Wrangellia: How the west was won

Triassic map of the world. But where is Alaska?

The Wrangell Mountains are Alaska’s most secretive volcanoes. We have looked at what they are (post I) and how they may have formed (post II). This area of Alaska has suffered the brunt of the most recent continental collision on Earth, and the Wrangell Mountains are an immense scar from this monumental accident. But there is something more hiding in the landscape. On either side of the Wrangell Mountains, both north and south, there is a strip of land which looks different. It has strange and unexpected fossils, corals from a tropical ocean far warmer than Alaska should have been. Go further away from the mountains, and the fossils disappear again. What is a sliver of the tropics doing in Alaska? In this third post, we will take a look behind the scenes and delve into history. It will take us to the final secret of the Wrangell Mountains.

Once these tropical fossils had been discovered, similar rocks were found elsewhere in North America. They follow the Pacific coast line, but with gaps. Vancouver Island is at the far end of their distributions: it seems to consist for 50% of these rocks, although the fossils are slightly different to those found at the Wrangell Mountains. The age of the fossil corals far exceeds that of the Wrangell Mountains. Clearly, the mountains grew on top of a much older land. But the younger was known first, and thus the elder was named after the younger: this strip of ancient tropical heritage is now called the Wrangellian terrane. Delve down into this terrane, and a thick layer of greenstone appears. The greenstone comes from an oceanic flood basalt, ten times as old as the proverbial mountains, which happened while much of the region was below sea level. The greenstone is not the oldest layer of the Wrangellian terrane: below the thick basalt is even older material, apparently coming from an island arc. Where was this arc? Why was it later flooded by a flood basalt? And how did this tropical sea end up, of all places, in Alaska?

Raising Alaska

It is all tied up with the way Alaska formed. Just like the birds that come to visit here every summer, Alaska is itself a migrant. In fact, it is a melting pot of many migrants. This is a complex place, an amalgamation of many different parts with many different histories. We need to go a long way back to disentangle the events that lead to the raising of Alaska.

The story begins more than 400 million years ago. The one constant in our world is change, and indeed many things were different. But some were not. The various countries around the Arctic, with all their disagreements and wars, have a common heritage. The plates that they call home possibly were always close together. At times they even exchanged parts. But Alaska wasn’t there. The rocks that were to become the future core of Alaska at this time belonged to Scandinavia: they were part of the Baltic plate. Still, plates will be plates. They split, drifted, collided, crumpled, stuck, and split again, in a dance of continental tango, akin to the ever-shifting alliances in Poul Anderson’s story Tau Zero, of travellers on a journey with no end. Alaska was born out of this dance.

One of the many collisions between the close group of plates formed a mountain range that can still be traced around the Arctic. It is most prominent in North Greenland and Ellesmere Island, but there is evidence elsewhere around the Arctic, from Canada to Siberia. It is called the Ellesmere orogeny. Exactly what collided with what is lost in time: this was 350 million years ago and the trail has grown rather cold. For a while, this collision may have unified some of the continents which now encircle the Arctic ocean. Of course, it wasn’t the Arctic at the time. The tango took place much further south.

But in the dance of the plates, all partnerships are temporary. The Arctic ocean began to form, in a way that is not fully understood. Some sea floor spreading was involved, but it was ultra-slow. There was also rifting caused by plates rotating away from each other. We don’t really know how much was spreading and how much rotation, but the effect was to form the Canada basin, separating North America from Siberia.

Parts of the Ellesmere mountains now began to move west along a transform fault, traveling over 2000 kilometers. Following the sideways motion, the separated part also rotated by 90 degrees. It slightly overshot, but when it finally came to a halt North America held on to its newly acquired appendage. This transported region became the northernmost part of Alaska. At the time it may have been a marine shelf, with a series of low-lying islands. To the south was the sea.

Alaska’s Brooks range was next to form. This area was part of the transported terrane, and as such can make a claim to be part of the Alaskan heartland. Now it came under stress from an approaching plate to the south, perhaps involving subduction. The approach occurred between 140 and 120 million years ago: it pushed up a mountain range and squeezed out an ocean basin in the process. Some oceanic crust belonging to that basin was squeezed up rather than down: it can still be found still in central Alaska. The approaching plate is given the name Koyukuk, and the collision added the Yukon-Koyukuk Terrane to Alaska.

