Contributed by Tom Bradwell (1.75m tall) and Rich Chiverrell
Dawn broke at 0430 (we understand but not by experience) with clear skies and wide views across the hills around Lerwick. The team assembled slightly later than this, well 4 hours later actually – at around 0830 – after a good night’s sleep following our 2-day extravaganza on Unst. The prospect of great weather called for a slight change of plan and we decided to split into 3 teams for the day: Derek, David & Tom headed west in the Hilux to hopefully find some nice big rocks on Muckle Roe; Rich and Matt went south in the Vito MPV in search of glacial sands; and Chris, Saskia and Vince went to gather more footage of the Project Leader in his well worn and very practical Drizabone field gear.
The island of Muckle Roe lies in St Magnus Bay but is only 25 m from the Shetland mainland at its closest point and is conveniently joined by a sturdy bridge spanning Roe Sound. Taking advantage of this team Hilux drove to the end of the public road at Muckle Ayre, parked and set off on foot into a chill NW wind towards the furthest tip of the island. Muckle Roe is composed almost entirely of Silurian/Devonian granite and is quite rightly a national scenic area. The landscape is quite different to that across much of Mainland Shetland, with distinctive red granite crags, precipitous cliffs, and an abundance of glacially transported boulders – so many boulders in fact that it soon became apparent that the cosmogenic sampling team were in for a good day! After a couple of kilometres walk they found the first signs that glaciers had once crossed the island from east to west, with a number of rounded ultramafic and meta-sandstone boulders scattered across glacially polished and broken bedrock surfaces. These boulders could only have come from the Shetland mainland and their presence was a clear indicator that a large ice mass covered the whole island group probably with a 30-km wide ice lobe flowing into St Magnus Bay. Unfortunately, these boulders in particular could not be sampled as they don’t contain quartz: the mineral needed for the cosmogenic nuclide analyses. Instead the team took quartz-rich granite samples from a glacially deposited boulder, a smaller cobble and some ice-worn bedrock. If only all sample sites were this good!
The team enjoyed a brief lunch stop of cornish pasty, squashed sandwiches, dried mango and caramel logs sat on glacially polished granite slabs overlooking the western cliffs with fine views to Foula and Eshaness. Derek even found the time and signal strength to send a couple of tweets. More sampling followed in the afternoon including a very prominent granite erratic nicknamed simply “big white” taking the final tally to 9 for the day. As the sun beat down, and temperatures soared into the low teens the weary 3 made their way back to the Hilux via the coastal path taking in some of Shetland’s (if not some of the UK’s) best cliff scenery. Vertiginous granite cliffs at Picts Ness and the Hole of Hellier were carefully navigated around before the samples were safely deposited in the truck.
Team ‘Elusive Quaternary Sediment’ following up some precise instructions from T1 Leader of go to behind ‘a well-known supermarket chain store’ there will be something there, and failing that drive around and find some stuff…… Pausing for some quick digital recognisance, emergency lunch supplies and then the section- bedrock and 1-1.5m diamict, job well done part one at least. The driving around aimlessly took much much longer! The coastal sections on the journey down to Hoswick proved equivalently disappointing, though interesting if you like windblown sand and peats inter-bedded of Holocene age overlying a thin glacial diamict. Matt and I then headed for Burn of Mail, and an eventual rendezvous with ‘the making of….’ documentary team. A cracking valley and showing the first set of convincing retreat moraines with ice flow down the valley eastwards from the mainland of Shetland. No sections but cracking geomorphology and a good boulder spread with the potential to record passage of the ice margin on land from the east. There was the tremendous opportunity to watch a future movie star in the making, as our film and outreach crew (Vince and Saskia) collected some of the final footage on Shetland for the U-rated comedy prequel to ‘Silence of the Lambs’. We then headed west to check out the southern flanks of Papa Sound, a stretch of marine waters extending from our destination on Wednesday ‘Papa Stour’ to the hinterland of ice on Shetland around Voe. Our brief ‘brief’ was to find boulder and if possible OSL datable materials, lo and behold we did, much of the lower terrain between Voe and Aith was ornamented with moraine ridges and glacial sediment documenting in this case the retreat of ice margins from the west onto Shetland. 15 m off the road inland of Gon Firth a 5m thick borrow-pit section through a moraine shows a sequence of a coarse grained boulder (>1 m) diamict overlain by a finer grained (>0.3m) poorly stratified till, but separated by 0.5m of stratified outwash sands probably lain down as wash down the front of the moraine. OSL samples were recovered and have the potential to add to the age control in this sector of the former ice sheet, particularly with paired cosmogenic ages if possible.
C3W team Vince and Saskia departed for home this afternoon, overloaded we know with excellent footage documenting the work of Britice-Chrono and the T1 team on Shetland, we thank them for their company, hard work and efforts, and wish them a speedy journey home…. A fine evening meal (cooked by chef Fabel) of Jalfrezi chicken with rice, poppadoms and indian snack selection was enhanced further with David’s home-made onion pickle accompaniment (recipe available on request). With ready made plans for tomorrow and Papa Stour hopefully on Wednesday, Transect 1 (onshore) feels like it is rounding the bend onto the home straight…..