Thursday, March 21, 2019

Shameless self-promotion and self-organizing

I keep losing the link to the Supplementary Information from my Geology paper (summarized as Geosonnet 42), so I'm posting the direct link here, where I hopefully won't lose it.
And before you tell me a better way to keep track of things in the digital age, GET OFF MY LAWN!

Monday, February 18, 2019

Geosonnet 51

When oxygen and oceans mixed worldwide

Out dropped the world’s first heavy metal band
With silica and iron side by side
This rocking BIF precipitate was grand.
But modern industry required more
Than hematite with intermingled chert
The silica component they abhor
Must be expunged by fluids which convert
The BIF into a high grade iron mine
A cooling basal fluid can’t displace
As much quartz gangue as pulsing solo brine
With carbonate fade in- not acid- bass.
When silica got kicked out of the band
The iron oxide satisfied demand.

Other geosonnets: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

Saturday, February 09, 2019

Sierra Sequoias from space

I wrote last year about the big trees of the Sierra Nevada mountains in California. One if the things that interested me was the ability of the Sequoia and the Sugar Pine to grow side-by-side, despite having very similar survival strategies- namely grow taller than everything else and live long enough for fire to clear our the shade tolerant trees so that your seeds can germinate.

Of course, as anyone who spends time on the forest knows, despite these trees having similar niches, they look quite different. The both have large trunks often bare of branches for the first 100 feet, but their vegetation has different forms. The Sugar Pine has very long, straight lateral branches, like the spars of a ship, while the sequoia crowns are more rounded. And because these trees are very large, it turns out that you can easily distinguish them in Google Earth. Here is a screenshot of the same grove I wrote about last year:

You can clearly see the long lateral branches on the pines (which also have somewhat bluer foliage). The larger, yellower trees with very wide trunks and rounded foliage are the sequoias.

Unfortunately, the sugar pine is in decline in many areas of its range, Here is a picture of dying trees in the national forest just south of the park:
The most obvious thing here is that the Sugar Pines are mostly dead. But there are other differences. Unlike in the National Park, here you cannot see the ground- the trees are growing too close together. One critique of the Forest Service is that it as lagged behind the Park Service in the use of controlled burns and recurrent fires. While I don't have the fire history of this exact area, the much thicker understory could be the result of decades of fire suppression. And if those trees are sucking up all the water, perhaps that has stressed the pines.

Sunday, January 20, 2019

Book Review: William Shakespeare’s Star Wars

By Ian Doescher
This is a stage adaptation of the plot of the original Star Wars movie, written in Iambic pentameter. It’s not done too badly, with lots of actual famous Shakespeare lines sprinkled throughout. And it is a clever idea. However, the joke gets old quickly; I gave up before they even got to Tatooine.

Sunday, December 09, 2018

Book review: The Great Way

The Way into Chaos
The Way into Magic
The Way into Darkness
By Harry Connolly

The Great Way is an epic Fantasy Trilogy by Harry Connolly. As the first two books end in cliffhangers, and the narrative immediately picks up afterwards, it is useful to look at them as volumes of a single story as opposed to related independent books. Luckily, the story is very good.

The story opens in the capital of an empire similar to Imperial Rome. Unlike the Romans, however, the Perdaini empire has a caste of scholars, whose sorcerous power is derived from ‘gifts’ brought by God-like- or alien-like beings. Once a generation, these beings visit, and this time, the visit goes terribly wrong.

A plague of ravenous beasts descends on the capitol, slaying the emperor and ravaging the city. The crown prince and a small portion of his entourage escape, including the two very different POV characters:  The first is Tejohn. An aging war hero who won fame and renown hunting down rouge scholars and quelling rebellion, he is the Prince’s bodyguard. The second is Cazia Freewell. The teenage daughter of a rebellious lord, she is kept in the imperial court as a hostage, where she is raised in the imperial culture and is studying to be a scholar. Despite their differences and hatred of each other, the POV characters are united in their desire to preserve the empire and protect the Prince, and they soon split up to run separate quests for him. As the plague spreads and the story progresses, however, the goal slips from maintaining the empire, to survival, of the characters, of civilization, and even of humanity itself.

As a fantasy adventure, this is a fast-paced, hard-hitting, and creative story. And I recommend it on that basis alone. But there are additional attractions that the story has to people of science.

One of the main thematic arcs is the position of scholars in society, and how their knowledge and power is handled and feared by society. This is seen through the viewpoint of Cazia, as she grows up and sees the wider world beyond the palace where he has been imprisoned, and also by Tejohn, who confronts his scars from fighting rogue sorcerers as he comes to the realization that they are needed in the fight to save humanity. Of course, this tale of an ancient fantasy empire is told by a modern American writer, and is prescient for scholars in the here and now. This becomes most clear in the third book, where Cazia experiences what modern scientists refer to as Cosmic Vertigo:

“I can look into the world.” The words barely made any sense, and she was the one saying them. “I can look into the world and see its parts.”

Just as clearly, she sees the fear, greed, and cunning that the rest of society feels when they realize she- like modern atomic scientists- can see and do things outside of the ordinary experience of most humans living their day to day lives. As the story takes place in a collapsing civilization, this is all the more important for all of us to appreciate.

