Monthly talks and occasional Field trips

We have a programme of 10 Monthly talks running from September to June each year, held on the second Monday of every month. All talks (unless specified otherwise) are at 7.30 pm (doors open 7.00 pm). Everyone welcome, free to CGS members, £3 for non members. From September 2022 onwards these will be held at St Andrew’s Centre, Histon: Hall 1, St Andrews Centre, School Hill, Histon, Cambridge CB24 9JE. The Citi 8 bus stops outside the Centre and the Guided Bus is 15 minutes walk away. There is a free car park approximately 200m along the road just past a small supermarket.

Our talks for the Sep 2021 – June 2022 season were online (using ZOOM). At present, we are not able to offer the September 2022 to June 2023 as hybrid talks by Zoom, but please contact us if you are not a member or not already on our ‘zoom’ mailing list. Once registered we will let you know if this changes (or if we can offer recordings for watching afterwards).

We organise a few Field trips each year. These include visits to local sites with geological interest and walks on the Fen Edge Trail to explore the landscape, geology and associated history. Most are open to everyone and often free (or with a small charge to non-members). All require booking by contacting us. Free Walk Guides to our series of Fen Edge Trail walks can be downloaded here.

Monthly 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.

Monthly talk: Monday 13th March 2023 7.30pm

The geology of the Northwest Passage

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

This talk will discuss a less well known feature of the fabled Northwest Passage: the four billion years of Earth history contained in the geology along the route. Alongside an overview of the spectacular geology, the talk will include a discussion of how geological research is conducted in the Arctic, how the region has contributed vital evidence in the ongoing debate about when plate tectonics started on Earth, and unexpected links with both Margaret Atwood and my College at Cambridge: Sidney Sussex. More info in this blog.

Previous events

Monthly 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


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

This walk makes use of the bus between Reach and Burwell to travel one way and walk back (or you can arrange to car share and leave a car at each end). The walk will start in Reach around 10 -10:30 am (exact time to be announced, depending on the bus timetable). We will have a brief look at the Totternhoe Stone quarry site in Reach, before walking a section of the Devil’s Dyke earthworks – passing the site of a Roman villa. We then cut into Burwell via Pauline’s Swamp nature reserve where (assuming there has been some rain) we can see some chalk springs. After crossing Stephen’s castle, we stop at Castle Spring LGS to see a rare exposure of the base of the Totternhoe Stone before travelling uphill and up the rock succession to Carter’s Pit – a disused quarry once dug to win the famous Chalk ‘clunch’ (the Totternhoe Stone again). We then make our way through the village – passing several historic sites and taking in the variety of local building stones in the walls and houses. The walk finishes at the edge of the Fens, once more, near the old industrial wharves on the Catchwater, running into Burwell Lode.
Length of walk 4.1 miles (approx 2.5 hours). For a slightly shorter option you can finish in the village centre rather than walk on to the lode. There should be the opportunity to grab a lunch in the various hostelries or the village coffee shop. Meeting place, exact timings and full details given on booking. For more information and to download the published Walk Guide see the Fen Edge Trail.

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

Volcanoes have long been recognized as important suppliers of volatile material like water, carbon dioxide, and sulfur dioxide to the atmosphere and environment. Volcanoes also shape the lives and livelihoods of over 100 million people on every continent. Recent advances in volcanology and instrumentation have demonstrated that volcanoes, like those that dominate the landscape of nations like Indonesia, emit significant quantities of volatile metals. In fact, individual volcanoes have been shown to emit as much selenium (Se), arsenic (As), and thallium (Tl) as the industrial pollution fluxes of whole countries. These vast quantities of aerosolized toxins represent a previously under-reported volcanic hazard that may present long-term health complications to nearby settlements. Yet, some of these metals may serve as micro-nutrients for bacteria, nourishing lush soil used or agriculture. Understanding how and why metals are emitted in volcanoes is a central goal of my doctoral research, and in this talk, I will share with you work addressing these concerns. I approach these questions by examining the chemistry and textures preserved in volcanic rocks, to understand how metals evolve in magmas located far below our feet. I focus my efforts on Java, Indonesia, one of the most volcanically active regions on Earth.

Previous Field trip: Saturday 18th June 2022 10.30 am

for ‘Celebrate the Fens

Fen Edge Trail landscape heritage guided walk on the Isle of Ely

Free, everyone welcome, but numbers limited so you need to book by contacting us.

The Fen Edge Trail is a series of (about 48) walks in Cambridgeshire that take you along the fen edge, guided by where the low fenland meets the higher land above about 5 metres above sea level. Downloadable Walk Guides give details of the walking route and the places of historic, cultural and wildlife interest that you see, as well as describing the local landscape and geology. This guided walk is on part of the Sutton to Haddenham walk, but is adapted to be a circular walk from Haddenham. Total 7.5 km (4.7 miles) and c.2 to 2.5 hours. Relatively easy walking, with one main slope up North Hill (from 20m in c.0.5 km) and a more gentle slope (up 20m over c.2 km). Shorter option (c.5 km/3 miles) possible (c.1.5 hours).

