Tag Archives: transect 3

1 o’clock, 2 o’clock, 3 o’clock rock (well…compressed mud), you can rock around the clock….

By Margot Saher and Lou Callard

Take some of the ‘finest’ brains in the country. Put them on a state-of-the-art research vessel which is filled to the brim with geophysical equipment, and has its own core scanning lab. Imagine what one could do with that! And what do we do with it? What is the scientific treasure we hunt? Mud. Six weeks at sea for mud (occasionally sand…)? We’ll be scrutinising it for years to come! Without mud the whole endeavour would be a failure; the mud must be treasured, cared for. It is the sedimentary archive that could answer the question of when and how the British-Irish Ice Sheet vanished. It is the wet lab coring teams that handle, care for and love the mud. There are two shifts: the Night-watch from midnight to noon, and the Day-team from noon to midnight. Whilst in the lab and, more importantly, out on deck, these have to wear armour: PPE (Personnel Protective Equipment) – a hard hat, hobnailed boots and some rather unflattering (generally oversized) overalls. The overalls are optional, but a sensible option at that; the job is a messy one, so unless you have an endless supply of clothes…. As the British Geological Survey (BGS) core team recover the mud to deck we have to wait – impatiently. How much have we recovered, and is it the right stuff? Even before the barrel is laid down we swarm expectantly around its end to get the first glimpse (and touch) of the treasure. The strength of the mud gives us so much information; we prod it, taste it…. Does it feel like silt, sand, clay; is it stiffened, reflecting the weight of former ice sheet bearing down on it? We recover everything from the core shoe, the core catcher; whatever sticks or falls out of the liner gets bagged, labelled, photographed and stored cool. But what is inside the liner is what we really want, it contains the story of the ice coming and going from the waters around these islands.

The liners are not easily released from the barrel; muscles are needed to get it out, and a tug-of-war ensues of scientists, BGS engineers, crew, random passers-by, anyone versus the barrel. But once the liner is out, it’s ours. The muds we desire are only useful if we know exactly where they are from, so labelling is everything. Every single core section has its own unique label, which will end up on its liner, caps, wrapping material, and the box it’s stored in. There are yellow caps for the tops and black for the base of each segment; which way is up matters! And that is only the beginning; there is no such thing as over-labelling, and that holds for cores sections, record sheets, scanned records, spreadsheets, photographs……

Lou: “The day shift consists of Steve, Zoe, Catriona, Kevin and me. Whilst Colm and Katrien spend the day planning where we will core next, we collect and process the cores. Generally our day starts at 11:20 with breakfast, which also happens to be lunch for the other crew members. Breakfast can be anything from a curry to fish and chips. Today’s option was Thai fish cakes, with noodles and sweet chilli sauce. Although having such a large meal first thing was rather odd to begin with, six weeks in it seems quite normal and a bowl of cereal would now disappoint. Shift begins with the midday handover meeting and our goodnights to the night team.

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Then work begins! We spend most of our shift either out on deck collecting and cutting the cores, or in the wet lab splitting, logging and packing the cores away with a constant dual stream of material either from the deep or from the MSCL cave. Frequently we split over 20 sections during our shift, and often it’s more than 25. Each section is 1 m long with each 1 m weighing between 10-12 kg, so after 12 hours of carrying, splitting, logging and packing it is a good workout. So the coring job may seem rather unglamorous and exceptionally mucky, and involves hard manual labour; it is also an exciting and rewarding part of the cruise. The sub-bottom profiles and bathymetry data provides a tantalising look at what might lie beneath, but it is only when the core is taken and the material viewed that you know whether or not we have captured the right material needed for the project, and whether there is something we can use for dating. Sometimes we are disappointed normally if we fail to guess correctly in the ‘guess-the-core-length’ sweepstake (Steve is slightly in the lead at the moment), but when a good core is opened, it changes the mood of everyone involved.

