Tag Archives: lacustrine

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.

This slideshow requires JavaScript.

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.

This slideshow requires JavaScript.

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

Minching about on a sunny Isle of Lewis

By Rich Chiverrell

Port Skigersta delta

Port Skigersta delta

One of the smaller ice-masses draining the former British-Irish Ice Sheet, the Minch palaeo ice stream drained much of the NW sector of the British–Irish ice sheet (∼15,000 km2) feeding sediments to the large Sula Sgeir fan fronting the continental shelf. But if this is small, standing on the east coast of Lewis (Outer Hebrides) looking across the sunlit, blue seas and skies east to the feeder fjords and mountains of the Summer Isles and Wester Ross helps one visualise how large this former ice sheet really was. Our aim for this ongoing Briticechrono Transect 8 fieldwork was to secure a series of targets for Optically Stimulated Luminescence (OSL) dating from outwash sands from Lewis, one of the outermost land-masses on the western flank of the Minch Ice Stream. This work will support previous sampling efforts targeting boulders on the Scottish Mainland and the Hebrides for cosmogenic nuclide dating. Previous OSL sampling had targeted the inner sector of the Minch on Skye and north of Ullapool. The team (Rich Chiverrell, Matt Burke, OSL Postdocs Rachel Smedley and Alicia Medialdea) set off first thing on Tuesday morning to join Transect Leader (Tom Bradwell) on Lewis. Departing a cloudy Manchester via Glasgow Airport we landed before lunchtime to blue skies, sunshine and searing temperatures at Stornoway Airport.

This slideshow requires JavaScript.

Inspired by our surroundings, the weather and the prospect of excellent sediments the four newcomers sped off to meet up with advance team Tom Bradwell, Adrian Hall and Maarten Krabbendam (from the Netherlands) at Port Skigersta in the far north of Lewis. The site an embayment on the western flank of the Minch Ice Stream gave stunning views across the water back to the ice source areas in western Scotland and beautiful turquoise seas. The sediments were very impressive with the sequence a stacked delta sequence with steeply dipping fore-set sands capped by top-set horizontally stratified gravel. Intriguingly the basal delta is buried by laminated bottom-set muds, in turn buried by a second delta fore-set and top-set couplet. The repeating delta suggests changes in water level probably lake level, dammed between the ice stream and bedrock rise into Lewis. We sampled both deltas close to the fore-set – top-set contact. And then for some geological tourism, the raised beach at Galsom guided by Adrian Hall, stunning and confusing sediments, all contributing to produce a plethora of hypotheses. Difficult to address under the banner of Briticechrono, the beach deposits (guess the isotope stage) appear altered by over-ride by ice, locally there is a surface diamicton and the beach pea/rounded gravels are probably thrust or stacked. We have targeted an outwash (ish!) deposit above a glacial diamicton, fingers-crossed for contributing to the debate. Excellent food followed at the Cabarfeidh Hotel our home for the next few days (well some of us!).

This slideshow requires JavaScript.

Day 2, still warm, still still (no winds) and the sunshine popped in later! After an epic breakfast (Lewis did us proud) back to the north and just south of the Butt of Lewis the west coast Swainbost Sands offered much promise. The sections were epic more glaciotectonics, tills, shells than you can shake a stick at, and the beach!!!! One of the best beaches I have seen in the British – Irish Isles…. Selecting targets was challenging, much of the outwash deposit was rich with shells, thrust, tectonised and not where it was deposited! How? Well by marginal movements and override by ice and at a substantial scale. Three sample locations were found and in the back, along with crucial in gamma detector comparisons, duplication with different detectors at some of the samples. The sampling completed our targets after ~36 hours on the islands, and so we racked our brains for other targets. After a quick visit ~5/6km south down the west coast of Lewis where we encountered convincing striae in steeply foliated Lewisian gneiss, where the glacial lineation trends cross obliquely the metamorphic structure heading northwest. We also prospected for sites further up-ice around Stornoway; another fine meal at the hotel and some gin-assisted colour-by-numbers approaches to former ice geometry and let’s see what tomorrow brings for our last 3-4 hours on this eye-opening island (hopefully a final sample)….

Unst and back again…….

A hobbit’s tale by Tom Bradwell’s ghost writer……

Concerning Unst, it is a delightful island in the northeast of Shetland, and the peace and quiet was interrupted the last two days by a team of geoscientists hunting for treasure. In this case treasure would be boulders or sediments that would allow the dating of ice margin retreat across northeast Shetland. We set off from Lerwick around 8 am armed with tools of the trade; rock saw, hammers, ground penetrating radar (GPR), percussion corer, RTK dGPS and a film crew. Getting to Unst required driving to a short 30 mins ferry crossing from Toft on mainland to Ulsta on the island Yell. Our time on Yell was brief with views of the rugged peat covered island on the journey from Ulsta to the next ferry terminal at Gutcher (north Yell) suggesting little prospect of glacially transported boulders. Hopefully Unst would deliver the goods! Following the Yell to Unst crossing, also brief (20 mins), we were ready to explore.

The journey to Yell....

The journey to Yell….

