Glacial rock flour and the preservation of Greenland fossil fish
Deborah Painter (USA)
The island of Greenland is now an independent nation called Kalaallit Nunaat in the language of the native-born people. Almost totally covered in ice, the world’s largest island can be compared to a bowl of ice having a rim of ice-free hills and mountains. The southern tip supports agriculture in the form of small sheep farms and cultivation of kale, strawberries and other crops, mostly for local consumption, but fish and allied products reign, accounting for about 89% of exports.
To anyone other than someone who calls this land home, much of Greenland might seem remote and perhaps forbidding. My father, the late Floyd Painter, might have thought the same about the great island before he was a master sergeant stationed there for a year. Yes, it was very cold and dark for part of the year, but conversations with him about his time there revealed that he actually had an interesting time in the land of the Midnight Sun.
My late father served in the US Navy and Army before his careers as an archaeologist and marine engineer. When in his early thirties, his Army career took him to Camp Lloyd on Michigan Bay, a part of the North Fork of Sondrestrom Fjord (“Deep Stream Fjord” in Danish). It is located 670 38’ North, 500 43.33’ West, HO Chart 5796. Sondrestrom Fjord now appears on maps as Kangerlussuaq (pronounced “kanger-loo-soo-ack”) and is located along the west-central coast. It is the world’s longest fjord.
Camp Lloyd, the US Army landing base, was first used by the University of Michigan as its summer base during the second and third Greenland expeditions in the 1920s. It also served as the landing beach for shipborne supplies destined for the Sondrestrom Fjord US Air Force Base. During World War II, it was known as Bluie West 8, and was a relay base for ferrying planes to Europe by way of Greenland, Iceland and other North Atlantic locales. Sondrestrom Airbase was approximately 16km west of the edge of the Greenland Ice Cap and on the last rapids of the Watson Glacier carrying meltwater from the King Frederik Ninth Land section of the continental glacier.
In 1953, my father was in charge of the barges, tugboats, and landing craft hauling cargo from the ships in the deepwater anchorage to the landing beach. When he had a few days off from this duty, compressed into the brief months when the Fjord was free of ice, he and some friends could pursue other things. These consisted of searching for Inuit cultural evidence, such as house ruins and caribou hunter camps. Floyd was sometimes joined by an Air Force sergeant friend, whose base was no more than 14km away.
The friend showed my father a site at the airbase where fossils abounded. A badly gullied area of compacted rock flour from the Watson River, this sloping terrain was at a lower elevation than the riverbed. Many thousands of small, oddly shaped gray concretions, most of them less than 15cm in length, were scattered about. Caribou and men had stepped on and broken most of them, but fish impressions were preserved in these broken pieces. It became my father’s goal to find intact specimens, and at last he discovered some lying undisturbed below the soil surface.
He decided to try an experiment with some complete specimens to split them open and see intact fish. In his hut, he had a steel barrel made into an oil-fired heating stove, which he kept burning constantly, even during the summer days, when temperatures were like a pleasant spring day in the Ozark hills of Missouri, USA, his home state. He placed a food container tin filled with water on top of the stove and took the concretions to the mess hall freezer. After a few hours there, they went to the steam bath he had prepared for them in his hut. Gently he steamed them for 30 minutes, and then it was back to the freezer for them. After repeating this procedure three times, they split at their weakest seams and revealed fresh-looking bones and scales. In comparison, those left split open and exposed to weather showed only the negative impressions of the bones and scales.
The sergeant knew that, long ago, the site where the fossils were found was a backwater or a still or very sluggish portion of the Watson. The river drained the glacier, which was closer to the site of the airbase in millennia past. Small fish were living in that ancient tidal river, and how they survived in water full of suspended rock flour puzzled him. Perhaps they came up the fjord in the winter when the river had less suspended sediment. In the spring, when the meltwater reached any fish that tarried too long in the river, they suffocated. The fish sank to the bottom and were covered in rock flour. Decomposition released body oils, cementing the sediment into a concretion before the entire fish could deteriorate.
But how did they reach this elevation? On one river bank, the deposits are above the bed and on the other, they are below the bed. My father came up with two logical explanations.
- 1. An ice dam developed at the foot of the rapids from ice coming down the Watson River, or ice pushed to the head of the fjord by storms or unusually high tides. Perhaps, rockslides or landslides clogged up the river at the last rapids. Perhaps, an extinct tongue of the glacier could have moved across the river, damming it for several seasons. This could account for the accumulation of ten meters of rock flour behind it. One can see the same accumulation of sediment in the light gray bluffs on the side of the river opposite the site. Once the dam was breached, the river quickly carved a wide canyon through the sediment to its original level, leaving the fossils high and dry.
- During the height of the Wisconsin Ice Age, ice covered the entire land of Kalaallit Nunaat. The weight depressed the crust below sea level over the glaciated north and north-eastern Arctic region. By about 9,000 years ago, the ice had retreated from the coastline. Slowly, the crust began to relieve itself of the weight and rebounded to its former elevation. The runoff of the meltwater cut channels back down through the crust. The fossil bearing deposit was still depressed below sea level. The Watson flowed and filled the trench with rock flour. The area was the head of the fjord and was of course salt water. As the rebound progressed to the present elevation of 40m above sea level, the river cut through its own deposited sediment while seeking sea level. The same process continues today. Salt lakes in the vicinity, such as Störe Saltso, also came about through crustal rebound.
Many years after my father’s tour of duty in Greenland, the idea of writing this article occurred to me and I consulted some palaeontologists, who put us in touch with Dr Lance Grande. Dr Grande is Vice President and Head of Collections and Research at the Field Museum of Natural History, Chicago, Illinois, USA. I sent some of the specimens to him for long enough for him to identify them. They are probably Mallotus villosus, from one of the family of small fish called smelts. He told us that the fossils are indeed Pleistocene and that the site has been fairly well researched since the 1950s. Note that some of the buildings and barracks of Bluie West 2 are also now open to the public as the Narsarssuak Museum just beside the Airport at Kangerlussuaq.
Acknowledgements
My thanks go to Dr Lance Grande for his invaluable assistance in identifying of the fossil fish and also my thanks to David Hawk for his skills in photographic restoration.
About the author
Deborah Painter is an ecologist and general environmental scientist with Whitman, Requardt and Associates, LLP specialising in transportation and industrial development planning to minimise deleterious environmental impacts. She lives in the USA.
References
Kangerlussuaq Museum web site. 2015. http://www.greenland.com/en/providers/kangerlussuaq-museum/
McAllister, D. E., 1963. A revision of the smelt family, Osmeridae. Bulletin 191 (Biological series number 71). National Museum of Canada 1-53.
Metal Traveler Bluie West One page. http://www.metaltraveller.com/en/trips/greenland/bluie_west_one.html
Scholz, Herbert and Manfred Baumann. 1996. Review of Greenland activities: An ‘open system pingo’ near Kangerlussuaq (Søndre Strømfjord), West Greenland. Geology of Greenland Survey Bulletin 176 – 1997 104-108.