New excavations at Westbury Cave: a palaeontological treasure trove – Neil Adams

After some fabulous blog posts from our MSc students over the last couple of months, our next contribution is from Neil Adams.  Neil is a former undergraduate student at Royal Holloway and since graduating in 2015 has been working as a Research Assistant under the tutelage of Professor Danielle Schreve.  Hope you enjoy this really nicely illustrated piece that Neil has compiled which gives a fantastic insight into the ongoing work at Westbury Cave.

 

Name: Neil Adams

Role: Research and Laboratory Assistant, Palaeoecology Laboratory, CQR

For the past year I have been lucky enough to work as a research and laboratory assistant in the Palaeoecology Laboratory, a key facility in the Centre for Quaternary Research at Royal Holloway. The majority of my time has been spent processing samples for mammalian fossils from sites across Britain. These sites have not only covered a diversity of ages through the Quaternary, from the Early and Middle Pleistocene to the Late Pleistocene and Holocene, but also a diversity of depositional environments, including fluvial and cave sites.

One of these sites, Westbury Cave in the Mendip Hills of Somerset, southwest England, was the focus of my undergraduate dissertation research at Royal Holloway in 2014-15, supervised by Prof. Danielle Schreve and Prof. Ian Candy. Westbury Cave is an unusual cave site, given that it was exposed when limestone blasting in Westbury Quarry blasted away most of the south wall of the cave in 1969! This revealed a cross-section through the Pleistocene cave sediments, but the palaeontological importance of the site was only realised when large mammal bones started turning up in the quarry crushing plant! The present exposure of cave sediments is over 30 metres high and 100 metres wide, which attests to just how enormous this subterranean cave system must have been before being occupied by ice age beasts and being filled with sediment during the Pleistocene.

The northeast face of Westbury Quarry (part of the Brimble Pit and Cross Swallet SSSI), the red box highlighting the exposed Pleistocene cave sediments that have been mostly covered by vegetation since quarrying operations ceased in 2003, the yellow box showing the location of the new section exposed during 2014 excavations. Photo: N. Adams.

The site is best known for its early Middle Pleistocene cave breccias (the ‘Calcareous Member’) that are spectacularly fossiliferous, with over forty vertebrate species, as well as disputed flint artefacts, discovered during original excavations in the 1970s-80s. These fossils provide a detailed record of multiple climatic oscillations and environmental changes during this period. However, the underlying Early Pleistocene silts, sands and gravels (the ‘Siliceous Member’) had historically received much less attention. New excavations of these largely unexplored and under-researched sediments in summer 2014 revealed a new assemblage of mammalian fossils, which has turned out to be of national importance.

A section of over 7 metres was cut through the Siliceous Member over four weeks in June and July 2014 to study its sedimentology, to take bulk samples for the recovery of vertebrate fossils, and to take samples for palaeomagnetic dating. Each sediment face was drawn and described in detail to build up a depositional model for the early history of sedimentation in Westbury Cave. Clast lithology of gravel clasts helped reveal where the sediment had originated from, and particle size analysis aided the interpretation of depositional processes. Larger fossils were recorded in situ during excavation, but over 720 kilograms of sediment samples were taken back to Royal Holloway for processing to recover small vertebrate fossils, which are often too small to notice by eye during excavation in the field.

One of six sediment faces exposed during excavations in summer 2014, clearly demonstrating the complexities of cave sedimentology. Striking angular unconformities, faulting, soft-sediment deformation structures, and lateral variation – just a few of the features to interpret! Photo: N. Adams.

The newly discovered fossils were used to produce biostratigraphical age estimations and palaeoenvironmental reconstructions. Palaeoecological preferences of the Siliceous Member taxa suggested that temperate climatic conditions prevailed in southwest England around a million years ago, with herbaceous savanna-like environments (for grazers and scavenging carnivores) surrounded by areas of more open woodland or forest (for browsers and mixed feeders). The fossil bones and teeth were identified to six mammalian families, including both small mammals (several rodent families) and large mammals (bovines, deer, and hyaena). A combination of biostratigraphy, palaeoecology and palaeomagnetic dating suggested that the Early Pleistocene sediments at Westbury represent a previously unknown time interval in British stratigraphy, since a notable lack of palaeontological sites has been recognised across Britain between ca. 1.8 and 0.8 million years.

Examples of fossils discovered during 2014 excavations: on the left, a bovid lower molar belonging to a species of Leptobos; in the centre, a deer first incisor; on the right, a vole lower molar. These fossils are well preserved with little evidence of abrasion from transport and the roots are intact in the first two examples. Scales, from left to right, are 10mm, 10mm, and 2mm. Photos: N. Adams.

