikasjoner/Special%20publication/SP11_02_Heldal.pdf. These are Oligoclase, which is a plagioclase from the sodium to calcium solid solution series (all combinations of Na & Ca feldspar are stable), along with Orthoclase, an immiscible potassium feldspar.
Colin had unlocked the Chapel of St Stephen for us; we had a welcome sitdown on the wooden pews inside this scaled-down Acropolis. From 1842 to 1889, four wealthy Greek merchants from Finsbury Square purchased half an acre from the South Metropolitan Cemetery Company (Fig 4).
The tightly packed monuments of the WNC Greek Necropolis are all orientated east-west, unlike the other graves which face onto the meandering paths. Most of the monuments had Greek inscriptions and dated from the Greek war of independence against the Ottoman Turks, which began with a massacre of protesters on the Island of Chios in 1822. The FOWNC publishes various leaflets, including an informative map of the Greek Necropolis.
Lecture: Etna: How does a volcano work?
16 April 2015
John, a geophysicist in the Department of Earth Sciences at the Open University, has studied the evolution of volcanic activity in Mount Etna, Sicily, since 1975, and this has given him a unique perspective on the reasons for its strange behaviour.
The talk started with a map of the area, 40 x 50km in extent, and an aerial view of the Valle del Bove, 5km across, with rocks sticking up through recent lava flows as the valley gradually fills up with lava. He showed how activity has migrated over the centuries and made a comparison with the Mount St Helens eruption of May 1980 and the idea of several collapses.
Guest and Brown (1973) imagined a magma chamber with sills and dykes, and the usual swelling as the chamber filled, as at Pozzuoli. To test this perspective precise levelling on Mount Etna started in 1975, with a very simple, very accurate technique, that could measure to within an accuracy of 0.1mm. The following year witnessed a tiny swelling, with the summit subsiding. In 1977 it was still swelling and in 1978 an eruption followed. Swelling on the flank in 1981 was followed by an eruption in 1983 with radial fissuring. The situation is very different from Kilauea, with its sudden flash eruption followed by re-inflation.
The measurement of horizontal movement became much easier with GPS from 1988. Horizontal movement indicates a magma gain, whereas vertical movement indicates a magma loss. The mountain undergoes gravitational spreading, fracturing the flanks, with compression at the base. Maps show the outward spreading between eruptions, but in one direction: towards the sea. So what if the whole volcano moves downslope towards the sea?
Luke Wolker et al (2004) discussed volcano spreading on a sloping basement; Etna appears to be sliding towards the sea at the rate of 1.6cm a year, though during an eruption there can be a reverse movement and the centre can be moved uphill. A plot of the long term vertical movement of the contours corresponds quite closely, since there has been a total subsidence of 5m in the graben running N – S across the summit between 1980 and 2014. This gives a mean rate of movement of 6m per century.
This stimulating talk gave rise to a lively discussion, and recognition of the benefits of long-term continual observation by an individual and team. More information can be found on the NERC Geophysical facility website: http://gef.nerc.ac.uk/reports.php
Conservation Day at Gilbert’s Pit with London Biodiversity Partnership
19 April 2015
The London Geodiversity Partnership and London Branch of the Open University Geological Society arranged a second workday at Gilbert’s Pit in Charlton, two years after the previous one. They were joined by Royal Greenwich Rangers, members of other geology groups, engineering geologists and local conservation volunteers from Shooters Hill. This has enabled the LGP to get a quotation from a company who specialises in the sort of steps we are envisaging for the east face. The next task will be to find the finance to enable us to proceed. Some larger trees and big branches on the south side will be lopped. A marvellous job was done with very many thanks to everyone involved.
Photographs by Laurie Baker, Di Clements and David Taylor
The Devil’s Punchbowl - led by Iain Fletcher
10 May 2015
Continuing the LOUGS annual tradition Iain led us on a geowalk around the Devil’s Punch Bowl at Hindhead in Surrey. The original series of geowalks were devised by Brian Harvey and in recent years Iain has been updating the walks. Much has changed at Hindhead as the A3 London to Portsmouth road has now been re-routed through a tunnel and the old route through the Devil’s Punch Bowl allowed to return to nature. As part of the geowalk we crossed the old A3, pausing in the middle of the “road” to read the information panel. Later we stopped above one of the new tunnel entrances to discuss how the local geology influenced the tunnel construction.
We started with a short introduction to the geology and a look at the BGS map before we set off on our circular walk. En-route we were to cross over Lower Cretaceous deposits; the Atherfield Clay, the Hythe Formation, and the Bargate Beds of the Sandgate Formation. As good exposures were somewhat limited we were on the lookout for breaks in slope, changes in vegetation and drainage and other clues as to the underlying geology. But first a historical diversion.
Making our way up to Gibbet Hill Iain told us about a sailor who in 1786 was brutally murdered as he made his way along the road to Portsmouth. The murderers were hung at nearby Gibbet Hill. Locals were fearful that the hill was haunted by the highwaymen’s ghosts and to help to allay their fears a Celtic cross was erected on the hill. We spent a bit of time examining this granite cross and admiring the views across the Weald.
Geologically, we started on the sandy beds of the Hythe Formation. Although exposures were limited we did find fragments of sandstone by the side of the footpath. Being poor quality agricultural land, heathland and woodland vegetation predominated. As we made our way out of the woodland the ground became more poorly drained and we noticed a change in the vegetation. These changes alerted us to the fact that we had moved on to the Atherfield Clay.
Further on, the sunken lanes provided a good opportunity to see the Bargate Beds. These relatively localised deposits are calcareous cemented sandstones which have been found to contain Jurassic ammonites reworked from the Oxford Clay. The sediments were derived from material eroded from the uplifted London Platform and deposited at a delta front. The calcareous, well-drained nature of the material makes it better suited for cultivation.
If you missed this trip and would like to explore the area yourself keep an eye on the Geotrails section of the LOUGS website as a description of the Devil’s Punch Bowl Geowalk will be available in due course.
Lecture: Crustal melting in the Himalayas - by Tom Hopkins
21 May 2015
Tom, a final year PhD student at the OU, started by saying it was the first time he’d given a full lecture, so there may be shortcomings, but he needn’t have worried. He gave a confident, clear account of his work so far, and his fascinating results.
He started with a magnificent view of Everest, followed by the story of the origin of the Himalayan orogeny starting at 220My with the beginning of the break-up of Pangaea, India’s amazingly rapid drift northwards until its collision with the Eurasian plate, the subduction of the Indian plate and the rise of the mountain chain.
His account of the geological elements of the chain and the major faults led up to the Leucogranites which outcrop near the South Tibetan Detachment, illustrated by a remarkable photo. There are problems associated with these granites: What is the source of the melting? Over how long a period did it occur? And what has been the effect? All these were investigated in Bhutan.
Most granites, igneous or i-type granites, have a Mantle origin. Himalayan granites are very different, and Tom’s contention is that these are s- type granites with a sedimentary origin. Verification of the hypothesis requires the detailed examination of the chemistry of the bulk rock, using zircon ZrSiO4, a common accessory mineral, and the oxygen isotope system 18O/16O, sedimentary rocks having heavier oxygen. Tom demonstrated that the granites plot in the Greater Himalayan Series and that there is no Mantle input. As melting evolves through time, recent melts may sample not only the Greater Himalayan sequence, but also the lesser Himalaya.
How to melt a rock? Three ways: heating, decompression, the addition of fluid. Using the evidence of muscovite and biotite, Tom eliminated fluid as a factor, arriving at decompression. He finished with a question. Did the melting trigger channel flow and the exhumation of the Greater Himalayas? Or are the granites simply the result of the exhumation?
Lecture: Geology in Space: Meteorites and Cosmic Dust - by Matthew Genge
18 June 2015
Before embarking on the body of his talk, Dr Matthew Genge, Senior Lecturer in Earth and Planetary Science at Imperial College, introduced us to the Imperial College Rock Library, an on-line resource with images of thousands of rocks in hand specimen and thin-section form together with an inexhaustible supply of technical information.