After this, things became more complex. Another terrane was added to Alaska: it is called the Yukon–Tanana Terrane and nowadays it covers much of central Alaska. This was clearly another microcontinent that docked. The new terrane attached itself to North America along the Tintina fault; the southern edge of the Yukon-Tanana Terrane is formed by the Denali fault.

The Yukon-Tanana Terrane docked with North America 150 to 200 million years ago, not in Alaska but further south. After attaching itself, the terrane moved north along the Tintina transform fault to finally arrive in Alaska. The dates put the attachment to North America before the formation of the Brooks mountains, but the arrival in Alaska was after. As it arrived, it pushed the Yukon-Koyukuk terrane to the west.

Just above the Tintina Fault, in a tiny triangle along the Canadian border, is the only part of Alaska that is actually original North American! Everything else in Alaska came from elsewhere. This triangle is, to the best of my knowledge, uninhabited. The nearest metropole is the twin town of Eagle City and Eagle Village, 30 km to the south, with a total reported population of 162. Every Alaskan lives on borrowed crust! America was build by migrants, but in Alaska the land itself formed that way.

And finally, it was time for Wrangellia to arrive. This was already a complex entity: Wrangellia consists of a variety of different terranes which had merged before arrival at Alaska. Like the terranes that preceded it, it came from the south and west, and like the Yukon-Tanana Terrane, it attached itself to North America first, and slid up to the north after that.

After Wrangellia came the Yakutat plate, which is still in the process of docking. This platelet also moved north, but was not strongly attached to North America and instead collided head-on with Alaska.

Source: T.E. Moore, S.E. Box, Tectonophysics 691 (2016) 133–170. Some labels: Arctic Alaska (AA), Farewell (FW), McKinley-Windy (MK) and Wickersham-White Mountains(WW); Yukon-Tanana (YTa, YTc, YTp); AX, Alexander; NAm, cratonal North America; PE, Peninsular; PW, Prince-William; WR, Wrangellia; YA, Yakutat. Major faults: 1., Chugach-St. Elias; 2., Contact; 3., Border Ranges; 4., Totschunda; 5., Denali; 6., Tintina; 7., Victoria Creek; 8., Kaltag; 9., Bruin Bay; 10., Castle Mountain; 11., Farewell; 12., Iditarod; 13., Poorman; 14., Southern Brooks Range extensional fault system; 15.,Kobuk; 16., South Fork; 17., Brooks Range deformation front

Origins

Clearly, Alaska is a hard place! It consists of many different terranes, arriving here one after the other over a period of several hundred million years. In fact, I have left out several of these fragments. A geological map of Alaska looks truly psychedelic. This was the place where all these platelets wanted to be, like Isolde searching for Tristan, or Beren for Luthien. But it raises questions. Why were there so many platelets along the North American margin? Where did they all come from? And what attracted them to Alaska? These are difficult questions to answer.

But an answer to the last question is beginning to appear. All these platelets were going to where they came from. They were going home.


The basement rocks in these wandering terranes is ancient. The oldest rocks are more than 500 million years old, possibly much older. Over time they experienced volcanism and stress, and collected debris in the form of sediments and fossils. These can be studied to look for similarities with other regions. The sediments and similarity in some fossil remains suggest that the terranes spend significant lengths of time close to the west coast of North America, in the nearby ocean. But the older rocks tell different stories. Their relations are not with America, and not with the south or west, but with regions elsewhere around the Arctic. They connect to Baltica, and it seems many of the terranes started out as fragments of that Scandinavian plate.

In one of several major collisions in this part of the world, Baltica had merged with North America. This collision formed the Caledonian and Appalachian mountains. But the wandering terranes had split off from Baltica before those events, and while the continents came together to form Laurentia, the shedded fragments were on their own journeys. One younger terrane seems linked to the Ural mountains, and was part of the Permian collision between Europe and Siberia. But this fragment too ended up adrift in the open ocean.

Around the time of the Baltica-North America collision, the lost fragments got caught up in a rapid westward drift. They moved around Laurentia, and into the Pacific ocean (Panthalassa). On the way they had moved around the Ellesmere fragment that was on the road to become northern Alaska. In a way, it was an early negotiation of the future Northwest Passage. The encircling of Laurentia was completed by drifting eastward to move close to the North America coast. Their journey finally ended when the old fragments of Baltica reassembled themselves and build up Alaska.

