Lake Tahoe and the evil 1098-T

Today I've been thinking quite a bit about Lake Tahoe. Why? Well, because I did my taxes. Let me explain. This post will begin largely as a rant about 1098-T forms, and the absurdity they represent. 1098-T forms are what you get when an educational institution gives you fellowship or scholarship money. For most of my graduate career, somewhere around half of the money I made came in the form of one of these things. In the last few years, it was almost all of the cashola. Because the money was given in order to facilitate research, it was untaxable. Money I made as an hourly employee TA-ing, or RA-ing, or whatever-ing, was taxed, BWRU paid payroll taxes on that salary, taxes were deducted from my paycheck, and I'd receive a W-2 at the end of the year. Easy. It was even decided in a few tax court cases that if you were a student pursuing a degree, then money given in the form of fellowships and scholarships was intended to further your education, and therefore not taxable income. This all changed a few years ago (from what I can gather, although the exact timing is difficult for my non-accountant brain to figure out, perhaps if the DZA is reading he can contribute his mad skillz). Now it doesn't matter at all what the money was given for, it all depends now on how it is spent, and the list of what is a "qualified education expense", and therefore non-taxable, is exceedingly short. All of the money you are given, except that spent on tuition and items required for attendance counts as taxable income. Items required for attendance includes things like books required for a class and certain fees, but absolutely nothing else. If you use your fellowship to buy a laptop, or do field research, or attend a meeting, maybe buy lab supplies, thesis paper, safety glasses, sample bags, field books, a hand lens and brunton compass... none of that counts as "qualified educational expenses." Room and board? no way. So, if you received 27,000 in fellowship money, and out of that was paid 9,000 in tuition and you bought no required textbooks, you must, at the end of the year, pay taxes on the remaining 18,000. That's right, you owe something over a grand. I'll pause here if you need to change your newly soiled pants.

I am no anarchist, and truth is I have no problem paying taxes, but the logic of this defies me. The university pays me in a way that they do not have to pay payroll taxes; no social security, no medicare, no disability, nothing. But then I have to act like an employee and pay taxes on the money, even though I get none of the benefits of being an employee (my social security pay-ins, for example, stagnate when I am on fellowship). It also astounds me that if I use the money for research related expenses, I still have to pay taxes on it, because none of them count as "qualified tuition expenses." Even though I was getting paid this way I was still officially a TA and/or RA, so how does BWRU get away with it? And how hard would it be for them to send a form letter to every student on fellowship telling them that they should pay estimated taxes or else expect to owe a few grand come April? Of course if I was loaded and owned a house then I could deduct the expenses as business related, but seriously, own a house? Pay mortgage? Qualify for a loan? What burns me up even more is that the focus of what is a qualified tuition expense really has nothing to do with the bulk of most graduate careers. Even in class-intense fields, you are usually done taking classes, at least for credit, by the third year. So, after that, during all of your research, you can deduct jack squat.

So this got me thinking about Lake Tahoe, South Lake Tahoe specifically, poor man's Vegas, a place a geologist like me could make my fortune! But I hate Vegas, and casinos, so let me forget the ginormous check I have to write the government to help fund this, and focus on the nice part of Tahoe. The geology, the scenery, the skiing, the hiking, the fact that if I hid in the forest the IRS could never find me...

Lake Tahoe sits astride the California-Nevada border at the crest of the Sierra Nevada. It is a very large and deep lake (roughly 500m maximum depth, that's the 12th deepest freshwater lake in the world), and is considered by many to be the westernmost basin and range graben. The lake is deep because there are active normal faults cutting through the middle and sides of the lake, separating the Carson Range to the east (Basin and Range) from the Sierra Nevada. These faults downdrop the block that makes up the bottom of the lake, thus creating an enormous bowl that holds water, and is therefore a lake.

figure from Garner et al (2000), GSA Bulletin v. 112, n. 5, p. 736-746

The following pictures are from the summer of 2005, and were taken at the southern end of the lake in Emerald Bay. If any of you are realizing for the first time that you somehow have to come up with a few grand because of how you were paid, well, at least these pictures are free. Actually, considering I am on the hook for about a month's wages, if anyone wants to purchase the original photos for some absurd price....