He then started provocatively: ’Geology is the study of the Earth: does it apply to space objects?’ Cut to a photo of the 500kt explosion over Chelyabinsk in February 2015, when 654kg of materials reached the Earth. There followed a brief and interesting history of opinion on ‘stones from the sky’ from Aristotle onwards, through to Ernest Chladni (1794). In the same year a ‘shower of numerous stones’ fell in Siena, Tuscany, and the following year a meteorite in Wold Cottage, Yorkshire, displayed in London, seen by Joseph Banks, and analysed, was found to have a higher nickel content than Earth rocks. In 1983 noble gases found in the 1911 Alexandrian meteorite were found to match those in the rocks of Mars. Current meteorite flux is 70 per year in the UK, but study of the phenomenon is easier in a sterile environment: the Sahara, or more particularly, Antarctica, where six weeks on the ice yielded 800 meteorites.
Until the Apollo mission most scientists assumed that meteorites came from the moon, but their make-up is quite different and most come from the asteroid belt between Mars and Jupiter. Irons consist of iron-nickel metal, stony irons of Fe-Ni and olivine, stony meteorites or achondrites are of igneous rock.
We moved on to the geology of Mars where volcanoes are different from those on Earth, because on Mars, being smaller, there is no subduction and no possibility of making eclogite. They are the result of simple convection with 2 plumes. Further, Mars shows clear deposits similar to braided rivers on Earth, and so does Titan, but these consist of hydrocarbons and ice. The Moon also challenges Lyell’s dictum: ‘The present is the key to the past’, because the Late Heavy Bombardment produced many more craters in the Lunar Highlands than in the Maria.
Chondrites (or primitive meteorites) have a composition identical to that of the Sun and have not formed on geologically active planets such as Earth, the composition of whose rocks is very different. With an image of protoplanetary discs in the Orion nebula, we were given a picture of the early Solar System. The formation of CAIs (Calcium-Aluminium-rich Inclusions) within these meteorites was discussed; were they from the inner disc? Likewise olivine crystals within glass – a magma droplet in space. The matrix is of very fine-grained clay minerals, which can contain amino acids, sugars and hydrocarbons. So, were the early Earth’s oceans and organics added by meteorites? These also contain pre-solar grains of silicon carbide that must have originated in giant stars or supernovae. Within the matrix of a meteorite is the whole history of the Universe.
He finished by answering his opening question: Geology is the study of anything with rocks in the Universe.
MIDSUMMER FIELD TRIP: Sarsens in the Medway Valley - with Geoff Downer
21 June 2015
On Midsummer's Day, Geoff Downer took us on a tour of various locations in Kent to look at sarsen stones in the Medway valley. Few rocks are more enigmatic than sarsens: little is known about their age, formation, or even where they formed. With Geoff's guidance, we considered these mysteries and tried to come up with some answers.
This trip was a follow-up to a visit two years ago to the more famous sarsens of Wiltshire, including those of Avebury. We started at the village of Cobham, west of Rochester. At the Church of St Mary Magdalene, Geoff briefly described what sarsens are: sedimentary rocks comprised of 99% silica. The grains are cemented by silica, hence they are silcretes. The Medway sarsens are well-cemented sand grains, unlike the Hertfordshire Puddingstone that contains flint pebbles of varying sizes (but equally well-cemented). There are some medium-sized sarsens in the grounds of the church. These appeared to have been broken up in the past, as they had straight edges showing that they had been cut or broken (Figure 1).
There were even a couple of sarsen blocks in the church wall. This is unusual, because sarsens are so hard that they are very difficult to cut into bricks. Most of the stones used in the church are flints, with some ferrocretes (iron-cemented stones).
Next we went to the Three Crutches, where four mammillated sarsens were left to commemorate the opening of the A289 Wainscott Northern Bypass in 1998. Three are mammillated on all sides, and one is mammillated on one side only. The stones were originally found half a mile to the west when the road was being built, in August 1997. Unfortunately, information that could help to date the stones - such as exactly where they were found or what rock formation they lay above - is not readily available. Figure 2 shows one of these mammillated sarsens.
Our final stops were Kit’s Coty (Figure 3), a Neolithic long barrow made out of four large sarsens, and Little Kit’s Coty.
Rather than describing Kit’s Coty myself, I will let Samuel Pepys do it for me:
We finished up by discussing the stones we had seen and how they might have formed.
Summer Long Weekend Torbay
3 - 7 July 2015
The focus for the week-end was to look at the rocks of the Devonian and Permian in Torbay to understand the structure of the rocks themselves and develop our understanding of the effect of the Variscan orogeny on the rocks. We were also to see the effect of the structure of the rocks on the physical geography of the surrounding area in terms of the development of industry and leisure.
Saturday 4th July 2015 - a.m. by Gill Hetherington
Berry Head at the Southern end of Torbay was our first stop to look out over the bay for an overview of the rocks for the rest of the weekend and then to look in more detail at the Devonian limestone and the neptunean dykes of Permian sandstone. From a viewpoint half way up the path, stood on the middle Devonian limestone, we looked northwards around the bay at early Devonian mudstone, sandstone and conglomerate around Goodrington and on to the Permian breccia and sandstone around Paignton and on round to the complex rock formations of Torquay and Hope’s Nose. All of these we were to look at later on in the week-end. Not one bit of Carboniferous to be seen.
We climbed up to the disused quarry at Berry Head (Fig.1) which closed in 1969 after having been worked for 300 years and at its peak between the wars produced 200,000 tons of limestone for buildings, agriculture and roads. The expansion of the quarry was hampered not by running out of the massive Torbay limestone but by reaching sea level and the need for preservation of the Napoleonic fort on top. The pool at the bottom of the quarry is well below high tide and is tidal as a result of its connection to the sea through Corbridge Cave. (See Fig.7). This quarry at Berry Head along with Longport and Churston quarries were important resources as they are massive limestones in the Brixham formation which show little evidence of the faulting and folding found in other limestone formations.
The early middle Devonian limestone often consists of interbedded shales and shaley limestone of coastal environments. Later deposition, in areas further off shore, became increasingly controlled by faults resulting in areas of highs and lows. In the high areas platforms close to the surface of the sea provided a warm and sunny environment in which stromatoporids and corals could grow and form massive, hard limestones.
The limestone at Berry Head is one of these large, strong reefs which got their strength from massive tabular and low conical stromataporids with some other corals which were all bound together. These are some of the most geologically important limestone rocks in England being the only ones formed at the edge of the Rheic Ocean.
The Limestone in this area is riddled with solution fissures (Fig.2) and caves thought to have been formed as a result of the high sea levels during the Ipswichian interglacial between 100 and 150 thousand years before present. Solution fissures in the quarry are highlighted by vertical neptunean dykes of red Permian sandstone, some with well grown calcite crystals at their margins. The aeolian desert sandstone of the Permian was deposited in pre-existing fissures and stand out today as hard red bands easily distinguishable from the surrounding limestone.
Our final stop on Berry head, after a welcome cup of tea in the café in the fort, was at the bird hide, not to look at the birds but at the rocks across in Berry Head. At the top of the formation the limestone is the same massive structures that we saw in the quarry. At the bottom of the cliff face the limestone layers are much more thinly bedded and show clear evidence of multi-phase folding caused by the massive movements of the Variscan orogeny. All of the rocks were involved in the Variscan orogeny, which took place over 100 million years, but the effects are mainly visible in the thinner beds of limestone. The final part of our morning session was down on the beach at low tide close to the Shoalstone outdoor sea pool. We scrambled across the rocks to get up close and personal to neptunean dykes which were horizontal across the beach. It was clear to see that they are sandstone and the relationship between them and the country rock with which they are associated. In some cases the sandstones stood proud of the surrounding rocks and in others they had eroded below the surrounding rocks showing the variability of both the sandstone and the limestone.
In some areas there were large crystals of calcite between the sandstone and the limestone. A very good but challenging morning trying to put into context the development of the area in terms of the rocks that we saw and the environment which changed them to put Permian rocks so close to Devonian rocks 84 MA apart. And what did happen during the Carboniferous?