Our work still isn’t quite complete, cleaning and maintaining the lab ready for the night team, labelling, cropping and archiving all photographs, and Zoe dutifully scans all of the deck sheets. At midnight the night team relieves us and then we head either straight to bed or take a detour past the kitchen to get a post shift snack. A day shift favourite is Nutella (somewhere in the multi-verse other nutty spreads might exist) on toast. It is hungry work, coring!”

Margot: “the Nightwatch consists of Kasper, Riccardo, Jenny, myself and occasionally Richard (if he can drag himself away from the Geophysics, picking core sites and mostly chatting on deck). As we start our shift, we tend to find ourselves in the middle of a coring transect that has been planned before, so we of the night often start our shift on station, vibrocoring. We’ve discovered that Riccardo has a special talent for working hard but still staying clean, while Richard has the useful talent for removing almost any sediment from an unwilling core catcher. Kasper’s Danish (or Viking) muscles come in handy for removing the liner from the barrel, and Jenny has useful BGS contacts (which saves us, for instance, from running out of sample bags). I myself have developed the modest knack of writing upside down, for liner labelling purposes.

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Splitting and description has to wait until we receive cores from Elke and the core scanner cave, and she works 6AM to 6PM. The early part of the shift can be quite calm, if the core stations we have picked are far apart. Quite often nature festoons such a quiet early part of the shift with an amazing sunrise. The pace picks up dramatically as the cores start to emerge from the MSCL cave. It can get a bit hectic if we’re busily splitting and describing, interrupted by receiving new cores from the seabed. Core sections everywhere! But the splitting is exciting, as we get to see the whole sedimentary sequence for the first time. Do we have the ideal core, which consists of a subglacial till at the bottom, conformably overlain by marine sediments deposited after the ice retreated? Are there perhaps some nice shells in it for radiocarbon dating? When we see something we could use for 14C dating, we take it out. As we are coring, we have a competition running: guess the core length. It is very tight at the moment; Riccardo is in the lead, closely followed by Jenny, and Richard is trailing miles behind, but it all can still change, even with only two days to go. Eventually noon arrives, when we hand over to the day team, and then plonk down tiredly for lunch, which, for us, is more like late supper. After lunch and a cup of tea it’s bedtime! And then at around 11PM (ish) we get up again, and the sequence repeats.”

Treasure.....

Treasure…..

As we both write this, the 212th core has been recovered from the large moraine in outer Galway Bay. There is some 6 tonnes of mostly mud in our refrigerated container, and we have picked more than 100 shells for dating. But we know exactly where every kilo came from, what it looks like, and which ones we want to target for further research. When we get back on land, we can hit the ground running…..

Photography mostly by Alex Ingle, except where it isn’t….

A room without a view……

By Elke Hanenkamp (MSCL Operator)

Enter my lair

Enter my lair

Six o’clock in the morning on board the RRS James Cook somewhere on the edge of Malin Sea in 1500m of water, and my shift as the MSCL operator starts right now. The dayshift (midday to midnight) is still fast asleep and the nightshift (midnight to midday) scientists are eagerly (or maybe more fatalistically) awaiting my arrival. The beginning of my shift marks the start for them that cores can finally be split and described soon (meaning more work for them), therefore I have been jokingly nicknamed “the harbinger of cores”.

My role during this expedition is to collect physical properties data (density, porosity etc) from the vibro and piston cores before they are split on board. I am operating a Geotek Multi-Sensor Core Logger (MSCL) in a containerised lab (also known as “the container cave”, I am in there all the time holed up with the cores). So the obvious question is – what is happening behind the closed door of the container? After the cores come aboard, they are cut into sections and labelled, and then stored for at least 6 hours inside the container to equilibrate to ambient temperature. Only after this period, the cores will be measured on the MSCL, because some of the sensors are temperature sensitive. It is not possible to prop the door open during the measurements, fluctuations in temperature would influence the data. That’s why I am holed up in the container most of the time, every so often delivering already measured cores to the scientists for splitting or taking newly labelled cores into the container.