Therapy for staring at ugly apatites all day

I spent time today helping a student pick out apatites for (U-Th)/He analysis. For those of you unfamiliar with this process, it is easily the biggest time sink in the whole method. After you chose a study area, collect samples, and separate out apatites, the really tedious part begins. For a variety of reasons, you have to be very selective when it comes to figuring out which grains to analyze. First and foremost, they must be inclusion-free. Apatites typically have 10's of ppm of U and Th in them, common phases that appear as inclusions (zircon and monazite) can have 1000's of ppm to weight percent U and/or Th, so even tiny inclusions can really screw up your analysis. This is an even bigger problem because the standard method for analyzing apatite involves dissolving them in nitric acid. Apatite dissolves easily in nitric acid, but of course zircon and monazite and absurdly tough to dissolve. So, they will contribute He to the analysis, but the inclusions won't dissolve, and we therefore won't measure the U and Th. Long story, I could go into more detail, but needless to say, your first priority in picking grains is to avoid visible inclusions.

Next, you'd like the crystals to have nice, recognizable crystal faces. Why, you ask? Well, during decay, the He nucleii are shot ~20 microns from the parent nucleus. So, if the parent atom is near the edge of the crystal, there is a good chance it could be ejected out of the crystal and for our purposes, lost. This is called alpha-ejection. We can apply a geometric correction for this, but it assumes a certain crystal form. (For more on alpha ejection see Ken Farley's 1996 paper in Geochimica [v.60 p.4223-4229] or Jeremy Hourigan's 2005 paper in Geochimica [v.69 pp.3349-3365].)

Then, we want them big. The larger the crystal, the smaller the alpha-ejection correction.

This is simplified, but you get the idea. Sometimes you can spend all day on a single sample, trying to find grains that are worth analyzing. Today I spent time looking at very ugly grains, so to boost my morale I am posting some of the pictures I have taken of my favorite apatite crystals. I have picked plenty of ugly separates in my so far short career, but I need a boost, something to re-energize thermochronic.

Also, I signed up for a google alert for the word "apatite" a few weeks ago. The two types of listings I receive from these alerts are:

1. Misspellings of the word appetite (yes, you should still proof-read even if you have spell check), about 6 per day.
   
2. Discount jewelry and/or crystal healing pages (you think if apatite created harmony all of the world's fission track and (U-Th)/He people would be entirely serene), about 3 per day.
   

So, with this post, I should have a listing for beautiful pictures of apatites separated from granitic rocks, some from China, some from Utah. I will also admit up front that I realize I have committed geology sin #1, and not included a scale bar. Take my word for it, they are all 60-150 microns in width.





Those are nice, here is one that has nice form and is huge, but has obvious inclusions


And finally, what do we do with them once we pick them? We pack them! We don't want to heat them directly with a laser, because that can volatilize Th. So, we put them in individual little platinum packets, and heat those. The pictures below show this process, starting with a crystal and Pt tube, and ending with a Pt "microfurnace." Getting pictures taken while holding the tweezers steady enough and in the right place to see everything is one of the greatest accomplishments of my career, hence the need to shamelessly share these all over the web.



Boom, throw it in the laser, dissolve, toss it in the ICP-MS, a little spreadsheet magic and you've got a paper.

Thermochronic's Favorite Online Journal

In college we used to be able to get paper copies of The Onion regularly, anyone traveling up to Madison for some culture on the weekend would always bring one back. When The Onion went online it spawned a rash of internet based time wasting unmatched in modern times. Sometimes their articles, although intended to be funny, are sadly on the mark (look at the publication date of that article). Many times, their science related articles are hilarious, here are some of my favorites, in no particular order:

• Evangelical Scientists Refute Gravity With New 'Intelligent Falling' Theory
• Rogue Scientist Has Own Scientific Method
• Bacon Good For You, Reports Best Scientist Ever
• Caltech Physicists Successfully Split The Bill
• Evolution in our Schools - What Do You Think?
• National Science Foundation: Science Hard
• Late-Working NASA Scientists Discover Moons Over My Hammy
• Creationist Museum Acquires 5,000 Year-Old T.Rex Skeleton
• Study Finds Jack S**t
• Revolutionary New Insoles Combine Five Forms of Pseudoscience
  

This last one isn't from the Onion, but it cracks me up nonetheless. I had it on my office wall in grad school, the caption to Figure 1 is perhaps the greatest part.

• Electron Band Structure in Germanium, My Ass

Enjoy.

Letter to the Editor

Yesterday I wrote and submitted a letter to the editor of the student paper here at ESRU in response to another letter written by an undergraduate discussing intelligent design. My thoughts on the matter are best summer up in this post, but I thought I'd post the original version of my letter nonetheless. I had to shorten the final submission to 250 words, yes, 250 words out of a 12 page paper. I will have less room than a Dominoes ad, but that's the rule! Doesn't matter how many letters are submitted. Anyways, here is the original version, with names omitted to protect the innocent.

