Monthly talk: Monday 12th June 2023 7.30pm

Describing rock samples

by Dr Mike Tuke

For ‘beginners’ this is a good introduction to the various types of rocks you may find (and some of the fossils they may contain), whilst for those more familiar with geology, it is a chance to gain more in-depth experience. 12 large rock samples will be on display and you will be asked to write a description of each sample. The descriptions can use non geological terms to cover, for instance, the colour, size, shape, texture and any visible features OR the descriptions can use appropriate geology terminology. During the last part of the evening Mike will give a geological description and interpretation of each sample. Bring paper and pencil!

Fen Edge Trail Walk: Saturday 17th June 2023 10.30am

For Celebrate the Fens Day

 ‘through the fen edge town that became one of the world’s most famous cities’

 Led by Martin Evans, CGS Fen Edge Trail Team

Approx. 2.5 hours to 1 pm. For Celebrate the Fens Day, this walk starts on the distinctive landscape feature of Castle Hill (a Chalk hill) and finishes at the Sedgwick Museum of Earth Sciences. It gives a landscape heritage and geological perspective to the city: the river’s gravel terraces, the chalk stream-fed river and the ‘fen’ meadows of alluvium and peat. The walk will also draw attention to buildings and places of historical and social interest. Guiding you through what is now a mostly hidden landscape, the walk takes you back in time, giving a glimpse into the city’s past and the natural history of the area, from ‘Ice Ages’ to sub-tropical swamps and fenland rivers. You will discover how its natural character still filters through, seen in the riverside meadows, the numerous water channels, the subtle changes in the height of the land and even in the building stones used in many of its famous buildings.

All welcome. Free as part of Celebrate the Fens Day but needs booking in advance. Easy walking, about 3 miles. For more details see the website www.fenedgetrail.org where you can also download the full Walk Guide. Contact us to book.

Visit to Cambridge Botanic Garden to see ‘Living Fossils’: Tuesday 27th June 2023 10.30am – 12 noon

 Led by Franziska Norman, CGS

Following Franziska’s fascinating talk on ‘Living Fossils’ to CGS in March, she has arranged a visit to the Botanic Garden where she will give a tour of the Garden to take in these ancient plants and see how they are growing and surviving in the UK.

The cost is just the usual entrance fee to the Garden of £7.20 or £8 including Gift Aid (free for Friends of the Garden). However, that will allow you to explore the garden after the tour is over and take refreshment in the café.

All welcome. Needs booking (more details given after booking). Easy walking. Contact us to book.

Fen Edge Trail Walk: Sunday 2nd July 2023 10am

Thorney – ‘an iconic fen island – monks, marshes and a model village’

 Led by Dot Halfhide (Thorney Museum) & Penny Coggill (CGS Chair & Fen Edge Trail Team)

In partnership with Thorney Museum and the Thorney Society. Well-known for its ancient Abbey, Thorney is also a good example of fenland’s interesting geological history. This will be a guided Landscape Heritage walk on the Fen Edge Trail on the ‘island’ of Thorney. The walk will cover cultural history, fenland landscape and  geology. Thorney, the ‘Isle of Thorns’, was a fen island surrounded by marshes until the drainage projects of the 17th century. It has been known since the 7th century for its major Benedictine Abbey; the large Abbey church remains impressive, even though much of it was lost in the 16th century. The Victorian village is of the characteristic local brick and is famous for being a ‘model village’, built in the 19th century under the Duke of Bedford’s ownership.

All welcome. £3 per person (payable in advance). Children free. Needs booking. About 2.5 hours to 12.30pm. Easy walking about 2 miles, slow walk, some on pavement, most on grassy tracks. For more details see the website www.fenedgetrail.org where you can also download the full Walk Guide. Contact us to book.

Field trip: Sunday 16th July 2023 10am

Great Fen Local Geological Site

 Led by Dr Steve Boreham, Chris Donnelly (CGS Geosites Team) & Henry Stanier (Wildlife Trust BCN)