Given the limited extent of excavations in 2014 and the significance of the findings, there was scope to recover further palaeontological, sedimentological and geochronological data from the Siliceous Member at Westbury Cave. Grant funding from the Palaeontological Association has enabled work to continue at the site this year. Excavations re-commenced in April 2016 for three weeks, uncovering a new section through the cave deposits. Fossils of at least four mammalian families new to the site (some of which are new records for Britain in the Early Pleistocene) were discovered in the field and over half a tonne of additional bulk sediment samples were taken to recover small vertebrate remains. These new fossils will help to improve the previous palaeoenvironmental reconstructions and to refine the biostratigraphical age estimates.

Excavation in progress in April 2016, bulk sampling a steeply dipping gravel unit. Photo: N. Adams.

Nothing stands in the way of a good section drawing! Photo: D. Schreve.

Attempts to provide absolute age estimates for the Siliceous Member by dating the sediments are also underway. Samples for coupled electron spin resonance and uranium-series (ESR/U-series) dating are currently being analysed by colleagues at the Muséum National d’Histoire Naturelle in Paris, and cosmogenic nuclide burial dating will also be employed following recent grant funding from the Quaternary Research Association. This is the first time absolute dating has been attempted at an Early Pleistocene site in Britain and, if successful, will provide important tests for the biostratigraphical age estimations.

A gamma spectrometer taking in situ dosimetry measurements of the Siliceous Member sediments for ESR dating. Photo: N. Adams.

With taxonomic work on the fossils ongoing and with hundreds of kilograms of samples still to process and sort meticulously in the lab for small vertebrate fossils (down to half a millimetre in size), a lot of work remains to be done. But the results of the work so far are currently being prepared for publication, so you will be able to read more about our work at Westbury Cave very soon!

 

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MSc Quaternary Science 2015-2016: Christopher Francis

…and from geomorphology to sedimentology and chronology.  Chris has chosen to complete his MSc. degree on a part-time basis over two years.  During this time he has also worked in the labs at Royal Holloway as an research assistant, gaining additional valuable work experience, some of which he has taken forward into this dissertation project. Enjoy his contribution!

Name: Chris Francis

MSc Dissertation Title: Sedimentology of a new deep water core from Llangorse, South Wales, helping refine the timing of deglaciation.

Techniques: Thin-section micromorphology, tephrochronology, sedimentology, standard physical parameters.

About: My main interest is studying environmental change at high-resolution with robust chronologies during the Late Glacial and Dimlington. Palmer et al. (2008) previously studied the site and created a chronology for ice wastage since the LGM using annually laminated sediments (varves) from a core taken near the medieval Crannog situated near the north shore of the lake. However, this sequence was incomplete with Late Glacial Interstadial and Loch Lomond stadial deposits seemingly missing. The varve chronology was also floating. This study aims to improve on this work using new cores taken from the southern trough of the lake, which are thought may contain a complete sequence since the LGM. A chronology will be constructed using tephra and the varved sediments while palaeoenvironmental information will be gleaned from the macro and micro-scale sedimentology and the physical parameters. This will help improve our understanding of the pattern and timing of ice wastage at Llangorse.

 

Figure 1. Example of thin section slide from Llangorse – scan of surface

 

Exposure: 000 : 00 : 00 . 400 Gain: 100 %Accumulated%=0

Figure 2. Varved sediments at the site

MSc Quaternary Science 2015-2016: Josephine Hornsey

From palaeoecology we move to geomorphology!  In this latest instalment, Jo Hornsey provides us with a brief insight into her field and lab research which is being conducted in conjunction with the British Geological Survey.  Jo was also lucky enough to be awarded funding from the Quaternary Research Association in order to help support her field expenses.

Name: Josephine Hornsey

MSc Dissertation title: Combined use of high-resolution remote sensing and field mapping to determine ice flow dynamics on Rannoch Moor during the Loch Lomond Stadial.

Techniques: Remote sensing mapping, field mapping, and sedimentology.

About: I am interested in glacial geomorphology and how this can be used to determine glacial extent and dynamics. To incorporate these interests, my supervisor and I developed a project with the British Geological Survey (BGS) which studied the glacial landforms (moraines, kettle-holes, and Roche Mouttonnees) on Rannoch Moor, Scotland, in order to resolve conflicting models of glaciation in this area, focusing on the Loch Lomond Stadial. This will help clarify the role of Rannoch Moor as a centre of ice accumulation in the Loch Lomond Ice Re-advance. Mapping the glacial landforms allows analysis of ice flow and, with the support of sedimentological analysis, ice direction.