In his recent letter to the editor entitled “Consider Creationism without bias,” Mr. Snuffleupagus confuses intelligent design, creationism, evolution, and a belief in God. Believing in God and evolution are not mutually exclusive, just as supporting the teaching of intelligent design is not a pre-requisite for people of faith. The reason intelligent design should not be taught in a scientific setting is because of how drastically it changes the definition of science. For hundreds of years, the scientific method has been applied in roughly the same way, creating testable hypothesis, conducting experiments, and refining those hypotheses. Inherent in this is the assumption that there are natural laws that govern the world. What intelligent design does is enter supernatural forces into the mix, something that by definition does not follow natural laws and is therefore untestable. It is one thing to push for supernatural explanations in branches of science most people consider esoteric, but the true test for intelligent design is whether or not you would accept supernatural explanations in all branches of science. Would you accept them from your doctor? Would you accept them from the building engineers or FDA food inspectors? How about physicists who handle nuclear waste, or forensic scientists providing evidence in a murder trial? Of course not, if you went to a doctor deathly ill and they came back with a supernatural diagnosis, you’d find another doctor, one who would run tests and perform experiments until they determined what was wrong using the scientific method. If the engineer’s assessment of the structural stability of your new office building was based on supernatural forces, you’d find another engineer. If you will not accept supernatural explanations in branches of science that directly affect your life, then you cannot accept supernatural explanations in any branch of science.

Please do not confuse evolution with atheism, or intelligent design with science. Evolution, like gravity or plate tectonics or electromagnetism, is a scientific theory; one that has been tested and refined thousands of times and is still the topic of very intense study. Intelligent design is not science, because it profoundly changes the meaning of science and of the scientific method in a way that is potentially very harmful. Belief in science does not preclude belief in a higher power.

Thermochronic
Postdoctoral Research Associate
Department of Earth Sciences

The Great Science Book Challenge #3

As some of you know from this earlier post, I am soliciting suggestions for good science books for a challenge I am taking on. I am also looking for other volunteers, but most important right now, with the March 1st deadline approaching, I need more suggestions for general audience science books. Thanks to those who have sent them along, and see the list so far in my sidebar. Cheers.

More than 3000 words!

In place of a well written and intensively researched post I am instead going to put up three random pictures. I've been experimenting with scanning slides recently, and these are three of my latest. They are



Point Reyes National Seashore. Anyone in Northern California is probably familiar with this place. It is also the northernmost outcrop of "Sierran" granites west of the San Andreas Fault, and the hypocenter for the 1906 San Francisco Earthquake. ...Or Something used this area as one of his first Where on (Google) Earth?



A view from the Marin Headlands (actually right across from one of the amazing folded chert outcrops) looking back south into San Francisco.




And finally, the Alabama Hills, a small range in the Owens Valley famous for it's spheroidally weathering granite hills and as a location for shooting movies, including Gunga Din, How the West Was Won, and one scene in Gladiator. That's the Sierra Nevada in the background.

Tc of Thermochronic, or, the temperature dependence of thermochronic's activity level

This weekend, for the first time in a long time, we had sunshine and temperatures above 20°F. This week we are going to get above freezing, well above freezing according to the local weather guy. I have now lived through the human equivalent of a diffusion experiment, and can report with some accuracy about the temperature dependence of activity and movement across phase boundaries. Temperature dependent diffusion is of course something I spend a lot of time thinking about, so here we go.

At moderate temperatures, I diffuse easily into the outer world, going for walks, running errands, bopping around outside with my camera. As the temperature approaches 20°F, it becomes increasingly more difficult to get me to diffuse out of my house. Once we get below about 5°F, willing diffusion (as opposed to going for the mail or shovelling snow) is essentially done with. Once you are over about 40°F, my outdoor activity levels have reached their maximum; this lets me define the ThPAZ (Thermochronic Partial Activity Zone) as the range of temperatures from 5° to 40°F, of course analagous to the HePRZ (Helium Partial Retention Zone) and FTPAZ (Fission-Track Partial Annealing Zone), just at much lower temperatures.
Of course the biggest difference between this diagram and similar ones you may be used to seeing for the HePRZ is the odd behavior at high temperatures, where activity again begins to decline. This high temperature inversion is highly dependant upon the partial pressure of water vapor in the system. At high humidities, the inflection point is at much lower temperatures, 80°F and I am done; at lower humidities the decrease does not begin until well over 100°F.