The Multi Sensor Core Logger is a quite versatile core measurement system, equipped with four sensors – Gamma Density, P-Wave Velocity, Non-Contact Resistivity and Magnetic Susceptibility. While the core is pushed past the stationary sensors, it is scanned, and data from all four sensors is collected at once when the core pauses at a measurement point (in this case every 2 cm). Sequential core sections are loaded on to the logger, this way a complete core can be logged in a continuous process while the data is displayed graphically in real time on the computer. Typically, with measurements being done every 2 cm, a 1 m section can be logged within 15 min, but overall measurement time for one whole core depends on the amount and length of each individual section the core is cut into earlier. The shortest core section we had so far measured only 21 cm. The amount of cores sections measured each day highly varies, but a couple of days ago, 45 sections were measured on the MSCL within my 12 hour-shift, with a total length of a little bit over 41 m (a new record).

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The MSCL gives us a non-destructive way of analysing cores before they are split and sampled. The measurements can help to characterise the physical nature of the individual cores, e.g. lithology, density, porosity, and will be used in combination with core descriptions and various geochronological data to better understand the timing of ice sheet recession. The high-resolution dataset from the MSCL should also allow us to make correlations between individual core sites in the Celtic, Irish and Malin Seas fringing the North Atlantic.

A view of the world

A view of the world

No rest for the wicked: T3 marine sector rumbles into life…..

By Richard Chiverrell

Sites and surveys for transect 3

Sites and surveys for transect 3

Leaving the Celtic Sea and the delights of the Celtic Deep, noon on Sunday 27th July, the Royal Research Ship (RRS) James Cook homed in on Britice-Chrono Transect 3 and the delights of the Irish Sea. For me work levels already high increased, with Transect leader duties to fulfil, and the challenges of finding till – glacimarine mud contacts throughout the sector, and do not forget the shells/fossils for the critical dating targets. That said without Katrien’s (van Landeghem) constant input and support it would have been ridiculous, the work in advance of the cruise identifying targets and new locations drew on considerable effort and collaboration focused on this marine sector of T3 over the past 2-3 years. The success of the efforts for T3 obviously relied on the excellent work effort, diligence and company of the cruise team, science crew, BGS and NOC Piston coring teams and the RRS James Cook captain and crew, all whom did everything they could to help us. Not singling people out, but I thank Katrien for constant input, advice and support as co-leader on this transect and Colm as Science Lead on JC106 cruise.

In the Celtic Sea, the ship was home to the friendly academic interplay between James and Daniel, the Irish Sea also offered up a number of longer standing and perhaps more vociferous historical debates! Understanding and interpretation of the nature and extent of glacimarine conditions in the Irish Sea basin has ebbed and flowed for 4-5 decades, with some proponents holding for a full glacimarine ice margin, others subaqueous margins with more restricted access to the ocean and the other end member glacilacustrine basins separated from the sea. For all these views a comprehensive borehole and geophysical survey targeting environments across the sea floor had the potential to advance understanding, but for Britice-Chrono we clearly needed glacimarine conditions and sediments to provide the marine shells and microorganisms that we can radiocarbon date to gain a chronology for retreat of ice from the basin. Marine fossils have been recovered from coastal glacigenic sediment sequences surrounding the Irish Sea for centuries, but debate continues over whether they are in situ or derived, eroded from the sea floor, during ice advance and then redeposited in glacial sediment. If in situ they offer the potential to constrain retreat of ice margins and the development of glacimarine conditions, if derived they cannot really advance our dating control. Some challenging fieldwork and some painstaking analysis of the fossils and microfossils lies ahead.