Figure 1: Looking east towards Loch Laidon on Rannoch Moor. Moraines can be seen in the foreground, with Stob na Cruaiche on the horizon to the left. (Photo Credit: Dr Varyl Thorndycraft).

Figure 2:

 A­ – Slope digital elevation model of area undergoing analysis on Rannoch Moor using NEXTMap Britain elevation data from Intermap Technologies in collaboration with the British Geological Survey (NERC).

B – the extent of A (Rannoch Moor) in relation to the rest of Scotland.

 

MSc Quaternary Science 2015-2016: Sylvia Kwong

Here we go with the third instalment from our intrepid MSc Quaternary Science students and we move away from the sedimentology and chronology side of things to look at a palaeoecological proxy.

Name: Sylvia Kwong

MSc Dissertation title: A comparison of chironomid-inferred summer temperatures with a Lateglacial pollen record from Tanera Mor, NW Scotland

Proxies: Chironomids, pollen

Chronology: Tephrochronology

About: I am interested in quantifying palaeoclimate changes from the last glacial-interglacial transition, a period of abrupt, rapid climate change. The palaeotemperature record from my project will be compared to the magnitude and timing of climatic change events in Greenland and to other sites in Britain and Ireland. This will provide insight into local trends and climate drivers of NW Scotland, an area which currently lacks published palaeotemperature estimates for the Lateglacial period.

Figure 1 – left: Picking chironomid head capsules under a stereo microscope; right: Identifying slide-mounted head capsules under a compound microscope

Figure 2: Orthocladiinae larval head capsule

Top 10 Highlights of the INTegrating Ice core, MArine and TErrestrial records training course

 

by Rachel Devine (1st year NERC DTP student, Royal Holloway University of London)

 

For those who don’t know, INTIMATE stands for INTegrating Ice core, MArine and TErrestrial records, just to get that one out of the way. In Quaternary Science, the INTIMATE network aims to better understand the mechanisms and impact of climate change by bringing together scientists to reconstruct and model past climates by integrating palaeoecological, palaeoenvironmental and palaeoclimatic records.  From 5^th-11^th June this year, I took part in the INTIMATE Example Research Training School in Stara Kiszewa, Poland (Figure 1), alongside 20 other early career scientists.

Figure 1: Image credit – http://intimate.nbi.ku.dk/3rd-intimate-example-research-training-school (Image may be used freely with reference to source).

 

The training week was aimed at graduate students and early stage researchers with an interest in palaeoclimate and palaeoenvironmental records across Europe and the North Atlantic. We undertook training through a mixture of lectures, discussions, lab work and fieldwork, and here are my top 10 highlights.

1. Meeting new people with different scientific backgrounds

We all do it – we see the same faces every day in our department and when it comes to talking science we can often get trapped in a little departmental bubble. It is always great to talk about science with new people, a example of this was on the first day when we worked in groups to identify the key research topics that underpin our research. We began by explaining to the rest of the group some of the key questions in our own research, or questions we have generally about aspects of Quaternary Science. We identified 5 keys areas:

a. The strengths and limitations of different climate proxies such as using fossilised insect remains to reconstruct past temperatures, or pollen to reconstruct past vegetation.

b. Comparing information across a range of scales from localised research sites to global interpretations.

c. Dating precision, and how to compare environmental records with different chronological resolution.

d. The impact of humans on the environment, and when this began versus when it is actually visible in palaeo records.

e. Defining the cut-off point for outliers in our datasets.

Despite our varied scientific interests across sedimentology, archaeology and biochemistry, we all had similar fundamental scientific questions but approached them from completely different angles. This was a real eye opener for me, as I could see first-hand how different fields of science take different approaches to palaeoclimate questions.

But it’s not all about science sometimes. Whilst in Poland I met other scientists who are at a similar stage in their career and we had good fun talking about the highs and lows of PhD life. It was reassuring to know that some of my worries about starting off in the big world of research are completely normal.

 

2. Seeing the Polish landscape through Quaternary tinted glasses

Every geologist/geographer loves field work. Let’s face it, it’s the best thing about the job. But how often do we get the opportunity to visit a new country and be given a tour of key sites by the very experts who conducted the original research? A huge thanks to Prof. Mirosław Błaszkiewicz, Dr. Dariusz Brykała and rest of the Polish team for organising a fantastic tour of Stara Kiszewa and its Quaternary history.

 

3. Learning new skills

For my PhD, I study glacial lake sediments which are essentially devoid of organic material. Well, maybe not completely devoid – there’s always pollen! The low rates of sedimentation that we see in some glacial lake systems mean that organic matter is buried very slowly. As a result, organic material is rarely preserved in the geological record, due to decomposition during burial.