Saturday 4th July 2015 pm - Goodrington to Saltern Cove by Pam Pettman
After lunch a short drive took us to the southern end of Goodrington Sands, a wide stretch of red Devonian sands much loved by holiday makers and visitors to Paignton, a resort at the centre of Torbay.
We had come at low tide to view the rocks along the short cliff sections forming low promontories between small rocky coves typical of this southern part of Torbay. The angular fragments of grey Devonian limestone in the red Torbay Breccia Formation of the cliffs were immediately obvious as we walked south, and showed evidence of imbrication. (Fig.3).
The coarse pebbles eroded from offshore coral reefs originally formed in the shallow tropical Devonian seas, are cemented in a matrix of fine red sands, having been brought short distances in flash floods and formed alluvial fans in the semi-arid basins of the early Permian. The breccia deposited in high energy conditions alternates with red sandstone bands, fining up in repeated sequences in the cliff. Further round the bay red finely bedded sandstones are interbedded with thicker, grey siltstone bands again showing energy fluctuations during deposition (Fig.4). These beds of Permian age appear at beach level here. Wide wave-cut platforms protect the headlands but the softer cliffs behind the coves have been protected with granite boulders from Dartmoor.
This area was greatly affected by Variscan deformation which uplifted the Devonian rocks and produced the gentle and overturned folds and the many faults seen in the cliffs and along the limestone foreshore. We searched the soft red sandstone for trace fossils, evidence of life in the lower Permian but now easily overlooked on the foreshore. Several theories exist about the strange circular arrangement of tiny stone flakes. (Fig.5). These are thought by some to be the circular burrows of primitive reptile-like creatures seeking to hide from the fierce desert sun, and by others similar to nest burrows produced by some reptiles today.
The thick Carboniferous deposits, although found elsewhere in North Devon and Cornwall are totally missing in the sequence and are believed to have been completely eroded over a long period at this point. Further round the bay, cutting through the cliff and continuing across the foreshore about a metre wide and standing about a metre above the beach is a yellowy coloured dyke of harder material containing limestone and pumice, a possible volcanic vent. (Fig.6). A short way further along the beach are limestone blocks showing fossilised colonial corals, found near a Devonian reef limestone band in the cliffs
Sunday July 5 2015 : a Jurassic Coast Boat Trip from Exmouth to Berry Head and Back by John Lonergan and Marie Knudsen
We were collected by coach and then travelled to Exmouth, where we boarded the “Pride of Exmouth” run by (www.stuartlinecruises.co.uk). There were over a hundred on this “Lego” coloured boat, all booked for a geological tour led by Dr Richard Scrivener (BGS). The passengers included parties from LOUGS, Wessex and Southwest OUGS, the Ussher Society, the Dorset association the U3A, and trip was run for the Proprietary Chapel of St Luke, Posbury. We sailed west from Exmouth to Brixham, with a mix of squally showers and tropical sunshine. The original plan was to go east to Lyme Regis, but the onshore wind made this inadvisable. Thus we sailed down into Triassic, through the Permian and Devonian, into the area we had studied for the rest of the weekend, pulling the geological story together.
We passed the sandbank formed from the Dawlish Warren Sands, eroded from Permian bedrock and deposited during the last glaciation. This also deepened the valley of the Exe to 45m below sea level. At Langstone Rock we saw Triassic Upper Exmouth Breccia unconformably over the Lower Dawlish Sandstone (255Ma), we continued through the entire Permian down to 295Ma. Past the Upper Permian Dawlish Sandstone, through which Brunel tunnelled his coastal railway, and past the repaired damage of last winter’s storms. This is aeolian sandstone, with impressive bedding structures, and easily eroded. The higher cliffs comprised the more resistant overlying breccia, and dissected by dry valleys.
Next past Teignmouth the River Teign draining Dartmoor and being used as a deep water port for huge vessels collecting kaolinite, quarried from the altered Dartmoor granite. On to Babbacombe, with the impressive landslide and funicular railway, the Petit Tor “marble” quarry in the limestone, and the limestone quarry at Long Point, with the underlying black shales of submarine mud. Past the dolerite of Black Rock and Hope’s Nose with its shallow-water reef limestone dramatically folded in the Variscan and recently quarried for gold!
Then past the triangular Thatcher Rock, by Triangle Point, all in Devonian Limestone. Around into Torbay itself, with the low cliffs in Torbay Breccia, and the line of the Sticklepath fault easy to see
After lunch and a walk around the delightful harbour of Brixham, (where Francis Drake’s ship the Golden Hind is moored) we boarded for the return journey to Exmouth. On departure we could see the fort, and quarry below, at Berry Head that we had visited the previous day. The quarried limestone was removed by water. We sailed further out to sea than on the way out so were able to see more of the ‘big geology’.
Fig 7 shows seacaves at Berry Head where the brackish water, which we had seen at the bottom of Berry Head quarry the day before, enters beneath the tideline. There are three levels of horizontal seacave formation as a result of marine transgressions during Ice Ages
Fig 8 shows a large overturned fault on Thatcher Rock caused by plate movement during the Variscan orogeny, a period of mountain building and continental collision that began in the Devonian Period, which lasted from 417 to 354 million years ago and continued through the Carboniferous.
Fig.9 Raised beach at Thatcher Rock formed during a warm period when sea levels were higher
Arriving at Exmouth we were treated to wind and kite surfers showing off their considerable skills and travelling at great speed past the boat. The mouth of the River Exe lies in Permian breccias and is fed by water run-off from the Dartmoor plateau. On the hillside above Exmouth there is a vast caravan holiday park, the largest in Europe, which apparently, announces its presence by the smell of fish and chips in summer! There are two extensional faults in the region, the Purbeck and Abbotsbury. To the east of Exmouth lies Orcombe Point, which represents the start of the Jurassic Coast and the Permo-Triassic boundary of the Wessex basin, which is where we ended our trip and returned by coach to Torquay.
Monday July 6 2015 am: Hope’s Nose Headland by Denise Atkinson
As it was the last time the group would be altogether Yvonne thanked Pat for a splendid trip.
Before walking down Pat gave us an overview of the area. It was exceedingly complicated, there are 2 major faults, the Lincombe fault and the Ilsham fault, and as a result the rocks are shifted, broken and eroded. She also told us the Torquay limestone here and the East Ogwell limestone 5km up the valley have been identified as the same limestone having been separated by the Sticklepath fault.
We came down quite a steep slope on the Norden Slates which straddle the Lower/Middle Devonian, a major fault having brought the Norden Slates against the Torquay limestone. Daddy Hole limestone is one of only 3 that have a name in the Torquay limestone, these are: Barton – top, Walls Hill – middle and Daddy Hole – bottom. The others are unnamed because they are so broken up. Microfossils ‘goniatites’ have been used to identify the rocks in these strata.
In the quarry there were 3 significant limestones from the bottom of the quarry to the grassy area on top.
As we went down we could see Black Head, a massive dolerite intrusion into the very top of the Devonian. When we got to the bottom some of our party scrambled down onto the lower wave-cut platform which was divided by a large fissure. On one side there were broken rugose colonial corals and stromatoporids – calcareous masses built up of horizontal layers and vertical layers, the upper surfaces showed patterns of polygonal markings, swellings and grooves. On the other side is a nationally important site for minerals structures where hydrothermal fluids led to formation of gold and rare palladium minerals. Small quantities of native gold occur as fine branching minerals.
Then we walked further along the cliff path and down another steep slope to see an Ipswichian raised beach, 120Ma, with a basal boulder bed at 8m which is laid unconformably on the Daddy Hole limestone and covered with debris and sand solifluction deposited in tundra-like conditions. It is home to 17 different molluscs. A similar beach on Thatcher rock has over 40 different molluscs. (See Fig 9)
The tension in the Variscan orogeny has formed a boudinage (French for sausage) in the harder limestone beds. The thinner shale layers above and below the limestone contain volcanic ash. Then we climbed back to the top of the headland to the cars and lunch at Kent’s Cavern after a most interesting morning. We said our farewells, expressing our appreciation for such an interesting day and indeed for the wonderful variety of the field trip.