There is a long-standing affinity between North America, Siberia, and Northern Europe. Vitus Bering comes to mind: he was a Danish cartographer exploring Alaska for the Russian navy, thus bringing together all three of the Arctic continental plates in his own life story. And now it seems that Alaska itself was made by European refugees, all traveling different paths to find their home. It is a true American story. People still move to Alaska to make it their home – these terranes moved there to re-assemble theirs. All of Alaska, with the exception of that tiny area where no one lives, has an exotic heritage.

Wrangellia

But Wrangellia has its own story to tell. In Alaska, the Wrangellia terrane forms an east-west belt, 45 km wide; it is the end point of a 2500 kilometers long range extending along the Canadian coast. And unlike other Alaskan territorial migrants, it did not come from Scandinavia. It came from Oceania.

Wrangellia did meet other migrants along the way. This complex region contains other terranes, swept up by Wrangellia long before its arrival at Alaska. The largest of these swept-up pieces is the Alexander terrane. It is much older than Wrangellia itself: Alexander is more than half a billion years old. Like most of the building blocks of Alaska, there is a Baltica connection; Alexander formed at a subduction zone along Baltica, moved away and joined the migration of platelets towards Laurentia. But it didn’t make it. It was intercepted mid-ocean.

In contrast, Wrangellia, the one Alaskan terrane not related to the current Arctic, appears to have formed as an island arc, roughly 300 million years ago. This was near the equator, in a tropical ocean. The southern part may be a bit older, at 370 million years; as many as four separate arcs may have come together to form Wrangellia. It merged with Alexander very soon after its formation, also around 300 million years ago. Alexander was perhaps sucked in by the subduction zone that caused the Wrangellia volcanic arc, overrode it and became attached. It was just a road accident.

For a while, the combined microcontinent had peace, as it drifted around in a tropical ocean. The area had sunk below the water line, perhaps with some remaining islands. But this existence was shattered 232 million years ago. The now oceanic plateau began a rapid rise as heat came from below. Eruptions started and layer after layer of basalt flowed. Initially the eruptions were below sea level, and formed pillow lavas, especially at the southern end of Wrangellia, but soon the area rose above the water. The basaltic eruptions continued for a million years. And this was no Iceland: it erupted several times more lava than Iceland ever has, and it did so ten times faster. The eruptions were intense, at 1 km3 per year every year. Normally events like this happen in pulses, and the eruption rates during a pulse could have been several times higher still – imagine a Laki event every other year! When it ended, a volume of at least 1 million km3 had been erupted, and all of Wrangellia was buried under several kilometers of basalt. Reconstructions put this flood basalt eruption in the northern tropics, in the eastern Panthalassa ocean, not too far from Laurentia.

There has been some discussion on how long this flood basalt eruption really lasted. There may have been more than one phase. Uranium dating has shown dates from 227 to 233 million years ago, and these may indicate different pulses. The end date is well determined, but the start date is more uncertain. The million year duration may have been underestimated. However, it was short enough that the lava flows do not show magnetic reversals.

There are few dykes in the basaltic layers, which suggests this was not a rifting event. This, together with the evidence of rapid uplift before the eruption, shows the hallmark of a fast rising mantle plume. Wrangellia was in the wrong place at the wrong time. It was just another accident in what was already an accident-prone plate, this wandering Jew of the oceans, a flying Dutchman doomed to drift from storm to storm.

The microplate, loaded with its large igneous province, now moved towards North America; it was presumably pulled in by a subduction zone between the two. It arrived around 120 million years ago. This was the third accident suffered by the poor plate plate! Whilst Wrangellia attached itself to the continent, a thrust zone developed with mountain building and granite intrusions on the North American side. This was the largest piece of crust to join North American since the Jurassic. After the docking, the subduction zone re-established itself southwest of the combined terrane.

The long sliver, perhaps somewhat similar in appearance to the Baja California, now started to move north along a transform fault, the ancestor to the Denali fault. The amount of travel is disputed: one model has it move north by 3000 km, another model only by 1000 km. In either case, 50 million years ago (or perhaps a bit earlier) the vanguard of Wrangellia finally arrived in Alaska, after a journey of a quarter of a billion years.

