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Mélange

February 21, 2015

Mélange: A mixture; a medley; odds and ends; a motley assortment of things, . . .

In geology, a mélange is a large-scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix.”

Jemseg church

However you look at it, St. James Church in Lower Jemseg, New Brunswick, is a mélange. Its architecture is a mixture of features and influences that somehow combine to make a charming and coherent building. Geologically, it can also be considered a mixture, though of course it is one produced by human agents rather than the immense forces that generate a mélange under natural conditions.

little_window

Even visitors with no knowledge of geology will immediately recognize that materials in the sturdy outer walls were derived from a variety of sources. Below and beside the windows, large blocks of dark purple sandstone contrast with various paler shades in the smaller blocks. The buttresses are armoured with wedge-split granitic rock, while rounded granite fieldstone can be seen in places in the walls. And then there is that soft, pale carved stone around the windows and the doorway. What are all these stones, and how did they get here?

The stones were pulled together through human expediency and opportunity. Jemseg, on the low-lying east bank of the lower Saint John River valley, is not a place endowed with wonderful bedrock, but the local geology is varied. Some of the stone came from nearby sources, but a bit of it travelled what might be called an unreasonable distance.

doorway

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Playground for a Polar Bear’s Picnic

January 3, 2015

playground overview

The Churchill part of the Hudson Bay Lowlands is replete with strange and obscure little corners. One of the strangest is this “playground that time forgot,” hidden away behind trees and boulders near the shore road between town and the airport. I assume that it was built back in army days and served for the entertainment of children who lived on the base. It is in the same area as the “golf course,” which always seemed a humorous name since this area of bog, boulders, and stunted black spruce is as far from a golf course as you can get, this side of the continental slope.

teeter totters

You might note that my photos of this playground are limited in their viewpoint and angles; these were constrained because I was shooting from the vehicle. When we arrived here we had just been surprised by an immense polar bear as we photographed roches moutonnées along the road, and it didn’t seem to be worth pursuing better photos if it meant that I might serve as the primary protein for a polar bear’s picnic.

Although it feels abandoned, someone seems to be maintaining this place at least in a basic way, so maybe it receives the occasional visit from children when the bears are absent. Or maybe the bears like a good seesaw.

roundabout

The ancient teeter-totter and roundabout would, in all likelihood, not be considered acceptable in a city playground that adheres to modern safety standards. But given the frequent visits from Ursus maritimus, these are probably relatively minor issues if you are considering the overall safety of this particular pleasure park.

playground climbing frame

Happy New Year!

© Graham Young, 2015

Dead in a Ditch

November 28, 2014

Silurian Stromatolites in the Grand Rapids Uplands

old burn

When this photo was taken in 2007 the appearance of the burn was more dramatic than it is today.

On the long drive northward from Winnipeg to Grand Rapids, I always look forward to seeing one area not far beyond where the road rises onto the Grand Rapids Uplands. After the monotony of the “great bog” north of St. Martin Junction, the curves and slopes make a very welcome change. When I first visited Grand Rapids 20 years ago, this area had been freshly burned; it was a blackened waste similar to the one that followed the larger fire north of Grand Rapids in 2008.

The ever-changing appearance of the burn is also a great relief to the monotony, as over the years we have been able to watch saplings grow into trees, scorched trunks slowly replaced by a new forest. The regenerating plants attract wildlife, and we have seen deer, foxes, and a variety of birds there. One fall day, we even had a lynx pad across the empty Highway 6 in front of us – a rare sight indeed!

The reality of constant landscape change was brought home last autumn as I again drove over the southern end of the Uplands, this time with Dave Rudkin and Michael Cuggy. We were surprised to see that, in a place where there had been roadwork in recent years, the ditch had since been stripped completely bare by local floodwaters. What had been gravel the previous summer was now a gleaming white dolostone pavement. It didn’t appear to extend very far but it did look interesting, and we made a mental note of the location as we zoomed past. Somewhere to stop on the return drive from William Lake, if time and weather permitted.

ditch_lengthwise2

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Portage Chute

November 14, 2014

Churchill River, Manitoba: August 24, 2014

From Portage Chute to Bad Cache Rapids, the entire riverbed is an unconformity.

From Portage Chute to Bad Cache Rapids, the entire riverbed is an unconformity.

Heading south from Churchill, the helicopter follows the river for the first 30 kilometres above its mouth. Then we head off overland, taking a straight-line shortcut instead of duplicating the river’s long dogleg. “Overland” is, perhaps, a bit of a misnomer, since the surface we pass over must be at least 20 percent open water, with much of the rest consisting of bog and moss, but as far as I know “overtundra” and “overmuskeg” are not words. Anyway, we fly low across this strangely-coloured otherworldly landscape for many kilometres, before rejoining the river’s course.

