Thursday, December 10, 2009

When is Pyrex not pyrex?

When sold to American housewives, of course.

I recently had to look up the composition of Pyrex glass, and in the process I came across this interesting article in Consumer Affairs.

As everyone who has worked in a lab knows, Pyrex is a borosilicate glass. This is important because this glass composition has a much lower thermal expansion coefficient than standard soda-lime glasses, making it more resistant to rapid changes in temperature.

Evidently, Corning got out of the consumer products business a decade ago, and then sold licenced the US rights to the Pyrex brand to another company. They now use the pyrex brand on a non-borosilicate glass product. These new products are tempered ordinary soda-lime glass, which is more heat resistant than ordinary window glass, but can still explode, according to consumer reports.

Tempered glass is made by cooling the outer layers of glass faster than the glass can conductively equilibrate. As the core of the glass then cools, it contracts, drawing the outer layers of the glass into compression, while putting the core under tensile stress.

Figure 1. Tempering glass

Just like rocks, compression decreases the ability of fractures to propagate, so the glass is stronger.

The tempered ovenware manufacturer has been very lawyerly about catastrophic dish failure, which means that it is up to us bloggers to speculate about causes.

In order for tempered glass to work, the glass must not undergo annealing at its operating temperature. The compressed and tensile layers are not in equilibrium, so if the rate of internal diffusion becomes fast enough to allow the strain to anneal out, the glass will at best lose its temper, and at worst fail catastrophically.

Diffusion rates obviously temperature dependent, but they also depend on composition. We also know that on historical timescales, hydrogen diffuses into window glass while alkalis leach out.* So a testable hypothesis is this:

Some combination of H-rich foods and baking temperatures accelerates the diffusion of H into the bakeware. This lowers the annealing point below baking temperatures, causing differential annealing and catastrophic failure.

This hypothesis should be easily testable** by even the most cash-strapped geology departments, so if any of you folks are setting up summer undergraduate research projects, here’s your chance to combine rheology and home economics.

* My dad must have read this study when I was a kid, because he depth-profiled Na and H in the shards when I hit a baseball through the garage window...

** If you go for it, please BE SAFE! Exploding hot glass = huge safety issue.

Tuesday, December 08, 2009

Space carnival 132

132 isn't just an isotope of barium and xenon, it is also the new space carnival.

Substantive blogging will resume when I have a change to upload photos.

Hang on, did I just redefine "substantive"?

Saturday, December 05, 2009

I did it

It is only a matter of time before this surfaces in the hacked email archive, so I figured I might as well fess up now.

To: Phil Jones
Date: March 15, 2008 8:34 pm EST
Subject: The deed is done.

Hi Phil,
Mission accomplished.
Crichton drank the whole glass. If this thing works as promised, that denialist scumbag will be dead in six months, and they’ll see nothing but natural causes. It won't solve our problems, but we gotta start somewhere.
Thanks for the bug; the stem cell ban here means that we can’t weaponize cancer like you Brits do.
You’re buying Christmas drinks at AGU this year.
The Lord’s Lemming

Tuesday, December 01, 2009

The future of coal

ABC radio did a segment a few weekends back on the future of the Australian coal industry, with a half dozen panelists from industry, unions, government, and other interested bodies. The link is here. Note that there is fine print a link to the transcript just above the comments section, if you prefer reading to listening.

Anyone wondering about the position of coal in the Australian economy should note that during last week's Emission Trading Scheme negotiations, there was a brief push to exempt ALL Australian coal from any greenhouse gas emissions program. Those negotiations have since broken down, as the opposition has ousted its leader in a no-confidence vote, appointed a new spokesman, and changed the official party position to one of obstruction and delay.

Under all currently proposed schemes, coal exports (which comprise about 3/4 of production) would be exempt.

Monday, November 30, 2009

Ternary diagram software

After spewing my guts out all night in an episode tragically unrelated to alcohol consumption, I spent a sick day in bed or behind the computer trolling through the forgotten corners of the internet. And look what I found! A ternary diagram plotter, which meets most of the specifications I asked for earlier this year. So if anyone else is interested in free 4 component 3-D plotting, check out CSpace. So far it looks pretty nifty to me.

Sunday, November 29, 2009

Dumbest climate education move ever

In the process of looking up information on edGCM, the educational version of NASA's General Circulation Model 2, I found out that they now charge $250 bucks.

What the fuck?

The whole purpose of this project was to provide a transparent, accessible climate simulator, so that people who are wary of trusting their future to voodoo climate models can actually download one, pick apart the code, and see how they work.

Only now, it costs hundreds of bucks to do so.

What kind of moron expects that skeptics who think global warming is all a hoax are going to shell out this kind of money? Or indeed any money at all? Convincing people that it was even worth a mouse click was hard enough, but this is fucking absurd!

In fact, putting it behind a paywall plays right into the hands of the conspiracy theorists, who will point to this as a coverup attempt.

So did Columbia sell the entire project to Marc Morano to cover their budget shortfalls? Or did they simply donate their brains to science (presumably nanotechnology)? With friends like these, who needs denialist shills?

Edit: Also, GCM stands for "General Circulation Model", as the Goddard site attests. Revising the acronym to "Global Climate Model" makes them look like they have no idea what their own product is.

Thursday, November 26, 2009

T-day 1 pm

Inside temperature 25C
Outside temperature 31C

T-day high noon

Inside temperature 24C
Outside temperature 29C

T-day 11 am

Forecast temperature 33C
Indside temperature 23C
Outside temperature ~27C

T-day 10 am

Forecast high: 33C
Inside temperature: 22C
Outside temperature: 24C

T-day 9:00 am

Forecast high: 33C
Inside temperature: 22C
Outside temperature: 22C

T-day 8 am

Forecast high: 33C (90F)
Kitchen temperature: 22C (72F)
Outside temperature 19C (66F)

Saturday, November 21, 2009

Thanksgiving thinking

Over the past few years, my stuffing recipe has gradually evolved into a stable combination of cornbread crumbs, apples, cranberries, celery, and mushroom, with appropriate herbs. This year, however, we have bumper rhubarb and snowpea crops. I ain’t putting the snowpeas inside the bird, but is there a way to incorporate some rhubarb? Or is it best left in pie or crumble? And isn’t fresh spring produce for T-day weird?

Wednesday, November 18, 2009

Tuesday, November 17, 2009

The boy is hot

El Niño generally means hot dry summers here in Southeastern Australia. And while it is not yet officially summer, it sure feels like it. The mean November maximum temperature here in Canberra is 22.7 C (72.9 in Feudal units). So far, for the first half of November the mean maximum has been 29.3 (84.7 F). And the forecast is for low to mid 30’s for the rest of the week. And while the mean monthly rainfall is 64.6 mm, so far we have only had 0.8 mm, although there is a possibility of thunderstorms at the end of the week. I wonder what summer will be like? At the very least, this should be an interesting backdrop to the carbon trading debate currently raging in the air-conditioned halls on the hill.

Saturday, November 14, 2009

Stars get lonely too

In the field of exoplanetary detection and characterization, relatively little work has been done on the mental health of the stars in our sector of the galaxy. However, a new paper by Israelian et al. has begun to change that. Their study shows that stars without planetary companions contain as much as ten times as much lithium as the sun.

Lithium, of course, is an antidepressant. Unlike molecular antidepressants like Prozac, it is stable at the temperatures found in the upper layers of luminous stars. Over time, this lithium mixes into the core of the star, where it is destroyed. So the observation that 50% of stars without planets have high levels of lithium suggests that they have been having lithium added via an external source, such as medication.