This means that the sediment records I work on are not exactly teeming with biological material that could be used to infer the past climate and environmental conditions. For example, the remains of insects such as beetles and non-biting midges (chironomids) can be used to infer past temperatures, but in glacial lake systems they are usually present in very low numbers or not present at all. So by default, I have tended to avoid training on biological proxies in the past, but prior to the INTIMATE training course, my supervisors suggested that I take the opportunity to develop my wider research skills and take full advantage of the expert training available in Poland, particularly on biological proxies. On the Wednesday morning of the training course, I took part in training sessions on testate amoebae, pollen, chironomid and macrofossil identification lead by Prof. Mariusz Lamentowicz and Dr. Stefan Engels. This was incredibly interesting and will be useful for my PhD as I’m hoping to find some macrofossils (Figure 2) which may be suitable for radiocarbon dating.

Figure 2. Example of macrofossils we identified from peat bog cores including rootles, moss and woody debris Image credit – Dominika Łuców

4. Seeing Polish varves in the flesh

Now those of you who know me will wonder why this isn’t top of the list, and some of you will be wondering. Varve is a Swedish term referring specifically to a type of sediment or sedimentary rock, with layers that represent one year of sedimentation. Throughout the Quaternary period, the low oxygen conditions of the lakes we visited in Stara Kiszewa, have been ideal for varve formation. Being a varve chronologist, I relished the chance to see and learn about new varve records and it was ace to be able to core some Polish varves and talk to the scientists who are working on these records. Bravo Poland, you have epic varves!

Figure 3. Varved sediment core from Lake Głęboczek (left) with high resolution image (right). Image credit: Rachel Devine

 

5. Gaining the confidence to ask questions

I’m not sure if I can speak for every PhD student, but in the past I’ve always been terrified to ask questions at conferences. What if people think my question is stupid? What if I make a complete and utter fool of myself for mispronouncing this obscure terminology I’ve only ever read and never spoken out loud? Isn’t question time for the big names in science? For me one of the best things about the training course was that every evening we had a talk from a Quaternary Science expert, and they were there to answer our questions… no matter how basic or complex they were. Essentially we got to pick their brains! It was fantastic and I have come away from the training week no longer terrified to ask questions! The reality is that all scientists love to see people who are engaged, no matter their level of knowledge.

6. Palaeo in the present

In my very limited time as a scientist, I have noticed that some palaeoclimate scientists get lost in the mysteries of the past and forget about how the climatic reconstruction of a particular lake, river or forest compares to current conditions and its implications. It was a welcome addition to the training course to have sessions on the modern context of the palaeo records we were investigating. The ongoing lake system monitoring at Lake Głęboczek is particularly interesting, and with the help of Dr. Dariusz Brykała, we even had the chance to conduct some analyses of the lake system ourselves.

Figure 4. Marie-Luise Adolph (left) and myself (right) at Lake Głęboczek conducting lake water measurements such as temperature, conductivity, pH and Dissolved Oxygen (DO). Image credit – Laura Gedminiene

 

7. Top tips from the experts

We had guest talks from Prof. Didier Roche, Dr Michal Slowinski, Prof. Christopher Bronk-Ramsey, Prof. Sune Rasmussen, Prof. Achim Brauer and Dr. Rik Tjallingii, all of which were incredibly informative, interesting and accessible. The unique thing about the INTIMATE Example course is that it provides a really relaxed environment for guest speakers to present and also for the audience to ask questions. We had some great scientific discussions in the evenings and all of the speakers were more than willing to offer both specific and more general advice for the next three years of my PhD research.

 

8. Sedimentology

Yes, one of my highlights was the range of sedimentary environments we encountered both in the lab and in the field. We retrieved and analysed peat cores, varved and non-varved lake sediments as part of our field training. We also conducted sediment logging at an exposure in Bożepole Szlacheckie, where approximately 5m of low-level lake sediments are overlain by 10m of glacial sands.

Figure 5. Lake sediment core we retrieved from the base of a modern peat bog. Image credit – Rebecca Kearney

9. Traditional Polish entertainment

Okay – so not exactly science-related, but this was a memorable end to our final night. Live music complete with cymbals, accordion and dancing. Top tip for any PhD student at an international training course – never go to bed early on the last night!