Coming over the steep bank, we can see that the river is still broad, but it is very different from the estuary you see at Churchill. Here the water rushes over its bed, with many treacherous shallows, boulders, and long stretches of rapids. After a stop to survey the cliffs beside Bad Cache Rapids, we are picked up again for the hop to Portage Chute. One hundred and twenty-five kilometres from the Town of Churchill, this will be the farthest we go during our several days of helicopter work in August, 2014. Around the steep rapids of Portage Chute we can see no landing place (the name “Portage Chute” apparently means “falls requiring a portage”), but a little way downstream a flat platform of bedrock extends from the cliffs on the river’s northwest bank. It is a perfect natural helicopter landing pad, and Frank quickly sets down. Once he gives us the all clear signal, we pile out and gather the packs, tools, and shotgun (never forget the shotgun, as there is still a risk of meeting polar bears even this far inland).

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The Raft of the Medusa

October 28, 2014

There is really no way of knowing what the media, scientific or otherwise, will grab onto.

A week ago, at the Geological Society of America meeting in Vancouver, I presented a descriptive talk that may well have been the simplest I had ever given to a scientific audience. We had just listened to a series of presentations, many of them by students and postdocs, which incorporated considerable amounts of “big science”: sophisticated imaging techniques, chemical analyses of fossil preservation, or multivariate statistical studies of large numbers of specimens.

When I got up in front of the same audience, I was a bit worried because I realized that my talk could have been just as easily presented in 1914 as 2014: I was describing a single specimen, illustrated with photographs. Nineteenth century Natural History, really. But it was such a strange specimen that it seemed worth presenting, and as it turned out, the reporter from Science News thought so too (here is his short article, freshly out).

Carboniferous (Pennsylvanian) fossil jellyfish from the Mecca Shale (Field Museum of Natural History, PE23963)

Carboniferous (Pennsylvanian) fossil jellyfish from the Mecca Shale (Field Museum of Natural History, PE23963)

Those of you who visit this page occasionally will know that I am, perhaps, obsessed with the topic of jellyfish fossilization. In addition to ongoing detailed work on Ordovician-age jellies from the William Lake site in Manitoba, I have been collaborating with my colleague James Hagadorn of the Denver Museum to figure out the global fossil record of medusae.

Jellyfish are rarely fossilized; many things have been published as fossil jellies, but few of those actually are preserved medusae. So we have been working through the world literature of all papers published describing “fossil jellyfish.” As we have studied the literature, James and I have determined which museums hold collections that need to be examined, and when the opportunity arises we will go and spend a day or two on a collections visit. When necessary, we will borrow material for further study: some of the fossils are easily interpreted, but others are problematic.

The presentation in Vancouver was about one of the specimens we had found in the huge collections of the Field Museum in Chicago. Preserved in a slab of the Carboniferous Mecca Shale from Indiana, it looked like a blob of pure white quartz sand surrounded by thinly bedded black shale. Except this was a sand blob with tentacles.

Paleontological collections storage at the Field Museum

Paleontological collections storage at the Field Museum

Spending many days with the specimen, photographing it in every possible way (double polarized photography is our friend!), we were able to recognize many features that allowed us to identify it as a chirodropid cubozoan (a group of box jellyfish still abundant in modern oceans). It is the same age as the box jellies in the well-known Mazon Creek Lagerstätte of Illinois, and it is very similar to the Mazon Creek box jelly Anthracomedusa turnbulli, but preserved in a very different way. We explained its unusual preservation in this manner: A body of pure quartz sand is very unusual in the middle of a black shale bed; this resulted from sediment rafting by the jellyfish, a process analogous to ice rafting. The medusa apparently stranded on a beach, ingested sand as it attempted to free itself, and then was washed or rafted into a lagoon where it was buried in anoxic mud.

The scientific manuscript describing this remarkable fossil is almost complete. Maybe this publicity will motivate me to get it out the door and move on to the next batch of “fossil jellyfish”!

© Graham Young, 2014

Vancouver Rain. Again.

October 24, 2014

October 17, 2014

maple leaf 1

maple leaf 2

Why does it seem to rain every time I go for a walk in Vancouver?  There has been precipitation on every day I have spent there on recent visits, even if it is sometimes just what the Irish would term a “grand, soft day.”

