– Open one and you never know what you may find!
(For a synopsis of some previous AGS evening lectures, scroll down…)
A wonderful fossil of what? Where did I photograph it (in the UK) and more importantly, what makes it unique?
The answer is in the photos below with the original edited image above ‘reversed’ to make it a little more difficult for people scanning Ichthyosaur pictures on the internet! The picture below with an ‘arrow’ shows a young or even unborn Ichthyosaur which died with its mother when they were both engulfed in a catastrophic underwater landslide or similar event in the Jurassic 200Ma. It was found in Kilve, Somerset in 1984 and at that time showed the earliest stage of growth of any baby Ichthyosaur ever found.
Congratulations to Kimiko Kambe-Gang of the AGS who provided the correct answer plus the museum (Bristol University) where I had taken the photographs. Worthy of a fossil prize! and the Museum certainly worth a visit.
A close-up of the baby ichthyosaur, head down, tail up, very sad.
The blue mineral below is what and sitting amongst what? Just to make it more difficult, which country is it from? For scale, hight is around 14cm.
The Blue mineral is CAVANSITE and is on Stilbite with this example originating from Pune (Poone) in India. Its chemical composition is calcium vanadium silicate hence the name. Crystal system : Orthorhombic – Mohs scale hardness : 3 to4 – Streak : White – Luster : Vitreous – Habit : Prismatic/acicular
Gabriel Hodes of the AGS supplied the answer almost as soon as the photograph appeared on the website! He is the worthy winner of another fossil prize, having won two previous competitions………(see below)
The two close-up pictures below were taken by me a while ago in an area just north of Barnet. What are the building blocks, where did I see them and what country did they come from originally?
Open to all. A fossil prize to the AGS member who gets all three answers correct!
The answer is Tuff, which is an igneous rock formed from the products of an explosive volcanic eruption. It is made up of rock, ash, magma, pumice and glassy fragments compacted and cemented into a rock. Some Tuff deposits are hundreds of meters thick and can be the result of one, or several subsequent eruptions. It has been used for thousands of years as a building material, with the Romans using huge amounts in the building of the Colosseum in Rome and numerous other buildings and bridges. It is very common around the world with the Rapa Nui people of Easter Island in the Pacific even using it for their wonderful Moai statues. More unusually, Tuff was used for an impressive doorway in Colditz Castle, Germany during it’s restoration in the 1500’s.
However, in the case of the photos below, Tuff was used in the construction of the restaurant and immediate area in ‘The Gardening Club’ garden centre, in Crews Hill, Enfield. The Italian owner of the garden centre had the blocks imported from Italy when he redesigned the building. Unfortunately that was some years ago and with new owners over the years the origin of the Tuff has been forgotten.
Sue Jacobs of the AGS Finchley, London got most of the answers correct and is a worthy winner of the fossil prize!
Three general photos of the restaurant showing the construction using blocks and turned columns of ‘Tuff’.
All photos RSF
The painting below is by Christine Poutney of a busy Mesozoic Era sea with a variety of species and pterosaurs (?) flying around overhead looking for a meal. Name specifically all the animals and the exact age and location!
Open to all. A prize for the first correct answer if an AGS member …….but only one prize per year!
Email me the answer (email@example.com) (or see me at the AGS evening meeting.)
1) Ammonite: Parapuzosia (Austiniceras) austini
2) Shellfish: Pecten beaveri
3) Fish; Ctenothrissa (Beryx) radians
4) Dinosaur: ‘Iguanodon’ hilli [nomina dubia]
5) Pterosaur: Criorhynchus sp.
6) Pterosaur: Ornithochirus sp.
The fossils of the animals depicted in the painting were all found near Pirton, near Hitchin, Hertfordshire, UK. They date from the cretaceous period, around 180 million years ago.
‘We know about the animals which lived in the area around Pirton in this remote period because they have left their fossilised remains, mainly skeletons or shells which have been found in the rocks of the locality. These mainly came to light during quarrying or mining operations undertaken one hundred to one hundred and eighty years ago when the area was peppered with Chalk quarries, Clay pits and Coprolite diggings.’
Please see the July edition of the AGS newsletter for a full explanation by Mike Howgate.
According to Mike, Richard Furminger of the AGS is a worthy winner as he did lots of research and got most of the answers correct! He has awarded himself a small fossil ammonite prize……….
Thanks to Mike and Christine for the idea for this competition.
Exactly where did I photograph this wonderful print ? The clue is in the picture……….
The answer is in the picture! I photographed this lithograph in the Lyme Regis Museum in Dorset, not far from where Mary Anning discovered the first Ichthyosaur. I guess this is a copy, the original is in the British Museum. A hand written inscription on the drawing states ‘A HEAD of one of the species of the FOSSIL ANIMAL from the Blue Lias, Lyme Regis, Dorset in the possession of H. T. De La Beche esq. Drawn on stone by H. Corbould. Printed by F. Moser, Cromer Street.
In the same cabinet as the drawing is the first ichthyosaur skull found by Mary and her brother Joseph in 1811. The Museum is packed with fossils and interesting information on the area and surrounding coastline. Well worth a visit…….
Mike Howgate was the first and only person to guess the correct answer. Well done Mike! He has already received his fossil prize………..One other AGS member got very close!
From April 2019
I spotted these wonderful chunks of rock last year. They were going to be used for landscaping in a picturesque site just outside London. Where did I see them, what type of rock are they and from where did they originate? Don’t be misled by the weathered colour, look at the close up below for the genuine colour and crystal structure…………
The answer is Gabbro, all the way from the Scottish highlands. Glaciers plucked them off the mountains and left them as erratics in Scottish fields. Lorries then brought them down to RHS Hyde Hall in Essex. Worth a visit, a wonderful place on par with RHS Wisley.
From January 2019
A beautiful mineral from the Mineral Hall of the Natural History Museum. What is it and where is it from?
The answer is Barite, an orthorhombic mineral from Harz, Germany.
(Julia Daniels, our AGS secretary, correctly identified the mineral, but not the origin)
From August 2018
Photos by RSF.
Where is this?
A really interesting and impressive geological site. In Great Britain and you should really know it!
The answer was: The Laxey Wheel near Ramsey on the Isle of Man and was named ‘Lady Isabella’ after the wife of the Governor of the island. The largest working water wheel in the world (72.5ft diameter) opened in 1854 and was used to pump water from a mineral mine 600ft away via a crankshaft and wooden actuator. A spare crankshaft is shown in the original photograph. Designed by Robert Casement, it took four years to construct and was working until the mine ceased operations in 1929. It produced vast quantities of zinc, lead, copper and some silver for over 70 years. It is now cared for by Manx National Heritage organisation.
AGS member Linda, from Harlow, was the only person to identify the site!
From April 2018:
What is this (item)? What is it made from? Where is it?
Easy enough if you have been there, and if you haven’t you should have been… In the UK this time.
Well the answer is, and nobody made an attempt at the answer, it is the mantle piece of the room known as Churchill’s Room in historic Bletchley Park, Buckinghamshire. A whole area as well as the main house telling the story of the WW2 codebreakers and the cracking of the Enigma code.
I guess the stone is Derbyshire ‘Marble’, which is of Carboniferous age from around 350my. (Thank you Gabriel) Really impressive close up, full of crinoids and corals and beautifully carved and polished.
Although not very geological a wonderful, interesting and uplifting place to visit.
Photo from internet showing Churchill bust on mantlepiece.
What is this? Where is it on show? Where did it originate?
Picture by RSF
Well, the answer is: It is an Iron + Nickel meteorite, around 800kg worth(!) found in northern France and one of the largest ever to hit Europe. Possibly from the core of an asteroid located between Mars and Jupiter. On display in an incredible place known as the Museum of Natural Sciences in Brussels. Along with 13 fossilised IGUANODON skeletons! They are an amazing sight……
NO correct answers although some entries were close but did not get the location….!
Where was this lovely old photograph taken and what was going on? : The answer was Hampstead Heath with a huge brick making operation under way in the 19th century. Large ‘clamps’ or stacks of green bricks can just be seen awaiting firing…….
Two AGS members, Gabriel Hodes and ‘Linda from Harlow’ were joint winners. Congratulations!