***I apologize for using Fahrenheit, but for discussing weather it is the only way my brain works. I have no feel for outside or room temperatures in Celsius. On the flipside, I can only think of science in metric terms. I have no idea what the range of granite melting temperatures in °F would be, or the average temperature at the base of the lithosphere. I'd have to do the conversions if I cared either way. We really need to standardize our units of measure.

Merit Badges and MacGyver

I know the MacGyver topic is getting a tab old now, but I was fumbling through the science-o-blogosphere (not as smooth off the tongue as geoblogosphere) and I found this "organization." They call themselves the Order of the Science Scouts of Exemplary Repute and Above Average Physique, and they have a variety of science merit badges they describe, one of which, shown here



is the MacGyver badge! This is the first time I have seen this page, but so far I really like the merit badge idea. Some of the others I like are

The "inappropriate nocturnal use of lab equipment in the name of alternative science experimentation / communication" badge.

and

The "my degree inadvertantly makes me competent in fixing household appliances" badge.

One I would like to see is a "successfully salvaged lab equipment from a dumpster" badge, just remembering some of my proudest moments.

Can't we all just propagate our errors?

This weekend I continued to work on a lab software upgrade for one of the labs I work in. This is all part of an effort on my part to streamline sample analysis, automate as much as possible, and make the data reduction smoother and more versatile. For those of you who care, I am doing everything with LabView, my programming platform of choice. My first step in the process is to go through the existing sets of code, figure out what does what, and decide if I want to copy the process or change things around.

This got me thinking, again, about error propagation. Most of the significant errors in the existing code are dealt with appropriately, but there are some very easy ones that are just ignored. Truth is, most calculations are fairly easy to propagate errors through, and I am a firm believer that uncertainty must be dealt with honestly, even if in the end it is insignificant. The most popular geochronologic data reduction tool (I am guessing) is Ken Ludwig's Isoplot. This does an excellent job with uncertainties, assuming of course the users report them all. But, Isoplot doesn't interface with the machines, and it can only work with the data it is given.

For this reason I think that the book An Introduction to Error Analysis by John R. Taylor (a physicist from the University of Colorado) should be required for anyone who works in a lab or with the data from a lab. All of the basic methods to propagate uncertainties are covered and explained very well. This doesn't discuss some of the more complicated methods common in geochronology (e.g. the MSWD), but for a starter and reference text it is well worth it. It also isn't directed towards the earth sciences, but again, the basics are the basics. For example, to calculate the size and correct for the depletion of a spike or standard shot of gas, you need to know the reservoir tank and pipette volumes, and the pressure of the gas in the tank (partial pressure if your gas isn't pure). Associating uncertainties with each of these measurements is fairly straightforward, so any number that comes out of these values, say size of spike, or a correction for ionization efficiency, should include those propagated uncertainties. Numbers without uncertainties really don't exist in geology, but they show up in data reduction all the time.

Dealing with errors in a realistic and representative way is the first step. Getting people to report them, even when they are crappy, is the second.

MacGyver Guest-Star Tangent, Masters of the Universe

So I've received many emails and comments asking me to post something about all of the important actors who guest starred on MacGyver, Patron Saint of Thermochronologists (I've proposed this as the new title for the show, I've yet to hear back from the studio). I plan on such a post, but I stumbled across something early in my research that I had to bring to your attention.

I was on IMDB.com linking through some of the people on the guest star list when I clicked on the link for Kristian Alfonso, who appeared in two episodes of MacGyver, Patron Saint of Thermochronologists. Under the list of movies she was appearing in, was

He-Man and the Masters of the Universe

! What is even better is that she isn't the voice for a character on a cartoon, no, this is going to be a live action thriller, with one of the writing credits going to M. Night Shyamalan!? Both Skeletor and Man-At-Arms are being played by guys from professional wrestling? This is nowhere near as exciting as when I first saw the preview for the also upcoming Transformers movie, but still. Actually, let's be honest, the movie will probably blow. He-Man is, however, a good nickname for a dude who works with helium, so even though I never cared much for the cartoon, it still grabs my attention.

This also got me thinking about the degree I had wished I had earned, that being a Masters of the Universe. I thought about this at a time when my alma mater was introducing yet another advanced degree title, something like Ph.D. in Earth Science or something. The argument being that for some people, advanced degrees in geological and environmental sciences, or geophysics, or whatever weren't specific enough, they needed something that fit their particular research more snugly. They worry that a potential employer would be wowed by their publications and letters of reference, but potentially cast them aside because their Ph.D. was in too general of a field. This is an argument I find completely ridiculous. I have a degree in geological and environmental sciences, I'd prefer it to just be geology (my research and skillz are focused in geology) but I never for once thought that anyone really cares that much. Wouldn't my CV be more important than my official title? This trend is common in undergraduate degrees, at least in the sciences, where your major can be in earth systems geosphere tract instead of geology, 3 or 4 variations on chemistry or biology, etc. It seems kind of absurd.