For those of us who live elsewhere, this could be looked at as fair recompense when the place is so unfairly blessed with topographic splendour. But maybe it is also a gift from the weather gods, an appeasement that permits us to remain contented with our own climates and locations. Maybe Vancouver rain is specially arranged for the visitor’s benefit, with the warm coastal sun scheduled to re-appear minutes after the departure of our flights eastward. If you, like me, are “looking forward” to a prairie winter, then it would be simply unbearable to think that Vancouver could ever get a string of autumn days of perfect crystal clarity, as well as those mild winter temperatures. Far better for us to always see this place in the rain, and to think that the residents must be miserable on account of the constant drizzle and mist, which are surely interrupted only by the occasional downpour.

Anyway, the rain does give vibrancy to the colours of plants and stones, even under such a flat grey sky. And I didn’t really mind getting a bit wet, since I was headed to the Vancouver Aquarium to commune with the jellyfish and comb jellies . . .

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Travels on the Churchill River

October 7, 2014
Below Portage Chute, the Churchill River is lined with steep cliffs for many kilometres.

Below Portage Chute, the Churchill River is lined with steep limestone cliffs for many kilometres.

In late August, I had what could be called the trip of a lifetime: I was invited by colleagues at the Manitoba Geological Survey to travel with them to examine sites up the Churchill River, far from the more accessible Hudson Bay coast.  With several days of helicopter time, we were able to visit many sites along the river and its tributary creeks. It was a tremendous experience to spend time in such a remote, stunning, and almost unspoiled landscape.

I returned with a wealth of fossil specimens for the collections of the Manitoba Museum, and also with a wealth of photographs. I have every intention of sharing a sampling of these, but circumstances have conspired against me as I have been fully occupied with other matters. Now that I have a bit of time, I am beginning the posting process.

If you are interested, the first batch of photos, providing a general overview of the Churchill River, can be found on my Museum page here.

More to come!

The riverbank near Red Head Rapids

The riverbank near Red Head Rapids

Four Bears

August 25, 2014

Churchill, Manitoba: August, 2014

bear_field

After three days of helicopter-based collecting up the Churchill River, we were planning to start today on a few days of fieldwork close to Churchill. The helicopter work was strenuous at times, with slogging up creekbeds and carrying fossil samples up steep slopes, so I was looking forward to driving to some of our study sites. The first of these would be the numerous outcrops and quarry pits spread through the large cove that we call Airport Cove (for the obvious reason that it is immediately north of Churchill Airport).

The bear as we first saw him

The bear as we first saw him

Yesterday evening we took a drive to town, and on our way back we were going past the cove when a fellow headed the other way motioned to us to stop and exchange information (they do this often here). He told us that there were four polar bears in the cove. Bears are seen frequently around here at this time of year, but nevertheless, four at once is not all that common. We were excited about seeing the bears, of course, but I also greeted this news with some trepidation, thinking what it would be like to be on foot in the cove under such conditions.

bear_shore

We were able to watch all four bears, but the photos here are of the one that we viewed closely over quite a period of time. He was a huge animal, and very lively in the cooler weather at this time of year. We were entranced to watch him stalk a goose, and then chase and catch it before it could take flight! His tremendous speed and agility were wonderful to see in a creature that weighs as much as a holstein cow, but frightening to think about in the context of fieldwork at any distance from the vehicle.

The bear seems proud of his goose, like a dog with a bone.

The bear seems proud of his goose, like a dog with a bone.

Fortunately today worked out well. We saw three bears (again), but one was from the safety of the vehicle, and the others, a mother and large cub, were a safe distance away. Still, we will remain vigilant for the remaining work days up here – we may spend evenings looking for bears to watch, but in the day we will be watching for bears!

Airport Cove may be a big place, but even one bear seems to fill it quite effectively.

Airport Cove may be a big place, but even a single bear seems to fill it quite effectively.

bear_cove

Airport Cove sunset

 

© Graham Young, 2014

 

The Rocks Remain

August 8, 2014

Victoria Beach, Lake Winnipeg, 2014

cobble shore

This section of shore has been armoured with cobbles and boulders in an attempt to reduce erosion. But where is the beach?

Along Lake Winnipeg in July it felt like business as usual. At Victoria Beach we rode our bikes down narrow gravel lanes through swarms of dragonflies and clouds of midges, basking in the perfect warm air and golden sunlight. The shop, bakery, tennis courts, and playground were busy. But what about the beach? If you listened to the residents, beyond the usual small talk, this question remained: what about the beach? And what about the scarps behind it?