Over recent years, the CGS Geosites team, with the help of Dr Steve Boreham, has been working with The Wildlife Trust BCN to highlight the geological importance of this key fenland site, also obtaining its designation as a Local Geological Site. This guided visit will explore the area to provide an understanding of the geology of the local and wider Fens and how it relates to both ecology and local history. We will see Holme Fen, which contains the remains of raised bogs and some of the deepest peat still surviving in fenland, and also the site of Whittlesea Mere, which has extensive deposits of shell (lake) marl. Underlain by Jurassic clay and ‘Ice Age’ gravels, the area also contains the ‘Fen clay’ from the Bronze Age marine incursion, seen within complex layers of buried peat or in small roddons at the surface, and the site of the ancient Trundle Mere, near to where the old River Nene enters the fenland. We will examine a core taken through the layers of peat that reveal the local history from the Neolithic and Bronze Age to the present. Visiting five sites, this will give a ‘behind the scenes’ insight into the Great Fen habitat restoration work and include a walk in Woodwalton Fen National Nature Reserve to enjoy the wildlife and see the historic Rothschild Bungalow. The area is rich in history and we will see the Holme Posts that show the dramatic effect of fenland drainage (particularly that of the famous mere), limestone blocks once destined for the walls of historic buildings as well as the remains of the old brick kiln at Ramsey Heights.

Easy walking during a few short walks. We can use the ‘facilities’ at Ramsey Heights Countryside Classroom, where we meet at 10 and return for a late lunch (coffee/tea/soft drinks provided but you will need to bring a picnic lunch). You will need to drive (in own vehicles) from Ramsey Heights Nature Reserve to the other sites – lift sharing may be possible.(Unfortunately, there is very limited public transport to within walking distance of Ramsey Heights NR and none to other sites visited). Info: www.wildlifebcn.org/nature-reserves/ramsey-heights. Full itinerary, maps and times provided after provisional booking. Shared minibus transport from Cambridge (cost TBA) may be possible for those who would like it. £5 CGS members (non members £6, subject to space availability).

Building Stones of Cambridge Walk:

Monday 29th May 2023 10am

For GeoWeek and Cambridge Nature Festival

 Led by Penny Coggill (CGS Chair)

Cambridge is a beautiful city! Why? Because it has a great number of very fine buildings – university, ecclesiastical, public and commercial – built with some affluence, which meant the owners could use stone, and the more fashionable and pleasing to the eye that stone was the better. Join us for this guided tour around the city to see how these different stones were used, where they came from, how building and architectural fashions changed over time with improvements in transport and see what stones are used today to enhance the built environment. Our locally sourced stones tell us about the past environments of the area –  as seen in the fossils that many of them contain –  from Chalk ‘clunch’ to highly prized Jurassic limestones. Others, such as granites and ‘exotic’ pebbles tell the story of earth’s history elsewhere in the world. You will never walk through the city with the same eyes again.

All welcome. 2.5 hours to 12.30pm. Easy walking. £3 per person (free for CGS members). Needs booking. Contact us to book.

Fen Edge Trail Walk: Sunday 21st May 2023 2.30pm

(postponed from 14th May)

The Old & New Bedford Rivers, Earith

‘along the great drains created in the 17th century by the Company of Adventurers’

Led by Peter Daldorph (The Word Garden) and Chris Donnelly (CGS Geosites & Fen Edge team)

This walk, at the southern end of the Ouse Washes near Earith, visits the two great ‘drains’ that created the Washes which now play a vital role in the flood management of the Fens whilst also being an internationally important wildlife conservation area. You will learn about the incredible construction of the the 100 Foot River (also called the New Bedford) by the Company of Adventurers in the 17th century during the ‘Common Wealth’ and the rule of Oliver Cromwell. This is also a good area to visit to understand the changes in the course of the River Great Ouse as it enters the fenland, and its links with the Old West River and the West Water.

All welcome, needs booking. £3 per person (to be paid in advance), children (under 18) free. Easy walking, about 2 miles, 1.5 hours to 4pm, but a longer walk is possible for those who wish. For more details see the website www.fenedgetrail.org where you can also download the full Walk Guide and accompanying podcast. Contact us to book.

Previous talk: Monday 15th May 2023 7.30pm

(NB The 3rd Monday in May not the 2nd, to avoid the bank holiday)

The Hunga Tonga-Hunga Ha’apai eruption and tsunami

– learning from recent events

Prof. David Tappin, BGS

The Hunga Tonga-Hunga Ha’apai tsunami on the 15 January 2022 was the first from a violent eruption for over 130 years, the last being Krakatau volcano eruption in Indonesia in 1883. The event was also the first dual eruption tsunami since Krakatau and the first recorded by modern technology. The resulting shockwave was the largest and most significant ever recorded, with the associated plume the highest on record. This talk covers the event and its ramifications in providing information critical to developing mitigation strategies from these events.