The obvious conclusion is that these isolated stars have a higher incidence of mental health problems. Lithium is commonly used to treat depression and bipolar disorder, and these diseases may be more common in stars isolated in the vast loneliness of intergalactic space without the companionship of planets. If this hypothesis is correct, then we would expect none of the high-lithium, medicated stars to exhibit variable luminosity associated with bipolar disorders.

Note: I couldn’t find this paper in the arxiv, and Nature only allows access to the abstract by the public. I read that, but I cannot rule out the possibility that I have misinterpreted the research as a result of their access policy.

Friday, November 13, 2009

I voted "NO" on the AGU governance changes

I felt the information given was one-sided and very corpoate sleazebaggy, the diagrams in EOS the other month made the new scheme look much more complex, and I'm a contrarian bastard. Also can't type and dress a toddler.

Wednesday, November 11, 2009

SHRIMP U-Pb age of zircons from the Jequie complex, Sao Francisco Craton, Bahia Brazil

This abstract describes the age for the igneous precursors to several high-grade metamorphic rocks (enderbites and charnokites. They fall in the 2.67-2.81 GA range that it typical for the Jequie complex of the central Sao Francisco Craton. There is a single trans-Amazonian measurement and a single 3.0 Ga inherited core.

As far as I know, the results have not been published in an English language journal, so there is no research blogging link.

Alibert, C., and Vidal, P., 1992, SHRIMP U-Pb age of zircons from the Jequie complex, Sao Francisco Craton, Bahia Brazil, in Fr., S.G., ed., 14th R. S. T.: Toulouse, p. 4.

Monday, November 09, 2009

Just another word for nothing left to lose?

When I was sixteen years old, I spent half a summer on a foreign exchange program. It was a big deal for me at the time- the first time I spent more than a fortnight away from my folks, the first time left the USA, the first time I drank beer and got tear-gassed. And the first week of that trip involved a rail trip to West Berlin.

It was an overnight train, and when we crossed the DDR border, they stopped the train, pulled us out of our bunks, and checked our passports and visas in the dead of night. The border guards were not friendly men, and when my friend Rahul had an irregularity with his visa, things got a little bit nervewracking. In the end they decided to let him stay on the train, and we spent the next 5 days in the walled city, with an excursion into the East on the final day.

We spent one morning staring into the empty no-man’s –land of Potzdamer Platz, and another afternoon leaving the haunted exhibits of the Reichstag museum, walking down a neglected stretch of the wall, and turning back towards the living part of the city after reaching the barrier in front of the Brandenberg Gate.

While there, we attended a history lesson given by a local college professor. In his closing statement to us, he said, “I don’t know if I will ever see the end of it, but hopefully in your lifetimes the wall will come down.”

Four months later it was gone.

Today is the twentieth anniversary of the fall of the Berlin wall. In te 20 years since then, it has become easy to take freedom for granted. The idea that people would be imprisoned for pursuing their dreams and aspirations seems barbaric, and the idea that they would be shot for trying to see the rest of the world seems absurd. But 20 years is just an instant- one 200 millionth of the history of the Earth. For most of that time there were no people at all, of course. But the idea that our lives are ours to live as we please is a very recent development even when you only consider the 200,000 years that we have walked this Earth.

Sadly, communism does not appear to be as dead as it seemed to be headed in the early 1990’s. While military parades and red flags have fallen out of favor in most places, many of the fundamental ideas that made the Eastern Bloc so vile have become entrenched in Western culture. The left’s political correctness and the Right’s truthiness are both examples of communist style diktats demanding that the universe conform to a group’s bland paradigm. The brutal treatment of “persons of interest” in the name of security is horrifying. And the slow and steady nibbling of little rights by zoning boards, risk managers, and lazy regulations is depressing.

But today is a day to put all those little things in perspective. To look back on the days of the cold war and celebrate just how far we’ve come towards being a unified pale blue dot for our brief stay here on planet Earth.

NftFC #1: Assembling West Gondwana in the Neoproterozoic: Clues from the São Francisco craton region, Brazil

ResearchBlogging.orgThis paper summarizes the assembly of the various mesoproterozoic blocks into West Gondwanaland. In this model, The SaoFrancisco/Congo craton first collides with the Rio de la Plata craton around 730 MA. This combined Sf-C-RdlP craton then collides with the Amazonia/ W. Africa craton at around 630 MA, sandwiching and deforming the Borborema terrane, and causing internal deformation in the SF-C-PdlP block. The ~Cambrian assembly of West and East Gondwana into Gondwanaland is not discussed.

Since all of these events postdate my rocks of interest by hundreds of millions of years, I read it uncritically for a general overview, rather than for any particular piece of information.

1. Fernando F. Alkmim, 2. Stephen Marshak, & 3. Marco A. Fonseca (2001). Assembling West Gondwana in the Neoproterozoic: Clues from the São Francisco craton region, Brazil Geology, 29 (4), 319-322

Saturday, November 07, 2009

The madness takes control: NftFC introduction

Notes from the filing cabinet: introduction

During my last little stint between jobs, I got a little bit organized. In fact, I sorted through and filed all my papers. Then my computer died, deferring by dream of referential organization.

But I will not be stopped. I've started the long and slow process of feeding all of them into my Zotero, and I thought I would invite all of you along for the ride. I have been a bit slack in the Researchblogging department recently, so here's my big chance.

Many of the papers are things I haven't read for over a decade- or even worse, papers that it feels like I haven't read in over a decade, even if they were published in the 21st century. So I am making some short notes to myself so that I don't have to reread them to know why I thought they were important enough to sneak out of the library at 2 in the morning to Xerox. And I figured, if I'm doing this anyway, why not contaminate the blogosphere with a little bit of science.

Note that these will not be formal outreach-style explanations of the work. Rather, they will be scientist working notes- Why I found it interesting, what the points I got out of it are, what I think is crap. So if any of you normal readers who are brave enough to still be reading here want to see how scientists* think about research, here's your big chance.

The rest of you have better run. Now.

* Well, this scientist. As with all single sample populations, YMMV.

Friday, November 06, 2009

The geologist’s guide to mass spectrometry

Mass spectrometry is important to geology. After all, rocks are made of atoms, and the different geologic processes can leave chemical clues behind that allow analysts to reconstruct a rock’s history. Despite this, the nitty-gritty details of using mass spectrometers and understanding the data they produce are often overlooked by many geologists. There seems to be some sort of false impression in the geological community that mass spectrometry is difficult, and perhaps even a bit dry and technical. While it is certainly technical, it is my intention to dispute the other claims. Mass spectrometry is wet and easy. You just need the correct frame of mind.

The basic principles of mass spectrometry are simple. First, you get some atoms or molecules so excited that they start losing their electrons. Then, before the excitement passes, you run the excited atoms (called “ions”) through an obstacle course of electric fields, magnetic fields, and physical barriers. This obstacle course separates the ions based on a particular attribute which is of interest to the analyst. For mass spectrometry, one of the attributes of interest in generally mass. Finally, you count the ions as they reach the end of the course.

There are lots of different types of mass spectrometers. The basic classifications are based on two factors: The method used for ionizing the molecules or atoms to be analysed is one basis for classification. The type of obstacle course used to separate the ions is another. Stay tuned for examples of different examples and explanations of how they work and what the results they produce actually mean.