Where did I photograph these fossilised trees? : Regents Park, within the Inner Circle, close to the waterfall in Queen Mary’s Gardens. The fossil trees were installed in the park after having been removed from the ‘Fossil Forest’ near Lullworth Cove by the Royal Botanic Society in the 19th century. There was a plaque to this effect sited near the trees which has now disappeared……..
Gabriel Hodes of the AGS has been awarded a fossil prize after identifying the site at the November Tuesday meeting!
Pictures by RSF
Where was this photo taken? : Parys Mountain in Anglesey, the site of an enormous copper mine which has been mined for its ores since the Bronze Age. A fascinating place and worth a visit.
Mike Howgate from the AGS visited the site last year and recognised it immediately. He was duly award a rare fossilised shell which I hope will take pride of place in his collection……..
Picture by RSF
SYNOPSIS OF RECENT TALKS
Tuesday Oct. 9th 2018 – “Microbes to Marrows”
Jane Tubb – Chairman of East Herts Geology Club.
Jane’s talk was on the evolution of plants and flowers from the first evidence of life 3.8 billion years ago. Both originated from a common ancestral organism known as prokaryotes, which was a single cell organism that lacked a nucleus. Some were anaerobic and some aerobic. Cyanobacteria, or blue-green algae is an example. The more complex eukaryotic cells evolved from that single cell organism into multicellular organisms which gave us algae, plants, fungi and animals.
Stromatalites are the earliest fossil evidence of life and are formed from layers of microorganisms, or cyanobacteria, alternating with layers of sediment during inter-tidal periods. Over millions of years they contributed vast amounts of oxygen into the atmosphere via photosynthesis. This was known as the great oxygenation event. They only exist in a limited number of areas today, the most famous being the shore-line of Shark Bay in Australia. Following on from this event, aerobic respiration was able to evolve and O2 was able to diffuse into the leaves of plants via the stomata.
Algae are a large group of photosynthetic organisms that are unicellular to multicellular, seaweed being an example of the latter. They differ from plants in that they lack many of the specialist cell types, roots for example. There is no exact definition of algae, with some authors including Cyanobacteria for instance and others regarding them as part of the kingdom Plantae and exclude all prokaryotes. There is no fossil evidence due to their fragility, as is nearly always the case with plant soft tissue. However, it is established that during the Cambrian there were ancestors of modern animal phyla and also algae present in the sea, as well as freshwater algae. By the Ordovician the first land plants had emerged.
Jane then explained the theory of vascular plants (tracheophytes) that have ‘plumbing’, or systems that distributes glucose from photosynthesis via the phloem and water from the roots via the xylem throughout the plant. This encouraged their growth and ultimately the ability to release their spores much further afield. Other developments were rooting systems, a supporting woody structure (Lignin) and to branch repeatedly. Soon, vascular plants had formed forests of tall trees. Spores, pollen and seed fossils prove the existence of early plants due to their tough outer coat and high incidence of fossilisation.
In contrast, non vascular plants (bryophytes) such as liverworts and mosses were small, low growing and limited in size.
The development of plants through each geological period was then explained, although as the speaker pointed out it was obviously just a brief description and would omit a lot of detail.
Late Precambrian 635-542my – Multicell organisms, algae, lichens, fungi, protozoans and intermediate stage between plants and animals.
Cambrian 540-495my – Algae present in sea, Arthropods on land so likely also freshwater algae.
Ordovician 495-443my – Early plants, molecular clock evidence. Fossil liverwort spores from Argentina 473–471my old.
Silurian 443-417my – Non vascular plants on land and diversifying. Probably also insects. Cooksonia fossils suggest they had no roots, had a stem with vascular tissueand were regularly submerged in their environment. Only 3cm tall and a transitional form of vascular plant.
Devonian 417-354my – Early plants and probably insects on land and soil levels building up. First insect fossil from Rhynie Chert, Scotland. Some early plants now 50cm tall; Asteroxylon, Psiliphyton and Rhynia.
Mid Devionian – major transitions from small plants to forests. Colinisation by plants slowed rivers and stabilised banks. Early plant roots were too shallow to have changed river systems, and meandering began in fine grained sediment produced by weathering of rocks and microbial activity. Major plants: Pseudosporochnaleans similar to modern tree ferns and palms. Archaeopteridaleans woody trunks and needle like leaves probably related to modern conifers. Lycopsids, lepidodendron and modern club mosses. Wattieza related to horsetails.
Carboniferous 354-290my – Horsetails, ferns, palm like trees, early seed plants. Exceptional preservation of organic carbon; low lying anoxic swampy environment as sea levels fell; faster burial with material from erosion; plants evolved more protection from animals. Numerous fossils of fallen trees, bark and roots (stigmaria) from lepidodendron indicate it grew to 30mt and was around 1mt in diameter. The bark tended to support the short-lived tree rather than wood. Calamites, a relative of the modern horsetail also grew to around 30mt. Cordaites, a gymnosperm grew up to 30mt in wet ground and related to modern conifers. Spore bearing ferns varied from small bushy modern looking plants to tree ferns which reached up to 20mt. Tetropods increasing and diversifying on land driving evolution of plant defences.
Permian 290-245my – Deserts widespread in Pangea, dry conditions favoured gymnosperms. Seed and true ferns present but tree ferns declined. First modern conifers and ginkgo present, possibly derived from seed ferns. End Permian extinction causes world wide die off of vegetation but most groups survive.
Triassic 245-205my – Post extinction left niches vacant for evolutionary innovation, proto mammals, dinosaurs and flowering plants. Angiosperms evolved which had stems, roots and leaves and produced a seed which originated inside the flower. Proven in 2013 when the fossil pollen of a flowering plant was found in a core sample and dated to 240my. The Arizona petrified forest fossils date from this time, as does the monkey puzzle tree.
Jurassic 205-142my – Pangea continues to split, plants strengthen defences as size of herbivorous dinosaurs increase. Brachiosaurus, with its long neck consumed vast amounts of conifer foliage which was the dominant land plant. Stegosarus and others grazed smaller ferns, club mosses, horsetails etc. Fossil forest in Dorset grew up, mainly conifers, tree ferns and cycads.
Cretaceous 142-65my – Atlantic starts to open, flowering plants dominate, conifers decline and the demise of seed ferns. Plants evolving to encourage insects for pollination, animals and birds to eat fruit and distribute seeds, first hardwood trees appear, oaks, maples, willows etc. 99my old beetle trapped in amber fossil was a pollinator to evergreen cycads. Monocots or grasses evolving, five types at least with a single stem and grazed by dinosaurs.
Tertiary 65-1.75my – As climate warmed hardwood trees began to dominate, displacing conifers. Origin of C4 photosynthesis where plants from hot climates are more efficient in dealing with drought and high temperatures. Cacti evolve with the species diversity thought to be due to global expansion of hot arid areas.
Quaternary 1.75my – present. Human intervention……….
There are 4 million known species of vascular plant plus 2,000 new species are described each year.
But, 20% plant species are in danger of extinction!
What next? And who knows what is going to happen? Jane illustrated her talk with some fascinating slides and also brought along fossil stromatolites, lepidodendron bark, ferns and stigmaria.
Thank you to Jane for a copy of her presentation which helped me enormously with this synopsis.
Tuesday Sept.11th 2018 – “Sharks in the Desert, Lab and Ocean”
Charlie Underwood – Birkbeck College, University London.
Charlie’s talk focused on Sharks, Rays and Chimaeras which were a branch of vertebrates that separated off from those with true bones (i.e. us) in the Lower Palaeozoic. As they are composed of cartilage, well-preserved fossil sharks are rare but spectacular, as a slide of a fossilised dogfish from Lebanon illustrated. In contrast their teeth are robust and are produced throughout life, which explains why shed teeth are such common fossils. The evolutionary development of this unique dental system is still being investigated. Teeth of these vertebrates have been adapted to form dentitions ranging from the serrated saw blades of deep-sea dogfish to the grinding plates of eagle rays. Charlie illustrated the point with slides of amazingly differing forms of teeth. Individual curved teeth, some straight, others small and pointed, flat for grinding and others grouped together.
A large number of fossil teeth and skeletons of saw sharks and saw fish, which is related to rays, have been discovered in phosphate mines in Morocco. Both of these fish have a pointed front or rostrum lined with sharp transverse teeth but the teeth are not the same and the fish are not related. Sharks and rays have a unique teeth replacement process with the saw shark teeth rotating up into position at the time of replacement, not directly up from the jaw as in other sharks. The saw shark and rays have teeth that are developments of modified scales with a central cavity surrounded by dentine and a hard enamel surface.