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Our journey from the Celtic Deep ~ 51°25’N to our first survey and core sites west of Anglesey around 53°15’N took just over 12 hours at a steady ~10 knots. Our first sites, a bit of a late addition and product of general brain-storming, were ~ 13-14 miles west of Holyhead and targeted the deep waters of northern extensions of St Georges Channel. The location kind of bridges T4 and T3, and we wanted some indication of deglaciation of the deep waters between Holyhead and Dublin. On reflection I was not sure what to expect here, but we had planned a sub-bottom profiler SBP and multibeam survey line as an initial exploration, but circumstances and our temperamental SBP conspired against us. The multibeam data on the other hand were excellent, it was a decent trough 2 miles wide 30-40m deep and we used the multibeam to avoid surface sand waves. Our aims were to avoid surface sand and access the underlying laminated glacimarine units, 2.5 hours and two vibrocores later, some success >3m of mud ending in reddish (an Irish Sea glacial signature!) stiff muds. These laminated or bedded sediments hopefully were lain down under marine conditions fronting the ice sheet as the ice margin retreated to higher ground east and north between Anglesey and the Isle of Man.

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From noon 28th July we moved east and north between the Isle of Man and North Wales, and into a region a large part for me where my interest in this research started, working for and collaborating with Geoff Thomas on sections and sediment all around the Irish Sea. In the deeper waters between the Isle of Man and North Wales, our multibeam data gave us a view onto a very well preserved glacial landscape of drumlins and flutes, moulded elongate low hills shaped by the passage of ice. Uncovered as ice melted and then preserved beneath water probably ever since, their summits are grooved with markings probably formed by ice-bergs calving from and then grounding on the landform surface fronting this glacier. Guided by the multibeam sea floor topography and our shallow geophysical data we targeted hollows in the landscape with shallow fills of sediment overlying the glacial surface. Our vibrocorer can penetrate to ~5-6m depending on the sediments, absence of large cobbles or bedrock, heavy seas and luck. Fingers were regularly crossed and the only wooden items in the all metal BGS vibrocorer cabin are now getting quite worn by us touching them for luck and the right sediments. Broadly we divided the Irish Sea basin into four sub areas, 1. South of a line between the Isle of Man and Barrow-in-Furness completed by 21.30 on 30th July, the deeper waters between the Isle of Man and western Cumbria by 18.30 on 31st July, the Solway Firth (between the Isle of Man and Scotland) by 5am 1st August and finally the deep waters west of the Isle of Man by 11.30am 1st August. >500km of survey line, 34 cores in total, almost all of them reaching the reddish glacimarine muds often laminated some with dropstones and in many cores stiff diamicts with clasts typical in character of Irish Sea glacial tills seen in coastal cliff sections around the basin. We had the sediment contexts we desired, the subglacial to ‘glacimarine’ transition and water-lain ice marginal muds from settings across the transect. The nature of this water-body and answers to the Britice-Chrono geochronological questions must wait on many months of laboratory analysis, but I left the Irish Sea northwards for the Malin Sea and T7, satisfied and with the feeling that the sediments and geophysics alone will fill in a significant and long standing gap in our understanding of the last glaciation of the Irish Sea.

The raging waters of the Irish Sea

The raging waters of the Irish Sea

Cruise 1: meet our Marine Mammal Observer

By Marian McGrath
dolph
Hello everyone! It’s been one week since we joined the RRS James Cook in Southampton, even though we didn’t actually leave the port till Friday the 18th due to technical problems with the vibro corer. My role on board is as the Marine Mammal Observer (MMO). The role of the MMO is to ensure the safety and protection of marine mammals from man-made noise pollution in the ocean. This can damage or kill cetaceans which have very sensitive hearing. The Marine Mammal Observer (MMO) is required by law to be aboard any vessel which is carrying out seismic surveys within Irish waters. On this vessel, Sub Bottom Profiler seismic equipment and Multibeam echosounder equipment are being used. In unprotected marine areas an MMO is required to carry out a 30 minute pre Multibeam echo sounder and Sub Bottom Profiler watch followed by a 20 minute watch during the soft start. Sound activity cannot commence until the MMO gives clearance after the 30 minute watch. If marine mammals are spotted within 500m range of the equipment during this watch then a further 30 minute watch is undertaken till marine mammals have left the mitigation zone. If no marine mammals were seen within this time then a soft start would commence. Once the ramp up procedure is started there is no need to stop the equipment during night time hours. The Multibeam and Pinger systems remain active during the survey unless we are on a coring station for longer than an hour in which case they are switched off. They are also turned off during the mid-cruise port call in Killybegs.