Tuesday, November 03, 2009

Happy Halloween

Thursday, October 29, 2009

Party like the Paleoproterozoic

The Paleoproterozoic was an interesting time. Oxygen finally settled into the atmosphere on a permanent basis, most of the iron formations we use to make cars, bridges, skyscrapers etc. were formed, and the removal of methane from the atmosphere cooled the surface until everything froze, creating a condition known as the “snowball Earth”.

Similar conditions may have reoccurred again in the Neoproterozoic, but since then, the tropics have tended towards being ice free. But will this last? A simple extrapolation says no.

Figure 1. linear extrapolation of the last three years of sea ice minima.

As you can see, sea ice has been increasing for the last three years, by about half a million km ^2 per year. With only 360 million km^2 of ocean on the planet, a continuation of this trend will freeze the entire ocean by the year 2724! We are all doomed.

Tuesday, October 27, 2009

Saturday, October 24, 2009

Asshole of the Month

The Asshole of the month award for October 2009 goes to the United Airlines Steward who harassed the woman sitting in front of me as we came in to land at Sydney this morning. She was flying with an 18 month-old in her lap, and a three-year-old in the seat next to her, with no other adult assistance. The flight was over 13 hours long. And the kids were great- there was a brief point where the older kid tried playing with the hair of everyone around him (including me), but in general they were quiet and kept to themselves the entire flight. No so for the steward, who went off on some passive-aggressive, sarcastic bombast. With slang. American slang. To an obviously non-American passenger. I don’t know what he meant by “fresh”, but I don’t think that word can really be applied to anything on a sold-out 747 that has been in the air for over 12 hours. Luckily all the other 400-odd people on board were acting sensibly, so the flight as a whole was surprisingly bearable. He should have been pinning a medal on the woman. Instead he made trouble. What an ass.

Thursday, October 22, 2009

Conversation is a two way street

After the GSA meeting ended today, I popped down to the Mall up the tracks to do some American shopping that the exchange rate was beaconing me with.

In the mall, I discovered a new form of salesmanship, which did not seem to exist in America the last time I went shopping here- the steamroller pitch.

As I was passing a stall selling some sort of froo-froo cosmeticalogical instruments, the lady at the stall said, “excuse me.” Before I could so much as introduce my self she had grabbed my hand, filed off the slickensites of my fingernail, and was well on the way to achieving an optical polish before I managed to express my disinterest.

This approach was repeated at the very next stall. Before I could utter so much as a “G’day”, the stallkeeper was thrusting his wares in my face.

“Excuse me, excuse me sir, how would you like some genuine Australian sheepskin ugg boots… You can wear them in…”

At this point I should mention two things.

Firstly, years in Australia has left me with a hybrid accent, which I can dial between 90% American and 70% Australian depending on the situation. While I have a way to go before achieving neutrality, I can generally bend it far enough in the correct direction to make a retail transaction without attracting attention.

Secondly, there is a genuine Australian Ugg boot factory about a mile from my work place. The guy there is fantastic- he gave LLLL a free pair of cute little baby uggs when we replaced Mrs. Lemmings boots. So I was curious as to whether they were doing well enough to sell overseas.

Dialing my accent down to its most ocker setting, I asked the salesman a simple question:

“Soowich factr’y are they made in?”

But he wasn’t listening, he was selling. He deflected his rapidfire exclamation of their virtues enough to mention the brand (which I have forgotten), until I deflected him again.

“So are they made in Austraaaaalia?”

He still hadn’t broken stride “They are made in China, but I can assure you that they sheep skins they are made of really do come from Australia, As you can see we have blah blah blah…”

And then he mentioned a price which was really not consistent with the quality of his boots. As he continued on, I realized that I had no choice but to interrupt him.

“Now look here, mate. Do you really expect me to pay twice as much for some Chinese factory worker to put the blokes down the street out of business, just so-”

All of a sudden is mouth stopped moving, and his eyes expanded until they resembled saucers.

I was amused enough to forgive him for his rudeness at that point and leave the lesson there, until he regained his composure enough to defend his actions.

“Well, what am I supposed to do, I can’t tell where you are from just by looking at you...”

And that, my friends is why we pause, introduce ourselves, and say G’day.

Conversation is a two way street.

Wednesday, October 21, 2009

GSA day three

Today was one big schmoozefest and storytelling day, and of course reposting other people's adventures is not a very polite thing to do. So I will let all of you non-existent readers fill in your own blanks. Have you combined hitchhiking with fieldwork? If not, what is the transport method you have used that is most likely to draw frowns from the front office staff..?

Tuesday, October 20, 2009

GSA day two- geoblogger meetup

Quiz time:

The GSA geoblogger meetup happened in...
A: pyjamas.
B: a basement.
C: a blogger’s mom’s house.
D: a pub.
E: all of the above.

Pseudononymous bloggers came...
A: in Burquas.
B: in superhero outfits.
C: in early, hid under the tables, and would’t come out until closing.
D: by conference call/ skype/ iPhone app.
E: all of the above.

We spent our time...
A: talking about blogging.
B: blogging about talking.
C: drinking.
D: taking phone shots of each other drinking for later BUI incidents.
E: all of the above.

The beer was...
A: outstanding
C: superfluous.
D: spilt on the pyjamas we wore in mom’s basement.
E: all of the above.

The pub closed...
A: early.
B: late.
C: after the cops were called.
D: as soon as they realized we were all cybernerds.
E: all of the above.

The most awkward line was...
A: I don’t read your blog.
B: I don’t read any blogs.
C: you know him from where?
D: why do you care about rocks?
E: all of the above.

The events that transpired in the Tug...
A: stay in the Tug.
B: are all over facebook.
C: will make a participant’s career.
D: will break a participant’s career.
E: all of the above.

Post answers in comments.

Monday, October 19, 2009

GSA day one

Well the first day of the GSA meeting has come and gone.

I missed the carbon sequestration talks, but did make it to a biogeochemistry talk on mesoproterozoic Brazil. Our booth ran a bit more roughly than I hoped when our magnet decided to misbehave back in Canberra, but we did give a few people the opportunity to run the instrument. I also caught Ron Schott's gigapan setup (didn't quite make the talk), and can say that he is as enthusiastic about it in real life as he is on his blog.


The leaves! We don't have fall colours in Australia, so red and yellow trees were certainly a hit.

Old friends. Some I've been dying to see, some I wan't expecting until they came around the corner.

The food and drink around town.


My brain. I fought a few unnecessary battles with my computer.

Internet protocols and software. Erasing a page of ip addresses then typing them in exactly the same should not be necessary to connect to the web.

The program book. for some reason, the web page is great, easy to use organization, but the printed book is a all over the shop.


Parenting is great preparation for jet lag. I felt no worse today than I do after a standard night of child-induced insomnia.

Tomorrow is the designated "Hi, I used to read your blog before I found better things to do with my time" night. Tune in tomorrow to see how good an icebreaker that line is. I can tell from the recent comments that many of y'all feel the same way.

Saturday, October 17, 2009

GSA is alomst here.

It is very late and I have a plane to catch tomorrow, but here are some talks I am looking forward to:


Roberts et al.; Session No. 87, OCC Portland ballroom 255; Monday, 11:20 AM-11:35 AM.


SOLOMON, Sean et al.;.Session No. 197, OCC: Portland Ballroom 254 Tuesday, 2:15 -2:45 PM


Anyone else particularly keen to see something? If so, comment (plugs welcome).