Starting in Haddenham, we will walk along the street out of town and then turn up through orchards to reach North Hill, at 40m above sea level, the highest point on the Isle of Ely and in the southern Fens. The hill is part of a ridge formed of c.155 million year old Kimmeridge Clay and Woburn Sands sandstone that runs along the southern edge of the Isle of Ely. Bring refreshments to have whilst enjoying the great views from the ridge across to Sutton to the north and towards southern Cambridgeshire to the south. The route and meeting details will be sent after booking.

Previous Talk: Monday 13th June 2022 2 pm

Brimham Rocks – Yorkshire’s answer to Cappadocia

Dr Reg Nichols, CGS Chair

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 Field trip: Wednesday 8th June 2022 2 pm

for Cambridge Nature Festival

Fen Edge Trail landscape heritage walk in Cambridge

from Castle Hill to the Sedgwick Museum

Free, everyone welcome, but numbers limited so you need to book by contacting us.

The Fen Edge Trail is a series of (about 48) walks in Cambridgeshire that take you along the fen edge, guided by where the low fenland meets the higher land above about 5 metres above sea level. Downloadable Walk Guides give details of the walking route and the places of historic, cultural and wildlife interest that you see, as well as describing the local landscape and geology. This guided walk (3 miles easy walking, taking about 1.5 – 2 hours) celebrates the publication of the Walk Guide (available by June) for this part of the Trail that passes through the ‘fen edge’ city of Cambridge. It links the walk into Cambridge along the north side of the River Cam from Milton (which finishes at Castle Hill) to the walk that continues on from Cambridge to Fen Ditton (starting at the Sedgwick Museum), along the south side of the river.

Starting high up on Castle Hill, you walk down through the heart of old Cambridge and traditional riverside grazing ‘fenland’, past historic buildings to finish at the world-famous Sedgwick Museum of Earth Sciences. The hill is part of a ridge formed of c.100 million year old Marly Chalk topped by gravel from an old terrace of the Cam, whilst the rest of the walk takes you across younger river terraces, dating from the last few hundreds of thousands of years and over much younger (probably only hundreds of years old) river alluvium alongside the river. Your guide, Martin Evans, is a committee member of CGS, an alumnus of Cambridge University and a long-term resident of Cambridge. He will be pointing out man-made features of historical interest on the way (which Cambridge has in abundance!) as well as commenting on the geology beneath at relevant points. As well as learning about the landscape of the Cam Valley, past and present, you will discover how it related to development of the ancient town and finally the city. You will also see a variety of local and exotic building stones. The walk goes past several colleges and takes in the famous ‘backs’, including the iconic view across the river to King’s College Chapel, as well as the nationally-renowned Fitzwilliam Museum. Famous pubs and tea shops are not forgotten, either!

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 6th 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 Field trip: Sunday 8th May 2022 10.30 am

Celebrating GeoWeek 2022 7-15 May

Building Stones walk in Cambridge

a guided walk starting at the Sedgwick Museum

As part of GeoWeek, this walk is open to everyone and free of charge, but needs to be booked as there are limited spaces. Book by contacting us.

A walking tour, starting at the Sedgwick Museum of Earth Sciences on Downing St, around the city centre to spot the variety of building stone used in its construction. Many of the ancient University buildings used a variety of fairly local building stones – e.g. clunch (Cretaceous Chalk) from East Pit at Cherry Hinton and Barnack and Weldon Jurassic limestones. Other, more exotic stones, can also be found at various sites in the city, including the shopping centre. Local cobbles, found in fields on the surrounding hills (but many brought from far away by ice sheets), have also been used for the walls of some buildings and on trackways. More information on Cambridge’s building stones can be found here.

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.

Other organisations’ events

Friends of the Sedgwick Museum

The Friends organise a series of lectures in Cambridge (doors open, 6.15 pm for 7.00 pm in the Department of Earth Sciences)  during autumn and winter and field trips during the spring and summer. They also organise overseas field trip in the UK and overseass. More information.

Cambridge Natural History Society

CNHS organise a series of talks (winter) and excursions (all year). Talks are usually held at the Attenborough Building next to the Zoology Museum. Visitors welcome (small charge) More information.

Courses at the Institute of Continuing Education of University of Cambridge

The ICE holds many interesting courses, at Madingley Hall near Cambridge, including some on geology, local landscape, evolution and archaeology e.g.  Extinctions: crises in the history of life  with Peter Sheldon

Free online courses

Future Learn has a number of short, online courses on geological and related subjects. These courses are free and very easy to follow. Ideal for introductions to many subjects. Courses include Extreme Geological Events, developed by Cardiff University, The Earth in my pocket: an introduction to geology and Extinctions Past and Present.

The Open University has free, online courses on Geology, for example: Earthquakes, Geological Processes in the British Isles, Introduction to geology, An introduction to minerals and rocks under the microscope, Life in the Palaeozoic, Mountain building in Scotland, Plate Tectonics, Volcanic hazards.

U3A Geology groups

There are a few local geology groups run by U3A: Cambridge    Peterborough

Other Talks

For details of many other talks and societies in the Cambridge area see the CONDUIT publication issued by the Cambridge Antiquarian Society. It gives contact details for the many organisations working to promote interest in history, particularly that of Cambridgeshire. The latest issue of CONDUIT can be downloaded from their website.


© Cambridgeshire Geological Society