Figure 6: INTIMATE Example 2016 enjoying local music, food and beer on final night in Stara Kiszewa – Image credit Rachel Devine

10. Making new friends

This PhD business is tough and it’s absolutely crucial to keep expanding your friendship circles. I made some great friendships whilst in Poland, and since returning to the UK I’ve made the journey over to Swansea to meet up with new friends from the course. After the training course, I really do feel welcomed into the INTIMATE network. I’m sure we will bump into each other at conferences in the future!

For anyone considering an INTIMATE Example Summer course – do it! Epic science, you’ll learn new skills, develop existing ones, and meet some awesome people along the way. Many thanks to the guest speakers, the organisers, and all the participants for a memorable week of Quaternary-fuelled fun.

MSc Quaternary Science 2015-2016: Luke Parker

As promised, here is our next instalment from one of our MSc. students who’s currently about 6 weeks away from submission of his dissertation – sorry for the reminder Luke!

 

Name: Luke Parker

My dissertation is on using optically stimulated luminescence (OSL) to date early hearth stones in the Western Nefud Desert, Saudi Arabia.

These hearth stones are stones which were used by early humans as part of fire places and can still be found today in the desert as scattered stone circles. OSL can be used to date the last use of these fireplaces since heating in antiquity should reduce the quartz OSL signal to zero. This signal is then gradually regained as the quartz grains are exposed to naturally occurring radiation, allowing us to determine the amount of time elapsed since they were last heated. Dating these fireplaces is important as there are many associated lithic artefacts nearby as well as potential human remains, making establishing a chronology for this area useful for understanding human migration and dispersal in this region of the Middle East.

Hearth stones, this image is an example from Libya (rather than Saudi!) but illustrates the sample type being analysed (Credit:  Simon Armitage)

 

 

MSc Quaternary Science 2015-2016: Richard Clark-Wilson and Joshua Pike

Continuing the theme of student projects, we will, over the next few weeks, be featuring short blog posts from our 2015-2016 MSc. Quaternary Science cohort.  These will give a flavour of the topics they are working on, methods they are applying and why these are important.

This week sees Richard Clark-Wilson and Joshua Pike summarise their work.

Name: Richard Clark-Wilson

MSc Dissertation title: Chronology and palaeoenvironments of lacustrine sediments in the western Nefud desert, Saudi Arabia

Proxies of choice: Stable isotopes and thin-section micromorphology.

Chronology of choice: Optically Stimulated Luminescence

About: My main interests lie in optically stimulated luminescence dating, stable isotope analysis, sedimentology, and theories of Homo sapiens dispersal from Africa. Taking these into account my supervisors and I formulated a project which aimed to date and assess the climate stability of humid phases, represented by lacustrine sediments, in the Nefud desert, Saudi Arabia. This will add valuable data to ongoing research in an area at the ‘crossroads’ of Hominin population movements out of, and into, Africa during the Pleistocene.

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Name: Josh Pike

Dissertation Title: Detailed sedimentological and tephrochronological study of annually-laminated deposits at Svärdsklova, Southeastern Sweden

Techniques: Micromorphology, tephrochronology, sedimentology and X-ray Fluorescence (XRF) core scanning

About: I am interested in the development of high-resolution palaeoenvironmental archives and chronologies, especially archives that are annually resolved. Using this, my supervisors and I created a project examining the annually-laminated (varve) deposits at Svärdsklova, Southeastern Sweden to understand the depositional processes leading to varve formation as well as constructing a chronology for the sequence. This will help to improve the Swedish varve chronology (13,300 year-long record), which during the Younger Dryas-Holocene transition is suggested to be missing more than 1000 years. The application of tephrochronology will also allow direct correlation and assessment of leads and lags in climate records from Greenland to Sweden.

Figure 1 (left). Example of varved sediments from Svärdsklova. Light band + dark band = 1 year.

Figure 2 (right). Example of varves being sampled for thin-section production (micromorphology)

Tills in Tunstall; reconstructing ice sheet flow from glacial sediments

This is a blog post written by Jenna Sutherland – Quaternary Science MSc. student 2014-2015

I have just completed my MSc in Quaternary Science here at Royal Holloway. The main focus of my dissertation research was to understand the dynamic response of an ice sheet to past environmental change since this is frequently poorly understood.

Ice sheets are inherently linked with the atmosphere and ocean, a change in one leads to a change in the other. So, looking in detail at the sediment that was laid down by an ice sheet that has fully disappeared through time allows us to thoroughly understand the processes of past ice flow and the style of glaciation. This enables us to predict how they might respond to changes in the future, meaning we can give more precise and accurate estimates of future sea level rise.

During the last glacial period (the last ice age that occurred from approximately 110 00 to 12 000 years ago) there were ice sheets just like those in Antarctica and Greenland, over Britain and Ireland, Scandinavia, and Canada.