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Marine mammal observations are carried out from the bridge. This gives the best view point of both sides and in front of the vessel. The equipment is always started during daylight hours to allow for MMO watches to be carried out prior to soft starts. Observations are undertaken using a reticular binoculars, a range finder and also by the naked eye. Distance to marine mammals is determined using this reticular binoculars and height above sea level. To determine the range one of the divisions present in the binoculars is placed on the horizon. A formula is then used to determine the distance of the mammal from the ship. The formula is: Distance (m) = (height of eye above sea level (m) x 1000/ no. of mils down from horizon). Throughout the duration of the survey, watches are undertaken throughout the day and any sightings are logged in a computer supplied by The Irish Whale and Dolphin Group. This will feed into a database which is constantly updated regarding location and numbers of various species. Throughout the day recordings are taken of precipitation, sea state, visibility, ship speed, water depth, cloud cover, latitude and longitude, wind speed and direction. So far on this survey Common Dolphins have been seen near the shelf edge of the Celtic Sea. First 4 adult dolphins were seen on the 21st July and later the same day 11 adults and one calf were seen.

BRITICECHRONO Fieldwork on the Isle of Man ~ November 2013

The leaving of Heysham is nothing like the leaving of Liverpool

The leaving of Heysham is nothing like the leaving of Liverpool

By Richard Chiverrell

For Transect 3 of BRITICECHRONO, THE Irish Sea East, north from the terrestrial component in Shropshire-Lancashire, much of the remainder will be be dealt with during the marine cruises. The Isle of Man is the clear exception with excellent terrestrial exposure of the Quaternary geology; it is an excellent candidate region for dating the decline of the ISIS. The Isle of Man occupies a position astride successive ice advances through the Irish Sea Basin and records evidence of fluctuations of ice in the Irish Sea basin. The glacial geology of the Isle of Man is extremely well known, and this knowledge forms the basis for recent BRITICECHRONO fieldwork on the Isle of Man.

Geomorphology of the Isle of Man (Thomas et al., 2006)

Geomorphology of the Isle of Man (Thomas et al., 2006)

Team Isle of Man consisted of Richard Chiverrell, Matt Burke, Daniel Schillereff (all Liverpool University), and David Roberts (Durham University), with meticulous planning (and no hastily rearranged flights) the intrepid team took off for autumnal bedock, erratics, sands, Manx queenies, cliff sections, gravels, sands, buried soils (?), kettlehole basins and ground penetrating radar on 4th to 9th November 2013….. We divided the Island five sectors documenting the northwards retreat, a) the Plains of Malew and adjacent hills (the South); b) the Peel embayment (the Central Valley) and on the northern plain c) outwash deposits of the Shellag Formation (the initial retreat); d) ice marginal sandar deposits associated with the Orrisdale Formation ice marginal oscillations (previously dated by Ian Thrasher) and e) outwash deposits of the Jurby Formations lain down during a more substantial 2-3km readvance. Together geochronology from these sectors would document the phased retreat across the Isle of Man and secure the timing of two well defined readvance episodes (Orrisdale and Jurby events).