Monday July 6 2015 pm: Hope’s Nose Headland by Jenny Parry
After lunch at Kent’s Cavern, we crossed the road and made the long, slow climb to the top of the downs. As we walked along the higher footpath by-passing Anstey’s Cove, Pat pointed out the features of the valley through the limestone which we were now walking across – this is the Ilsham Fault. Beneath us the area is riddled with caves and underground drainage systems (as Kent’s Cavern) and deep solution holes (noted overlooking a wooded area along the way). Of note, the area on top of the downs is an SSSI for butterflies and assorted grasses.
At a stop overlooking Redgate Bay, we noted the Ilsham Fault running through the bay and the effects of a heavy, massive jointed and dipping limestone sitting on top of soft erodible shales, causing dangerous rock falls into the bay – marked as unsafe but obviously still used by some groups. At the next stop above Withy Point, we had a good view of the quarry below, where fissures in the white karst limestone had been infilled with red sediments. Pat pointed out a hanging valley further along the coast, reflecting a change in sea level, and rounded boulders could be seen high in the cliffs – erosion features from an ancient desert environment. We then descended the 300 feet to Babbacombe Harbour (Babbacombe has the highest cliff top promenade in England!) Walking around the bay, we noted a dolerite sill which had intruded into what are known to be the Upper Devonian Salton Cove Shales (showing evidence of a baked margin). Above the shales is the Middle Devonian Barton limestone, therefore the beds have been reversed. The spring line, where the limestone is sitting on the shales, had produced many miniature waterfalls.
Further around the bay into Oddicombe, we could see the massive landslip and its effects on the cliff above, and, on Petit Tor Point, the quarry where the colourful limestone (marble) of the same name is quarried. From here, we ascended via the funicular railway to Babbacombe Downs and the walk back, past the strangest cricket pitch in the centre of a dry combe!
Tuesday July 7 2015: A Geological Walk around Torquay by Christine Hogdson
Our starting place, Torquay railway station, was built around 1850 using the local Devonian limestone, pale grey with characteristic near-marble texture and fossil content. We identified brachiopods and small colonial corals, a few solitary rugose corals, seen here in cross section as a star within a circle, and one stromatoporid – a lime- depositing sponge. Blocks of calcareous arenite form a contrast round doors and windows. This is Binton stone, the fabric of Exeter Cathedral and used here as a status symbol. It comes from the Greensand bed at Salcombe Regis, near Sidmouth.
The road downhill to the sea gave us a panoramic view of our Torquay Bay route and, out to sea, London Bridge Arch. The South West Coastal Path follows the arc round the harbour and town, along the seafront, and passes across Corbyn’s Head. This promontory consists of 280 million year old Permian breccia - intermittent flash floods in a desert environment have deposited varied stratified beds. These were clearly seen in the cliffs as we went down to beach level on the eastern side. A normal fault is obvious from the dislocation of the pale mudstone and purplish sandstone strata. This sedimentary sequence has been dated from volcanic ash showing that these are the lowest of the Torbay Permian breccias. They were quarried to form the base of the earliest Torre Abbey complex buildings. Continuing erosion taking place is evidenced by a sea stack. This shows small stone fragments set in a finer matrix – a typical deposition in part of a breccia fan. See Figure 10.
Corbyn’s Head beach was the landing place for the ten Premonstratensian monks who came to Devon from France in 1196. It remained the only harbour for centuries since high cliffs fronted the rest of the bay. The religious order’s preferred isolation was ensured by the wooded hills around the Tor Valley, there was no coast road hence the only access was by sea. Onshore extensive large sand dunes (now a Pitch and Put course) protected the raised ground of a head terrace which formed, post glaciation, as the River Tor cut through. This flat well drained area with good soil and fresh water, plus the safe fishing nearby provided an ideal site for the White Cannons community to flourish. Transport by ship of limestone and other stone from sea-edge quarries promoted the extensive building of the monastery. The sea wall that protects the Torbay Road used Devon stone, not immediately local, that was brought in at a time of town expansion during the Napoleonic Wars.
The Royal Navy used Torbay as an anchorage and Torquay became a resort. Reject material from prestige construction provided a wide selection of stone fit for sea defence. Grey Devonian limestone placed alongside red Permian sandstone gave a time gap of one hundred million years between blocks! Types of rock reflect the events that had occurred as warm seas became arid desert areas. Some of the extensively used Permian breccia contained large Devonian fossiliferous limestone clasts with corals and crinoids.
We passed the Spanish Gardens, named from the housing of Armada prisoners of war in the Abbey Barn (then owned by the Duke of Devonshire, the religious community had been dispersed on the Dissolution). Following the lower road into Torquay Harbour we crossed the new walkway bridge and made our way uphill, past the Imperial Hotel, to the cliff edge. From here we clearly saw the contrasting dips of the strata making up the London Bridge. Pat explained that the weakest point in the contortion of the upturned syncline here had eroded into the arch. Quite simple really! Below us was Dyers Quarry in an ideal sea edge position. See Figure 11.
Returning down Park Hill Road we looked down into Living Coast, the zoo and aquarium, and saw the penguins that hatched there this spring. Beyond the modern Marina and Crab Bridge, with its claw-like pillars, we crossed reclaimed land towards the town. The recently built Rock Walk, a flight of well-spaced steps, took us up to the vertical Devonian limestone cliff that is the exposed plane of a strike-slip fault (total movement about 5 kilometres). The softer Permian breccia has been eroded away. Before recent redevelopment a junction was still visible behind building; alas conservation requests were refused. Still at low tide a reef of the breccia, Harbreck Rock, is visible off Torre Abbey Sands. The Sticklepath fault cuts right across the peninsula and extends to the continent. It is still active and it is named for the village which actually experienced in 1955 what was described as a ‘good’ earthquake (over 3.0 and under 4.0). Contemporary with the Bristol Channel/Bray Fault, it originated during the Variscan Orogeny. We finished our walk with a visit to the Abbey site, first looking at the oldest ruined part. We recognised Corbyn’s Head Breccia at the base, and above various rocks, with some quarried from Broadsands (on the south side of Torbay). Stone brought from the Dart Valley included red sandstone from the far side of the River Dart.
Lava (tuff) from Exeter was also seen. As in many old churches, this variety is explained by the practice of rarely doing a journey without a return load. We met Norden slate again, used for damp-proofing as well as roofing the Abbey Barn. The arches round the barn doors used alternately red breccia and Bindon Sandstone. For the main building archways only the superior sandstone was used. There was widespread demolition of the church and part of the monastic buildings as a consequence of the Dissolution. However the south and west part was less damaged and converted into a house in 1662 by the Cary family, who stayed there until 1930. Around 1740 extensive Georgian r emodelling gave its present appearance. We admired the replacement moulded windows and the clock front of golden Hamstone, from Ham Hall, Somerset. This well cemented Jurassic Upper Lias limestone can be readily shaped. We inspected a very early coffin lid of Purbeck ‘Marble’, identified by Pat as that specific limestone (from seeing a particular viviparous band and her knowledge of similar tomb lids at Corfe Castle). And for something completely different, we found large twinned feldspars in the Dartmoor granite plinth of a recent structure in the grounds.
We said our farewells expressing appreciation for such an interesting day and indeed for the wonderful variety of the field trip.
LOUGS and WSGS Bicentennial William Smith Sussex Field Trip - with John Lonergan and Sue Vernon
12 July 2015
We met at Haywards Heath station on a rather damp summer day. And then shared cars for a circular survey of William Smith’s work in Sussex, as Canal Surveyor and the Father of English Geology. We started at Whiteman’s Green, near Cuckfield, where Smith found the lower part of the right shin bone of an Iguanodon in 1808. It was later sold to the British Museum to pay his debts, then passed onto the Natural History Museum, and was only identified by Alan Charig in the 1970s. We looked at reproductions of his 1815 map of England and Wales, and his Sussex County map of 1819, and other versions, and could see how his maps became more complete as he added in the results of further travels. This is a significant achievement, as he tells us he mapped while travelling on horseback, stopping to record exposures, we also read from his letter on his work in Sussex as printed in John Phillip’s memoir of his uncle.