Fossils of whale types were first found in Egypt in 1880 in mudstones and sandstones in a photogenic area near Birket el Qurun Lake, and scattered amongst them shark fossils and teeth. 36 shark species were identified and 35 species of batoids or rays from the late Eocene. It would appear the whale skeleton acted as a reef for predators and supported different shark and ray species on the sea floor. Other species would have existed and hunted higher up on open muddy shelves or shallow sandy areas.
Charlie showed CT scans of modern sharks and rays and using virtual techniques the less dense material or skin could be ‘removed’ exposing the skeleton. This was followed by all the bone removal which finally left just the teeth, including developing teeth. These could then be rotated and examined in detail. The use of techniques such as bulk CT scanning to study fossil and modern animals greatly add to information and understanding of fish evolution and development.
The talk was well illustrated with some fascinating slides and examples of the CT scan imagery.
Tuesday 14th August 2018 – AGS Members evening
Two talks from AGS members and the ‘Golden Egg‘ competition.
Brimham Rocks in Yorkshire – Doug Daniels
Doug showed us pictures of the balancing rock formations known as Brimham Rocks in North Yorkshire. He and Julia visited the area twenty-five years ago and although he classed them as ‘holiday photos’ the photographs showed what a geologically interesting place it was, and still is, to visit.
The rocks were formed around 320 million years ago and are mainly Millstone Grit, which is the main building stone of the Pennines. Many of the stones show evidence of cross bedding, faulting and other geological phenomena. The Devensian glaciation period originally helped to sculpt the rocks but since then, rain and wind have further eroded the rocks into the strange shapes seen today. The formations have been given some equally strange names, such as The Idol, The Camel, The Sphinx and others, and are up to 30 feet high.
The area is surrounded by the Yorkshire countryside and looks well worth a visit!
Manchester Building Stones – Stephen Krouse
Stephen wanted to show us the interaction between humans and geology in cities, in particular Manchester which he had previously visited. He explained that cities evolved due to their proximity to rivers, canals, road and railways, as transportation was one of the most important factors in their growth.
Due to the proximity of the Manchester Ship Canal it was not only possible to build from local stone, as had been done since Roman times, but also to import building stones from far and wide.
Stephen showed us some interesting photographs of the countless different stones used in the construction of some impressive Manchester buildings, from Victorian times through to more recently.
Cost was not so much an issue when the cathedral, churches, town hall, main library and concert hall were built. They are all stunning examples of the best architecture of the time and show how the builders utilised some of the more exotic and unusual building stones available. Some well known and others not so: Darley Dale sandstone, Red sandstone, St. Bees sandstone, Peterhead granite, Indian sandstone, Welsh slate, green and red ‘slate’ formed from Ordovician volcanic ash, red granite from Finland and limestone with fossil corals and brachiopods. Even the more recently built ‘Holiday Inn’ Hotel has the most impressive limestone containing excellent examples of fossil corals and ammonites.
Another interesting place to visit while you are in the North!
The ‘Golden Egg‘ competition was hotly contested with four entries from AGS members. Penny Badham, Stephen Krause, Sue Jacobs and Richard Furminger.
Two judges chose Sue Jacobs entry ‘In Search of Spotty Rocks’ as the winner, and Sue duly took home (for the second time) the impressive trophy with its stand and protective glass dome!
Tuesday 10th July 2018 – Ros Mercer from the Essex Rock & Mineral Society.
‘Geology of New Zealand’ 30 Members attended.
105 million years ago New Zealand and Australia, along with Antarctica, were part of a massive land mass called Gondwana.
Around 85 my, New Zealand separated from Gondwanaland and Australia due to sea floor spreading and moved into the Pacific Ocean, much of it sinking below sea level. Known as Zealandia, the continent began to break up and experienced 5my of upheaval due to its presence at the boundary of Australian and Pacific plates. It finally re-emerged as New Zealand. The Kaikoura Orogeny followed later and gave birth to the Southern Alps, and although eroded away over the last millions of years they are still growing due to the continents collision.
There are major active volcanoes in North Island such as on White Island and in the Taranaki area. Most of the island was buried under 200mt of volcanic ash and pumice when Mt. Taupo erupted 26,500 ya. It is now Lake Taupo caldera. There are huge areas of ignimbrite hundreds of metres thick.
Auckland is built on a volcanic field that has been active as recently as 600 years ago. Scattered through the city are dozens of volcanic cones. There are also two important goldmines in the area, Martha and Waihi.
As well as the volcanic activity there are geysers producing flow deposits, abandoned sulphur works, large geo-thermal power stations, evidence of ‘Lehar’s’ in roadside cuttings and large deposits of Rhyolite lava.
South Island has many ‘braided’ rivers as a result of glacial periods over the last two million years where river valleys have filled with thick layers of sediment. Jade is found in these river valleys also as a result of glacier outcrops up in the mountains. The Maori’s produce beautiful jewellery from the nephrite and serpentine jade, which is only found in South Island.
During Ros and her husband Ian’s three-week tour of New Zealand they also visited Hokitika Gorge, Franz Joseph and Fox glacier with moraines and striations on rock surfaces. They also experienced saucer shaped clouds over Mt. Cook, sub tropical forest areas, Milford Sound, Waterfalls, Seals, Monro beach and the Haast Pass, one of only three roads that cross the Southern Alps.
Ros called their trip ‘Extraordinary’ and it certainly looked and sounded like it.
After the talk Ros and Ian showed off their fantastic selection of rocks and minerals collected during their three-week tour.
Tuesday 12th June 2018 – Dr. Tom Booth from the Natural History Museum. 29 members attended.
“Cheddar Man” and how researchers obtained all that surprising information about the physical appearance of our earliest ancestor.
Tom recounted how the title ‘Cheddar Man’ was given to a skeleton recovered by accident in 1903 from Gough’s Cave in Cheddar Gorge, Somerset. It is still the oldest complete skeleton found in the UK. It was determined that the skeleton was 10,000 years old (Mesolithic) and was from the time when Britain was still connected to Europe via Doggerland. It was an adult male who was probably in his early 20’s, of slim build and around 1.6mt tall. At that time the country was densely forested and he would have been part of a group of mobile hunter-gatherers. They would have lived in skin tents, used stone tools as harpoons, arrows and spears etc. and probably have domesticated dogs by this time. Most probably they used caves as burial sites rather than living in although cremation may also have been carried out.
DNA was extracted from the petrous part of the temporal bone which forms part of the inner ear and from this sufficient genetic information was obtained to assist in facial reconstruction, and also to establish other genetic characteristics. His most probable profile is that Cheddar Man had blue/green eyes, curly hair, was lactose intolerant as an adult and had a fairly dark skin. He and his kind had only migrated into Northern Europe a few thousand years before and there had been no time for the skin to lighten. The genes for lighter skin became more widespread in European populations later than had been previously thought.
The Dutch Kennis brothers reconstructed the face using all the available information and produced a face with personality, quite uncommon in reconstructions, which is now famous worldwide.
Tom finished his fascinating talk with the statement that Cheddar Man could be the descendant of everyone alive today or nobody!
Tuesday 8th May 2018 – 28 members attended.
“Learning Geology in Ethiopia” by Stephen Krause BSc who is a member of the AGS and is also a lecturer for the WEA in North London.
Stephen talked of his 6 month visit to Ethiopia in 1969 on a pre-graduate trip working for the United Nations Development Program and the Ministry of Mines of Ethiopia. This was during the Haile Selassie reign as Emperor. The East African country is bordered by Somalia, Kenya and Sudan and is split by the Great Rift Valley.
The main objective was to investigate and survey any likely areas of economic mineral deposits. This included making maps from aerial photographs, investigating likely areas and the taking and analysis of samples. Drilling for core samples was also carried out at times. The terrain was difficult and particularly after the frequent torrential downpours which often resulted in flash flooding. The country varied from 500 feet above sea level to 130 feet below with the Danakil Desert being almost as low as the Dead Sea, with its evaporite minerals and salt mined for many centuries. Stephen travelled around with a small group of geologists, an interpreter and several armed guides. They frequently camped out during their travels and collected large quantities of rocks and minerals from likely areas. These were returned to their base camp were they were screened, crushed into tablets and then analysed using a x-ray spectrometer. From these samples a reliable indication of the mineral density could be obtained and if considered economic a more investigative mining approach could be taken. Gold, Silver, Copper, Lead, Chromite and other minerals were all found and even Thorium.