Source: https://www.eoas.ubc.ca/research/wrangellia/7skolaibase.html. Their caption: Photograph of the base of the Nikolai Formation in the Wrangell Mountains, Alaska. Westward-dipping Paleozoic arc volcanic rocks of the Station Creek Formation overlain by Early Permian shale and limestone (Phc-Hasen Creek Formation; Pgh-Golden Horn Limestone Lentil), isolated lenses of Middle Triassic ‘Daonella-beds’ (TRd), basalt flow-conglomerate with local pillows, and massive subaerial flows on the north side of Skolai Creek. Photograph by Ed MacKevett, Jr.

Rock layers of Wrangellia. Click on image for higher resolution

The defining feature of the Wrangellia terrane remains its layer of ancient flood basalt. This now forms the Nikolai Greenstone, and is found on both the south and north side of the Wrangell Mountains, and presumably underneath the mountains as well. It is also seen on the south flank of the eastern Alaska Range.

This vast volcanic field extends even further: it surfaces as far west as the Alaska Peninsula, and as far south as Vancouver Island, albeit under a different name: the Karmutsen Formation. The image shows how dominant this layer is. It reaches a maximum thickness of over 6 kilometers! Wherever this thick sequence of greenstone is found, you can be sure to be looking at rocks from Wrangellia.

The thick scar tells the story of what can happen to an innocent bystander. Ignoring the Lurking maxim (‘don’t be there’), it managed to step on the toes of one of the world’s major events. The event is now named after this bystander: the Wrangellia Large Igneous Province. And by giving it its name, Wrangellia also took the blame for the consequences.

The million years of rain

The Triassic was not the best time to be alive. The continents had now come together to form Pangea: they were bunched up, surrounded by the world ocean (Panthalassa). At one side of Pangea there was an intrusion by the developing paleo-Tethys ocean, more or less where nowadays China is located. The climate had turned hot and dry. This is not uncommon: supercontinents tend to cause hothouse climates with high CO2 levels. The desert age culminated in the Carnian, between 237 and 227 million years ago. Rocks from this time are found in many places across the world: they are often dull red, dried and baked.

Over time things slowly improved, as the paleo-Tethys began to split Pangea in half, but especially the interior of Pangea was a hostile place. Wrangellia, not being part of Pangea, knew nothing about this. But this was the world into which Wrangellia erupted its flood basalt.

Triassic sandstone, as seen in Sydney, Australia (source: wikipedia)

In the middle of this age of the desert, 232 million years ago, things briefly changed. It can be seen in rocks around the world, often as a grey stripe that runs through the red desert rocks. It tells a story of a much wetter world. In the midst of the desert, the rains had come. Across Europe, conditions changed. Drought-tolerant plants were replaced by ones adapted to more humid conditions, and dolomite formation shows that the water table had become much higher. The Great Wet is seen in rocks in Morocco, Nova Scotia, Colorado, China, India and Papua New Guinea, amongst others. New rivers formed, extending deltas and depositing sediments into the sea. And the deep sea was not safe: carbonates stopped forming, indicative of a change in pH of the water. This was a world-wide change. The change was not identical everywhere: whereas Pangea became wet, Gondwana may have seen some drier regions. The change seem to have started quite suddenly, but it ended more slowly over a period of perhaps several million years. After that, the desert returned and the world quietly forgot about this wet interlude, the million years of rain.

The cause appears to have been volcanic. This is indicated by two things: an increase in temperature by a few degrees (perhaps 4 to 7 C), and an increase in the ‘light’ isotope of carbon. Both indicate CO2 being added to the atmosphere, of non-biological origin. The only such event known from this time which is large enough is the Wrangellian flood basalt eruption. The time fits, and Wrangellia is now seen as the prime suspect for causing the million years of rain. It was its flood that caused the rain. These rainy years are now called, with all the creativity of scientific writing, the CPE: the Carnian Pluvial Episode.