Saturday, December 08, 2018

The Greenland impact crater

This is a brief note on the recent Science Advances paper on the Hiawatha Impact crater, a large, recent crater which lies under the Hiawatha glacier in extreme northern Greenland.

In the past, I have bagged out impact crater scientists and being alarmist and even dangerous. However, this discovery is the real deal. Similarly, I have occasionally criticized the “glamour-mag” approach to scientific publication, but in this instance, a big splash is appropriate, because it is a big deal, and the evidence is overwhelming.

The short version: Ice penetrating radar and analysis of glacial outwash sand show a large (31km diameter), recent impact crater under a Greenland glacier, complete with central peak. The outwash shows shocked quartz, probable melt glass, and PGE anomalies consistent with an iron (or stony iron) impactor. This is not one of those ancient, deformed, maybe-if-you-squint-you-can-see-a-circle crators, this is in your face and completely obvious to anyone who has studied even a little geology.

Like many short format papers, a lot of the details are in the supplementary materials.  For example:
This is a recent discovery because of global warming! Prior to 2012, the outlet glacer emptied into a lake. It is only ni the last 6 years that it has retreated onto land, so that the sediment they sampled and found the shocked quartz, impact glass, etc in was only exposed from beneath the melting ice sheet a few years ago.
They are planning on running conventional gravity surveys to look for rebound, but because all the ice is melting, the melt signal dominates the GRACE gravity signature.
No known impact ejecta is known from any of the North Greenland ice cores, making the crater likely to be older than the oldest of them (about 100ka). Ice cores are regularly checked for volcanic debris, and it is unlikely that they would miss something this large and close (quick math suggests the ejecta volume should be about 200-600 km3, making it a medium to large VEI-7 equivalent).

The crater overprints pre-glacial river valleys, and this is (as the authors state) probably Pleistocene in age (10ka-2.5Ma).

The melt glass should be datable via Ar/Ar dating, but it is not clear if they have recovered a large enough volume of the material to date at this stage.

I would expect a tektite field from an impact this size, but it isn’t clear where those tektites would end up. If they fell on ice (By definition, the Arctic was mostly ice-covered during most of the Pleistocene), then they would get carried to a moraine (on land), or float around until the ice was exported through the Fram Strait and melted somewhere in the NE Atlantic Ocean.

There is a controversial Younger Dryas impact hypothesis, which basically calls for an Arctic impactor as a trigger for the Younger Dryas cooling and extinction of the Clovis culture in North America. I would be careful connecting this crater to that event, as the NEEM ice core, less than 400km away, doesn’t have any reported ejecta, as known tephra are mostly basaltic. 

Finally, they report carbon in the silicate impact melt. That seems odd to me, as neither crustal gneisses nor iron meteorites have much carbon.  they should do ion probe d13C to get the isotopic composition. Who knows, maybe the impactor hit a peat bog.

Sunday, December 02, 2018

Book review: Eaten by a Giant Clam: Great Adventures in Natural Science

By Joseph Cummins

This book combines the biographies of about two dozen natural scientists from the age of European colonialism. It describes their lives, how they got into natural science, and what contributions they made.

Individually, must of these stories are interesting. However, read as a book, there is very much a repetition of the following story: Wealth anti-social person who doesn’t fit into normal life uses their wealth to go to far flung corners of the world, and look at stuff.  While not every single story goes exactly like this, it is very much a pattern describing the 400 year history of the misfit natural scientist. I suppose that is useful to know that this is not a new phenomenon, and there are obvious questions to be asked about how this sort of culture clashes with modern professional science, but consideration of these issues does not show up in this book. In general, it started to drag fairly early and never picked up.

Sunday, November 25, 2018

Sierra Sequoias

On our most recent family holiday back in America, I wanted to take the kids to see the Giant Sequoias of the Southern Sierra Nevada. I hadn’t seen the enormous trees since I was a teenager visiting colleges at the end of high school. I’ve read a bit about how there is concern that these beautiful organisms may be susceptible to drought and climate change, so I figured better to squeeze them in than regret. We ended up going to Mineral King, a remote southern part of Sequoia National Park. Our main activity there was a hike up into the alpine lakes of the high country. However, we did manage a short walk through the big trees.

The forest had an overstory of sequoia and sugar pine, with some ponderosa (and/or Jeffry) pine and an understory of white fir and incense cedar. By early July the forest was already quite dry, and even at 7000 feet elevation, it was still warm. It was obvious that there had been fire come through some parts of the forest- many of the firs, and some pines and cedars had been singed.

The coexistence of the Sugar Pine and sequoia trees did surprise me a little bit. After all, both trees have evolved to tower over the canopy, survive fires, and reseed afterwards.  It seemed a bit odd that both species would be growing side by side. However, an unrelated article on droughtproofing Australian grazing land made me wonder.

Although the Sugar Pine and the Sequoia have similar above ground growth strategies, they are quite different below the surface. Sequoias have a very shallow root system, while sugar pines have a substantial taproot. And in the most severely fire damaged areas, it appeared that the Sequoias were re-establishing best in the gullies and drainages, while the pines (sugar and ponderosa) were doing better on the more exposed slopes. Either way, the sequoias seemed to be doing just fine- old growth, secondary post-logging regrowth and saplings all seemed to be healthy. If anything, the pines seemed to be suffering worse than the sequoias.