Apart from the salt lakes and desert areas, there were huge areas of flood basalts containing columnar basalts and volcanic plugs with other areas of limestone deposits. A productive mineral location was often a ‘Bald Mountain’ as they were known, or an elevated area with little or no vegetation indicating possibly copper or other deposits. Access to more isolated areas was quite difficult at times and although many roads had been built by the Italians during their occupation of the country during the late 1930’s and early 1940’s it was often not economically viable to build access roads.
Stephen admitted his visit was a fantastic learning curve and good preperation for university, while at the same time helping a developing country to locate and utilise their mineral resources.
Tuesday 10th April 2018 – 39 members attended.
“Virtual Fieldwork Using Google Earth” – Dr. Ian Watkinson from the Royal Holloway University of London.
Ian started off his talk by asking the 39 members present who had actually used Google Earth, and a significant number indicated that they had. A smaller number of those had also carried out geological fieldwork.
Satellite imagery had been used by the military since the 1970’s and Google Earth as a computer program became freely available in 2005.
The actual image portrayed in GE is a satellite image overlain on a grid type topographical image, not just a standard digital image.
Ian showed us evidence of the usefulness of GE in showing the disappearance of the ice cap on Puncak Kaya, Indonesia over a period of fifty years. An old image compared to a recent GE image showed the total lack of ice cover…….
With geophysical overlays GE can be used to show earthquake data, plate boundaries, magnetic sea floor spreading anomalies, age of ocean crusts etc.
More simply, it can show up raised beaches on coastlines, evidence of long past earthquakes, a Himalayan thrust fault, uplifted coral reefs, even evidence of the lateral motion that had occurred during the Christchurch earthquake by showing a huge kink in a major roadway. An interesting view of the San Andreas Fault area in California showed sand ’uplift’ on the surface at the site of an old earthquake crack or fissure. Another GE image showed the area of the 1959 landslip on the Madison River, Montana, and still evident today.
Ian pointed out that although Google Earth was a fantastic tool it was not an alternative to actual geological fieldwork but could be supplemented by it……..
Tuesday March 13th 2018 – 31 members attended
“The Active Volcanoes of Italy” – Dr. Tony Waltham of Geophotos.
Tony explained that the five major Italian volcanoes, Vesuvius, Campi Flegrei, Etna, Stromboli and Volcano originated due to subduction activity at the boundary of the Eurasian and African plates.
Vesuvius itself sits inside the Monti Somma caldera which formed during an eruption 20,000 years ago. The former was responsible for the most widely know explosive eruption when in AD79 it completely devastated Pompeii and Herculaneum over a 24 hour period. The initial Plinian phase released a column of ash and pumice 30km high which due the wind direction quickly covered Pompeii with over two meters of debris. There were several different stages but finally a pyroclastic flow of around 700degs centigrade completely enveloped the town and killed those that still sheltered there. 19th century archeologists introduced the technique of filling the empty body mould with plaster thereby preserving the final moments of the unfortunate person.
Herculaneum, which at that time was on the coast, was completely destroyed and buried under 20 meters of deposits from an early stage pyroclastic surge. Over 300 bodies have been found sheltering at the beach in boat or storage houses.……. Only a few bodies have been found in the town.
Campi Flegrei, west of Naples, is the site of a large caldera formed around 40,000 years ago. It contains active steam vents, boiling mud, water filled craters and large quantities of Neapolitan yellow tuff from a more recent eruption. Over 1 million people live inside the caldera which is expected to produce more eruptions in the future. Pozzuoli is in the centre of the caldera and experiences the Bradyseism effect where the ground can ‘inflate’ due to magma chamber filling. This can result in up to 5 metres of vertical movement change. The effect can sometimes help predict a likely volcanic event.
Tony had visited Mount Etna in Sicily a number of times and on one occasion when he and a friend had hiked to the top it had started to erupt. Due to the more unusual route they had taken they had missed warnings that all visits to the peak were forbidden……Parasitic vents produce most of the ah ah lava flows from the volcano and have resulted in damage and loss to several houses and tourist buildings during the 20th century. Several attempts have been made to divert the lava flows away from populated areas, including earth barriers and explosives, with mixed results. The most destructive eruption occurred in 1669 when several villages were lost and the town of Catania threatened.
Volcano is a volcanic island north of Sicily which last erupted in 1890. There are numerous steam and sulphur vents and also shallow mud pools in which locals and tourists ‘bathe’ for supposed beneficial effects. The surrounding sea also has warm water vents.
Stromboli volcano has a distinctive pattern of eruption where almost every twenty minutes or so it erupts explosively but mildly, sending ash and fragments into the air. Tony admitted it was his favourite Italian volcano and he and his family had camped out all night near the summit in the past. Now not possible he added…..
The talk was illustrated with some wonderful photos of volcanoes and eruptions and also the destruction they have caused around the world.
Tuesday January 9th 2018 – 25 members attended
“Richard Owen, the man who invented Dinosaurs” by Dr. Chris Duffin from the NHM.
Chris mentioned that Richard Owen was described by his schoolmaster as being ‘lazy and impudent’ in his early school life at Lancaster Grammar School. However, he eventually became a medical student at Edinburgh University followed by further study at St. Bartholomew’s Hospital in London. There he prepared cadavers and organs for anatomical demonstrations and completed his studies, becoming a member of the Royal College of Surgeons.
However, a visit to Paris at the invite of Georges Cuvier, (the famous French naturalist) instilled in Owen a lifelong interest in fossils.
In 1835 he married Caroline, the daughter of William Clift the conservator of the Hunterian Museum in London, and being a talented artist it was she who illustrated his numerous papers and articles. His output was tremendous and he produced over 600 publications in his life.
In 1839 he was given a section of bird bone from New Zealand and was able to deduce that it was from a giant extinct flightless bird, the Moa. Years later when more complete skeletons were discovered he was proved correct.
Owen prepared a report on British Fossil Reptiles using Megalosaurus, Iguanodon and Hylaeosaurus as the basis of his memoir and for this coined the word ‘Dinosaur’, or terrible lizard, for which he is best remembered today.
Gideon Mantell, a contemporary of Owen’s may have helped to gather information and specimens for Owen’s papers but the two were often at loggerheads over the identification of prehistoric reptiles. Owen also had differing ideas to Charles Darwin on evolution, and was very critical of some of his theories, which resulted in further conflict. He was also often accused of crediting himself with various discoveries excluding any credit for the original discoverer, which did not help his reputation.
However, he was at the forefront of a move to have the then British Museum natural history departments re-sited into a purpose-built new museum, now known as the Natural History Museum in South Kensington. For many years a bronze statue of Richard Owen stood at the top of the first flight of stairs in the Museum, but has now been replaced by a figure of Charles Darwin……..
Owen was also involved in the construction and siting of the Crystal Palace dinosaurs, following the Great Exhibition in Hyde Park. He was at the head of the table during the famous banquet in the body of the Iguanodon, New Years Eve 1853.
Chris concluded his talk by saying that Richard Owen may have been good or bad but he was still a brilliant anatomist of his day.
Tuesday December 12th 2017
“Why Planet Earth is Habitable” by Dr. Philip von Strandmann from UCL.
The Earth has been inhabited by life for almost 90% of its 4.5 billion year existence. However, life requires very narrow climatic and chemical conditions. The implication therefore is that Earth has maintained such conditions necessary for life for billions of years. This cannot be a coincidence, which means that there must be active processes that keep Earth habitable, despite cataclysmic events such as meteorite impacts, volcanoes, continental drift and mass extinctions………..
Philip quoted Mark Twain “The two most important days in your life are the day you are born, and the day you find out why” at the start of his talk.
The earliest evidence of life on earth dates back to around 4 billion years ago, or almost the entire age of the planet. It had a hydrosphere, or a combined mass of water, within 260my of formation and could maintain some form of life. This has been interpreted from the mineral Zircon, or ‘our window into ancient earth’. Oxygen levels increased and CO2 decreased, the sun warmed the planet and temperatures varied between 15° and 35° and by 3bya plate tectonics were occurring (possibly).