Day 1 Monday – Travel and reccie day for some: Roberts, Dave, was first to arrive, apparently having set off before dawn, from whence he set gainfully on reacquainting himself with some former haunts, having spent a happy 12 months on the Island as a post doc in the mid- to late 1990’s. A very good day followed, bedrock sites on the southern flanks of Man, and a search for the famous Foxdale erratic train….. Meanwhile following a 9am lecture to the second years on European peat climate records, Chiverrell (Rich) tried to find his unusually elusive postdoc, Burke (Matt) who had been set the not insignificant challenge of cramming too much equipment into a car that had now seen better days. But second success of the day followed, 2x GPR antennae, 1x RTK Trimble GPS, tripods and staffs, monolith tins, 3x gamma detectors, the Roberts Rocksaw and cosmo kit, luminescence tubes and gearing, plus two scientists, can fit….  Third success, catching the boat from Heysham to Douglas, only 60 mins early for check in this time….. By 10.30 we had all collected in Andreas in the far north of the Islands, via in Dave’s case some old haunts in Douglas and a fine meal in the Sulby Glen Hotel for Matt and Rich.

Day 2 Tuesday – The Plain of Malew: The excellent recognisance by Dave helped us make short work of the very south of the Island. Bedrock samples a quartz arenite and quartz vein (sample 1 and 2) from Cregneash Peninsula overlooking the Calf of Man, where ice skirting the western flank of the Island has scoured and streamlined the topography and permission given by a very helpful landowner. The search for outwash sand and gravels for OSL proved slightly more taxing, with in the late afternoon a former bedrock quarry near Ronaldsway airport, Turkeyland Quarry, yielding a thin outwash deposit (sample 3) and a very enigmatic buried weathered soil, possible 14C target. And a fine dinner of Manx queenies and skate courtesy of chefs Matt and Dave. The final member, Schillereff (Dan), of the team flew in that evening to provide expertise on the kettlehole sediments, and revisit what might have been the locale for his undergraduate dissertation.

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Day 3 Wednesday – The Foxdale Granites and moving northwards:With permission from Manx National Heritage (Isle of Man Government) in order, the ‘holy grail’ site for BriticeChrono was very quickly lined up, the Foxdale granites. Ice flowing north to south penetrated through valleys from Glen Maye and Foxdale valley building to eventually bury and consume the Isle of Man. In Foxdale at the col at the head of the valley (~200m) a granitoid is exposed, and the erratic train holds a place of significance in the geological literature, including the attention of Charles Darwin (1842) as a classic example of transport of glacial boulders from low to higher ground including the summit of South Barrule. With the permission and assistance of Manx National Heritage several boulders were identified on the slopes of South Barrule near an Iron Age hillfort, 260-190m upslope and 1km distant from outcrop (samples 4 and 5). Foxdale granite is quite tough; boy did they take some chiselling. The four cosmogenic nuclide samples proposed for the Isle of Man form a coherent group in the south of the Island and a strong altitudinal gradient from 480m to 135m. There have been no previous attempts to obtain CN ages for the Isle of Man. Second success of the day, was Dan finding his kettlehole, perhaps not unexpected though given there are two on that stretch of coast with very similar stratigraphy. With the cosmogenic samples in the boot, Dave took his leave and departed for the UK.

Day 4 Thursday – the Central Valley, Kirk Michael and Orrisdale: With Dave gone, OSL sampling was very much to the fore. First up the Central Valley of the Isle of Man extending Peel in the west to Douglas in the east, where geomorphology shows moraine ridges arcing north and northeast indicating penetration of ice from the coast. The Ballaharra sand and gravel quarry shows a 12m sequence comprising basal 12-4m gently dipping fore-set planar sands and massive stratified gravels overlain by an upper (4-0m) top-set channel of horizontally stratified gravels with interbeds of planar and planar rippled sands. Western sectors of the current exposures are dominated by glacial diamicts and testify to an ice marginal setting. The sequence described is an ice proximal delta, with an ice contact slope immediately behind the worked exposures (samples 6 and 7). The late morning, saw a confrontation with high tides, the tides won. Slightly later, we began our run through the three retreat stage formations exposed on the Northern Plain of the Isle of Man. First Shellag Formation outwash at Kirk Michael (sample 8), with us filling the time taken to collect gamma dosimetry with sample the Kirk Michael (KM3/4) kettlehole deposits for our tephrachronologists to search for Icelandic volcanic ash layers. The KM3/4 kettlehole includes a basal cold stage lake muds that predate the lateglacial warming (sample 9). The Orrisdale Formation on the Island is quite well dated, with Ian Thrasher’s research, but we selected the northern most sandur trough in the sequence for further work (sample 10-11).