Previous talk: Monday 17th April 2023 7.30pm

(NB The 3rd Monday in April not the 2nd, to avoid Easter)

Living Fossils in Cambridge University Botanic Garden

Franziska Norman, CGS Committee and ex Chair

This talk will introduce you to plants that have survived practically unchanged for many millions of years and so have become a living window into the time of the dinosaurs. Fortunately, although none of them are native to the UK, you don’t have to travel far to see them, as many of these can be found in Cambridge University Botanic Garden!

Previous talk: Monday 13th March 2023 7.30pm

The geology of the Northwest Passage

Dr. Owen Weller, Department of Earth Sciences, University of Cambridge

Previous talk: Monday 13th February 2023 7.30pm

Fossil brachiopods shells as outstanding archives of climate in the deep past

Dr. Claudio Garbelli, Department of Earth Sciences, University of Cambridge

Brachiopods are present in the marine benthic communities all over the Phanerozoic and they were the dominant bivalved organisms in the Palaeozoic. Their calcite shells have a high preservation potential, allowing the palaeobiologists to reconstruct their life histories from individual to community level. Because their physiology constraints, these organisms change in response to environmental parameters, and they thus represent a powerful archive of past oceans conditions and climatic variations. Also, their episodic growth patterns provide a sequential record of growth increments which can then be analyzed through morpho-structural and geochemical proxies for tracing environmental variables even at seasonal scale. Fossil brachiopods shells can thus be considered excellent archive for the study of ancient ocean condition.

Previous talk: Monday 9th January 2023 7.30pm

An evening of short talks by members

Dr Mike Tuke:  ‘The cooling of teapots and igneous intrusions’       By thinking about the factors which control the speed of cooling of teapots we can see how these same factors affect the speed cooling of igneous intrusions and thus of the degree of metamorphism. This will involve the presence of Teapots!

Lee Wells:  ‘Basalt Trap Feature rocks’   A collection of igneous ‘lumps’ from ‘trap stone’ sites.

Dr Martin Evans:  ‘Phonolite – the singing stone‘   A quick look at the distribution, geological origins, and mineralogy of this uncommon extrusive rock and its use for roofing (and xylophones!) in central France.

Penny Coggill:   ‘Lost industrial heritage of Cambridgeshire’    On a recent ‘Investigating Old Maps’ course at U3A a short end-of-course presentation was required. There are a huge number of old quarries (pits) around the villages of Cambridgeshire – most of which are “invisible” to all but inquisitive minds. I sought to use one set of early OS maps to identify as many of the old pits, quarries, kilns, wells as I could all of which were dependent on the underlying geology. This, I hoped, would help to identify potential Local Geosites within the county.

Dr Reg Nicholls:  ‘The Borrowdale Volcanics group – arguably the most attractive Rocks in England!’

Previous talk: Monday 12th December 2022 7.30pm

Paleoclimateology from Snowball Earth to Anthropocene

Dr Colin Summerhayes, Scott Polar Institute

This explains how greenhouse gases and temperatures varied through time, giving us alternating periods of warm ‘greenhouse’ climate and cold ‘icehouse’ climate over the past 800 million years. It explains how it is that Antarctica was once covered by subtropical forests, and why ice sheets did not cover it until 34 million years ago. It also explains the origins of the global Ice Age of the past 2.6 million years, explores the roles of the Sun and of the Earth’s orbit in controlling past climate change, and provides a past natural analog for today’s unnatural global warming. The past is the key to understanding the future.

Previous talk: Monday 14th November 2022 7.30pm

Natural Hazards turning into disasters

Dr. Ekbal Hussain, British Geological Survey

Globally, two thirds of deaths arising from natural hazards in recent decades were caused by geological hazards. But how and why do natural hazards turn into disasters? In this talk I will explore this question through the lens of one particularly troublesome hazard: earthquakes. The death toll for a given earthquake magnitude (and mechanism) will depend on geographic location, the social vulnerability of communities and the quality of the building stock. This talk will compare and contrast global trends in earthquake fatalities and aim to extract common themes that exacerbate the impact of natural hazards, and consider where and why these turn into disasters.

Previous walk: Saturday 29th October 2022 c.10am

Additional walk due to popular demand!

Guided walk from Reach to Burwell

BOOKING NEEDED

Fen Edge Trail guided walk, visiting two Local Geological Sites, Carter’s Pit and Castle Spring at Burwell, led by Dr Reg Nicholls, Chairman of CGS Free to CGS members and to non-members in celebration of the Festival of Geology. 

