by Tom Bradwell (Day 15: Friday, 04:44) (with some photography by Alex Ingle)
The last time we ventured into Shetland territory it was in pursuit of far-travelled rocks laid down by the last ice sheet, strewn across hard-to-reach islands – Foula, Papa Stour, Out Skerries, to name just three. Our successful 10 island-tour of Shetland took place in 11 carefully planned days in May last year, when the 6-strong team worked from dawn til dusk to ensure that they didn’t return home empty handed. Those precious rock specimens have since been analysed at Glasgow University; their exposure age is helping to unravel the ice sheet history of Shetland and the surrounding area. This time the Britice-Chrono team are on the high seas, aboard the RRS James Cook, looking for glacial seabed mud and ice sheet imprints along the extreme edge of NW Europe, from the Outer Hebrides to the Norwegian Channel.
In this part of the UK, in July (at 61.5 degrees N and still within the offshore Exclusive Economic Zone) dusk stretches beyond midnight and the sun reappears before 3 am, after only the briefest of nights. That being said, working on the night shift is still a challenge. The geophysical data collection and seabed coring programme on the James Cook works 24/7. The ship’s crew operate on 4-hr ‘watches’, and the science team are divided into day and night shifts (8am to 8pm) to allow around-the-clock working. Punctual, brief, morning and evening meetings allow seamless handover between shifts, an update on the day’s progress, and an all-important weather forecast for the next 48 hrs. Day and night shifts for the science team are similar in content but different in the details. Apart from the darkness, the cold, the nocturnal fatigue and the daysleeping, we have dinner for breakfast and sometimes breakfast for dinner; which mixes up the body’s normal everyday cycle and turns the daily routine on its head. But after 2 weeks on the night shift, having a roast beef lunch at midnight seems almost normal. Although going to bed when the sun is at its warmest will never feel quite right to me. And the AM vs PM confusion is always there, nagging away.
As we collect geophysical data, recover seabed samples and describe cores well into the night, the daysleepers perform the same rituals as the nightsleepers but just in a different time zone. We say ‘good morning’ to people instead of ‘goodnight’; we cheerfully get down to work on Wednesday night and carry on into Thursday morning; we relax on deck after some ‘early evening’ exercise; and drink a beer instead of pouring that first cup of coffee. But perhaps my favourite bit is not really ever knowing what day of the week it is. Waking up after a full ‘night’s’ sleep to find it’s still the same day as when you went to bed. Confusing, but curiously liberating!
Anyway, back to the science. Yesterday’s leg of the cruise took us 60 nautical miles (or roughly 111.11 kilometres) north of Muckle Flugga lighthouse, Shetland’s northern tip – a point on the Greenwich meridian still in UK waters but on the same latitude as Narsarsuaq Glaciers in east Greenland and Suduroy in the Faroe Islands. We took 9 seabed cores during a 12 hour transit back towards Shetland, each one penetrating different sediment, and each one hopefully holding its own clues as to when the last ice sheet retreated and when sea levels rose. The spectacular sequence of moraine ridges on the seabed NE of Shetland is unique within the British Isles, both in its unusual shape and the number of landforms preserved. Although we’ve known about the moraine pattern for a while, and what it means for the last ice sheet to cover Shetland and the northern North Sea, the age of these features remains elusive. What we find when we analyse these cores will hopefully help clear things up.
For me, the crucial part of the Britice-Chrono project comes when linking geological evidence onshore and offshore — something that has often proved difficult in the past. As an Earth scientist, interested in glacial processes, the distinction between terrestrial and marine is a blurred and relatively unimportant one. A bit like the difference between morning and evening when working the night shift at this latitude…