Thursday, October 15, 2009

Hadean zircon bingo

I realize that my geoposting here has been slack of late, but work has been flat out preparing for the Portland conference. This evening, however, I managed to do some internet dating, geology style. The cross-building remote operation which we ran today at work has now been tested across town. Assuming the tubes are aligned for us next week, we will hopefully have a mount of Jack Hills zircons under remote control from booth #301 at the Geological Society of America conference. If you're there, swing by and see if you can find relics of the oldest known terrestrial material.

Wednesday, October 14, 2009

Have you seen this bird?

Back in 2005, Mrs. Lemming and I hiked the Grand Canyon, starting down from the south rim just as the Sun rose over the frosty cliffs. We were lucky enough to see not one, but two California Condors on our walk down.

Because the condor is critically endangered, all of the birds are labelled and tracked by conservation officers. A complete list of the birds released in Arizona can be found here. Browsing this list, I noticed that the bird pictured above is missing, presumed dead.

A brief correspondence with the conservation officers revealed that the bird disappeared in January 2009, just over three years after this picture was taken. If anyone has seen the bird since that time, please contact the Peregrine Fund via their web page.

The other bird we saw, number 72, is currently listed as "doing well in wild".

Friday, October 09, 2009

LCROSS impact in half an hour

NASA is about to crash a satellite and a spent upper stage into a shadowed crater near the Moon's south pole, to see if it acts like a giant cold trap and holds significant water.

I'm guessing that it will be low-to-none. This will be disappointing to exploration dudes, but is far more interesting scientifically.

The moon has not yet risen here in Australia, so it will not be possible to observe the impact.

I wish the NASA TV folks would speak metric, though.

Thursday, October 08, 2009

GSA meeting presentations

One of the reasons I have not been blogging much recently is that I have been spending too much time on the internet for work. Much of that involved collating research done using our instruments that is being presented at the conference. So for anyone interested in applications of zircon geochronology to geologic problems, I have a list.
And, yes. The time scale is correct to within a pixel, and uses the international standard colors. It is the ICS timescale, though, not the GSA one.

Tuesday, October 06, 2009

Space carnival

Number 123.

Number 122.

Monday, October 05, 2009

The Arctic sea ice prognosticator of the year is...


The JAXA minimum arctic sea ice extent value for 2009 was 5249844 km2, which was recorded in September 13.

The final score for each contestant is the value of their Gaussian curve at 5249.844, and is listed in table 1.

Table 1: Contestant final scores and original guesses.

The results are plotted in figure 1.

If I recall correctly from the original comments, Hypocentre is a hard rock geologist, and the 2nd through 5th place winners were all climatologists.

Figure 1. Contestant curves and final 2009 minimum sea ice extent (red line).

Hypocentre, as the winner of the contest, may now nominate a topic for a future blog post (post nomination in comments, please).

Everyone else, tune in next (northern) summer solstice for the 2010 version of this contest.

Commentary, corrections, and sour grapes are welcome in the comments section.

Tuesday, September 29, 2009

Portland here I come

I am currently planning on attending the Geological Society of America meeting in Portland Oregon next month. Australian scientific Instruments has a booth- number 301- and we will hopefully be able to control some ion probes over the internet. I don't know if I'll have access to the talks yet, but if you're at the meeting, stop by, shoot some zircons, and say hello.

Monday, September 28, 2009

Sunday, September 27, 2009

That's not old

Given that different people have different view on what 'old' is, I thought I'd share this figure from my thesis.

I apologize to any tectonicists who may have wandered in here for describing the Braziliano Orogen (The South American correlate of the Pan-African; one of several continental suture events that led to the amalgamation of the Gondwanaland supercontinent) as 'cover'. But let's face it folks. Thrust sheets get in the way just as much as mud piles do.

So if it seems like I haven't updated my blog for a while, use these numbers to keep a perspective on things...

Saturday, September 19, 2009


33-Sulphur, the colloquial name for the atom with 16 protons and 17 neutrons in its nucleus, is one of science’s more interesting characters. Many elements have multiple isotopes. Sulphur, for example, has four (mass 32,33,34,36). And while isotopes are chemically similar to each other, they can be separated to some degree in biological of physical systems. These effects produce what is called mass-dependent fractionation, where the degree of enrichment (or depletion) of the various isotopes is a function of their mass.

Mass dependent fractionation of various isotopes is used for everything from making nuclear bombs to predicting the mass of ice-age glaciers. In the case of Sulphur, it is generally measured by comparing the ratio of 32S (the most abundant isotope) to 34S (the second most abundant). Calculations show that the fractionation of 33S from 32S should be about half of the fractionation of 34S from 32S. Since 33S is about 8 times less abundant, and the signal is expected to be half the size, measuring it seems like a silly think to do.

That all changed in 2000 when Farquhar et al. showed that Archean sulphides showed a 33S anomaly that was not consistent with mass-dependent fractionation. This anomaly is expressed as Δ33S, the difference between the expected value (based on extrapolation from the measured 34S/32S ratio, and the measured 33S/32S ratio, and is generally only present in archean sedimentary rocks.

One of the few processes that produces mass-independent fractionation (MIF) is photolysis of sulphurous gasses by UV radiation (the exact mechanism is still being researched). So the presence of these anomalous ratios in early sediments is generally thought to be an indicator that there was no ozone or other UV-blocking layer in the atmosphere at that time, and there were enough atmospheric suphur-bearing compounds to be dissociated by that radiation.

In 2003 Mojzsis et al. did some classy ion probe work (using a non-SHRIMP instrument) on in-situ sulphide grains so show where in the rock the anomalous D33S was located. Our approach was somewhat different.

My hypothesis was that the Monica Lewinsky scandal of the late 1990’s caused enough hyperventilation to such all the oxygen out of the atmosphere and return the surface conditions of Earth to those of the late Archean. So I chose to test this hypothesis my analyzing sulphide minerals grown in the 1998-2000 time period, to see if a non-zero Δ33S was present. We are breathlessly awaiting the results...

Friday, September 18, 2009

Health insurance blather

Our health fund recently ran a radio ad, suggesting that their product is superior because they paid out 90% of their rates as benefits. This figure is 5% higher than the industry average here in Australia.

Internet rumor has it that the US is aiming for 80%.

Translated into academic language, if your aspiration is to go from a C to a B-, you'll have a tough time getting an A.

Monday, September 14, 2009

Final Arctic minimum sea ice prognostications

The final guesses are shown above.
In the comments of the last post, Crandles was nice enough to put a data table up. With minor corrections, that table is included below. Unfortunately, due to the lousy table support in blogger, I've simply screen captured an excel spreadsheet. Comment if you want the numbers.

Finally, here is a comparison of the aggregate guess to the Wegener Institute forecasts.

Feel free to post links to other professional forecasts in comments, and I will add them. From a statistical point of view, our 'alarmist plateau' has a statistically strange shape.

As discussed in the rules, the prize is a blog post on the topic of your choice. If you're feeling cocky, post your topic now. Otherwise, continue to trash-talk amongst yourselves. And keep watching IARC-JAXA's latest numbers. We should have a winner by the end of September.

Thanks y'all for playing, and feel free to suggest ways of over-interpreting everybody's estimates.

Saturday, September 12, 2009

Thursday, September 10, 2009

New Job

As of this morning, I work as a geochemist for Australian Scientific Instruments, a small engineering firm that builds scientific instrumentation, including the SHRIMP. It is a part-time position, so I still get to spend two days a week with LLLL, while still getting paid to push the frontiers of science. So far it has been great- I spent the day learning how to set up sulfur isotopes on the multicollector, for the purpose of teasing 33S anomalies out of really old mud. Tomorrow will be swimming lessons, a playgrounds, and possibly the zoo.