Sediment deposits on the coast of eastern England originate from the Last Glacial Maximum (the period between 21 000 to 27 000 years ago). During this period, ice advanced as far south as the Isles of Scilly in the Irish Sea Basin and north Norfolk on the east coast. Although we know the maximum extent of the ice, the exact ice flow pathways and behaviour of the British-Irish ice sheet has been heavily debated throughout the last century.

My field location, Tunstall, is located in the East Riding of Yorkshire on the Holderness coast. Due to rapid coastal erosion on the east coast constantly exposing new sections of sediment, Tunstall is ideally located within the boundary of LGM tills to capture the sedimentological signal of different ice masses during the last ice age.

A rare sunny day on the north-east coast

 

My aims and objectives of the research were to:

• Assess each different sediment unit in the cliff face at Tunstall. What the sediment is made up of and what it looks like can help to infer the environment in which the sediment was laid down
• Identify the lithological composition within the sediments. Knowing where each lithology came from enables us to see where the glacier ice originated
• Determine whether the sediments at Tunstall are related to the wider regional stratigraphy published in the literature (The Skipsea and Withernsea Till units)

As with any research, field work is the best part (in my opinion) and I was lucky enough to have part of this research funded by the Quaternary Research Association (QRA). Altogether I spent about 15 days in Tunstall, split over various weekends.

 

What the majority of the cliff face looked like at Tunstall. Distinct sediment units can be seen via a change in colour and composition, indicating different depositional environments

A large amount of time in the field was spent describing the features of the sediment that are immediately visible to the eye. Sediment logs were drawn up, whereby each different sediment unit from the bottom of the cliff to the top is described in detail (different sediment layers stacked on top of each other represent the order in which they were laid down, the oldest sediment being at the bottom), noting the grain size of the sediment, its colour and composition (eg. clay, sand, gravel, boulders).

No one said field work was glamorous…..Collecting fracture measurements from the till at Tunstall

 

The length of the cliff face was photographed and mapped to create a ‘facies architecture map’ in order to characterise the key spatial features of the cliff, and enable the variability along the cliff to be assessed.

The position of stones within a sediment is a useful way of inferring ice flow directions, stones that are elongated orientate their longest axis parallel to the main stress direction. The dip and orientation of up to 50 stones per sample were measured using a compass-clinometer and the orientation of striations on stones as well as vertical fractures within the sediment were also taken.

Glacially striated boulder, the lines or scratches represent the direction of ice flow

 

Numerous samples of sediment were taken from the cliff and taken back to the lab for further analysis….

Particle size analysis (does what it says on the tin) was undertaken in order to infer how well sorted the sediment is. If the sediment is made up of similar sized clasts, it is well sorted. The particle size offers an insight into the erosion, transportation and depositional history of the sediment.

Clast lithological analysis involved identifying where the stones in the sediment have come from, and helps us to provenance the exact pathways of the ice. When the ice moves along the ground from its source area, it rips up, or ‘entrains’ bits of the underlying bedrock and incorporates them into the base layer of the ice. This sediment gets transported as the glacier travels further. Identifying the exact source will help to trace the locations of where each lithology is present in England, and therefore, identify with confidence the place that ice must have flowed over. I identified around 300 stones per sample, that’s 2400 rock identifications in total!

After all this hard work, the results of my research are promising and I am currently working towards getting my paper submitted for publication. This will contribute to helping us to understand more about the dynamism of the British-Irish Ice Sheet during the LGM, used in predicting the likely response of future ice sheet change.

Field work at Rostherne Mere, Cheshire

Being my first blog for the CQR, I’ll start by introducing myself .  I’m Alison MacLeod, Lecturer in Physical Geography in the department but for the next three years I have a full-time research position funded by the Leverhulme Trust.  I also run a 3^rd year lecture course on Glacial Environments.  The main focus of my research is on the identification and analysis of high-resolution (ideally annual, like tree rings) records of past environmental change both in the UK and other parts of Northern Europe and I use a variety of methods to work out the age and link these records.  As part of this I conduct field campaigns in order to gather suitable material to analyse.  Last September saw my first field expedition for my new Leverhulme project which was targeting high-resolution lake records covering the time period from the end of the last glacial period to the present day (c. the period from c. 16,000 years before present).  Between the 10^th and the 14^th of September myself plus colleagues (staff and students) from the department of Physical Geography at the University of Utrecht (Figure 1) collaborated to bring over their coring platform to allow us to sample the deep sediments from open lake basins.