Philip mentioned the Gaia theory that ‘Life is a self regulating system’ although there is some debate about this.
The established ‘carbon cycle’ is essential to maintaining a healthy planet and the long-term removal of CO2. The weathering of rocks is key to this process by producing calcium carbonate in the oceans which helps to lock up the carbon dioxide. This is eventually returned back to the atmosphere via volcanic eruptions and other processes.
The theory of a global thermostat is one that responds to hot and cold. Heat speeds up chemical reactions, causing rocks and rainwater to draw down carbon dioxide levels more rapidly, thereby cooling the planet faster. The cold temperatures will slow down this process, volcanoes will add CO2 faster than it can be removed and the planet will warm up again. This cycle has helped to maintain a climate hospitable to life.
Levels of Lithium in limestone vary with the weathering process and will generally increase in warmer periods and this fact has helped in proving the theory of the ‘thermostat’.
Some worrying trends – The earth’s average temperature has increased by 1.5degs in the last 150 years with the last 15 to 20 years showing record high temperatures. CO2 levels in November 2017 were 405.14ppm. Arctic sea ice is declining rapidly, sea levels are changing, methane levels are up and ocean circulation patterns are changing.
Philip stated that we are beyond the point that we are able to stop the increase in global warming even if we stopped burning fossil fuels altogether.
What can we do? Personally, professionally and politically?
We do not have the option of doing nothing.
‘We do not have the power to destroy earth; it will always recover in time. (But) we do have the power to destroy ourselves’.
24 AGS members braved the cold Church hall to listen to Philip Strandmann’s interesting talk. The gas to the heating units had been turned off due to a fossil fuel gas leak outside……… We were not informed.
Tuesday November 14th 2017
Frank Stokes Memorial Lecture:
“Connoisseurs of Minerals: the Freeman and Simmons Collections”
by Dr. Monica Price, Collections Manager, Mineralogy & Petrology of the Oxford University Museum of Natural History.
We often talk about connoisseurship when discussing fine mineral specimens; well-formed, richly coloured, lustrous crystals in aesthetic groups and unique combinations, are beautiful natural works of art but they are also repositories of scientific information. Monica’s talk focused particularly on two collections made by connoisseurs at very different times in history. The first was made by Dr Richard Simmons in the 19th century and the second by Pearl and Sid Freeman (both members of the AGS) in the 20th century. Both mineral collections are very special to the Museum, and Monica explained why……..
Dr. Richard Simmons MD ( 1781 – 1846 )was an early collector of excellent minerals, amassing a substantial collection during his life, and which he donated to the Oxford University Museum in 1832. He added his own labels to each of the specimens and most of them are still intact and with the collection today. He also introduced a ‘green dot’ system to the minerals for identification purposes which have been a help in collating and cataloging the complete collection recently. 68 of the outstanding minerals came from the former Merehead Quarry near Shepton Mallet, Somerset, which is now known as Torr Works, a busy limestone quarry.
Monica showed some amazing photographs of Pearl and Sid Freeman’s collection including: Dioptase on Cerussite, Baryte, Pyromorphite, Mimetite, Apophyllite and many more. The highly detailed and clear photographs were taken using a special technique which gave a greater depth of field than normally possible, thereby ensuring the crystals were in focus from front to back. There were some amazing combinations of colour, shapes and forms and Sid and Pearl obviously knew which minerals were of the more rare or unusual types. The collection is made up of over 1300 items, just under half of the Freeman’s collection as the others were purchased by a dealer. However, the museum did photograph the entire collection before it was split and therefore every mineral of their collection is catalogued. All are now organised and any AGS member wishing to view the collection would be most welcome providing they contacted Monica first. Due to the oxidation of iron sulphide which results in pyrite decay all minerals prone to such problems will be double bagged to provide anoxic storage conditions and have silica-gel crystals to remove any moisture. A ‘Blue Strip’ indicator is also being utilised which undergoes a colour change when any problems are encountered. Sid and Pearls mineral collection is obviously very safe in the hands of the Museum…….
EXCEPTIONALLY PRESERVED CAMBRIAN FOSSILS, EARLY ANIMAL LIFE, AND WORLD HERITAGE IN YUNNAN
Prof. Derek Siviter from Oxford University Museum. 10th October 2017
Among the hills and lakes of the Chengjiang area, Yunnan Province, South-West China, mudstones of Cambrian age (some 520 million years old} are yielding a spectacular variety of exquisitely preserved fossils. Since the discovery of the first specimens in 1984, many thousands of fossils have been collected, these comprising not just the hard shells of animals, but also their soft tissues in fine detail. This remarkable preservation has produced fossils of outstanding scientific importance and rare beauty.
The Cambrian Period (490-542 million years ago) witnessed the first appearance in the fossil record of nearly all the major animal groups that have sustained global biodiversity to the present day, these combined appearances comprising the so-called ‘Cambrian Explosion’ event. The Chengjiang fossils are testimony to this event and study of them is contributing fundamentally to our understanding of the early evolution of animal life. The global importance of the Chengjiang fossil sites was recognised in 2012, when they were awarded World Heritage status at the UNESCO ratification meeting in St Petersburg.
The fossil ‘Largerstatten’ of the Chengjiang area has produced thousands of fossils since 1985 when it was first discovered. Very few other sites in the world have produced such well-preserved fossils of soft-bodied animals. Trilobites with appendages and some Arthropods are also preserved even though made up of organic material, as well as soft-bodied worms. The Kunming area produces most fossils, including a brachiopod complete with pedicle, similar to examples today. A proto arthropod related to brachiopods has its head intact as well as its optic nerve and brain, making it invaluable for research. Some examples are flattened but many have been preserved miraculously in 3-D form.
There are also early cephalopods and early fish like vertebrates, plus a trilobite relative but all organic and well-preserved. Some examples are quite sophisticated animals, while others are simpler biota.
The Cambrian explosion was a real diversification event and the significance of the Chengjiang largerstatten is that it has captured a time when nearly all the phyla were introduced into the fossil record.
Derek showed some fantastic pictures of the fossils and also the area of China now well known for it’s amazing finds. 29 AGS members attended.
28 members attended for the Tuesday 12th September 2017 meeting and :
“The Textures of Peridotite Rocks of Sub-Continental Mantle Origin” by Dr. Bryan Tabor from Harrow & Hillingdon Geological Society.
“Processes involved in the development of igneous and metamorphic rocks involve some combination of crystal growth, solution, movement and deformation, which is expressed as changes in texture. Recent advances in the quantification of aspects of crystalline textures have opened new avenues of research that extend and complement the more dominant chemical and isotopic studies”. Bryan explained that it was on this theme of trying to find achievable measurement that his PhD thesis, and his talk, was based.
The deepest man has been able to drill into the earth’s crust is around 12 kilometres. The mantle xenoliths which were studied represent part of the Earth’s upper mantle, which is far deeper. These olivine rich rocks have been brought to the surface as intrusive or extrusive igneous rocks from as deep as 400 km. The examination of the textures of these Peridotic rocks were put into three major groups:
Grain size and size distribution
Grain shape and shape distribution
Contact relationship of the grains.
The groups were essential as most geological materials do not approach an ideal state and only if the grains were perfect spheres would there not be a problem! Bryan camped in the French Massif Central region for many months examining and collecting samples, a number of which came from a quarry at Molines.
Crystalline textures of mantle peridotite rocks have been the subject of detailed qualitative descriptions and ‘thin sections’, examined under polarised light, have been likened to nature’s stained glass windows. However, qualitative assessment is subjective, and a more positive method was required.
Optical scanning, skeletisation and computer measurements of individual grains were carried out as well as examination of whole thin section slides. Hand drawn skeleton outlines of grain sections and a Carnoy pixel-counting program was used to produce a summary of the measurements. Multiple thin sections were prepared so that variability could be explored.
More than 300 measurements were taken and standard deviation and crystal size distribution calculated. The relationships of crystal shapes were also examined.
Electric Discharge Disaggregation techniques were carried out on samples in Switzerland which blew apart the rock sample and separated the minerals. X-Rays, CT scans and mineral visualisation techniques were carried out in order to substantiate that final achievable measurement was possible.
Tuesday 8th August 2017 MEMBERS EVENING
Two talks from AGS members Bruce Rimmer and Vic Taylor plus the ‘Golden Egg’ competition. 24 members were present.