Although selling the instruments isn’t actually part of my job description, if there’s anyone out there wishing to turn several million dollars of stimulus money into a world-class analytical facility, leave me a note in the comments.

Wednesday, September 09, 2009

OMG look at Mars!

Look up at the sky tomorrow morning (and that morning only), and the planet MARS IS HALF THE SIZE OF VENUS! At 1.5 AU distance, the red planet suptends 6 seconds of arc, while the larger Venus, at 1.3 AU, suptends 12. But this relationship will not last forever! As Earth catches up to Mars in its orbit, and Venus pulls away, this ratio will increase. So act now! Mars has not been this close for 16 months; it will not be closer until tomorrow! And this arbitrary geometric relationship will not occur again until 25 May 2010!

THIS IS NOT A HOAX! The planets will not cease their orbital motions while you procrastinate! Link this post, email your friends, and tweet it now!

Monday, September 07, 2009

Geological Society of America meeting

Are any of y'all going to be in Portland this October? If so, what are you looking forward to seeing, hearing, and/or saying?

Sunday, September 06, 2009

Looking for reference help

Anyone out there with a GSA bulletin subscription willing to help me find a paper published when I was 9 weeks old?

Saturday, September 05, 2009

Metamorphic petrology is cool, part eleventy zillion

It is abstracts like these that make me wish for journal access:

Drüppel, Kirsten; Lehmann, Christian

Fire bombing of the Tell Halaf Museum in Berlin during World War II - reconstruction of the succession of events based on mineralogical investigations

Basaltic monuments from the Aramaic Tell Halaf (built ca. 1000 BC), Syria were severely damaged during fire bombing of the Tell Halaf Museum, Berlin in World War II. While the museum burst into flames part of the statues were covered with burnt bitumen from the roof of the museum, mixed with fragmented quartz of the roofing cardboard, grinded basalt, limestone artwork, and gypsum casts. Detailed mineralogical investigations of the thin carbon coating on the statues revealed that additionally a number of unexpected, non-basaltic minerals formed in the bitumen via temperature-dependent reactions due to the thermal impact by the bomb blasting and subsequent reequilibration during burning of the exhibition hall. The source material of these newly formed phases was provided by the basalt, the gypsum casts, the limestone artwork, the museum roof, the museum pipe system and, last but not least, the incendiary bomb itself. Phases include sphalerite (zinc of the pipe system + sulphur of gypsum casts), smithsonite (zinc of the pipe system + calcite of limestone artwork), wollastonite (calcium of the limestone orthostats + silica of the roofing cardboard), pyrite (iron of the basalt Fe-oxides + sulphur of the gypsum casts), alkali feldspar (saltpetre of the incendiary bomb + basalt plagioclase), and apatite (phosphorus of the incendiary bomb + calcium of the limestone). A conspicuous feature of samples close to the impact is the abundance of silicate glasses. Observed mineral-forming reactions suggest initial temperature conditions of > 980 °C near the fire centre and of 850-980 °C throughout the museum. The cold water used for fire fighting finally resulted in crack-producing stress that caused severe shelled fracturing of the statues.

European Journal of Mineralogy, Volume 21, Number 2, March 2009 , pp. 443-456
DOI: 10.1127/0935-1221/2009/0021-1901

Saturday, August 29, 2009

New definitions from the International Astronomy Union

Last month, the IAU got together for their first meeting since the redefinition of Pluto that some of us predicted: And sure enough, there are more definitions.

The nations of the world now only include the G8- Canada, France, Germany, Italy, Japan, Russia, United Kingdom, and United States. All other countries have been redesignated as ‘dwarf nations’ to reduce the burden of memorization on school children.

Although it was an international astronomy meeting, the USA was formally reduced to five states: Hawaii, California, Arizona, New Mexico, and Texas. Those former states and territories whose observatories do not host at least one telescope with a 3 meter primary mirror have been relegated to the amateur anonymous land category. The union felt very strongly that reducing the trauma caused by the memorization of state capitals justified this change.

And finally, the periodic table of the elements has been redefined. Instead of 112 elements stretching from hydrogen to copernicium, astronomers will recognize only hydrogen and helium, relegating everything else to the category of ‘metals’, irrespective of the behavior of the electron shell.

Friday, August 28, 2009

Carbonado cathodoluminescence challenges
When I was a PhD student, I published a short paper in the Proceedings of the VIIth International Kimberlite Conference on luminescence from radiation-induced crystallographic defects in carbonado, a type of polycrystalline diamond. Being a proceedings paper, it was short format- 4 pages, and 6 figures. This work found its way into my Thesis, of course. But since the structural and stylistic conventions of a PhD thesis differ from that of a conference proceedings, that version was 49 pages and 34 figures. After graduating, I tried to publish a condensed version of the full work, but I couldn’t get it accepted anywhere- the conclusions were no different than the short version that came out in ’99, so it was considered uninteresting, old news, and beating a dead horse. I gave up submitting it sometime in 2003 or so.

Fast forward to last year. Yokochi et al. (2008) publish a lovely paper of carbonado spectrometry and microtexture. Their photomicrographs are probably the best published to date. They see the same spectrographic peaks and textural features that have been known since Fettke & Sturges (1933). And with the addition of some nice stable isotope and argon work, they find a novel way to put it all together.

Figure 1: Yokochi et al.'s figure 1b, showing euhedral phenocrysts in a bright matrix. I reckon the CL-dark areas in the upper left of the figure are probably from epigenetic radiation damage. Evidently he prefers another explanation.

In the process of interpreting their fabulous images, they say:

These circular textures are analogous to CL images of carbonado from Central Africa in previous studies (Magee & Taylor 1999, Kagi et al. 2007). Although these authors interpreted them as a result of radiation damage, our cathodoluminescence images show no link between the circular texture and the pores in which the radioactive elements might have been resided. Moreover, the size of this circular texture is occasionally larger than the range of a-particle influence (20 µm). An alternative hypothesis for this particular sample may be that this circular texture had first formed as phenocrysts at earlier stage, and the rounded shape and vague boundaries imply either a partial dissolution of the phenocrysts prior to the formation of the flow structure or an annealing that has erased the sharp boundary after a discontinuous growth.
Now, I don’t think their interpretation is correct. In fact, I have a highly detailed case to support our original interpretation- which is that grain-boundary-crossing CL quench features are epigenetic in origin. But it has been sitting in the back of my garage since we bought the house because nobody has ever doubted the short&sweet version before. Hopefully, the emergence of an alternative hypothesis will make the longer argument relevant.

So, if I’m not blogging here, it means that I’m trying to track down co-authors from a dozen years ago in order to get this paper submitted. Or it means my daughter’s sick. Or the garden needs attention. Or I’m wasting time on facebook instead of wasting time blogging.

Just like carbonado cathodoluminescence features, there are not several competing hypotheses for light blogging here at the lounge.

Fettke, C.R., and Sturges, F.C., 1933, Structure of carbonado or black diamond: American Mineralogist, v. 18, p. 172-174.
Kagi, H., Sato, S., Akagi, T., and Kanda, H., 2007, Generation history of carbonado inferred from photoluminescence spectra, cathodoluminescence imaging, and carbon-isotopic composition. American Mineralogist, Volume 92, pages 217-224.
Magee, C.W. & Taylor , W.R. (1999): Constraints from luminescence on the history and origin of carbonado. Int. Kimberlite Conf., 529-532.
Magee, C. W. 2001. Geologic, microstructural, and spectroscopic constraints on the origin and history of carbonado diamond. Ph.D. Thesis, Australian National University.
Yokochi, R, Ohnenstetter, D., Sano, Y., 2008, Intragrain variation in d13C and nitrogen concentration associated with textural heterogeneities of carbonado. The Canadian Mineralogist Vol. 46, pp. 1283-1296.