Manitoba’s lakes have been having issues of one sort or another for decades. Most summers Lake Winnipeg has trouble with algal blooms as a result of increased nutrient flow from farms and cities, though the extent of this problem varies from year to year. In 2011 the shores of Lake Manitoba were devastated by high lake levels, after Assiniboine River flooding resulted in heavy use of the Portage Diversion channel. This year water has again been very high on Lake Manitoba and Lake Winnipeg, after heavy precipitation in the late spring and early summer.

The freshly cut scarp reveals stratified sand

The freshly cut scarp reveals stratified sand, soil, and roots.

On Lake Winnipeg, cottagers always reckon that their shorelines suffer from increased erosion because Manitoba Hydro keeps water levels high, the better to power dams on the Nelson River system. This could certainly be a cause, particularly when this high lake level is augmented  by unusual rainfalls. But there is another factor, a geological one, which most people ignore because of its subtlety and complexity.

The land of Manitoba has been slowly rising for the past 10,000 years or so, as the crust rebounds from being pressed down by glacial ice that was hundreds or thousands of metres thick at the height of the last ice age. The ice melted away from south to north, so the southern part of the province is now closer to equilibrium and is rising slowly. In the north, the rebound is still more rapid (even farther north, near Churchill, the rate of rise is close to a metre per century!).

I suspect that the wood at the base of this slope is the remnant of someone's stairs to the beach.

I suspect that the wood at the base of this slope is the remnant of someone’s stairs to the beach.

Postglacial rebound may seem like an interesting if remote phenomenon, but its effect “on the ground” is this: Lake Winnipeg’s outflow is at the northern end of the lake, and since this is the part that is rising more rapidly, the basin is gently tilting southward (imagine what happens as you tip a dish full of water). The lake is gradually moving across the flat lands at its southern end, reclaiming the marshes of the Red River Delta and the beachfronts of Ponemah and Matlock. Given enough time (before this land is again subject to large-scale glaciation), the lake will surely arrive where downtown Winnipeg stands today.

But this will take centuries or millennia. Meanwhile, whenever there is high water the lake will take advantage of it, moving just a bit farther southward and chewing away at the wonderful shorelines of Grand Beach and Victoria Beach. These shores are soft, being composed largely of sediment left behind by that glacial ice. The waves readily remove sand and gravel from the beaches and scarps, leaving behind only the larger boulders, and the shoreline continues to retreat. From a human standpoint this seems unfair and a great shame, but we can only hope to slow down nature. It will always win in the end.

4 wood1

The scarp may be moving back, but the gneiss and granite boulders aren't going anywhere.

The scarp may be moving back, but the gneiss and granite boulders aren’t going anywhere.

6 dock road

7 dock

sunset1

A lot of detail on the geology of the Lake Winnipeg basin was published in: Lake Winnipeg Project: cruise report and scientific results; Todd, B J (ed.); Lewis, C F M (ed.); Thorleifson, L H (ed.); Nielsen, E (ed.). Geological Survey of Canada, Open File 3113, 1996, ; 656 pages, doi:10.4095/207501 

 

© Graham Young, 2014

Surveying Mount Sylvan

July 11, 2014

the mountain

Ah, Mount Sylvan. Such a magnificent sight. And nearby, those huge rocky cliffs reach up to the sky!

the cliff

I admit this is not really such a grand landscape as it might first appear. In Manitoba’s Interlake you have to take your topography where you can find it, and heaps of quarried limestone may well be the tallest features from one horizon to the other. The quarry at Sylvan is not a particularly good fossil locality, but in contains a fascinating succession of shallow-water carbonates that represent deposition under fluctuating environmental conditions.

Jim and quarry face

Jim Bamburak of the Manitoba Geological Survey examines a dolostone face at Sylvan Quarry. 

Bryozoan-containing cherts at the base of the quarry are succeeded by a variety of other units including thin-bedded dolostones, microbialites, beds showing internal brecciation, and some intriguing clay-like horizons. One stromatolitic interval has yielded odd phosphatic bits, and we periodically revisit the site with the hope that more diagnostic phosphate components will show up (ideally parts of early fishes, but other things would be fine too). So much depends on how active the quarrying has been in the intervening months, and how much of the faces we can see. Last Monday, when I took these photos, the faces were muddy and we could not get to them very easily, but we will be back. We just have to be patient . . .

Jim and blue clay

The thin grey horizon is in the Ordovician Fort Garry Member of the Red River Formation; the transition to the Stony Mountain Formation is located near the top of the quarry.

Please excuse the relatively poor image quality in these photos. It was my first day in the field this summer and I had somehow managed to forget to pack a camera, so the iPhone had to suffice!

 

© Graham Young, 2014