Bruce Rimmer: ‘Platinum – It’s Mineralogy, Extraction and Applications’.
Platinum was first discovered and used by Colombian Indians before the 15th century and was usually found in conjunction with alluvial gold deposits. In 1748 it was first reported as a ‘new’ metal. Due to its high melting point it could not be smelted, but by the 18th century it was possible to obtain higher purity by dissolving the ore in acid and burning off the impurities. Currently, the main sources are from sulphide deposits associated with nickel and copper deposits and originate from mafic or ultramafic igneous rocks. The principal sulphide minerals are Pentlandite, Chalcopyrite and Pyrrhotite. South Africa produces over 70% of the world’s platinum with Zimbabwe, Russia, Canada and others contributing lesser amounts. In SA the deposits are mined approximately 1500m below ground although other extraction also takes place from open cast areas. The refining of the platinum ore is a complicated and expensive process and involves many stages, including tumbling, flotation and separation followed by smelting above 1200°c. Its properties are numerous and include high density, high resistance to corrosion, very ductile, malleable and a high melting point. Platinum has many uses, including as a catalyst in fuel cell production, in vehicle catalytic converters, in the glass industry, as an electrical contact and due to it’s purity, in medical instruments, tooth implants, stents and of course jewellery. The price in the world’s market place can be very volatile due to the supply risk from South Africa and can be as much as 1000 US dollars/ounce! Because of its rarity and cost it is a highly recyclable metal and is indispensable in our modern society.
Bruce complemented his talk with a variety of graphs, pie charts and photographs and made it a very informative lecture.
Vic Taylor: ‘Green Skies And Brown Clouds On Lanzarote’.
Vic spoke of his investigations into the prevalence of ‘rusty’ olivine in the xenoliths he had found at two separate volcanoes on Lanzarote. The volcanoes were known as Montana Colorada and the other Caldera de los Cuervos, with the former having greater amounts of ‘rusty’ olivine than the latter. On a further visit a year later and with the assistance of his son and two grandsons Vic carried out a fairly scientific investigation into the differences. As no collecting of samples was allowed in the National Park he had to use purely visual observations to establish the density of the ‘rusty’ patches on the xenoliths. Having instructed his ‘assistants’ on the niceties of estimating the coverage the following data was produced;
Ceurvos – 49.5% of xenoliths no sign of rusting. 0.70% show 100% rust cover.
Colorada – 13.1% .. .. .. .. .. .. 11.1% show 100% rust cover.
The two volcanoes were evidently producing different olivines in their xenoliths even though presumably they were fed from the same magma source, being that they were only two kilometres apart. Geothite is an essential mineral of iddingsite and changes to a reddish brown rusty appearance when weathered. Vic queried the term ‘weathered’ when the rocks had only been exposed for less than 300 years in a particularly arid environment. However, in the later 1824 eruptions it was noted at the time that the new volcanoes that were being formed showed hydrothermal activity with water and steam geyser-like eruptions. Water was therefore available for iddingsite to be produced from the weathering of the olivine and maybe would explain the rusty discolouration; or not.
Another trip is planned in the near future to investigate further!
Golden Egg Competition.
There were four entries this year:
‘Astrobleme Evidences’ or the remains of meteorite impact craters.
A substantial piece of impact breccia, a meteorite and tektites on show.
Two lovely framed water colour paintings .
Goredale Scar and Janet’s Foss waterfall in Yorkshire.
AI Dinyo Langi, a unique volcano in Tanzania, text and photos presented in a large framed poster.
A variety of volcanic samples from around the world with labels explaining their origin and type, plus photographs.
After much deliberation by the judges the ‘Golden Egg’ was awarded to Richard Furminger and presented by Chairman Mike Howgate.
Mike Howgate doing the presenting……..
Tuesday 11th July 2017
‘Virtual Fieldwork using Google Earth’ by Ian Watkinson was postponed.
Mike Howgate, our Chairman, graciously stepped in and gave an interesting talk on Archaeopteryx, feathers and flight without the aid of Powerpoint or slides. 30 AGS members were present:
Archaeopteryx and the Dino-Birds..
A critique – part one of twenty.
Due to the absence of our invited speaker I gave an impromptu and unfortunately, as it was at ten minutes notice, unillustrated talk on my current thinking on Archaeopteryx and the so-called Proto-feathers which now adorn restorations of many dinosaurs.
I started out by outlining the history of the discovery of the first three specimens of the fossil bird Archaeopteryx, which were found in the Solnhofen limestone of Baveria in Germany. The first specimen was a solitary feather, discovered in 1859, and which was given the name ‘Archaeopteryx lithographica’, even though a single feather could not be diagnostic of a species. But that is another story.
The second specimen, an almost complete skeleton, was bought by the British Museum the following year and expertly described by Richard Owen. The third specimen was complete, and this iconic example resides in Berlin.
Archaeopteryx became the classic intermediate fossil between two distinct classes of animals, in this case reptiles and birds, and became a cornerstone of Darwin’s Theory of Evolution. However two problems still remained. How did flight and feathers evolve and which group of reptiles did the birds evolve from? The current consensus among Vertebrate Palaeontologists is that birds evolved from a terrestrial bipedal dinosaur, generally considered to be something like Velociraptor. I am one of the few palaeontologists who disagree with this theory.
One problem for the Dinosaur to Bird evolutionary link was pointed out be Gerhardt Heilmann back in the 1920’s. It is that while all birds, including Archaeopteryx, have a furcular ( wish-bone ) no such structure has been found in dinosaurs. Over the last fifty years, since the Dino-Bird theory became popular, the search has been on for a dinosaur furcula and many times it has been announced that a dinosaur furcular has been found. Unfortunately NOT. One such was an alleged growth series of furculae associated with Allosaurus skeletons. Unfortunately there were more furculae than skeletons and the furculae had already been described, correctly, as sternal ribs from one of the Allosaurus skeletons.
Then all seemed to be saved for the Dino-Bird theory. A dinosaur with proto-feathers had been found in China. The ‘theory’ that Birds evolved from Dinosaurs was now a FACT! The ‘proto-feather’ name was even proposed by a group of experts who were specially invited to China to see the evidence. However one of them blew the whistle. After they arrived in China they were told that they could NOT see the evidence, in a small Compsognathid Dinosaur called Sinosauropteryx prima, unless they agreed beforehand that what they were going to see were feathers! So they came up with the name ‘Proto-feathers’ so that they could see the evidence! You work it out!
And what of the structures which got to be called ‘Protofeathers’ ? They look nothing like feathers. Similar structures occur in Pterosaur wing membranes and are described as stiffening rods and better ‘proto-feathers’ can be seen in Ichthyosaurs* which are marine reptiles. The proto-feathers are just collagen fibres and nothing to do with the evolution of feathers. But don’t let awkward facts get in the way of a trendy theory, sorry FACT!
M.E. Howgate M.Sc. FLS
* ‘Proto-feathers’ from an Ichthyosaurus in the collections of the Huntarian Museum in Glasgow. The skull with area of ‘Proto-feathers’ behind the lower jaw and a detailed microphotograph. Photographs by Mike Howgate.
MY version of Mike’s talk, not quite so detailed……..
The first example of Archaeopteryx (ancient bird or wing) was discovered in 1861 in the Solnhofen limestone quarry in Bavaria, Southern Germany and bought by the Natural History Museum in London for £700. A second more complete example discovered around twenty years later now resides in Berlin. All examples have teeth, a bony tail, three ‘fingers’ with claws and evidence of plumage or feathers, miraculously preserved in the very fine shale. The limestone is so fine that it was split and utilised for lithographic plates for many years.
Many claims have been made over the years for connections between flight, feathers and Dinosaurs. NO dinosaurs have so far been found with furculae. The so called furculae or wishbone found with Allosaurus skeletons were in fact gastric ribs or gastralia. Seven were found with three skeletons, a statistical impossibilty if they were furculae. Plus they were described as gastralia in the original monograph with the furculae suggestion being added in the later reprint. The successful fully flying reptile would have had to evolved either by initially gliding down from trees and progressing to full flight or by being a bi-pedal fast running animal eventually able to achieve flight. (like a swan)
Many fossil skeleton finds have been made more recently, especially in China where claims have been made for evidence of ‘feathers’, which more than likely are stiffening fibres, as in a wing membrane from a Pterosaur. The connection between Dinosaurs and feathers is now so popular that even plastic models are covered in feathers. The speaker called this trend ‘Nonsense!’……….