Yokochi, R., Ohnenstetter, D., & Sano, Y. (2008). INTRAGRAIN VARIATION IN 13C AND NITROGEN CONCENTRATION ASSOCIATED WITH TEXTURAL HETEROGENEITIES OF CARBONADO The Canadian Mineralogist, 46 (5), 1283-1296 DOI: 10.3749/canmin.46.5.1283

Wednesday, August 26, 2009

Why investors need stoichiometry

I was browsing the internet recently, eyeballing some of the ASX releases of various other exploration companies working in the NT, when I noticed the following release (pdf).

The headline announcement is “MgO values of up to 37.9% after removing LOI.”

A brief aside:
Magnesium is commonly mined from magnesite, MgCO3, and a brief description of several mine types can be found here (pdf). Magnesite decarbonates at a few hundered degrees C to MgO + CO2. As shown in the article above, ore grades are often reported as %MgO after LOI (so pure magnesite would be 100%).

Magnesium is a very common element, though, and is found in all sorts of other less economic minerals, such as pyroxenes, dolomite, hornblende, talc, etc. But it is generally less economical to extract Mg from these minerals. If, as this AXS release suggests, their exploration model is a Kunwarara-type sedimentary magnesite deposit, then they may want to demonstrate that their magnesium is actually in magnesite, and not some other less economically useful mineral.

So I wondered, is the magnesium content of dolomite after LOI greater or less than 37.9%? Dolomite, CaMg(CO3)2, decomposes to CaO + MgO+2CO2, which is lost. Using masses of 15.9994 for O, 24.3050 for Mg, and 40.078 for Ca (via webelements), we get a LOI-removed MgO content of 41.8%. So any bulk analysis greater than this amount must contain some phase that is more MgO rich than dolomite (like magnesite, the stuff we are looking for).

Trouble is, their highest reported value is 37.9% MgO, from what they describe as “dolomite nodules”. Assuming no other Mg bearing minerals, 38% MgO corresponds to a rock that is about 90% dolomite. Now, finding dolomite could be very exciting in some parts of the world where carbonates and magnesium are rare. But the Georgina basin is full of dolostone.

Of course, if there is no calcium in the rock, then their can't be any dolomite, and it could very well contain magnesite. We don’t know what the other 68% of the rock is made of. But given that they report dolomite nodules, and dolomite has a higher post-LOI MgO content than what they found, there is no reason to believe that they have any magnesite.

Read this part carefully:
I am not an investment advisor. Anyone who buys or sells shares based on my advice will probably end up broke. But I am a geochemist. And based on the calculations above, these reported results are consistent with having found a common rock type in the Georgina Basin, and not magnesite.

Monday, August 24, 2009

Banning powerpoint is not enough

Recently, Kim suggested that an SMU dean was not acting correctly by banning technology from the classroom. I’d like to back this dean. In fact, I don’t think he goes far enough.

Powerpoint, podcasts, and filmstrips are just the tip of the Cryogenian iceberg here. If we really want to get back to teaching old-school, there is an equally pernicious development that has to be addressed before a classroom can be truly free of newfangled gimmicks. We need to ban chalk.

Forget about all the arguments over allergies, unfashionable smudges, and unacceptable strontium blanks. The real problem with chalk is that it is too new. How can the effects- and dangers- of a teaching technology be fully appreciated for a device that is a mere 0.07 gigayears old? When I was a kid, those slate blackboards weren’t even slate yet, and the Cretaceous was just a twinkle in a basal therapod’s eye.

Now, I am not a lubbite. I had no complaints about the moon-forming impact, the emergence of continents from the primeval sea, or even plate tectonics revolution. And I’m coming around on this whole oxygenated atmosphere thing. But chalk? Let’s be honest here, folks. For 85% of the Earth’s history, there were no fossils, much less undeformed diagenetically unaltered ones. Cemented coccoliths have no place in the 21st century classroom.

Thursday, August 13, 2009

Phase diagram question

What do you guys use to plot ternary phase diagrams?

Does it run on a PC?

Is it Excel-compatible?

Does it do 3-D (4 component) systems?

Does it correctly plot error ellipses?

If the answer to all those is yes, please let me know.

Saturday, August 08, 2009

This is not a mud volcano

Thursday morning, I got home to the sound of the sinks glugging and an unpleasant smell. A quick glimpse at the back drain revealed the problem- sewer clogged up. One rapid response plumber later, we had determined that our line as far as the drop to the main line was clear. As he said to me, “You can hire a mechanical digger, but you’ll save a whole lot of money if you just dig.” So, shovel and pickaxe in hand, down I went.

Three hours later, I had uncovered the downpipe cap, and quickly changed and sponged off (shower would have dire side-effects) to run out to a job interview. I returned to find the following:

Figure 1. Sewerage eruption vent. Note the splash marks on the back fence, indicating minimum plume height.

The plumber used the term “geyser” to describe it, and said that he had to wait for about an hour for it to subside enough for him to get to work. After ponding in the veggie patch, the flow ran under the fence and down the laneway to near the bus stop. And the stench. Oh, the stench.

Figure 2. The laneway to the bus stop was inundated.

This was the point where he called the utility, as only a main line blockage could account for the volume and type of effluent. There were vegetable bits from species we haven’t eaten for yonks, and the shear volume was more than our 100mm pipe could contain. This was a broad-based community based effort, with the curried squirts, greasy logs, and uptight stones of all our neighbors joining into a gray sludge of maximum entropic state.

I’ve been mopping up and sterilizing ever since, despite such complications as the fact that the effluent flow eroded so much dirt away that I had trouble finding fill for the hole. Despite the churning in my tummy and the phantom scent of sludge being imagined by my brain, the worst is hopefully over. I must ask, though:

Do any of you read this blog while eating your lunch?

Thursday, August 06, 2009

The Pacific Ocean is 2.5 trillion km wide

According to Cosmic Variance, the Bones episode on which Sean consulted was transmitted at 8 pm on 9 April 2009. On 12 July 2009 this broadcast was received here in Australia, where I watched the show.

Because TV transmissions are electromagnetic radiation, and travel at the speed of light, we can use this delay to determine the distance between California and Australia. The delay was 94 days, which is 0.26 years. So the distance is 0.257 light years. This is about 2.4 trillion kilometers, or 16,000 astronomical units. Thus the width of the Pacific Ocean (which separates California and Australia) is slightly larger than the distance between Proxima and Alpha Centauri, in the closest stellar system to our own.

Now, some of you may find this hard to believe. After all, surely if you can’t clearly get channel 6, then a TV transmission from 2 and a half trillion km would be hopeless, right?

Not necessarily.

Here in Canberra, our NASA Deep Space Network is currently tracking Voyager 1 at a distance of 110 au. This is 147 times closer than California. Assuming that radio transmission strength follows an inverse squared distance law, the signal from a California radio station broadcasting from the edge of interstellar space would be 22 thousand times weaker than that from Voyager 1 for a given transmitter power.