While there we inspected the Tilgate Sandstone monument, with fine ripple marks, and braved the rain to see the location of the quarry which Gideon Mantell illustrated, and the location of his (or his wife’s) discovery of another bone in 1821, from which he named the Iguanodon.
From there we went to Barcombe Mills, on the Upper Ouse Navigation, this was the site of 3.5 mills in the Doomsday Book, the 0.5 being shared with a neighbouring parish! There were a series of wind and water mills, for corn, oil, fulling and paper at various times up until recently, and a button factory. The oil being from linseed, hemp, rape or mustard seeds, with the oil, and the cake waste, exported by canal, and later by rail. Now it has been pleasantly landscaped, with trees, and the location of the mills and industry is not easy to understand.
This canal was intended to serve the local rural area, carrying lime and chalk, aggregates and coal, and to link Newhaven and Lewes to the Turnpike near Balcombe, and then to extend on to Cowfold and Slaugham. The lower part was surveyed by Jessop from 1787, with Smith working on the Navigation below Lewes up to 1796 (and recording the section of Newhaven cliff in 1808). The Navigation got to Freshfield (near the old Bluebell Railway halt) in 1802 and to Lindfield in 1809. Progress was slow in the upper reaches, as while the Navigation paid off its debts it was never prosperous. Smith worked on the northern section from Lindfield to Upper Rylands Wharf, on the Turnpike south of Balcombe, between 1808 and 1812.
We then went on to Upper Rylands Bridge, after sheltering from the weather in the Royal Oak in Barcombe. Here we saw the navigation, and the site of the wharf, with the wharfingers’ cottages. Smith also produced an estimate for an extension on to Slaugham, and then a survey for a connection to John Rennie’s Grand Southern Canal Project. He describes that as unprofitable, thus assumedly unpaid; the survey is still held in the East Sussex Record. Neither of these was built, and the second was to have included a 1200 yard tunnel under the Forest ridge and eighteen locks to a junction near Three Bridges.
While the canals were one revolution in transport, the railways were the next, and overlooking Rylands Bridge is the splendid Ouse Valley Viaduct of the London and Brighton Railway. This is 1457’ long, with thirty seven 37’ arches, and 96’ above the valley floor at its highest. J.U. Rastrick was the Resident Engineer, and David Mocatta the architect, it was built in 1839-40, with ten million bricks brought up the Navigation from Piddinghoe, as the Heddon Stone from Newcastle used for the Italianate parapets balustrades and pavilions on the ends. Weight was reduced by adding the distinctive oval shapes into the piers.
Rylands Wharf was used as a transhipment point for traffic onto the Navigation to Lewes, until the railway reached there in 1846. In the 1990s Railtrack carried out extensive repairs, but used Caen Stone for repairs.
Oceanography Experience 2015 - National Oceanography Centre, Southampton
The Oceanography Experience in July was an opportunity for many of us put our recently acquired oceanography knowledge into practice. I attended the second of three sessions this year and the first morning of our session coincided with the release of S330 Oceanography exam results so many of us started with good news and for those who hadn't done S330, background information was provided.
The Experience consists of two days: one aboard the RV Callista, Fig. 1, on the River Itchen and out into Southampton Water and one day in the classroom at National Oceanography Centre, Southampton. The objective was to investigate physical, chemical and biological aspects of the estuary. On the catamaran we were divided into teams and took turns collecting water samples, preparing water samples for chemical analysis, controlling the CTD which takes depth, temperature and salinity readings, measuring Secchi depth, and recording and collating all of the data. Fig. 2.
The crew also conducted a plankton trawl and two dredges - one near a refinery and one further away. The sediment from near the refinery smelt noxious and had no evidence of life. Sediment from further away was teaming with life: edible seaweed, brittle stars, snails, spider crabs, and invasive limpets.
On the NOCS day we were treated to a lecture by Dr Rachael James about the effects on ecosystems of carbon escaping from carbon storage systems. We learnt how to use nautical charts, looked at graphs plotting nutrient concentrations and temperature/salinity depth profiles at different locations in order to consider whether the estuary was well mixed or not, and explored the NOCS aquarium. We also looked at the plankton, including copepods, fish larvae, and phytoplankton collected the previous day under the microscope, Fig. 3, (with thanks to Brian Loranger).
In addition to the oceanography content, this was also an excellent opportunity to meet other OU people, share a Thai feast in the evening, and learn about the work of NOCS. Special thanks to Mike Hermolle, Brian Dickie and Moira MacLean for organising such a brilliant experience.
The OU's Oceanography module is no longer being presented but response to the Oceanography Experience has been enthusiastic so if there is sufficient interest, it will be offered again in July 2016. If you are interested, please email Mike at firstname.lastname@example.org to help gauge interest.
Day Trip: Fossils and Geology on the Isle of Sheppey - Led by Fred Clouter
5 September 2015
The aims of this visit were to collect fossils and examine the exposure of the London Clay sediments from the Lower Eocene (Ypresian). Warden Point is a very good site to see this clay layer and also for finding fossils on account of the slippage of the cliffs and their erosion by the North Sea. The London Clay exposure at Sheppey is between 48 and 52 Million years old.
The visit took place on a grey but dry day, starting before low water. It was led by Fred Clouter who is the local expert on the fossils found in the London Clay along this coast.
Larger than any fossils were the calcareous concretions (septarian nodules) broken nodules littered the foreshore and some were visible in the exposed cliffs (Photo 1). Evidence of the banding of the nodules was visible at the furthest point we reached (just beyond the collapsed WWII pill box). These nodules formed in situ at an early stage in the deposition of the clay, probably as a result of the release of carbon dioxide from decaying organic material in the slowly consolidating mud. The nodules are usually covered by an abundance of trace fossils on their outside surface, indicating that the concretions must have been fully formed before being buried more deeply. Most of the trace fossils are difficult to interpret but one of our group found a nodule with a very clear trace which appeared to show where a burrowing creature had vertical feeding tubes. Later, as the nodules become buried more deeply, the pressure caused cracking which allowed fluids to enter the nodules leading to the crystals which can be seen within the broken nodules. These nodules were collected during the C19 and processed to give a form of cement, prior to the development of Portland cement.
Although the clay layer holds many fossils it is very difficult to see any sign of this abundance in the exposed face. The only fossils which we saw in the clay were the vertical tubes of “lobster burrows”- parts of these fossils were also found on the beach. The cylindrical fossilised burrow is usually enclosed in a thin phosphatic shell. The degree of preservation varied enormously, with parts of some burrows in the cliff face being very soft, whilst those found loose on the beach were much harder. None of the fossilised burrows we found showed any sign of animal remains.
As well as the cylindrical lobster burrows other, more rounded, cream coloured phosphatic nodules were also found. These sometimes contain fossil material, and one of these showed the claws and legs of a crab (Zanthopsis?) or small lobster (Photo 2).
Two particularly interesting items that were picked up were pieces of fossilised wood showing very clear evidence of attack by wood boring creatures. Although commonly called ‘shipworms’ the holes penetrating deep into the wood are actually tubes occupied in life by the wood boring Teredo bivalve.
The largest group of fossils, by far, were small pyritised fossils. These occurred in large numbers in certain areas of the beach, especially near to the collapsed WWII pill box. Many of these small pyritised items were clearly identifiable as pieces of wood or twigs. Remnants of the Nipa palm have been found, including leaves and fruits, but we only found one small fossil which appeared to have come from this type of palm. Much more difficult to spot were pyritised sea creature fossils (photo 3) –although often very distinctive our group found only a very few such fossils. The pyritisation process involves the production of disulphide through a bacterial sulphate reduction which can occur in the decomposition of organic-rich marine sediments.
As well as the larger fossils, and the numerous small pyritised items littering the foreshore, the clay also contains small bones. Fred Clouter explained that the best place to search for these small bones is where wave/tide action leaves lines of small debris running down the beach. No one found anything on the way out but a younger member of the group found a shark’s tooth on the return. Someone commented that children often find the best fossils – they have good eyesight and their lower height puts them closer to the ground.