Anyway, I then decided that instead of making degrees more specific, we need the broadest one possible, namely, the Masters of the Universe (MsUn). Think about it, any potential employer would immediately associate the holder of such a degree with s superhero, one that is confident enough in himself to wear leather underwear. In addition, He-Man allegedly got his power from the mineral Korodite, which makes the inclusion of this degree in an earth science framework even more plausible.

According to Wikipedia, Captain Ivan Drago, err, I mean Dolph Lundgren played He-Man in a 1987 film adaptation, which I haven't seen. But I have high hopes, not for this movie, but for the surge of energy it will give the movement to create a Masters of the Universe program somewhere in the world.

Angus MacGyver, Patron Saint of Noble Gas Labs

I'd like to nominate MacGyver as the patron saint of noble gas thermochronology labs. I had originally thought that perhaps he could represent all labs, and perhaps I need to expand my definition, but I have my reasons. Let me explain. For those of you who don't know, MacGyver was one of the greatest television action heroes/good guys of all time. Like most TV heroes, he almost never failed, but what made him unique were three important characteristics.

1. He hated guns. Except in one early episode, he never touched them. This leads directly to point number 2, but also explains why my mom let me watch the show. I like this, noble gas thermochronologists are a peace loving bunch.
2. "Mac" was resourceful, and often called upon his vast background in "science" and "engineering," crafting weapons, picking locks, breaking through security systems, opening doors, and in general saving the world using his Swiss Army Knife, duct tape, and whatever pieces of junk happened to be lying around. I'll get to this later. Oh, and for the record, I don't care if most of what he did was BS, it was still sweet. And, allegedly the producers made things slightly impossible so stupid kids in places like Sacramento didn't try to replicate his bombs and booby traps, just an idea.
3. He was supposed to be Canadian. Seriously, how many other Canadian action heroes were huge on American TV? Richard Dean Anderson, the actor who played MacGyver, is a Minnesotan who only took to acting when his hockey career was put on hold, which in my opinion is the best training an American can have for playing a Canadian.

MacGyver is the patron saint of noble gas labs because of his resourcefullness. On TV, MacGyver destroys a laser using smashed up binoculars and cigarettes, plugs a leaking vat of acid with a chocolate bar, and made a bomb out of cold medicine. In the time of need, he has no budget, and has to work with what is around. Doesn't that sound familiar! How can I fix this with the half broken old lab equipment that is lying around ? I summon my inner MacGyver all the time, clamping together 3 different size KF flanges so I don't have to order the proper reduction fitting, using the brackets I had made for the pneumatic valves for every structural support need except the pneumatic valves, the old UHV gauge controller with the "warning, may produce lethal shock" sticker that I "rescued" and used for 2 years. The list goes on. Not as impressive as the real MacGyvers, but hey..

In addition, MacGyver just looks like a geochronologist.


Check it out, here he is checking on his LMT heavy fraction. Ooooooh, lots of heavies, yes!


And here he is at the power source for the magnetic sector mass spectrometer. Hmmm, I think the problem is with the z-deflector, maybe the accelerating voltage is low...



This is when he was trying to figure out which integrated circuit blew during the power outage, man this takes forever. Thank god I have my leather bomber jacket


OK, I think the tube is ready for the reactor. And, let me add, that is obviously a paleontologist in the background, they probably want MacGyver to tell them how old some ash beds are, that's all they ever want from us.



Check out my LMT lights, I can totally get enough kspar out of this for an Ar MDD analaysis. But first, let me have a drink from my NHL water bottle, go Sabres!


And he even does field work. On the Colorado Plateau! Must be a detrital zircon thing. Let me guess, there's a Grenvillian Peak. By the way, polar fleece long before it was popular. Mac was a trendsetter.

So in conclusion I am trying to think of all of the random things that were commonplace in my lab. Aluminum foil, of course, rolls and rolls of Reynolds Wrap, Q-tips, unwaxed dental floss for the cryogenic cold trap, binder clips, balloons, cinder blocks, toothpicks, the little radioactive source from a film duster....Nothing compared to the great one, but a start. I'm interested what other non-traditional lab supplies are in use out there.

And, by the way, his first name was Angus, at least according to the infallible oracle of all knowledge. It only came out in the last episode, the same one where he found out he had a long lost son.