Luckily, that power is not constant. Voyager 1 has a 20 watt X-band transmitter. In contrast, San Francisco’s KCNS (UHF channel 38) pumps out an effective radiated power of 5000 kilowatts; 250,000 times more power. As a result, even at the astronomical distance at which California lies, the TV stations there still have up to ten times more signal than the old space probe.

Thus, my interpretation of California being on the outer edge of the Oort Cloud is entirely plausible.

The take home message, of course, is that when people accuse Californians of being way out there, they are vastly understating the situation…

Friday, July 31, 2009

Minimum Arctic Sea ice betting pool- final update

With exactly 13 hours to go before the close of bets, the betting pool for minimum Arctic sea ice looks like this:

Only Doc is still mathematically eliminated.

Thursday, July 30, 2009

Where are all the crackpot Tychos?

We all know that crackpots have a number of identifying features. These have been enumerated on other blogs; I won’t rehash that material. However, I would like to examine one particular point.

When crackpots compare themselves to great scientists, it is almost always to Galileo. As he was a persecuted genius ahead of his time, this is not surprising. This is how crackpots self-identify. But Galileo was not the only scientist in such a situation. Even in the limited field of 17th century astronomy, Tycho Brahe was in the same category.

Brahe, the last great pre-telescope observer, mapped the night sky to a precision not seen for another century. He had by far the best dataset of the time period, and while Galileo had to deal with house arrest in his later years, Tycho was poisoned, either by his king for being an embarrassment, or by Kepler for not handing over his data.

So why aren’t there more wannabe Tychos?

I think the key is their perceived contributions. While Tycho is seen as having been a meticulous, workaholic data collector, Galileo is often thought of as a guy with a single flash of cross-disciplinary brilliance that changed everything. Just point this navigational aid into the night sky, and BLAM! The universe has changed.

Of course, this interpretation overlooks the huge effort that Galileo put in, but we’re taking about perception here. His lens grinding, observing schedule, and other elbow grease producing work is generally less emphasized than his brilliant idea is.

So why does this appeal to crackpots? Because. They don’t just want to be game-changing scientists; they want it to be easy. I’ve never seen a crackpot whose theory required years and years of dawn-to-dusk data. Crackpot theories invariable offer simple, pat solutions that obviate the need for further rigorous study. The whole point of having a simple explain everything theory is so that they can go around feeling smug without having to crunch through weeks of data analysis. There are no crackpot Tychos because he is seen to have worked too hard to be a role model for them. Crackpotism isn’t just intellectual laziness; it’s ordinary laziness too.

Monday, July 27, 2009

Do you give 110% for science?

I recently skimmed a PhD thesis which contained attempts at geochronology of some unconventional uranium ore minerals. The U concentrations in the data table ranged from about 400000 ppm to about 1700000 ppm, with a mean around 1100000. Now, I am the last person on Earth who has a right to complain about imperfections in a PhD thesis. Indeed, one of the reasons that you are reading these autoqueue posts is that I'm rereducing some of my PhD data from scratch to get it publication worthy. But still. More than a million ppm? Evidently it passed the review in this form, although it is possible that we were looking at a pre-corrections copy. Still. An A for effort, perhaps? Or evidence that in addition to the traditional pass/ pass with corrections/ fail categories, we also need an option to "fail, and send back to 7th grade."

Saturday, July 25, 2009

...And returned safely to the Earth

40 years ago today, the Apollo astronauts splashed down in the Pacific Ocean after visiting the moon. While it is nice that they went there, it is even better that they came back. Especially since they brought rocks with them.

The scientific return from the Apollo mission is often understated. Just the other day, Mark at Cosmic Variance said "But what grabbed me was the exploration, and the adventure. Not the science.". But while it is true that the mission was not designed as a scientific experiment, the scientific return was nothing short of phenomenal.

There were a number of non-geologic accomplishments of the mission- such as the first collection and return of solar wind, and various discoveries relating to lunar ranging, etc. But the rocks alone are worth considering.

"...and all we brought back were some rocks." is a common criticism on the Apollo program. Of course, geology isn't about the rocks. Geology is about the stories rocks tell. And what a story.

Prior to the return of Apollo 11, people really had no idea what the Moon was made of, nor how it got there. Based on Terrestrial geology, people made various educated guesses about the composition and origin of the moon. And they were all wrong.

Earth is thought to have formed by the collisions of tens to hundreds of smaller bodies. In contrast, the Moon condensed from material vaporized during one of these Earth-forming collisions. It then cooled, crystallized, and aside from some sporadic magmatism, had done little else since.

Despite being co-genetic with the Earth, the Moon is completely and totally different. In fact, it is so different as to be beyond any of the theories dreamed up prior to the return of the Moon rocks. As such, it set a pattern for the characterization of other planetary bodies- first in our own solar system, and more recently, around far away stars. Time and time again, planets defy our expectations. The geysers of Triton and Enceladus. Perchlorates on Mars. The extreme eccentricity and small orbits of extrasolar planets.

The key revelation from Apollo- which has been repeated every time planetary science has stepped farther out into the galaxy- is this:
Planetary formation is stochastic. Planets are not like aluminum atoms, electrons, or whatever-it-is that the LHC is supposed to discover. There is no formula you can devise to predict the details of all the planets in the Galaxy. They are not interchangeable. You have to actually go out and observe them, in order to figure out their stories. This lesson was first learned from the Apollo samples, and it is incredible important. Because every time scientists forget it, the universe shows them up.

Wednesday, July 22, 2009

Minimum Arctic Sea ice betting pool update

With about 9 days to go, the pool looks like this:

Here are the guesses, in no particular order:
5200 ±75
4555 ±60
4150 ±100
4800 ±75
4675 ±65
4900 ±80
4700 ±50
4700 ±200
3900 ±100
4250 ±100
4300 ±100
4000 ±75
5325 ±75
4400 ±100
4600 ±100
4000 ±100
4920 ±500
4535 ±25
4235 ±100
4000 ±350

Those guesses which have been mathematically eliminated at the 2 sigma level are dotted. As the rules allow for eliminated contestants to re-guess, Doc and Alistair may guess again if they so desire.

In order to help people guess intelligently, the Y axis has been labeled to show the maximum value of a curve of given sigma. As you can see, guessing with an uncertainty of ± 200 in the well populated areas of the pool will not be very productive.

Contest ends at the beginning of August UTC time. Rules and original announcement are here.

Please put any additional guesses in this thread, giving value, sigma, preferred color, and a bit about your background.

As previously stated, guesses are to be in the form of extent and sigma (a mathematical measure of uncertainty), in thousands of km2 You may use decimal places if you insist.

Your guess will define a Gaussian curve.

The function with the highest value for x=minimum daily measured ice extent (from the lowest daily 2009 value from IARC-JAXA) wins.

As of 21 July, the sea ice extent was 7,848 thousand km2.

Monday, July 20, 2009

Mapping tips- differential weathering

When mapping a moderately weathered area, it is important to keep in mind that preservation-based selection effects may strongly bias the observable outcrop. Figure 1 shows some dolomite subcrop (with a silicified stromatolite) in red soil.

Figure 1. Dolomite subcrop with silicified stromatolite. Hammer for scale.

Since dolomite (plus or minus alteration) is the only rock that crops out in this area, it would be tempting to map the area as dolomite. However, as this historical digging shows (figure 2), the rock in the area actually consists of interlayered dolomite, shale, and dololutite. But the shale and dololutite are friable, so it is only the hard, massive dolomites (or silicified fossils) that are present in natural outcrop.