Figure 1 Team selfie, top left to bottom right: Hans van Aken, Wim Hoek, David Maas, Alison MacLeod and Keechy Akkerman If you have questions please e-mail me at: alison.macleod@rhul.ac.uk

This type of sampling (Figure 2) has not been systematically done in the UK for many years (perhaps decades) due to a lack of facility available for use.  However, research using this type of platform is prevalent across the rest of Europe and is essential if we are to access key sites which will allow us to further progress our understanding of climatic change and environmental responses in the UK. Big thanks to the UU crew!  The majority of current work sampling UK Lateglacialsequences is restricted to the sampling of shallow lake margins or in-filled lake basins.

Figure 2 Our UWITEC piston coring home for 5 days (equipment belongs to University of Utrecht, Department of Physical Geography)

So, now the introductions are over, where were we and what did we find?

We had been very kindly granted permission to access Rostherne Mere in Cheshire by the reserve manager Rupert Randall (Figure 3) from Natural England.

Figure 3 Rupert Randall (centre) from Natural England

Rostherne is the largest Mere in Cheshire (Figure 4) and it is also the deepest being 31m at its deepest point and on average being about 13.5m.  It is located only 19km from the maximum extent of Last Glacial Maximum ice in the UK (Figure 5) and as a consequence of this is likely to have begun to accumulate sediment relatively soon after the climate began to warm and the ice receded.  In terms of lake formation mechanisms, it is potentially a complex story but the simplest explanation is that it represents a hollow that developed following ice recession (kettle hole).

Figure 4 Rostherne Mere looking northwards with the boathouse in the foreground and the platform in the centre of the view.

More complex proposals relate to much later formation via salt solution (there are salt formations in the nearby geology) and even more complex proposals suggest a combination of both mechanisms.

Figure 5 The context of Rostherne (large black dot) with respect to Last Glacial Maximum ice limits (red shading).

So, what were we up to?  There is a lot of research being undertaken on the Rostherne Mere.  A group from Loughborough University are working on the present day ecology, and the history of the lake over the more recent past, and it is this work we in the CQR are looking to integrate with and extend.  Our interest lies predominantly in the older sediments that were laid down at the bottom of the lake when it first formed and we aim to answer questions such as when did the lake form and what has the climate been like in this region since it formed? Once we have summarised the information from Rostherne, we will then try to integrate this record into wider data we have gathered to assess for patterns and trends in the style, magnitude, timing, duration and rates of climate changes across the UK and Europe.

As I mentioned previously, the Mere is so close to the maximum ice limit it would also be one of the first places to become ice-free when the climate began to warm (c. 17,000 years ago). After this point it would have started to gather sediment from its catchment that records information about the local and regional vegetation and climate.  Because of this, it is possible that it may preserve one of the longest records in the UK.  However this is potentially complicated by the formation mechanism but I’ll save more details on this for my next instalment!

Another reason we are interested in this site is because the water is so deep – 31 metres (m).  This allows special conditions to develop in the water such that below between 15-25m the water is anoxic meaning there is no biological activity can take place below this point, due to a lack of oxygen, and as such the sediments should be undisturbed.  The depth is also significant because it allows the water column to become layered (thermally stratify) with warm water at the top and colder at the base. This changes at particular times of the year.  Thus meaning that there is the potential for detecting annual to seasonal signals in the sediment building up on at the bottom of the lake (like tree rings) something like we see in Figure 6 and 7.

Figure 6 A short 10cm section of core from Rostherne Mere

Figure 7 A nicely laminated, 1m-long core section from Rostherne Mere

Figure 6 shows light and dark layers. Our hope (once fully analysed) is that each couplet of light and dark represents one year of deposition in Rostherne Mere and that by looking at the composition of each layer, and how this changes over time, we can say what the climate was like each year since the lake formed.  We can also count the couplets (using a microscope) to see how many there are and therefore how long the lake has existed for.  There may be breaks where the layers are not so clear and it is in these sections where we will apply other techniques such as radiocarbon dating of plant material and tephrochronology (the study of volcanic ash layers; Figure 8) to help us date the sediments more securely.  Other proxy analyses which will be carried out on the cores will include pollen (vegetation), chironomid (midges), diatoms (water conditions) and sediment chemistry (amongst many others…..).

Figure 8 Volcanic ash shard under an electron microscope – approx. 0.05mm in its long axis (not from Rostherne).

So now that I’ve justified the science component what are some other facts and figures from this trip?