The visit ended with Fred Clouter discussing the difficulties of preserving pyritised fossils, and a suggestion for using Ronseal Wet Rot Wood Hardener.
From the various fossils that we found it is obvious that the London Clay exposed in this area contains a huge variety of fossils, both from the living creatures and from the flora in the Eocene. This is because the clay here was laid down some distance from the mouth of a large river. Fred Clouter’s website contains an interesting 1870s report from the HMS Challenger expedition indicating what conditions might have been like in the area of deposition.
Anyone wishing to visit this site should be aware of two dangers. Firstly there are areas of VERY soft mud – pictures can be found online of Wellington boots left behind in the mud by people who became trapped, and an earlier OUGS group visiting this area saw such a pair of boots stuck in the mud. Secondly there is the risk of getting trapped by the incoming tide – ideally any visit should be timed for an outgoing spring’ tide to maximise the time available.
London Clay Fossils of Kent and Essex by D.Rayner, T.Mitchell, M.Rayner, F.Clouter (ISBN: 978-0953824311)
Further info: Fred Clouter’s website http://www.sheppeyfossils.com/pages/Freds_page.htm
Lecture: The oceanic-driven decay of the Breidamerkurjokull glacier into Jokulsárlón lagoon, Iceland - by Mark Brandon
17 September 2015
Dr. Mark Brandon from the OU’s Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR) started his lecture in an area far removed from Iceland, namely Antarctica. The connection is the melting of ice sheets. With satellite maps he demonstrated that parts of Antarctica are warming up, resulting in ice sheet change: the ice is decreasing, but not at the surface.
He then ‘lifted the ice’ to reveal a mountain range; in the east is an ice sheet on land, but in the west is a marine ice sheet, which underneath is losing 10 metres a year. Even using an autonomous underwater explorer, however, it is impossible to get close enough to the ice to find the cause.
Hence the emphasis on Iceland, which is much more accessible, and where the glacial ice shelf has been in gradual retreat at Jokulsárlón since 1954, when it nearly reached the seaward edge of the lagoon, but is now losing 260x106m3y-1. A glacial river feeds the lagoon, whose temperature is 0.1°C while that of the ocean is 5°C, so twice a day salty, warm water flows in below the outflow, which is cold and fresher. Physics allows the exact calculation of how much the ice has melted. Within 250m of the ice face the ice melt signature has been mixed away, although within that area there are huge variations in adjacent pockets. This was illustrated with diagrams and equations that were impressive, though hard to follow, showing huge variations in the temperature of the water with large horizontal and vertical gradients in adjacent areas.
As the shelf retreats the glacier moves more quickly, speeding up the loss of ice. The lecture ended with an evocation of the Thames Barrier and its hundredth closure. The message was clear.
Mark referred us to a Research Article on plumes in the ocean by Dr Tom Cowton, University of Edinburgh, in the Journal of Geophysical Research: Oceans. (AGU publications). It can be accessed via : http://onlinelibrary.wiley.com/doi/10.1002/2014JC010324/suppinfo
Joint Day Trip to Stour and Wrabness with East Anglia branch
11 October 2015
We met our leader, Bill George, at Wrabness Station then started by examining Wrabness Church. This has a distinctive ground level belfry (actually the bell mechanism is in a wooden cage!), and the walls were made of flint, some now rendered. We then walked down to the estuary of the River Stour.
We walked along the beach to see the cliffs showing 34 Lower Eocene ash layers and Pleistocene Channel deposits with gravel and brickearth. The ash layers are rhythmic and from the North Atlantic Igneous Province, 62-53Ma, from when Europe and Greenland were splitting apart. We also saw the fault William Whittaker of the BGS mapped in the 1880s, and the channel structures in the beach marked out with the more resistant layers.
An EAOUGS member who was assisting with a friend’s dinghy joined us briefly. Peter Collins (NHM and LOUGS) met us from his beach hut with his boxes of fine fossils, including the magnificent mammoth teeth he found here on the beach. It was a fine, sunny day, and we found a fine, Georgian tea shop in Mistley, near the Towers, for refreshment before the journey home. An area worth more field trips!
Lecture: Tectonic Evolution of the Alps - by Mike Streule
15 October 2015
Dr Mike Streule, Rio Tinto Teaching Fellow at Imperial College, London, introduced his lecture with a panoramic photograph of the Western Alps, the main subject of his lecture, showing clearly at least two orogenic episodes. He started with a bit of history dating from the late 1800s, with what was referred to as ‘the Alpine Nappe problem’, when Marcel Alexandre Bertrand developed the wave theory of mountain-building. He identified sheets of rock and rock assemblages, but the reason for the buckling of the Earth’s crust remained a mystery. Alfred Wegener (1880 – 1930) developed the idea of Continental Drift, greeted with general incredulity, and then John Tuzo Wilson (1908-1993) elaborated the theory known as the Wilson Cycle, showing that continental masses come together and break apart in a regular sequence: the rifting of continents by Mantle plumes, seafloor spreading and the formation of ocean basins, the progressive closure of ocean basins by seafloor subduction, followed by continental collision and final closure of an ocean basin.
This introduction was followed by a series of palaeogeographic maps from 200Ma, from the break-up of Pangea, to the present: an entire Wilson cycle. The granites of the Mont Blanc Massif are 200Ma old and are pre-Alpine, present in the southern margin of Europe, yet they lie over more recent formations. The Piemont Ocean, formed in the Jurassic, separated Africa from Europe, and it is the closing of that ocean, together with a degree of rotation of the plates, that has brought Africa into collision with the southern margin of Europe, with increasing deformation from West to East. Mont Chenaillet is an ophiolite obducted as a result that closure.
The subduction of the Piemont Ocean crust dates back 65 Ma. At 40Ma in the middle Eocene the Valais sediments were subducted and collision tectonics in the late Oligocene (25 Ma) led to the Jura bulge. Extensional followed by collision tectonics led to faulting and thrusting, creating the major terranes of the Western and Swiss Alps. In the final views, to the east from the Grand Combin, and west from the Dom (Valais) the different nappes can be clearly seen. In answer to a question it seems that there is still some ‘shunting’ in the Alps.
This is a vast subject and Mike has provided the following references for those who wish to read further :
Hands-on at Herne Bay for S209 Students
18 October 2015
We ran our traditional introductory day for students, in most untraditional good weather! It was mostly led by Geoff Downer and Iain Fletcher, with a little support from me. Both transmitted their enthusiasm for real rocks and field geology, which this is a good opportunity to experience. We had new cliff falls to examine to demonstrate slope (in)stability, in addition to the sedimentary rocks in the glen and the metamorphism in the armour stone on the beach, all at Beltinge, near Herne Bay. We then went along to Reculver, the extent and preservation of the wall around Reculver Roman Fort, at the north of the Watsum Channel, still surprises me. We ended up walking along the sea protection to study the Thanet Sand in situ, a treat for those who only see it in boreholes under London, and to the dinosaur footprint. The students who came included a local resident who came out of interest, as well as students who are further advanced in their degree, but saw our introductory day as a good way to see more in the field, so it isn’t just for S209 students– all are welcome.
The Scarplands of Lincolnshire: From the Lincoln Edge to the Wolds - Led by Diana Smith
23-25 October 2015
Friday 23 October 2015 - Ursula Scott
John Ruskin maintained that Lincoln Cathedral was the most precious piece of architecture in the British Isles. I think he may have been correct. It is a magnificent building and to find that our hotel for the weekend was right next door was a huge bonus.
Lincoln cathedral stands on Lincoln Edge, an escarpment of Middle Jurassic limestone which has been quarried since Roman times and used by Bishop Remigius in the construction of the cathedral. The limestone is of the inferior oolite group, is relatively easy to carve and has been used both decoratively and as ashlar. Also used, but mainly for internal decorative purposes, was the costly, high status Purbeck marble. This dark stone contrasts well with the creamy white/yellow Lincolnshire Limestone. The cathedral was built in the 11th century in the Romanesque style.