Previous talk: Monday 10th October 2022 7.30pm

Darwin and the geology of Galapagos

Prof David Norman, Dept of Earth Sciences, University of Cambridge

Charles Darwin is, of course, justly famous for his detailed compilation and analysis of the evidence that formed the basis for a non-theological explanation of the diversification of organic life on Earth through the publication of “On the Origin of Species” in 1859. His subsequent books reinforced these views, and history shows that he was able to establish new branches of scientific investigation, and that his theoretical model was largely correct – even though he couldn’t induce the underlying mechanism that made it all happen. As a consequence, he stands alongside Newton as one of our intellectual pillars. But what if he had not published for fear of offending society and his deeply religious wife Emma: would we even remember him? I think we most probably would remember Darwin because the early part of his career saw him establish himself as one of the most able observational and interpretative geologists in the world (Geikie was shocked to realise this in 1907!) – Darwin just got distracted from his “first love” by all those organisms.

Previous talk: Monday 12th September 2022 7.30pm

Metals in Magmas: Tracking Metal Chemistry and Magmatic Processes in Indonesian Volcanoes

Dr Nick Barber, Dept of Earth Sciences, University of Cambridge

Yorkshire folk are often quoted as saying that in Yorkshire everything is bigger and better – perhaps Brimham Rocks near Harrogate fall into that category! This National Trust park has amazing natural stone pillars that rival anything seen in Cappadocia Gorem National Park. They are of Carboniferous age, Millstone stacks that tower on top of a plateau rising up from the Nidd valley. Their 3 dimensional aspects display the fluvio-deltaic sedimentary structures beautifully. Deposition was in a braided river system fed from the Calidonides to the North East infilling the Variscan Craven Basin systems. Far from being constructed by Druids or the result of the biblical deluge, these rock formations are thought to be the product of glacial assisted sand and ice blasting.

Previous talk: Monday 9th May 2022 7.30pm

Celebrating GeoWeek 2022 7-15 May

Geoconservation past, present and future

Dr Colin Prosser, Natural England

Although most people think of wildlife when they think of nature conservation, geology is part of nature and geoconservation is part of nature conservation.  Britain has been a world leader in geoconservation since 1949 when the government passed the first national nature conservation legislation which explicitly made provision for geoconservation.

This talk explores the origins of geoconservation in Britain, how it became recognised and included in legislation, how sites worthy of conservation were identified, and how it has evolved to where we are today. It touches on Local Geological Sites, Sites of Special Scientific Interest, National Nature Reserves, UNESCO Global Geoparks and World Heritage Sites, the rapidly growing global interest in geoconservation and the challenges and opportunities facing geoconservation in the years ahead. In doing so, this examination of geoconservation past, present and future will explain the links between  boulders, lunacy, ‘robot planes’, a Cambridge geologist and the 6^th of October.

Dr Colin Prosser is the Principal Geologist at Natural England, the government agency responsible for nature conservation in England. He has over 30 years of experience in geoconservation, applying legislation, shaping policy and developing practical approaches to conservation on the ground. He is a past President of the Geologists’ Association, a member of the UK Committee on UNESCO Global Geoparks and of the Black Country UNESCO Global Geopark management Team and has served on the Geological Society of London’s Geoconservation Committee. He is an editor of the Proceedings of the Geologists’ Association, specialising in papers on geodiversity and geoconservation, and has published over 100 papers, books and articles on geoconservation.

Previous talk: Monday 11th April 2022 7.30pm

Plesiosaurs, Pliosaurs & more – excavating the Jurassic’s marine reptiles

By Richard Forrest, Chair of Peterborough Geological and Palaeontological Group

The fenland of eastern England is underlain in many places by Jurassic clays which have been heavily exploited for brick-making and other commercial purposes over the past two centuries. Many thousands of fossils of marine reptiles have been uncovered during quarrying operations and form the largest such collection anywhere in the world. In many cases, bones can be retrieved undistorted and free of matrix; much of our knowledge of the anatomy of plesiosaur and other marine reptiles is built on these finds. Bricks are still manufactured on a large scale and, although highly mechanised extraction destroys many fossils, significant new finds are still being made.

This talk centres on the excavation of two such specimens, a pliosaur from the Kimmeridge Clay of north Lincolnshire and a juvenile specimen of Cryptoclidus, a  long-necked plesiosaur, from the Oxford Clay near Peterborough. Their importance lies not only in the fossils themselves but in the scientific information we can retrieve from careful and systematic recording of their excavation.