Evolution saw its chance. This was 20 million years after the Permian-Triassic extinction which had devastated the world. Very little had been left, and in the harsh, arid world of the Triassic life had been slow to re-establish itself. Coal deposits show a long hiatus. Still, life can be hard to stop and in spite of the conditions and the terrible start, species had eventually become more diverse and grown in abundance. And now, suddenly, conditions became benign. Not everywhere: especially the seas show an extinction event, perhaps not unexpected after a subsea flood basalt. But elsewhere, life saw an opportunity. It exploded into a huge diversity, turning the Earth into a massive tropical rain forest. To give just one example: amber became widespread at this time.

Similar explosions of diversity can be seen in our world. The tropical rain forests and the tropical reef are home to much of our own world’s diversity. Both of these ecological systems are very young. The Amazon rain forest, for instance, did not exist 20,000 years ago. When it formed, ecological niches suddenly appeared everywhere, completely unoccupied. It gave every mutation a chance to survive and develop. The huge diversity of the fish species of Lake Malawi also arose from its youth. And the same happened during the million years of rain.

Saturnalia, one of the first dinosaurs

One group of animals in particular benefitted. Early dinosaurs had appeared some 10 million years earlier, but they were limited in number, and remained small and largely insignificant. Now they went for it. The first true dinosaur fossil footprints date from the million years of rain. Before the rains, dinosaurs accounted for less than 5% of faunal fossils. Afterwards, 90% of fossilized fauna were dinosaurs. Both the ancestors of Triceratops and Tyrannosaurus Rex were now abroad. The dinosaurs came out as clear winners, and when the conditions deteriorated again, they remained on top. It would remain this way for the next 150 million years. Dinosaurs ruled while Wrangellia drifted, merged with North America and moved north. It took a sudden worldwide catastrophe, 10 million years before Wrangellia reached Alaska, to finally topple them.

This part of the story of the million years of rain seems eerily echoed in Charles Dickens’s novel on legacy, “Bleak House”:
As much mud in the streets as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill.

But the complex land of Wrangellia has one more story to tell. For another group also first appeared during the rains, although they would need to wait a long while for their chance to rule the world. The oldest known fossils of mammals date from the million years of rain. In a way, we too are a gift from Wrangellia.

Of course, every story has its critics. The evidence for a rainy period is very strong. Whether it affected everywhere, and whether it was episodic or continuous, is still a matter for discussion. And what was the role of the peculiar paleo-Thethys ocean in this? A lot of the evidence for rain comes for regions surrounding this ocean. The relation of the rain to the Wrangellia flood basalt could do with more evidence. It comes from a lack of other strong candidates, and from the agreement in time. Perhaps another qualifying volcanic event could still be found. But at the moment, Wrangellia is the prime suspect as the cause of the million years of rain.

Other parts of the story also have caused disputes. Some argue that the platelets that docked with North America had originally come from North America itself: they returned home. It is hard to be sure. The argument is based on similarity with other regions in the northwest of the US. However, this leaves the strong relation to Baltica unexplained. An elegant solution would be if those US regions themselves also came from Baltica. Science dissects and rebuilds the story lines with each new discovery. Like the world, the story changes every time we tell it. But the story still needs to be told.

We have come a long way. From a little known but majestic volcanic range in an arctic wilderness we have travelled through a continental collision which is still affecting Alaska today, shaking Anchorage just a year ago. But we have gone further, and found that much of Alaska came from northern Europe, outcasts from a time of turmoil. And the rocks on which the Wrangell volcanoes were build turned out to derive themselves from another age of turmoil, one which changed the world. Both the age of the dinosaurs and the age of the mammals can be traced back to them. We ourselves are the final secret of the Wrangell Mountains.

Albert, January 2020

And the winner is ..

79 thoughts on “Wrangellia: How the west was won

    • Brilliant Albert! She story became more and more more interesting!
      Now can you send a printout of the gps-tracks, I’d like to claim Alaska back to its motherland on the Baltic shield!

  1. Awesome as ever Albert: really enjoyed reading this. It’s a real art to be able to condense so much research into an essay that is digestible.

  2. Awsome Article
    Just a thing: the rainforests surivived the Glaciations
    But in very very reduced extent
    The ice ages where indeed very very dry
    And most tropical forests where replaced by grasslands.

    But: in every rainforest arera on Earth There are biodiversity hotspots where diversity is much much higher than sourrounding jungle.

