Kategori: Okategoriserade

The weather is against us. I am back at the “Hilton” in Constable Point with a few other scientists, who are likewise stuck because of the storm. Apparently there is a big low-pressure centre hovering over Iceland that is hitting the East Greenland coast with 60+ knot winds and heavy rain. This is far too dangerous for the helicopter to fly so a flurry of phone calls between Kap Stosch, the helicopter pilot in Constable Point, the POLOG main office in Copenhagen, and myself are trying to fix alternatives.

The story is that we are unlikely to fly tomorrow because the scheduled flights must take priority (if the weather improves that is). So it looks like it will be one day later, but the winds are supposed to last for anything up to five days.

Just depends on when it is safe to fly.

At least I have the chance to update all of my field notes – and keep track of the blog!

Ben quickly helicoptered over to the airfield at Constable Point to organize our next load of provisions and arrange for export of the fossils being shipped down from Kap Stosch. All is ready for tomorrow

Meanwhile back in the camp….

It has rained constantly for three days. We sat in camp and sorted through our fossils for shipping. Grzegorz ventured out in the rain to take some samples for laboratory analysis. He also managed to get upriver to that final spot and collected several concretions containing fish, ammonoids and an unusual large skull. These were immediately packed for shipping. We can look at them in more detail later.

We gave Ben a call to see how he was. Very pleased to hear that he will join us again soon!

(Ben’s story)

After a two-hour flight along the coast through a rainstorm I touched down in the town of Scoresbysund at 01.00 in the morning. I did not know what would happen but I was met by a nurse in a two-seater quad bike and driven straight to the small hospital. The Danish doctor was waiting for me. After unwinding both the bandages and bloody compress he had a look – “nice cut you have there. This might hurt a bit”.

Seven stitches later I began to wonder where I am going to stay. Scoresbysund is tiny, only 400 people, and it was the middle of the night. Luckily the doctor said that he had plenty of room, and I could stay at his house until I got a flight out.

Besides, he already had another patient in “convalescence” – an English visitor who had fallen ill while collecting botanical specimens.

Would my return flight be for Kap Stosch or all the way back to Sweden? The doctor’s response was laconic – “you are OK to keep working, I’ll just show you how to take out your own stitches”.

Looks like I am staying then.

A few phone calls to both our logistics company POLOG, and the SPRS the next morning and it was all sorted. I would join the group again after four days when they moved camp to our next field location on Ymer Island. There we would be looking for evidence of ancient bony fishes and the earliest tetrapod transition from water onto land.

Today started well with a plan to head downstream along the Blue River to sample the Permian strata on the coast. We also wanted to see if we could access a large valley called Otocerasdal, which was our last target for the fossiliferous concretion-rich layers. Unfortunately, after a 2-hour hike up and down the deep ravines along Gaffeldal (intending to bypass the Blue River ice tunnel) we got a view up the valley – it was completely filled with ice and a high sandstone cliff blocked the entrance at the lower end. The only access would have to be by traversing the ridge top on the other side and come down from above.

We will have to save that job for another day.

The lower end of the Blue River opened up on the coast. We crossed down into the Permian strata and recovered some brachiopods –stalked filter-feeding invertebrates that have a distinctively asymmetrical valved shell.

Geologically speaking, we had also just walked through the greatest mass extinction event of all time. Over 80% of all life disappeared at the end of the Permian, paving the way for new organisms to radiate including many modern groups.

We also just crossed the Permian-Triassic boundary, representing the dawn of the Mesozoic Era and the beginning of the “Age of Dinosaurs”.

The eastern side of the river had a sparse cover of concretions. These produced some Claraia and the ammonite Wordieoceras.

Everybody then headed down to the river mouth. Ben stayed back after finding a superb specimen of the fish Australosomus. He had taken out some tools to clean away the matrix – a brush and scalpel, the latter used to flake off encrusting dry mud and rock from around the bones.

He then caught us up at the bottom of the river while we stopped for some photos and a bite to eat.

Re-packing the backpacks we started heading out. Unfortunately as Ben swung his bag up onto his back the scalpel slipped out of its container and cut through both the bag and Ben’s leg. His cut was too long and deep for us to deal with. Patching it up with dressings from our medical kit, we left Ben with Henning at the bottom of the river while Grzegorz and Lasse hiked out to call for help on the satellite phone.

Four hours later the helicopter arrived to fly Ben out for medical treatment.

The rest of us sat in camp waiting to find out what would happen next.

We worked down river as far as the ice tunnel taking GPS waypoints for the most important outcrops. We located some of the older horizons and found parts of giant ammonite, Otoceras, which would have reached the size of a bicycle tire. Several examples of the large snail Belerophon were also recovered, as well as a very large coprolite (100 mm in length) containing chewed up ammonites.

We moved back upstream as far as possible, finding organic rich shale layers with pyrites (iron disulfide) and masses of Claraia; these “clam-like” bivalves seemed to have tolerated the low oxygen conditions on the ancient Triassic sea bed.

Considerable amounts of plant material, including horsetails and some seed-like structures, were also found indicating a close proximity to land.

There is one last upriver exposure we need to see. It looks promising but we have run out of time fore today.

Another discovery was Arctic fox tracks. Sadly we did not get to meet the owner for a photo session!