Helicopters, Fishing Boats, Mountain Goats, and lots of Horse Flies

The other day I saw a talk given by a friend of mine whom I met during my first real geologic field experience. When I was an undergrad student at a tiny liberal arts college in the American Midwest, my advisor was a co-PI on a project looking into the development of the Canadian Coast Ranges. I was mainly a field assistant and hauler of rocks, but I did manage to get a (now embarassingly poor but at the time pretty sweet) senior thesis out of it. More important, I got to spend two field seasons in northern British Columbia and meet all kinds of geologists who helped me form my idea of what my science career would look like. A geologic post about the area might come some time, but for now I am simply posting some of the field photos I recently scanned (from back in my Kodachrome days). All of these pictures are from near the Skeena River, just east of Prince Rupert, B.C. I mainly worked on the Quottoon Pluton, mapping fabrics and contacts, with some P-T-ometry and thin section work back in the lab. Working in BC is pretty incredible. The geology is spectacular. The only real downsides are that it rains almost all the time, and that there are more black flies, mosquitos, and horse flies per square meter than anywhere I have ever been. My field books from those seasons are covered with their guts. Anyways

This is one of our camps, you can see our tents in the saddle. All of the work was helicopter based, we'd put in for a week or two at a time. Pretty amazing for sure. I must admit my mode of field transport has been all down hill since then.

I have no idea what the name of this lake is.

These two might explain why I ended up buying and reading and recommending A Beast the Color of Winter (see sidebar). We did most of our hiking on goat trails, and would see them all over the place. They are really amazing animals. I'll never claim to be a mountaineer, but these things, even the babies, make us all look like cows. I am pretty sure that acrophobia has been selected against in mountain goats.

How Old is this Rock?

I had originally meant to take on the Just Science week Challenge, where I'd write a new entry every day about science and science only, no Bears, no music of the week, no asinine and unproductive bill brought up by some pandering politician. But, I flaked. Brian of ..Or Something fame kicked this challenge's ass. But, I decided that instead of daily posts, why not one ginormous one, guaranteed not to be read by even my most dedicated friend? So here you go, the science of Geochronology. I intend to come back to different aspect of this topic in the future, just as I have discussed it in the recent past.

Geochronology is an umbrella term for all of the techniques we use to determine the absolute ages of rocks and/or individual minerals. All modern geochronology is based on measuring the stable daughter atoms produced during the radioactive decay of naturally occurring elements, most notably uranium (U), thorium (Th), potassium (K), rubidium (Rb), and lutecium (Lu). It is now common and fairly simple to measure the absolute abundances of these elements in rocks, or in many cases individual crystals, with a high degree of precision. As a geochronologist, the real work comes with figuring out what those ages mean.

The title of this post is a question I've been asked many times, and in truth is impossible to answer. Rocks have very complex lives and change continually on a variety of timescales. Each radioactive parent and stable daughter nuclide has specific characteristics that determine their inclusion and retention in geologic materials. When you date a rock you are really dating some event or process that the rock experienced. Some systems can be interpreted to record the age of formation of a rock. Others record the time when a rock cooled to a certain temperature. I've seen geochronologic data misused by lots of different kind of people. There is of course the young-earth crowd, but I really don't want to waste time on them (in this post). What is more disconcerning from my standpoint is how often I have seen data misused by trained geologists. In the past year I've seen talks where sanidine K-Ar ages from the 1970's were compared with U-Pb ages from the 1950's; I could tell that the speakers grasp on the philosophy and method of geochronology was simply nonexistent. I am more lenient when non-geologists misunderstand radiometric dating techniques, but when the data is something that you depend on, well....What it really comes down to is:

1. What are the chemical and physical properties of the parent and daughter nuclides?
2. When did the mineral that contains the parent and daughter nuclides form? Is it igneous, metamorphic, has it been deformed or recrystallized?

Calculating an age is pretty straightforward, all you need to know if

1. the number of parent atoms
2. the number of daughter atoms
3. the decay rate of the radioactive parent

When I've taught radioactive decay to classes in the past, I've found that one of the biggest mental stumbling blocks that students have to overcome is how a process which is completely random on the scale of an individual atom (whether or not it will disintegrate) can, on a larger scale, be completely predictable. It is of course all a probability thing, each radioactive atom has a specific probability that it will decay (the decay constant). Below is a graph of observed decay rates from a "radioactive parent nuclide," compared to a expected line.