    These biodiversity hotspots in rainforests are seen as Ancient ”Forest cores” that surivived the glaciations.
    These tropical rainforest cores coud be 59 million years old remains from the Paleocene and Eocene.

    But yes most of the rainforests and forests everywhere vanished in the dry ice age climates

      • Lurking
        Ice ages are very dry
        Lots of Atmospheric moisture locked away in Glaciers

        With less rainfall .. the forests vanish during the Ice ages
        Glaciations are times of huge deserts and grasslands

    • Yes, there were cores left. But a lot of what later became forest was grassland. That gave the funny development of the forest elephants. There were some around Knysna in south africa (now extinct, I believe) and in Congo. Elephants are not forest animals, but the forests sprung up around them and they managed to adjust. Now of course the forests are under pressure again, from agriculture and from changing rainfall patterns. In the Amazon, the equatorial forest is expected to survive as it benefits from two rainy seasons a year. Away from the equator, there is a single wet season, and at the higher temperature the forest dries out in the long dry season. Hence the Amazon fires.

      • A warmer world, means warmer seas and more evaporation and humidity in the air ..and more rainfall

        If we let the forests be… they will expand in the warmer and wetter climates…
        Sahara will dissapear replaced by forests

        During the Eocene, deserts and savannah did not exist .. Only tropical forests ( soon we will be back in the Eocene )

        • That is too simple. The enhanced rainfall is correct, but the evaporation from the ground (and vegetation) also increases. So things dry out faster. If you have a wet 6 months and a dry 6 months, the extra wetness is lost before the dry season is over. So things get drier, and the enhanced growth from the wet season just gives more fuel to the fire. No forest can survive annual burning. This is why the Amazon will shrink, and why Australia is on fire. Both predicted and happened as expected. Both were hardly a surprise. It depends on which area of the world you look at.

          • As long as the icecaps exist There will be a drying effect as they locks away moisture

            Humans CO2 emission are enormous and the CO2 is rising so quickly that the icecaps hardy have time to melt
            In 200 years we coud be at much over PT ( permian – triassic levels of CO2
            Very alarming!

            Once the Icecaps are gone in 10 s of thousands of years
            Lots of water and moisture will enter the atmosphere and ocean.
            Eocene was world – wide humidity

            But This discussion is better for the VC bar

          • The formation of the Antartica Icesheet 34 million years ago associated with dropping co2 levels

            Had an enormous impact on the Oligocene climate.
            The drying up and reduction of the global rainforests

            But the really severe droughts started 3 million years ago just before the onset of the glaciations

            Without the Ice ages drying.. our human ancestors may have never left the trees…

            Mankind is the evolutionary result of the Apes trying to surivive the drier and drier more open conditions during pleistocene glacials

          • No forest has annual total burning, but do not underestimate man’s ability to control forest fires up until he cant because accumulated dead biomass that used to burn periodically and be removed eventually burned in adverse weather and the burns out of anyone’s control because there are no natural firebreaks from earlier fires. California did just the same as the australians, now they let nature take its course much more. Californians now ‘fire harden’ their homes so they are immune from adjacent forest fires.

      • The Forrest elephants of Knysna are not completely extinct, there are a few left, and I believe there is a project to introduce more to strengthen blood lines.

        • I am happy to hear that. The last time I was there we were told they were down to four.

  3. Amazing how detailed your knowledge and learning is, Albert. I struggled through all the wandering plates and in the end realised how much our world must have changed, changed and re-changed over millennia.

    Thank you for a fascinating read!

  4. Not mentioned in the article is that the process of continental crust fragments docking to the west coast and then sliding north to accrete onto Alaska is still ongoing. There’s another of those fragments sliding north now. And Los Angeles is sitting on top of it. All of California west of the San Andreas is on its way to join Yakutat in another few tens of millions of years.

    Meanwhile, is there any trace left of the plume that caused the flood basalts? I only ask because that last map, the Triassic one in Mollweide projection, puts Wrangellia at that time at approximately the latitude of present-day Hawaii …

    • The latitude is not far off Hawaii. We don’t know what the longitude was. The continents have over time drifted west, so the hot spot might have been further to the east. There isn’t a clear trace anywhere. Te place to look would be in North America.

  5. Interesting. Now also nice quak swarm near Hrómundartindi, close to the gap between the eurasian and north american plate.