Figure 2. Historical diggings showing actual stratigraphy. Massive dolomite is confined to thin layers, and the dominant rock is shale and dololutite. Lizard for scale.

Friday, July 17, 2009

Was Carl Sagan really all that?

Chris and Sheril have a new book out on scientific failures to communicate. I haven't read it, as it was not available in my local bookstore here in Oz. Fortunately, here in blog land, my failure to even see the book qualifies me to review it. From what I'm told, the late Carl Sagan is used as an example of a great science communicator. Trouble is, my local bookstore didn't have any of his books either. Lomborg and Plimer, yes, but no Mooney or Carl.

A lot of scientists enthusiastically cite Sagan as one of the inspirations for their careers. And that is fine. But here's the thing. Sagan was a great preacher, sure. But for the most part, he preached to the choir. Welders and car dealers aren't nearly as excited about him as astronomers are. So when it comes to finding a way to bridge the gap between science and the technophopic world, he is probably not the best example. In fact, I'm not really sure who is. but I reckon that the late Steve Irwin would be in the running.

Tuesday, July 14, 2009

Geologic bad habits

I am far from a perfect geologist. One of my most annoying habits, both to my self later on and to my colleagues, is that I often forget to put a scale bar in my field photos. Obviously not knowing the size of various features results in substantial information loss, so this is something that I tried to specifically address during our 2008 field season.

The one item that we don’t leave the truck without is a GPS. For one thing, all data has to be tied to a location point- there’s no point taking a picture of the biggest gold nugget evah if we don’t know where it is. And secondly, in areas on subdued topography, incomplete drainage, and/or thick scrub, the GPS is the best tool for finding one’s way back to the vehicle. So, I decided that the obvious thing to do was to add a scalebar to my receiver. Here’s the result.

Figure 1. slickensides and veining in sandstone. GPS gradations are centemeters.

Do any of y’all have geologic habits bad enough to necessitate the use of pink paint markers?

p.s. Kim, Sinistral?

Saturday, July 11, 2009

This could have been me

My PhD work involved fieldwork in East-central Brazil. After about a year of correspondence with a geologist at the Bahia state survey who was an expert on the stratigraphy, the plan was for me to accompany him into the field. As someone who had worked in the area for decades, he was in charge of the logistics, while I, the student from the top notch analytical school, was in charge of all geochemical and geochronological analyses.

That was the plan.

My flight into Salvador arrived at 12:30 am. When my collaborator met me at the airport, he informed me that he would no longer be taking part in the project, and that I was basically on my own. That I eventually managed to get samples and results (the writing up of which is the reason this blog is on autopilot) was a miracle. But it was pure luck that I didn’t end up like these guys.

For those of you who don’t read All my Faults are Stress Related, or Arizona Geology, five students, three American and two Brazilian, were recently arrested for geological sampling without the proper paperwork. The Americans are required to stay in Brazil until legal proceedings are finished.

Brazil is a country with complicated bureaucracy and spastic enforcement. Unlike these guys, I had a proper multiple entry business visa, as I was going to Guyana for a related project before starting my fieldwork. Upon my return, the border guard slashed the expiry date on my visa by two months, to the day BEFORE my outgoing flight, just because he was cranky his soccer team was losing on the television. Had a similar cop asked why the guy named in our permits was 400 km away from the sample site, I would have been in an even worse situation than these folks. So please spare a thought for people caught in a system where, even if you do manage to navigate the Byzantine labyrinth of regulations, sadistically capricious enforcement can still screw you over.

Friday, July 10, 2009

Should reviewers phone a friend?

Role playing time, lemminglets. Suppose you are reviewing a paper. Also assume, that like most papers these days, that it has multiple authors, each of whom applies his expertise to the problem at had. And finally, assume that you are an expert in some, but not all of the fields used to solve the particular problem being reported in this paper.

What do you do if one of the key points in the paper that is not your area of expertise seems fishy. For example, if the paper is on your field area, what if some of the lab results seem fishy. Or if you are an analyst, what if the experimental setup seems odd.

Assuming that you are a successful researcher, you probably have long-time collaborators who are experts in these fields. So, what is the best way of accessing their expertise, given that some sort of confidence generally surrounds papers in review.

By ‘best’ I mean best for science, but if any of y’all want to interpret this as ‘best for me’ or ‘best for the editor’ or ‘best for the author’, that is fine too.

Sunday, July 05, 2009

Arctic sea Ice pool: 4 weeks to go

With 4 weeks left to guess, the graph for the 2009 Arctic sea ice minimum gaussian guessing game is looking like this:

Contestants have solid, colored curves. The thick black/grey curves are the Ensemble 1 and 2 outputs from the Wegener Institute’s June 2009 Sea Ice outlook. The collective contestant’s pdf is the dotted light grey line (click to embiggen). It has grown from a bimodal distribution around the 2007 and 2008 minima, to a trimodal distribution with a third peak around 4000. Nick Barnes (4700 ± 200, pink) still needs to take another guess, if he so desires.

The current value (as of Friday) is 9,500 thousand km2.

Saturday, July 04, 2009

Happy Fourth of July

It's time to celebrate freedom from despotic tyrants, pyrotechnics, and BBQ. The first two aren't really big here in Australia, but the following suppliment to the third category makes up for all that.

BBQ sauce. Made from beer. What more could you want?

Friday, July 03, 2009

Naughty Geology

A few months back, I blogged about the client with a spam filter so tight that it embargoed emails about single young zircon dating. After conferring with said clients, it turns out that they’ve had other issues as well. In its animatronic zeal to rid the internet of pornography, this filter also blocks image files that it suspects are explicit. What sort of images? Well, anything containing a lot of pink, as it turns out. So, rose quartz, rhodocrosite, Mg-rich garnets, and other titillating mineral images have been known to disappear into the computer program’s private locker. Luckily they ship geologic maps as GIS files instead of images, or I’m sure they’d be targeted as well.

This got me thinking. How common are explicit geologic formations? You’d think that will all the zillions of folded, rounded, curved, or protruding structures on this planet, at least a few would be shaped like something that would constrict the coronary arteries of a shrill old censor. So, this is my challenge to the blogosphere: Find juiciest, most risqué geologic image that you feel comfortable posting, and put it out on the internet. Your traffic in tragically maladjusted lapidarians will expand tremendously, I guarantee.

Sadly, all I can offer in this department is this backscattered electron image of a rutile. To most people, it is simple igneous compositional zoning of Nb, Sn and W, which reflect electrons more efficiently than titanium and therefore appear bright. But to the dirty regolithic mind, this only needs legs, arms, and a head to become a swimsuit model. And no, I don’t need to leave the lab more often.

Figure 1. Detrital Phanerozoic rutile believed to be of pegmatitic origin See Birch et al. 2007 for geochronology and trace element characteristics.

Tuesday, June 30, 2009

Non-violent protest

As the 20th anniversary of the Chinese student crackdown comes and goes, my daughter has decided to celebrate by learning the methods of passive resistance and non-violent protest. The other day, Mrs. Lemming went out, and LLLL did not think that this was a fair or just activity by the leadership of the family. So, she staged a lie-in at the front door, complete with chanting and refusal to clear access to the front door. I suspect that the only reason she didn’t make a sign to wave is that she doesn’t know how to read or write. Her ability to render the message “My Mummy” in print will be limited until such a time as she learns the letter M. She does understand other visual statements, though. He shorts over jeans says only one thing: Until mummy comes back, I’m dressing even worse than dad.

Figure 1. LLLL organizing a lie-in behind the front door.