Actually, these particles aren't radioactive, they are chocolate. These are the results of the great M&M experiment from a class I taught in 2004. M&M's, it turns out, are fantastic for illustrating this principle (pennies would work just as well, but for some reason the classes are never as enthusiastic about those.) M&M's have an "M" printed on only one side of the candy. So, you put 100 of these in a paper cup, dump them out onto your desk, and count the number of pieces that landed with the "M" side up. These are considered to have decayed, so you remove them, place the undecayed candies back in the cup, and repeat until all of the M&M's are gone. I even had them calculate an M&M "half life", the result of which you can see in the corner of the graph (± 1 sigma). I'd have groups of students do this with 100 pieces 5 times each. Then we'd compile the data as a class. Most people are comfortable with the idea that you have a 50/50 chance of an M&M landing heads up, but if a particular piece decays is random. This is directly analogous to the decay constant for a radioactive element. Each atom has a specific chance of decaying. The only real difference is that decay constants are in terms of some time value (per year, second, etc..), while the M&M decay constant is in terms of "rounds." These results are always impressive to me, that we can get such good results from ~4000 "atoms," especially when the average zircon used for U-Pb geochronology contains hundreds of trillions of U atoms, boo-yah, counting statistics.

U-Pb geochronology is unique among geochronometers in that it is actually two separate decay systems in one. There are two relatively abundant naturally occurring isotopes of uranium, ²³⁵U (which decays to ²⁰⁷Pb) and ²³⁸U (which decays to ²⁰⁶Pb). ²³⁸U is by far the most common (now), but every crystal or rock or anything that has ²³⁸U also has ²³⁵U. The ²³⁸U/²³⁵U ratio is actually exceedingly well known; it probably ranks up there among the best known numbers in physical science (thanks to the nuclear weapons industry). Why is this number so constant? Well, because different isotopes of U have the exact same chemical behavior, so they are never fractionated. But, fractionation is a topic for another post. What is important though, from a geochronological standpoint, is that every time you measure a U-Pb age, you are actually making two completely independent and separate geochronologic age measurements, one for the ²³⁸U-²⁰⁶Pb system, and another for ²⁰⁷U-²³⁵Pb. ²³⁸U has a longer half-life, and therefore decays more slowly.



This figure shows the evolution of different U and Pb isotopes in a closed system over time. Basically, start out with 1000 atoms of ²³⁸U and ²³⁵U, and let them evolve for 4.5 Ga. In truth, of course, the materials we use have trillions of times more U, and ²³⁸U and ²³⁵U are never equally abundant, so I've normalized the graph. But, you see the point. The solid lines are U, with red being ²³⁵U and blue ²³⁸U. The dashed lines are Pb, with red ²⁰⁷Pb and blue ²⁰⁶Pb. Either one of these can be used to calculate an age. But, the real power of the technique comes when we use both. Because the decay schemes are independant, the ratios evolve separately. But, if ur measurements of the decay rates are correct (which they are), then the ages from the two systems should agree. The collection of agreeable isotopic ratios is referred to as concordia.
The red dots represent specific time values, and the blue line is called concordia. U-Pb age determinations which fall on this line are called "concordant." There are a variety of processes which can cause ages to fall off of concordia (Pb-loss, multiple crystallization events, etc..), which actually lends more power to the technique. So, every time someone calculates U-Pb ages, they are actually also double-checking the decay constants of the isotopes. If these changed over time, as a few non-scientists claim, then concordia could never work. We actually use the above diagram, called a Wetherill plot, and a similar plot


called a Tera-Wasserburg diagram, to evaluate U-Pb data. These two methods have their different strengths, which I won't go into here (right now at least.)

U-Pb geochronology has a lot of other advantages. The primary crystal we analyze, zircon, does not like to incorporate Pb into it's crystal structure, which means that almost all of the Pb we measure is the product of radioactive decay (U likes to substitute for the Zr in the zircon structure.) Zircon is also great, because it is very common in rocks, and, as people like the famous ..Or Something wrote about, is tough enough to survive significant erosion and transportation and therefore pops up in sedimentary rocks all the time, giving a great deal of insight into sources and transport of sediment.

It also turns out that Pb does not diffuse out of zircon very quickly. In many cases, even if the system has experience really high temepratures, high enough to melt many common rock forming minerals (quartz, felspar..), the zircon will survive and retain it's U and Pb. If you have carefully evaluated the textural relationship of the zircon to the rock, you can often say that the zircon U-Pb age marks the time of crystallization of that crystal, and perhaps that rock.