  6. Nick Zentner’s lectures on Youtube cover quite a bit about terranes moving up the west coast of the American continent and docking. He covers it more from a Washington State perspective than an Alaskan perspective (hardly surprising given where he is employed), but it’s another piece of the fascinating story of where the west coast of Mexico, the United States and Canada originally came from.

  7. There is an ongoing swarm in Reykjanes, not in Thorbjorn, but in the next fissure swarm, 5km west.

    Very interesting…

      • yes, Alaska is Very complicated…. both above and below ground. Stellar post, Albert! Gold Star! i’ve not run across a more detailed explaination of how it works. And is still washing up against different plates. Best! with Your bad weather. We are also having some storm warnings….. which i will hear about from the warmth of my rocking chair. 😉 motsfo

        • Posting to you from the epicentre of that bad weather, Stourport on Severn, Worcestershire, and by any standards it’s pretty bad.
          Some in the UK may have heard of a woman’s body being recovered from the River Teme nearby after she and a man ended up in the water. He was rescued pretty quickly and is recovering in hospital.
          I didn’t know her, but the man, Gordon, is a friend of mine.
          It’s almost entirely unlikely that any form of stupidity was involved,as Gordon has river-smarts about him and actually lives on a boat, but I don’t think now is the right time to be pressing him for details.
          The Teme is one of the major tributaries of the Severn and is fast flowing at the best of times. Right now it could be described as full on violent, even 2 days after the storm.
          The Severn’s level is expected to peak later today, but we also have some intense squalls lined up for this afternoon.
          I’m on standby to help a friend to get their stuff into my shop’s store rooms if required as where they live will be vulnerable if there is any further significant rise in the water level.

          I know it’s a singular event and thus it is not on its own evidence of climate change, but I also know that we had our “50 year storm ” only 13 years ago.

          Make of that what you will.

          • Yes, thankfully, both shop and house are safe.But there are some flooded streets a little over 200m from here , along the course of the Stour, which joins the Severn about half a mile from here.

            Stourport tends to avoid most of the flooding because as opposed to both Bewdley (about 6km upstream) and Worcester (20 KM downstream) the river sits well down in the valley here and the natural flood plain such as it is, is either park land, or the riverside fun fair, which is out of season anyway.

            The shop sits on a more elevated river terrace, only about 150 m from the bridge, but it’s up quite a steep incline.

            But a friend lives in a bungalow reserved for people with disabilities , just across the bridge, and not far above bank level, so there is realistic concern there, but so far so good… without much of a safety margin though.

            If this afternoon’s rain is heavy and prolonged she’ll need help.

          • Its partly a combination of actually worse weather, building on land likely to flood and in some cases what were micro-industrial (eg smithy) downstairs and dwellings upstairs when built are now housing. Round here (Thames floodplain) it does flood and typically the ‘old’ part of the village is fine (although may be cut off for a while) but all the newer dwellings (incl converted barns etc) get flooded periodically (5-20 years). The original settlers knew a thing or two. Similarly the micro-industrial (usually alongside the river or close to a bridge) probably expected to flood periodically but it was worth it for river transport or good trading position.
            The other important point is that local news is not national. I doubt 20 houses flooding in yorks or devon would get into the national press at all 20 years ago, now its headline news.

          • Mostly true. And the land has become drier on average as drainage was improved: farmland along the Thames that would flood annually is now usable year-round. So people forget why the old villages were located where they are. But I have also seen flooding caused by improved drainage and dredging up-stream, and in one case by a new bridge that did not leave enough space for the river. Nowadays, improved flood defences on one place can cause flooding somewhere else. Rivers do need their floodplains. But I am glad that Stourport is (mostly) ok.

          • All true, Farmeroz.
            Stourport is a town that owes its existence to the early part of the industrial revolution, when the Staffs- Worcester canal was built, connecting the Potteries to the Severn and thus , via what was then an international port, Worcester, to the wider world.
            Hence many of the small scale local industries (forges and tanneries) were initially built alongside the canal, which is about 25 ft above the river.
            Later industrial developments were built on the riverfront, and most of those are currently flooded, with Stourport Marina just downstream of the town being currently cut off by a substantial depth of water.