• Deepest water cored in: 29.3m (there is a weather station anchored over the deepest point)
• Depth of sediment recovered: 13.85m (previous record for the site was 10.5m but no detailed work was carried out on the cores).
• Sediment plus water depth cored: 43m (we were using previously unused cable and rope on the winches!)
• We hit some form of diamict (sediment containing grains from clay-gravel/pebble size) at the base – this could have potentially been deposited by the glacier before the lake formed.
• Number of cores obtained: 24 overlapping cores each 1m-long
• Problems encountered and overcome: cores coming up from >40m below the lake surface have a tendency to de-gas if left in the sun on the edge of the platform (they expand and if not correctly handled can ooze or explode out of the tubes – see below for an example of the tubes).
• Number of bagels eaten for lunch: 10
• Number of Little Chef breakfasts consumed: 5
• Amount of weight gained: too much!

I realise this is not really giving much information on the science, but that will come in the next instalment once I’ve done some detailed work.  Just a wee taster for now of what the plans are.

What else have I learnt? That it is always good to make friends with your local friendly tree surgeon so that when you get stuck in the mud he’s willing to tow you out (Figure  9).  And, that if you have a rope and a REALLY strong magnet, you can find and fix just about anything metal at the bottom of a lake!

Figure 9 The downfalls and perks of fieldwork. Getting stuck in the mud vs getting a ride in a Unimog with chipper and crane.

Some more gratuitous shots from the trip for you to enjoy:

Platform construction – this took about 4 hours (and another 4 hours to dismantle). The gate in the background was 310cm wide and the platform was 280 cm wide so we just made it through!

Batch 1 cores keeping cool in the shade of the boathouse. These are the tubes I mentioned above. If the caps are not on tight the sediment begins to ooze out.

Happy Dutch team commuting to work via zodiac boat…if only every day could be like this!

Our core cutting, splitting and recording industry at the B+B. Wim and David (left) are cutting and Adrian and Ian are wrapping the cores (right). We also record the cores after we open them using notes (to tell us what type of sediment is there – sand, silt clay, banded sediment etc.) and photographs because sometimes after they are open they start to dry out and decay/oxidise which can make features more difficult to recognise later.

Half of the fruits of our labour!

We need to do a lot of work to analyse all 24 1m-long cores we collected in detail but I will be able to update you sometime next year with developments on progress.  Alison

The ancient origins of British mammals

By Melissa Marr  (2^nd Year PhD student) Between 26 000 to 21 000 years ago the earth was in the grip of an ice age and global ice sheets were at their maximum extent. Most of Britain was covered with glacial ice and the mammal species that existed were very different from today, consisting of species that had particular adaptations to cold environments. Temperate adapted mammals – those species that rely on warmer climates – were restricted to the Mediterranean peninsulas. As the ice sheets retreated and temperatures rose at the end of the last ice age these warm-adapted species began to emerge from their ‘refuges’ and recolonize Europe. My study focuses on a period starting around this time (c. 15 000 years ago) and covering a roughly 5000 year period which saw four marked and abrupt periods of warming and cooling. How did these rapid changes in climate affect mammal species re-entering Britain from Europe? This is the over-riding question of my PhD research. To answer this question I’m combining two techniques – ancient DNA and 3D geometric morphometrics. Mammals can respond to changes in their environment in three main ways; by adapting, by changing their range and/or by going locally extinct. These responses will leave a signature in the genetics and in the shape and size of the bones and teeth of ancient animals. Most of my time so far has been spent visiting museums and examining material excavated from caves and archaeological sites which has been a fantastic opportunity to meet curators and study the anatomy of long dead mammal species. To take samples for ancient DNA analysis I have to carefully drill within the bones of these fragile specimens and remove the powder. Back in the specially adapted sterile laboratory at the Natural History Museum, London I extract, amplify and sequence the DNA. By comparing the DNA sequences of these individuals I’m able to reconstruct the history of extinct populations.

Drilling a mid-late Holocene beaver cranium for ancient DNA at the Sedgwick Museum, Cambridge

I also spend a lot of time creating three-dimensional images of skulls, teeth and long bones. To do this I use a laser which creates a surface ‘map’ of the object and CT scanning which uses X-Rays to build up ‘slices’ of both the surface and interior of the object. By looking at the changes in shape of anatomical features in relation to climate I can make suggestions as to how the morphology of species was adapting to their changing environment.

Post-processing a 3D laser surface scan of an ancient beaver cranium

Around 8000 years ago the final collapse of the glacial ice sheets isolated Britain from the continent and ended mammal immigration back into Britain, giving us the native mammal communities that we have today. Determining how these communities developed in relation to climate change will allow us to gain insights into the impact climate has on the evolution of mammals over millennial timescales and, possibly, offer information that can help predict how climate change will impact our mammal fauna in the future.