We journeyed about as far north as you can drive on Unst to Herma Ness in the northeast, here hopefully our targets would provide the most northerly of our Shetland grid of sites. To cover the ground we divided into two teams: OSL and sediment group (Rich, Matt, Chris, Vince and Saskia) and Rock gatherers (Derek, David and Tom). For one of us (Rich), the plan for finding sediments involved following the footsteps of a predecessor at the University of Liverpool, geologist Derek Flinn who published extensively on the glaciation and glacial geology of Shetland in the 1970-90’s. An article on ‘The Milldale Glacial Lake, Herma Ness, Unst’ by Derek Flinn appeared in The Shetland Naturalist in 1992. Part of the mapping by Flinn identified an enigmatic outwash fan raised above (70-110m OD) the valley floor on the west flank of Burra Firth valley. The attraction for us lay in the potential for glaciolacustrine deposits to include sands for that elusive deglacial outwash material. Matt and Rich hiked up Milldale Burn and examined numerous exposures on the left bank that showed 3-4 m of sandy diamict, but no outwash. Meanwhile Chris explored the feeder outwash channels and confirmed an inflow feeding the deposit from the south. Our plans to run GPR survey were sabotaged by the Holocene, a very annoying 3 m of undulating and hagged peatland. All in all not a great success (except for some TLC for a new-born lamb by Chris), and then we abandoned the feature as, probably an outwash fan but composed of materials coarser and problematic for sampling. We then explored the other end of the Loch of Cliff and there are other bench like features also suggesting the presence of a former glacial lake but no sign of the sediments. Disheartened, we investigated other possible sections for glacigenic material in Norwick and Bray of Skaw, but the only prospect on the north margin of the sandy beach at Bray of Skaw we later revised interpretation of coarse cobble gravels to that of a storm beach buried by interbedded wind-blown sand and peat.

This slideshow requires JavaScript.

For the team searching for rocks, the day was exhilarating and slightly frustrating, exploring the stunning landscape of Herma Ness walking from the car park at Cleva Ness to the tip of the headland north of Hermaness Hill, the far northeast of Unst and Shetland, overlooking the remote offshore rocks of Muckle Flugga. A great circular walk, but the entire area was covered with peat, and little sign of bedrock or boulders, notwithstanding the promising bedrock lithologys. Thus no evidence of glacial activity, in the form of sculpted bedrock, erratics, pseudoerratics or striations, was found. The team drew a blank in the northeast on the headlands of Skaw. Hill of Clibberswick though covered with bedrock exposures sadly there was no clear evidence of glaciation, no boulders and the bedrock was ultramafic metagabbro. Even though not promising a sample was taken for possible cosmogenic nuclide dating using the 36Cl isotope.

Tired, dazed and confused the two groups reconvened in the lounge bar of the Baltasound Hotel, having acquired our chalet style hotel rooms, for some much needed Shetland Ale or Guinness. Much debate followed, focussing on the apparent lack of glacigenic sediment and boulders, as well as the challenges of some very complicated bedrock, much of it not suitable for cosmogenic nuclide dating. Baltasound Hotel did us proud for dinner with an excellent array of foodstuffs: scallops, salmon, haddock, fish cakes and steaks. The Baltasound Pub (same place different room) did us prouder with beers, single malt and Eurovision! A lengthy evening ensued of spirited debate, and a tantalising fragment of local knowledge; “try the boulders south of the ‘Westing Road’ they look out of place……..”

This slideshow requires JavaScript.

Day 2, after an excellent breakfast and a detour to debate the beach deposits at Bray of Skaw, we continued the search for boulders starting at Keen of Hamar walking through extensive exposure of Serpentinite and Britain’s largest chromite mine, at the coastal cliffs, we finally discovered that elusive evidence for glacial activity we had been searching for a glacial diamict that buried the Serpentinite showing glacially smoothed and scoured surfaces, these striations testifying to erosion by ice. Sadly the slopes littered with debris from the mining offered no prospects for cosmogenic nuclide dating.

This slideshow requires JavaScript.

Finding bedrock: returning to the extensive north-south valley containing the Loch of Cliff, we explored the hills around Hargal Burn examining bedrock ridges and erratic boulders marked on the BGS geology sheets. Though not completely ideal, the rock team sampled the stoss and lee side of roche moutonnee form composed of psammite. We then followed up the wisdom received in the pub the night before on our journey back to the ferry in the south of Unst. Sure enough on the Westing Road, many boulders were visible, and a short journey west, 100 m distance from the Standing Stone south of the road we found a series of psammite boulders potentially moved by ice and containing good quartz veins. So after a shaky start we were ready to leave with 7/8 samples promising cosmogenic nuclides from the northernmost target of our sampling campaign.

This slideshow requires JavaScript.

The return home went like clockwork, catching both of the return ferries promptly and all for excellent value, £54 for two cars and eight people return travel! We left Unst at 17:55 and made it to the excellent fish and chips shop/restaurant in Brae by 19:00, and what a feast awaited. The second best Fish and Chips in the United Kingdom, Frankies, battered scallops, pan fried scallops, mussels in blue cheese, ham and garlic, battered haddock, sea food tagliatelle and smoked haddock fish cakes, this place is off the scale, exceptional we cannot recommend it more highly. The team tired, satisfied, happy and ultimately successful returned to our digs near Lerwick for some much needed rest. Tomorrow waits with further sampling planned and our sampling grid beginning to fill…….

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.

This slideshow requires JavaScript.

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).

This slideshow requires JavaScript.

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.

This slideshow requires JavaScript.

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

This slideshow requires JavaScript.

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…..