            Fortunately for us, most residential developments from the last 150 years were positioned well above the river.

          • Sorry to hear about the situation down south. Here in Scotland it was just another big storm. A few weeks ago, a violent storm happened. Overall flooding has been far more regular too, as well as severe coastal erosion.

            It’s a combination of building on the wrong place (near water or flat flooding terrain) plus the normal ocasional violent winter storms which are made more intense and frequent by warmer ocean temperatures (climate change)

            Unfortunately England is going to be the European country mostly affected by flooding in the next decades, whilst south Europe will suffer from desertification, and central Europe by incoming waves of migration and summer storms.

          • Tricky sorting the threading here. Yes, certainly housing going onto the Thames floodplain is a problem in certain places; not helped by planners turning down suitable sites and picking unsuitable sites for ‘incomprehensible’ reasons. Its also not helped by planning regs that encourage housing close and in settlements without realising that, in much of lowland england, these are themselves there as the only high ground in a floodplain. Adding development there HAS to go on sites known to flood sporadically but since its discouraged elsewhere, what else can people do?
            I do not think extra drainage per se is much of a problem in the Thames valley, to be honest. The opening of all the sluices a few years ago was an eye opener of how you can seriously reduce (in this case avoid completely) flooding by taking steps in advance to remove as much water from the system.

          • Where I saw the drainage being a problem was not on the Thames itself, but on the tributaries. Around the area of the Windrush, water from the Cotswolds gets into those streams much faster and the streams can’t cope.

          • While I have concern for the flooding in the UK, I can’t help but remember that the level of Flooding that my hometown is experiencing is quite similar to what we had in 78/79 in Jackson MS. I remember it quite well since I had to juggle routes to get to my mandatory polygraph test downtown.

            Had to retake it the next day when the examiner found out I was stoned at the time.

          • If people are serious about mitigating against floods, plant trees around the headwaters, and soften the banks . Allow the banks to become wetlands where possible, instead of defined banks

      • While in college (back in the pre-Cambrian) I did a report on the Basin and Range geology. I have a lot of respect for the geologists who were the first to figure that mess of terranes and orogenies out. Like assembling a puzzle blindfolded.

  8. Asian elephants are forest elephants, I don’t think elephants much care provided they can get enough food.

    • Probably they care when it is time for mating. Difstinct species!! 😊

  9. Fantastic, Albert! A wonderful read; all three of them.

    With thanks, Neil.

  10. The Reykjanes swarm has moved over to the peninsula tip but is still continuing.

    • All manner of interesting things to learn there – including that Illinois has a State Fossil.

  11. The latest radar image of Lake Taal shows all the fish pens on the lake.

    • Why has this been altered to no longer work? It worked yesterday.

      Put it back.

      • Nyiragongo is similar in size to halemaumau s lava lake

        Nyiragongo haves far more numerous smaller crustal plates and smaller bubbling.. that makes Nyiragongo look much larger in photos.

        Albert This illusion is correct right ?

          • These are the calderas to scale

            Nyiragongo is a tiny volcano compared to the immense massive of Kilaūea.
            Kilauea is 50 000 km3 and spanns 200 kilometers if you count from Loihi to Puna Ridges tip ( Kilauea is long and will grow into a long Mauna Loa like behemoth in the future )
            Kilaūea is a giant. And still not in its peak of activity.

            Nyiragongo is around 10 km wide
            And most of the upper cone can easly be fitted inside halemaumau.
            But they are so diffrent in geology and history..
            Its not a fair comparsion 🙂

          • Kilaueas high partial melting rates makes that common boring ”Thoelitic Basalt”

            Nyiragongo feed with very small ammounts of partial melting haves faaar stranger and rarer rocks.

            What will happen to Nyiragongo in the future?

  12. On Rejkjanes peninsula, IMO warns to enter caves in the Eldvorp area (west of Thorbjörn) because of deadly gases. Another sign of ongoing magma intrusion, I think.

  13. Very interesting article, there must be other parts of the world like Wrangellia, but not that many I guess.
    By the way, not that far west from Wrangellia … If I use the ‘rain alerts’ app and zoom in on the Shishaldin volcano crater, I see a clear red dot. The app is updated very regularly, so I guess that Shishaldin has a small lava lake. Can anyone confirm this?

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