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Entry Two: Finding our feet and our fossils

 

Finding Our Feet and Our Fossils

The purpose of our expedition to Greenland was to gather fossil plants that would help us to investigate a great mass extinction event that occurred about 200 million years ago at the transition from the Triassic to the Jurassic. This extinction event is noted for the early evolution of Dinosaurs, unlike the better-known Cretaceous-Tertiary extinction event that is known for their demise. In the 1930’s a British paleobotanist T. M. Harris described fossil plants of Triassic-Jurassic age from numerous localities in East Greenland. As such, our plan on arriving was to re-collect from two of Harris’ localities (Kap Stewart and Primula Elv) and to search for new fossil plant sites. Our preliminary survey of Kap Stewart by air suggested there was good potential for collecting in this area. However, the presence of good accessible fossils could only be proved by a walk through the area, so, our first survey was critical. Would we find fossil plants, or would erosion and weathering have obliterated these localities last collected more than 70 years ago?

On the beach just 15 minutes walk to the south of our camp, we examined our first rocks. We had immediate success; a small rock exposure with fossil plants. The fossils were moderately well-preserved, and we determined that the locality would be worth revisiting for subsequent collecting. As we continued our reconnaissance further along the beach, on a beautiful calm day, little did we realize that the fossils we had seen at this locality were to be the last ever collectable, for storms later that week would soon erode this locality away. 

The team soon found more fossil plants further along the coast in several thick dark gray to black shale beds lying at the top of thick banks of unthawed snow and ice. The fossils were abundant and spectacular, exactly what we had hoped for! Among many others, we identified stems of Equisetites (a plant related to modern horsetails), and fronds of both Dictyophyllum (a fern) andAnomozamites (a plant similar to modern cycads). Not only were the plants identifiable, but their original cuticle (the waxy coating on plant leaves) was very well- preserved in many of the specimens. The presence of this material was key to our original plan. Back in the lab, we would be able to examine the cuticle microscopically and count pores (stomata) in its surface, from which the levels of carbon dioxide in the atmosphere 200 million years ago could be calculated; perhaps giving us clues to the causes of the mass extinction event. So, this was a locality that we should start to work on soon; if the snow bank began to thaw access to the fossils would become impossible!

Still further along the beach we found more fossils, but here the snow hindered, rather than helped, our access. We would have to rely on some good weather if we were to make the most of collecting at this point. As we moved on, it was not only the snow that prevented us reaching more plant localities, but the sea as well. It was time to move inland, and to investigate the next most likely place to find good exposure of fossil plants: the banks of the river Lakse (Lakseelv). Sadly, the river provided no good exposure and we only succeeded in upsetting a Rock Ptarmigan and her chicks and a Ringed Plover who tried to draw us away from her nest with a feigned broken wing.

That evening, since the sun was not going to set (in July its daylight 24 hours a day in Jameson Land), we decided to complete our reconnaissance with a walk to the north of the campsite along the coast. After some 45 minutes of walking we began to see rocks high up in the cliff that looked as though they might hold plant fossils. However, after a long day, the steep climb up convinced us to postpone any further exploration until tomorrow.

Plotting our new northern locality on a map we named it South Tancrediakløft (STAN for our packing labels) as the nearest named locality was a cleft some mile or so to the north called Tancrediakløft. The climb up South Tancrediakløft was hard and treacherous (one lost geological hammer and two rucksacks thrown several hundred feet down the cliff attested to this), and it was often necessary to dig a path out in order to advance upwards. By the end of the day we had identified at least four plant horizons some containing conifers such as Stachyotaxus, some ginkgoes such as Ginkgoites,some cycad-like plants such as Anomozamites and Pterophyllum,some ferns such as Dictyophyllum and Thaumatopteris and some seed-ferns such as Lepidopteris. The last two Lepidopteris andThaumatopteris are particularly important, as their presence is key to determining the position of the Triassic-Jurassic boundary. Lastly, and almost most importantly, we found a good geological marker unit – a fossil clam-rich layer known as the Jamesoni Limestone – that would act as a reference horizon enabling us to compare our locality with others sampled in 2002 and with Harris’ original localities collected in the 1920’s. This important geological marker horizon would also enable us to predict the position of the Triassic-Jurassic boundary. Knowing the location of this boundary was essential, if the data we gathered were to help us understand how the Triassic-Jurassic mass extinction event occurred, and what plants it effected.

One last locality was to be added to our list, Raevekløft, but it was over two weeks before we found plants here and added it to our collecting schedule.

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