Thank you Mike.
Tuesday 13th June 2107
“Internal Features of Gemstones” by Pat Daly from Gem-A
Pat explained that inclusions and flaws found in almost all gemstones can be observed using a gemmological microscope with an angled lighting option or even using a standard 10x loupe.
The inclusions would assist in determining if the stone was genuine, synthetic or had been heat treated to enhance the colour and even from which locality.
A ‘Horsetail’ inclusion (as in the plant) in a demantoid garnet would prove that the stone was genuine, as this particular flaw is impossible to reproduce in an artificial garnet.
Similarly, fissures or ‘feathers’ can occur in emeralds and this is expected and proves it is a natural stone.
Synthetic rubies can contain bubbles which would not be expected if the stone was of good natural quality, as for instance in a Star Ruby. A glass filling technique is used abroad to fill fractures in rubies, Pat’s advice was to be careful who you buy from!
Diamonds can contain pyrope and olivine crystals and some diamonds can even contain a diamond crystal as an inclusion.
Moldavite, a tektite from a meteor impact has complicated inclusions, folded and refolded from the impact but these would not be evident if it was synthetic.
Almost any translucent stone can be examined under a gemmological microscope and its internal structure studied. For instance, hematite in quartz, moss agates, small cauliflower-like hematite growths in Jasper, fire agates with irradesence and even inclusions in Baltic amber, including detail down to the hairs on the trapped insects. Finally, rutile in quartz will show up as reddish needles with the stones being polished to show them off for the best effect.
Pat showed numerous photographs of Gemstones with various inclusions to illustrate his interesting talk. – 34 Members attended.
Tuesday 9th May 2107
“Chromite, Tungsten & Iron: Mineral deposits and mines in Portugal” by Lesley Dunlop from Northumbria University.
Leslie’s interest in the minerals of Portugal followed on from her earlier studies of deposits in Devon and Cornwall.
With a geological map of Portugal she pointed out how the rocks are older in the North, being pre-Cambrian and Silurian but younger towards the South of the country. An Ophiolite complex near the northern Braganca district hosts chromite deposits in its ultrabasic rocks and has hundreds of disused shafts and adits from mining which continued up until the 1950’s. A photograph showed an example with black flecks of chromite in a metamorphic rock which would have been derived from a depleted mantle source.
Travelling South, the Panasqueria granites are associated with the Tungsten and Tin deposits, the former being very important since the 1930’s and still being mined today, mainly for heating and lighting elements, machine tools and as a high temperature alloy. The Romans originally mined the tin deposits which were found in veins above the granite in the country rock. Wolframite is the Tungsten ore and Cassiterite the Tin ore.
The Iberian pyrite zone in Southern Portugal is primarily worked for iron but gold, silver and copper are also found. Pegmatite is a primary source of Lithium which is mined in central and southern Portugal and becoming increasingly important with the interest in electric vehicles powered by Lithium–iron cells. It has a similar composition to granite but can contain much larger crystals of feldspar and quartz, as Lesley illustrated with some excellent photographs.
Aside from the minerals in the country, Estremoz and Borba in the South have huge marble quarries, worked vertically in open cast pits and have lifts large enough to hoist lorries to and from the quarry floor.
Lesley mentioned many other places of interest, including the Lisbon coastline, Ordovician quartzite ridges, mine tailing or waste tips, Mouros museum (although closed) and also of course mentioned the great climate and the dodgy roads!
Tuesday 11th April 2017
“Sandstone Fantasies of Jordan” by Dr. Tony Waltham of Geophotos.
Tony explained that he and his wife had visited Jordon many times over a number of years and although he called it ‘boring Jordon’ because of its scrubby, flat, desert areas, the wonderful World Heritage Site of Wadi Rum, the Nabataean capital of Petra with its elaborate sandstone mausoleums plus its geology made up for it.
The country itself is almost landlocked, being surrounded by Saudi Arabia, Syria and Israel and only having one connection with the Red Sea at the Gulf of Aqaba. The Dead Sea is an important tourist resort and is 400 metres below sea level. A slide of Tony’s wife floating around reading illustrated how the sea is around ten times saltier than most oceans and also shrinking, due to the siphoning off of its water source for agriculture.
Wadi Rum near Aqaba is a rocky and desert environment with canyons cut deep into the sandstone and granite rock. The Nabataeans carved images of humans and animals into the rocks forming the valleys when they inhabited the area around 300BC. Modern Bedouins live in tents and houses nearby and drive four wheel all terrain vehicles for transporting the many tourists around the area, a complete contrast to when Tony first visited in the 1980’s.
He mentioned Black Iris’s growing wild, phosphate mines, dolerite dykes in granite, volcanic plugs, showed images of huge landslides caused by flash flooding, tall pinnacle’s of Cambrian sandstone with bedding and most impressively, some wonderful pictures of the Nabataean ‘Treasury’ and ‘Monastery’, elaborate, temple like sandstone buildings carved into the rock at Petra. Along with hundreds of other smaller buildings cut into the rock, they were all originally built as mausoleums, for interning their dead and are fairly small inside. The sunlight showed up the incredible colour banding in the rock and also ‘Liesegang’ rings in the sandstone roofs inside some of the tombs, caused by precipitation during the formation of the sedimentary rock.
Tony’s talk was superbly illustrated with his own photographs and fluctuated somewhere between being a travel talk and a geological lecture. He was very enthusiastic and made it a very interesting and educational evening.
Penny Badham from the AGS bought in some wonderful rocks collected from the area during a visit in 1994 and also one of her well executed watercolours of the ‘Treasury’. See below….
Tuesday March 14th 2017
“Stones said to have fallen from the clouds” – Prof.Paul Henderson. UCL.
From the earliest recorded meteorite fall in 1492 through to the 1800’s the idea that meteors may have originated from space was not well received. Sceptics put forward theories that volcanoes, subterranean gases, debris from hurricanes and many other ideas were much more likely. The theory they were from volcanoes on the Moon or a sign from God were also accepted. It was not until a major fall in Siena in 1794, witnessed by locals and European visitors that scientific investigations were carried out, papers and books written by academics and the study of meteors really began to develop. The Wold meteorite in Yorkshire of 1795 and a further large fall in France in 1803 helped to convince most that the meteorites did fall from the sky, but much further away than previously ever imagined. Now we understand that most of these extra-terrestrial rocks originate from the asteroid belt between Jupiter and Mars, can be microscopic dust or over 1000meters in diameter, as in the K/T event.
The last recorded fall in Britain was in 1991, in Mr Arthur Pettifor’s back garden in Glatton, Cambridgeshire. So keep looking………
Paul Henderson gave this interesting talk to 32 attentive AGS members, along with some fascinating slides and facts. Julia, Doug, Mike and C.D. bought along the related objects shown below and we thank them very much.
Tuesday 10th January 2017 – Synopsis
‘IGUANODON’ by Dr. Chris Duffin, Scientific Associate at the Natural History Museum.
Gideon Mantell was a famous geologist and paleontologist in the 1800’s and a passionate collector of fossils. With his wife Mary he was credited with finding the very first Iguanodon tooth in Tilgate Quarry, Sussex in 1822. Whether he found it, his wife or possible a quarry worker was never really established. The name was conceived due its similarity to an Iguana tooth, although considerable larger.
Further finds and a bone assemblage discovered in Maidstone Kent in 1834 enabled Mantell to make the first attempt at a reconstruction. He made one well-known error by placing the (then unknown) modified thumb on the nose to resemble a horn. This is still depicted in Richard Owens reconstruction in concrete and steel in Crystal Palace Park. (see ‘Gallery’ page of the website)
The discovery of much better specimens in later years revealed that the horn was actually a modified thumb.
Before that was established Gideon Mantell suffered a carriage accident in 1841, resulting in a spinal deformity and death in 1852 from an opium overdose. His deformed spine was removed and pickled and stored at the Royal College of Surgeons. Unfortunately it was thrown away in the 1960’s …….