A fire destroyed the roof in 1141. The cathedral was restored but shortly afterwards in 1185 a large part of the cathedral collapsed as a result of an earthquake, leaving only the west front. Replacement in the English Gothic style was commenced in 1192 in the time of Bishop Hughes but in 1237 the main tower collapsed – possibly another earthquake or perhaps new technology getting beyond the builders. By 1311 the tower had been replaced with the addition of a spire which made the cathedral probably the tallest building in the world. This spire blew down in a storm in 1548 and has never been replaced.
Restoration of such a large and important building is continuous and extremely costly. The fabric is cared for by a large team with a variety of skills and we were lucky enough to be invited to meet some of the stonemasons in their workshop at Masons’ Yard where we were welcomed by head mason, Paul Booth. He delivered a short talk on the restoration work being done by his team of nine masons after which we wandered around the workshop and chatted to a few of his colleagues. (Figure 2 and 3).
Most work is done on the ground although sometimes it is necessary to go up on the scaffolding. Templates are taken in situ of the pieces of stone which need replacing. Measurements are sent to the quarry and the required sawn blocks of stone are delivered to the yard where the masons work them with mallet and chisel as did their medieval counterparts. However, chisels are now made from tungsten steel instead of iron and mallets from nylon rather than wood. Use is also made of air tools and today’s work benches, or bankers, are now height adjustable. Masons have used marks to identify their work and even today each carved replacement stone bears its creator’s mark.
Like all chefs who have their own knives, masons have their own chisels, some of which have been designed to fit the owner’s hand more comfortably than an “off the shelf” model. Apparently one of the older masons who retired from the workshop a few years ago, went to live in Shetland where he retrained as a blacksmith and started making bespoke chisels for his ex-colleagues. Medieval masons were aware of the corrosion problem when using iron for fixing pins and dowels and for the most part encased their metal in lead. Brass dowels were tried in some repairs but it was found that after a while the brass shattered like glass, possibly because of a reaction with the mortar. Galvanised or stainless steel is now used.
Depending upon the complexity of the design it can take a mason from 3-6 months to complete a piece of work so imagine the distress caused to the mason whose finished work, whilst waiting to be installed had a piece knocked off it by a passing scaffolding board. I understand that the piece was stuck back on! It is believed there was an exchange of masons at Lincoln cathedral in medieval times as there are clusters of pillars which are of similar construction in both Lincoln and Nideros cathedral, Trondheim in Norway.
After our visit to the yard we paid a visit to the cathedral where we identified the stone in the west front which we have adopted to help with restoration funding. We spent some time inside marvelling at the beauty and craftsmanship around us before settling down in the cathedral cafe where we found their refreshments restored us rather more quickly than it takes to restore a worn out piece of stone.
Saturday 24 October - Richard Trounson
After breakfast on Saturday morning, we were met in the hotel Reception by Paul Atkin, the quarry manager of the Cathedral Quarry who gave us a résumé of the history of the quarry. We then proceeded in convoy to the Quarry, (Figure 4), which is situated on the northern outskirts of the City, down a short lane off Ermine Street, and is flanked by allotments and a housing estate, but has a view towards the towers of the Cathedral. We were joined there by Don Cameron, of BGS, and national Secretary of the OUGS.
The quarry had originally been opened as a lime-kiln quarry in the middle-to-late nineteenth century on land belonging to the Dean and Chapter, and had not originally been worked for dimension stone. In Roman and medieval times, quarries had been worked for building stone in the vicinity of the cathedral itself and the hotel, but the thick beds there rapidly thinned out in the direction of the quarry, due to faulting and glacial excavation. In the 1920s, the Cathedral was in a bad state of repair, and following a major fund-raising effort, the opportunity was taken to exploit the beds of suitable building stone in the quarry as an economic source of dimension stone, (Figure 5), given that the land was Cathedral land. The quarry was however quiet during the war and post-war period, when there were other priorities.
By the 1980s, when authentic restoration had become important, there was no longer an extant planning permission, and the quarry site had become encroached on by the neighbouring housing estate. The cathedral had therefore been purchasing Mid-Jurassic limestone from central France instead. However, a new planning permission was applied for on an additional area, and working re-commenced.
Annual output was now variable, but generally amounted to some 200 tonnes of finished product. Much of this went to the cathedral but some elsewhere. There was now a proposal to secure future supply by acquiring further land in the allotments area, but opposition was likely owing to the proximity of the housing estate. The company also bought in stone from Ancaster, and indeed a number of blocks of Ancaster stone could be seen lying on the quarry floor, as well as the quarry's own output. We walked over and inspected the beds from which stone was worked (Figure 6).
Paul explained that the work of extraction was all performed in an annual campaign, an external contractor (Foxes) being brought in to carry out the work of ripping stone from the face. The quarry has a number of machines of historical/ industrial archaeological interest, including a tripod crane. Diana Smith took advantage of a break in Paul's exposition to explain that the celebrated Lincolnshire "freestones" came from oolitic horizons relatively high in the Lincolnshire Limestone Formation where the rock, like the freestone from Portland, was not cemented, but "welded", as a result of compression of the grains, which are very well-sorted, fine and even-grained. The resulting building stone differed from, for example, Bath Stone, which was largely spar-cemented. The "welded" freestone had significant advantages, both in terms of workability, and in resistance to weathering.
We then walked over to the sheds on one side of the quarry and were shown the stone-cutting process, which utilised a water-cooled, diamond-headed saw and the guillotine to crop the stone. Inside we inspected a number of very fossiliferous blocks (containing aragonite bivalve and gastropod shells) from the "Silver Beds". (This is the local term for some the beds in the quarry from which the freestone is worked for carving, the other bed currently worked being the Red Bed).
Having thanked Paul and taken our leave, we drove north to Scunthorpe, passing the Tata Steel works on the way into the town. Our destination there was the North Lincolnshire Museum. This had been established using the building and grounds (on which a modern extension has been constructed) of the former vicarage of St Lawrence Frodingham, which stands on one side of the museum site. The museum has galleries covering local geology and natural history and local archaeology and social history, as well as decorative arts, spread over two floors. We were told that it was due to close shortly before Christmas for an extensive refurbishment programme and the creation of a new gallery.
The geological section on the ground floor has good displays, in lit aquarium-like cases, showing a variety of Lower Jurassic fossils, typical of those found in the area, and their habitats, (as well as some modern equivalents). The range of fossils included ammonites, crinoids, echinoids, corals, brachiopods and bivalves. There was also a display of some plesiosaur remains found in Lincoln. At the entrance to the gallery there was a large piece of the fossiliferous Frodingham Ironstone, which had formed the foundation of the local economy in modern times, and which was the focus of Diana Smith's next short talk. We were told that the Frodingham Ironstone Member, of Sinemurian age in the Lower Jurassic provides an oolitic and calcareous iron ore of the minette type associated with Alsace Lorraine. It also provides a local building stone, and in that connection could be seen as part of a narrow band of striped ironstone carbonates found typically in Lower Jurassic and Middle Jurassic strata trending from Hook Norton to Cleveland. It appears to have been associated with a particular paleogeography.
There has been much discussion as to the origins of the Frodingham ironstone, (Figure 7), but there seems to be increasing support for the view that ooids of various iron minerals precipitated out in brackish lagoons in the proximity of laterite soils, and with rising sea-level these were then swept out into open sea and re-deposited in a marine environment with fossil debris into what became a matrix of calcareous mudstone.
In modern times, the Frodingham Ironstone began to be exploited in the mid-nineteenth century as an iron ore in the area, being mined locally both opencast and in mines. Historically, it formed the basis of the local iron and steel industry now represented by the Tata Steel works, but was a very low-grade iron ore, and no longer economical for use in modern conditions. Its original advantage was that its high calcareous content meant that it could be used without a special flux, and for a while it was blended with higher grade ores from Northamptonshire. However, mining for ironstone ceased in the area in the late 1980s, and in recent years the Tata Steel works had relied only on imported iron ores.