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Day 5 Friday – Jurby Readvance and the Dog Mills: The final day of OSL sampling, we tackled the Jurby Readvance, with two good lithofacies in off-lapping readvance over-ride sequence 3 (samples 12-13), just below a phenomenally well exposure kettlehole, including a prograding delta into the basin (one for the Quaternary community to revisit). The last sample of the day, on the east coast, the Dog Mills proglacial lagoonal sands (sample 14). Thus the sampling over 4-5 days spans the entire retreat sequence on the Isle of Man and two readvance episodes.

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Day 6 Saturday – Bride and seeing what you can do with GPR: With everything complete samples wise, the spare day was just that and with a 19.30 hours departure giving us some leisure time….. What do two Quaternary Geologists with a day spare? Well with 2x GPR antennae and a GPS set up, we assess the performance of GPR for Irish Sea glacigenic lithologies using the Bride Moraine, arguably one of the best if not the best exposure of glacitectonics on the NW European Archipelago. Do we need to know the internal structure of Bride?; well we could just go and look at the 60-80m high cliff sections or read a GSP Thomas paper for that. Again with helpful landowners guiding the way, we gained access to the cliff-tops above Bride, and surveyed 2.5km of the most undulating glacigenic terrain you could hope to meet. The very promising results in hand; we then also set sail for home…..

Luminescence dating sampling at Cherry Orchard Farm, near Delamere

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By Richard Chiverrell

Another day and another quarry, but this time the BriticeChrono Terrestrial team Rich Chiverrell and Matt Burke met up with some friends, with luminescence dating team Geoff Duller and Holly Wynne from Aberystwyth and stratigraphic geru Geoff Thomas to tackle the delights of rural Cheshire, Transect 3. Breaking all the rules for BriticeChrono quarry investigations the sun was out and not a snowflake in sight or site for that matter. Cherry Orchard Farm is one of a series of sand and gravel quarries to the east of the mid-Cheshire Sandstone Ridge, recently sampled for cosmogenic nuclide (CN) dating.

The site (location 17 on the map) makes an intriging pair with cosmogenic nuclide location ‘Urchin’s Kitchen’ (location 16), a deeply incised bedrock channel eroded subglacially. We hope to compare the performance of luminescence and CN dating techniques with pairings like this. The setting contains numerous the active and former sand and gravel extraction sites around Delamere Forest, and is located on an extensive (8x5km) gently undulating triangular terrace or bench raised >10m above the floodplains of the Weaver Basin. The terrace is fed by channels flowing from the Sandstone Ridge and presumably a former ice margin on the southern edge of zone 5 (see the map).

Quarry operator (Richard Wilding) was fanastically co-operative and allowed us full access to the sections which reveal shallow water sandur and fine-grained glaciolacustrine sands. The sands were a dream to sample, well sorted, stratified, the right grain size for luminescence dating and with excellent exposure throughout the section. Four samples were taken arrayed vertically through the sequence, though probably almost identical in age given the depositional environment, we sampled different lithofacies or depositional environments. The lengthly process was completed in 5 hours, it takes 60 minutes to record the gamma dosimetry (with a field gamma spectrometer) for each sample, which gave plenty of time for discussion, strategy and logging. Then for some differing journeys home, it can’t take that long to drive to Aberystwyth can it?! Can’t wait for the dates and the next phase of sampling on transect 3…..