We trekked to the far side of Stensiö Plateau today (approximately 4 km) to find an access out onto the north facing cliffs along the coast. We are again trying to locate the “Stegocephalian horizon” to find more fossils of aquatic temnospondyl amphibians. The climb up from the camp passed through the same Anodontophora fassaensis beds that we surveyed days before. A more detailed inspection, however, had located numerous slabs of fine siltstone that were covered in ripple marks, evidence of currents frozen in time for 250 million years

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There were also numerous burrowing traces and scratch marks left by worms and small arthropods. A significant discovery was a concretions filled with conchostracans. These are tiny arthropods still found in shallow freshwater ponds today.

The top of the plateau was spectacular. An endless field of flowers, streams and ice all glittering in the sun. We hiked across, sliding down the snow banks until we came to a gap in the high basalt cliff; we had marked this previously on our geological maps and Google Earth satellite images. The slope was steeper than expected, and after slipping and scrambling down part of the way we decided that it was a little too risky to continue. We therefore split the team to work along the nearest ridge and also further along the plateau. Both sites turned out to be rich in trace fossils including burrows and resting outlines of small limulids or Horseshoe crabs.

No more bones were located, but the large collection of trace fossils has confirmed our interpretation that the palaeoenvironment was a very shallow inshore system with considerable freshwater input.

A treat on the walk home was a face-to-face meeting with an Arctic hare. It posed for a few photographs before bounding off.

Spent the morning resting and packing our fossils for transport back to Sweden. Everything needed to be marked with GPS coordinates, labeled and inventoried so that we have an accurate record for the registers in Uppsala. We have permission from the Greenland government to remove 400 kg of samples. This will be accessioned into the Museum of Evolution at Uppsala University, which already houses Sweden’s premier collection of Mesozoic vertebrate fossils.

The sun has been out for the last 48 hours so we are now working in T-shirts.

We have also done a few night visits to the closest outcrops (again don’t forget we have 24 hours of light).

Today we climbed down into an adjacent valley, Gaffeldal. There are lots of Musk Ox tracks along the ridges where the vegetation cover is thicker. We also came across the body of one unfortunate Musk Ox that seems to have slipped on the mud into a crevasse and died at the bottom.

The foot of Gaffeldal turned out to be an impassable cliff. There is also overhanging ice and a 20 m long ice tunnel blocking our passage down the Blue River to the oldest Permian strata on the coast.

We therefore returned our attention to Blockeln – Round 2 going to us this time.

Henning collected another beautiful Australosomus in the river, and we found ammonites, more coprolites and the skull of a large coelacanth, a type of archaic lobe-finned fish that is still alive today in waters off of southeastern Africa and Indonesia.

The best-known Triassic coelacanth from the Wordie Creek Formation is Laugia greenlandica.

We will try the Blue River again in a few days but another trip over the Stensiö Plateau is planned for tomorrow.

Today was exhausting but productive. We decided to tackle our second objective, which was to sample the famous “Stegocephalian horizon” on the far side of Stensiö Plateau. This rock layer was the source of numerous temnospondyl amphibian fossils described in the 1930s. We climbed up to about 700 m on the south side of the plateau and crossed over the top for a spectacular view of the Finsch Islands and the pack ice stretched across Gael Hamke Bay. We then climbed through a gap in the basalt cliff and down onto the Cretaceous sandstones that overly the Triassic sequences. Henning picked up an ammonite, which was badly weathered but clearly of Cretaceous age.

Further down the steep scree we located the bivalves Myalina kochi and Anodontophora fassaensis, giving us a correlate from strata on the other side of the plateau. There were also large stromatolite mounds – these are sediment accumulations accreted by photosynthesizing cyanobacteria.

Finally after scouring the slope for about an hour Grzegorz shouted out that he had found some bone. We all scrambled across to look at what turned out to be bone fragments in an oolite – a microbially accumulated limestone indicative of shallow water conditions. After splitting the rock we identified some small temnospondyl skull and limb girdle elements (probably from long-snouted trematosaurs), as well as a 30 mm long jaw with teeth resembling procolophonids. These were terrestrial herbivorous lizard-like animals, globally distributed during the Triassic.

We headed back to camp with our prizes, but it was long and tiring climbing up the ridge and down again from the top of the plateau.

Will have an easy day tomorrow to get over it.

The sun was out as we set off for our collecting trip. We packed wrapping paper, sample bags and small chisels for our assault on the concretions. We were not to be disappointed. The first few hours on the slope yielded well over 100 specimens of Ophiceras, the most abundant ammonite known from the Wordie Creek Formation. Many of these were also exceptionally preserved, showing the taxonomically important sutures between the internal shell chambers. Ammonites, like the modern day Nautilus, used differing fluid densities within their shell chambers to control buoyancy. The configuration of the walls between these chambers, as well as the exterior ornamentation and shape of the shell, are critical for identifying different species.

We found prolific specimens of the bivalve Claraia and some more fishes including Bobastrania, Boreosomus, and a similar species Australosomus.

Most significant, however, was the recovery of numerous large coprolites.

Coprolites are fossilized droppings, and are actually quite characteristic in terms of “who did it”.

Curiously, one of the “coprolite” masses had very little phosphatic matrix, and showed a conspicuous longitudinal alignment of its constituent fish bones. Under the hand lens these revealed minimal corrosion by gut acid, meaning that we might have a fossilized regurgitate – a vomited accumulation of indigestible fish fin spines that were coughed up some 250 million years ago!