In 1878 the remains of 38 fossil Iguanodon’s were found in a coalmine at Bernissart in Belgium at a depth of over a 1000 feet. It was established that they lived around 125mya during the early Cretaceous. The assembly of 36 females and 2 smaller males have given rise to many theories on their deaths and also where and how they lived. Were they drowned in a gorge during a massive flood? Did they all die inhaling noxious fumes? Or was it similar to a modern elephants graveyard?
Whatever, the number of complete skeletons enabled Louis Dollo, a French born paleontologist to establish the position of the modified thumb with certainty. Along with four other fingers it would have been a slashing weapon and used for defense. He also established that the teeth, which met at a steep angle, gave a parallel bite and were suitable for grinding leaves and foliage, as an Ornithischian herbivore. Their pubis bone faced backwards at an angle allowing for a larger digestive tract. These huge animals would have measured up to 13 metres long, weighed over 3 tons and been bipedal although capable of walking on all four limbs.
9 of Dollo’s reconstructions are still on show in Brussels.
Chris gave a fascinating talk on a topical subject to around 38 AGS members, introducing all the Victorian personalities involved in the early discoveries with lots of slides and detail.
Some specimens bought in by Eric Freeman and displayed for the talk.
Tuesday 13th December 2016 – Synopsis
“Our Heritage – Stone Tools and Rock Art” Bob Maurer from Harrow & Hillingdon Geological Society.
Bob brought along some wonderful examples of horn, flint and sandstone Palaeolithic tools. (see photos) The latter type he found several years ago in a cave in South Africa and has been dated to 700,000 years old. Two other examples were attempts to fashion flint-cutting tools himself during a two-day ‘Flint Knapping’ course. He was determined to discover the skills and intricacies required to produce a Stone Age tool.
The talk guided us through the early attempts 2.5 mya to fashion stone tools (Oldowan), through to later more sophisticated tools and weapons.
Around 1.7mya ago during the lower Palaeolithic man began to improve on basic cutting tools by fashioning stones with many more cutting edges and sophistication. More advanced primitive people of 700,000ya were quite capable of removing hides in one piece, dismembering the carcass and cooking the meat, as well as being fully clothed in animal skins. Evidence of tanning processes to soften the skins have also been found.
Bob illustrated the talk with a number of slides of cave paintings in Libya, depicting Bovid and Aurochs which were introduced to North Africa around 15,000 to 20,000ya, during the Africa Humid Period. Altamira Caves in Spain date from the same period and show Palaeolithic herds of European bison and bulls. With sea levels much lower it was possible that man migrated down through Italy into Sicily and into Africa. Rock art in the Akkakus Mountains of Libya show wide horned Bovid herds and in the Libyan Museum tethered and harnessed animals. Man is depicted with Caucasian features and wearing dress like kilts.
Other similar cave paintings show dogs hunting gazelle, humans with head ornaments and war scenes while others show stylised dance scenes with muscle and movement depicted. The colours were mainly red and were made from iron oxides, such as hematite or ochre ground up and mixed with animal fat and blood etc.
Bob also described the oldest musical instrument ever found, a long, thin flute- like instrument with five finger holes found in Hohle Fels cave in Germany, made from a wing bone of a Griffon vulture and dated at 40,000 years old.
An interesting lecture with plenty of colour slides to illustrate the talk and actual stone tools to examine.
Tuesday 8th November 2016 – Synopsis.
‘Carbonado-Diamonds From Space’ by Prof. Hilary Downs, Birkbeck University London.
Not your average diamond, but micro diamonds found in Carbonado rocks in alluvial deposits of West Africa and Brazil. They can range from 1um to 200um in size but mostly are nearer 10um and are used mainly in industrial processes. Previous opinion was that they had originated from deep within the earth, but recent theories suggest they may have arrived on the Earth’s surface by impact with a comet, asteroid or some other carbon rich object.
They are not polycrystalline or mono-crystalline diamonds as recovered from Kimberlite pipes but were shown in electron microscope images to be cube-like crystals. When tested they were approximately 3 Ga (3 billion) years old. Some rocks had a glassy crust and shock features as well as radiation damage and metal inclusions, all indicative of an impact from space. They contained VERY rare Nitride minerals, some not normally seen even in meteors and there were other hollow needle like crystals of unknown minerals. Evidently there are no carbon planets in our solar system, therefore it has been suggested that they may have originated from outside our solar system, although this has now been discounted as unlikely. More likely a Titan-like moon impact created high temperatures in a carbon rich atmosphere, thereby causing ‘plasma’ to form which then condensed to produce Carbonado, similar to chemical vapour deposition. This would explain the porosity, crystal morphology and the nitride metals, but it is only a hypothesis………..so watch this space.
Tuesday 11th October 2106 – Synopsis
‘Mesozoic Marine Reptile Renaissance Part Two’ Dr. Mark Evans, Leicester Arts & Museums Service.
The Mesozoic Marine Reptile Renaissance Part Two: Sauropterygians
Following on from the talk last year on the recent increase on our understanding of ichthyosaurs and their relatives, the talk focused on the sauropterygians. This was the longest lived group of Mesozoic marine reptiles ranging from the Olenekian (Early Triassic) all the way to the end of the Cretaceous and included the plesiosaurians of the Jurassic and Cretaceous. Recent years have seen a flood of new taxa from the Triassic of China. Some of these are similar to European taxa from the Germanic Basin and the Alps demonstrating interchange between the western and eastern areas of the Tethys Ocean. Among the new discoveries are members of a newly recognised enigmatic group, the Saurosphargidae, which may well be the sister group of the sauropterygians proper. The durophagous placodonts, the earliest diverging sauropterygian group, is also represented in China. Together with European material these new finds have improved our understanding of the evolution and palaeobiology of this somewhat overlooked group. Renaissance is also happening closer to home in the study of the Jurassic plesiosaurians of the UK. Dr.Evans summarised ongoing work on early Jurassic rhomaleosaurid plesiosaurian specimens, including those from the Leicester collections, which indicated that their diversity was higher than previously thought. He also described the skull of a giant pliosaurid plesiosaurian discovered in recent years in Dorset. The whole talk was illustrated with some wonderful coloured, life-like reconstructions of the marine reptiles.
Tuesday 13th September 2016 – Synopsis
“Virtual Fossils – Soft Bodied Sensations from the Silurian” by Prof. Derek Siveter from the Oxford University Museum.
Derek’s hobby of Palaeontology many years ago turned into a career spanning more than forty years. His talk concentrated on the Silurian period (around 425my.) and the remarkable fossil finds in Herefordshire Konservat-Lagerstatte. These are worms, molluscs, brachiopods and arthropods, plus others, entombed in nodules and beautifully preserved. (see photo) They occur as calcite in-fills inside the nodules and were encased in clay almost immediately after burial, which helped preserve them. The nodules themselves were discovered in a volcanic ash layer from where the calcium helped to produce calcium carbonate which replaced the soft tissues of the animal. The fossils are very small, just a few millimetres usually and cannot be ‘prepared’ or removed from the the surrounding matrix by normal methods. Instead, they are ground down in 20µ increments (20 thousandths of one millimetre), then photographed, then ground down again, photographed and so on until the fossil is destroyed (!) The photographs are then downloaded into a ‘Spiers’ software program which reconstructs the slices into a 3-D image or ‘Virtual Fossil’. The enlarged coloured images can then be studied in detail, including all the soft parts, and also turned into models of the animals. Derek gave a fascinating talk and showed us numerous wonderful photographs.
My photo of fossil with permission.
For more info on this subject click on the link: www.shropshiregeology.org.uk and look at the suggested reading topics.
Tuesday 12th July 2016 – Synopsis
John Pearce – ’30 years collecting with the Sussex Mineral and Lapidary Society’
John has been around the UK and the world in his quest to find the ultimate mineral. Field trips to The Isle of Sheppey, Wells in Somerset, Cumbria, Skye, Namibia, Lanzarote, New Jersey, Bulgaria, Ireland, India and the Faroe Islands, to name a few! He has paddled around with Wellington boots full of water, abseiled down cliffs, crawled through tunnels, scrabbled around quarries and been down several mines and one time found so many specimens he had to ship them home by sea; seriously. Wulfenite, Barite, Stilbite, Azurite, Peridotite, Zeolites, Galena, Gold, Samsonite, Chabazite are a just a few of the beautiful minerals that John has found over the years. The descriptions of the trips and the photographs of some of his beautiful finds made it a fascinating talk.
TUESDAY 14th June 2106 – Synopsis