Diana also referred to the rich faunas found in fossils in the local rocks, which formed the basis of the museum's collections. Recently discovered rocks near Scunthorpe contained fossil hagfish and sharks. Following this we looked around the displays, and some of us then took lunch in the museum café. Others went to various eateries in the town, where the newspaper hoardings bore witness to the mothballing of the Tata Steel Rolling Mill, which had just been announced, and which represented a considerable blow to the local economy. Before re-assembling at the car-park, most of us took a look at the Church of St Lawrence. This is built of Frodingham Ironstone, with windows, quoins and crenellations in Lincolnshire Limestone. Diana pointed out that the limestone was streaky, like Ancaster Stone, but it was not possible to say that it actually came from Ancaster, as opposed to from some similar horizon elsewhere.
Sunday 25 October - John Lonergan
We started the day by returning to the cathedral, examining the plinth under the statue of Alfred Lord Tennyson, who was born nearby, in Sowerby, (Figure 9). The plinth is igneous and weathering badly, and has been repaired superficially with cement. (Not that this will help, as the plinth also shows evidence of cracking due to the large compressive load from the very heavy cast statue).
Looking at the nearby chapter house, the base course is Old Walton marble below and the paler Lincolnshire Limestone above. The marble is less permeable and acts as a damp proof course, further protection being provided to the base of the wall by hooded mouldings; pushing the water away from the walls. (Figure 10).
From here we went south to Copper Hill Quarry, (Figure 8), to see the Bajocian (middle Jurassic) Ancaster Limestone at Ancaster. The weathered Ancaster Limestone is characteristically described as streaky bacon due to the variations from changing water levels, currents and chemistry during deposition. Deposition took place in clear, agitated, shallow water in which lime was precipitated as both ooliths and pistoliths. There are also shallow water bivalves and gastropods are associated with colonial algae and corals. Oolite shoals were moved and redeposited by currents, and cross stratification is preserved in the bed forms. Flowstone is visible on the joints. As were replica vintage biplanes flying from the adjacent RAF station.
Both Ancaster Rag and Freestone can be seen in the quarry faces, and the Freestone further divides into Weatherbed, Hard White and Basebed. Lincoln Cathedral is built of Ancaster Stone (though they now use the nearby Glebe Quarry), as is Holborn Town Hall – the area of use increased dramatically with the rise of the railways. (We saw Ancaster Freestone used in our Lincoln’s Inn field trip earlier in the year).
The limestone was deposited in a basinal sea covering the East Midlands Shelf, fringing the London Platform. As three sides of the sea were land locked, the other being marine, the opening and closure of the seaway led to varying sediments and chemistries, and thus to the unique reddish pattern. As the sea way fluctuated fauna could not always enter the basin; and this can be seen in the different fossils, sea level curve and changing sediment types. Later there was a hiatus (still stand) due to sediment filling the subsiding troughs, and cut off the basinal ocean from the Tethys: after this the Great Oolite carbonates were deposited.
Members Evening Talks
19 November 2015
Eddie Yeadon : "The Restless Rocks of Racetrack Playa"
The July 2015 issue of Physics World described an investigation into how rocks on the floor of a dry valley in the Californian desert apparently moved by themselves leaving long trails in the dried mud on the valley floor. After a 6-year investigation into several candidate hypotheses, they established that the peculiar circumstances, both geological and meteorological, of the location were the cause. Winter rainstorms or meltwater formed large shallow ponds which could freeze on the surface, trapping the rocks, which had broken from dolerite cliffs, within large ice sheets. The rocks trailing in the soft, wet mud left tracks which solidified after the ponds had dried up, leaving the evidence that the rocks had moved, but not the cause. An interesting part of the article was the quantitative analysis of forces acting on the rocks in different circumstances.
Jim Camp : "The trouble with le Mont-St-Michel"
Le Mont-St-Michel, on the border of Brittany and Normandy in northern France, is arguably the most famous abbey in the world. However, human intervention threatened to change the area beyond recognition, jeopardising the future of this popular tourist attraction. The coast around Mont-St-Michel was extensively drained, increasing the land available for agriculture. This led to increased sedimentation rates. A bridge built to improve vehicle access to the abbey diminished the power of the river that flushes the bay. The river was further hampered by the building of a dam. This talk discussed the effect these changes have had, and how they were remedied to restore the maritime nature of le Mont-St-Michel.
Ursula Scott : "California: Holiday Snaps of Painted Canyon and some mud volcanoes"
A hike in the Mecca hills had us clambering over piles of fallen rock, dropping down chutes, sometimes with the help of rickety old ladders, squeezing along tight slot canyons and finally emerging into the wonderfully decorative Painted Canyon where Precambrian gneiss, migmatite and anorthosite with Mesozoic granitic intrusions are overlain conglomerate of granitic debris. Spectacular. The nearby Salton Sea is a shallow, saline lake which was accidentally created by the engineers of the California Development Company in 1905 and fills the low point of the Salton Sea trough which previously had been occupied by the ancient and much larger Lake Cahuilla.
Yvonne Brett : "Sikkim, a mini-paradise in north-east India"
An independent kingdom until 1975, Sikkim maintains a separate identity and requires an entry permit as you enter through a traditional arch by the fast-flowing Tista River. Situated in the Himalayan foothills between Nepal and Bhutan, within a bend of the Himalayan Main Central Thrust zone, its topography is extreme, rising from about 300m to 8,583m in little more than 100km. The presiding deity is Mount Khanchendzonga, whose white peaks dominate the scene, weather permitting! Beautiful valleys, very steep wooded slopes, and abundant wildlife make this small state a paradise.
The Monsoon makes travel difficult as roads are washed away. The rocks vary from high-grade gneisses to Precambrian low-grade metamorphic rocks and Gondwanan and Tethyan sediments. We travelled from Darjeeling up to Pelling, near the previous ancient capital, cross-country to the present capital Gangtok, visiting Buddhist monasteries and sacred lakes, one at about 4,000m near the border with China, and then back down the river to Siliguri, for a return to Kolkata and the Ganges.
Lecture: Fossil Fakes & Deceptions - by Paul D Taylor
10 December 2015
Dr. Paul Taylor is a Researcher at the NHM specialising in Bryozoans, but has an ongoing interest in the subject of this lecture and gave us a lively and learned historical review. He started by listing the reasons for faking fossils: commercial gain, scientific deception and educational fun for children, and went on to analyse and illustrate the different types of fakes.
There are those that are elaborated, such as the addition of a snake’s head to an ammonite, a reference to the mediaeval belief that St Hilda of Whitby changes snakes to stone. Composite fakes put different parts together, the most famous example being Piltdown man (Eoanthropus dawsoni) 1912. Charles Dawson (1864-1916) was an amateur archaeologist who built a reputation on finding fossils, many of which turned out to be fakes after his death in 1916. Another more recent is Archeorapto liaoningensis, smuggled out of China in 1999, reviewed in the National Geographic, and sold to the Dinosaur Museum in Utah as the link between dinosaurs and birds. Others include a rodent fossil made in 1843, crinoids etc.
Counterfeits are made to make money from the unwary, often originating in Morocco or China. Bogus fakes include many trilobites. Of particular interest was the story of Johann Beringer, Professor in the Faculty of Medicine in Wurzburg, who was the victim of a hoax by two colleagues who planted fossils, carved in Triassic marine limestone, on Mount Eibelstadt for him to find. He published Lithographiae Wirceburgensis in 1726, completely taken in. When the hoax was finally revealed, all three men were disgraced. The fraud was on a massive scale and many of the fakes still exist. Under the heading of fraudulent provenance is the case of V J Gupta, who between 1969 and 1989 wrote over 1000 papers on fossils reputedly from the Himalayan region, but which had been bought from dealers or stolen.
Finally, we had a case of self-deception. Randolph Kirkpatrick (1863-1950), assistant keeper of lower invertebrates at the NHM, in 1912 published ‘The Nummulosphere’, propounding the theory that all rocks have an organic origin.
This very entertaining and erudite talk, with accompanying illustrations, followed our usual pre-Christmas refreshments and was warmly received.