K-Ar dating, or the more powerful Ar/Ar variant, works essentially the same way. Minerals like to take up potassium, and one isotope of potassium is radioactive. Minerals don't generally take up any argon, at least none in the crystal structure. So we measure the amount of K and the amount of Ar and we can calculate an age. The reason Ar/Ar is different is that we can use a proxy for measuring the K content, this makes the measurement process and the information we can recover from a crystal much more powerful. I will post about Ar/Ar geochronology later, I don't want to go into the details. I think one of the most amazing and interesting proofs of the K-Ar system was published in a 1997 paper by Paul Renne et al.,

P. R. Renne, W. D. Sharp, A. L. Deino, G. Orsi, L. Civetta (1997) ⁴⁰Ar/³⁹Ar Dating into the Historical Realm: Calibration Against Pliny the Younger, Science, v. 277, p. 1279-1280.

In this study they dated ash from the 79 A.D. eruption of Mt. Vesuvius. This is one of the hardest kinds of analysis to do, on a geologic time scale barely any time has passed for Ar to accumulate. But, as shown below, they actually nail the date reported by Pliny the Younger (a recording witness) well within error.

Pliny the Younger would have predicted 1918 years, they got 1925 ± 94.

The chemical and physical behavior of Ar makes the K-Ar system very powerful. Unlike Pb, Ar is a light gas, and when a rock is hot, Ar can diffuse out of the system almost instantaneously. We know a lot of Ar exits rocks into the atmosphere, about 1% of what we breathe is argon. Anyways, K-Ar, or Ar/Ar dates don't really tell you when a rock or crystal formed, but more when it cooled to a certain temperature. This is analogous to the (U-Th)/He system I blogged about here. Different minerals retain Ar differently. So, in the same rock, Ar/Ar ages from 2 or 3 different minerals can help chart the cooling history of the sample. Radiometric techniques that are primarily dependent on temperature are called thermochronometers. The elite earth scientists who use thermochronometers are thermochronologists. Think of thermochronologists as the navy seal or olympic athlete of the geology world.

So how old is this rock? Well, it depends. Do you want to know when that crystal formed? When the rock cooled near the surface? When the crystals that make up that sandstone formed? When the sandstone was deposited? All ages are not the same, but interesting things can happen when you hit the geochronic.

Earthquakes, Radon, Satellites, and Humidity

I have a habit of downloading and reading random earth science articles with catchy titles. Sometimes I stumble on ideas that are allegedly prevalent in some branch of earth science, but about which I knew nothing. I recently had this experience when looking through the latest issue of Tectonophysics. The article I am talking about is by S.A. Pulinets and M.A. Dunajecka from Ciudad Universitaria in Mexico. As a disclaimed I will state now that I am neither an earthquake expert or an atmospheric chemist, so I would be interested in hearing the opinions of specialists in either of those fields. I'd hate to inadvertently promote pseudoscience. The full reference is

Pulinets, S.A. and Dunajecka, M.A. (2007) Specific variations of air temperature and relative humidity around the time of [the] Michoacan earthquake M8.1 Sept. 19, 1985 as a possible indicator of interaction between tectonic plates, Tectonophysics, v. 431, p. 221-230.

It has been known for a while that radon levels in the atmosphere can correspond to tectonic activity. Direct measurements of radon levels have shown large fluctuations immediately preceding earthquakes. What this paper presents is the idea that instead of a direct measurement of radon levels, remotely sense temperature and humidity measurements can be used as a proxy for the same phenomena. When Radon in the air decays, it ionizes other nearby molecules or atoms. These newly formed ions are then hydrated by atmospheric water, with the result that air humidity drops. The latent heat of evaporation is released from the water during the phase transformation, which results in a temperature increase. So, big pulses of Radon into the atmosphere, as are associated with tectonic activity and seem to occur leading up to earthquakes, results in an initial decrease in humidity and increase in temperature. The radon flux reaches a maximum and starts to decrease just prior to the "seismic shock", during which time there is a corresponding rise in humidity and drop in temperature.

Truth is I do not feel like that good of a filter for climate data, because from my perspective, the data presented in this paper do not seem as tell-tale as the authors imply. There are many swings in temperature and humidity that are not associated with earthquakes. But, I am still intrigued. I have heard the term "earthquake weather" before, which usually makes me chuckle.. But the temperature and humidity swings presented in this paper would definitely be noticeable. Anyways, I'd love input from anyone who knows more about this, I learned long ago not to trust everything that is published (as a matter of fact, I am counting on that for this paper I am working on, perhaps these authors have been asked one time too many when that paper is going to be done, and they just wanted it out the door). They reference many similar studies, which is reason enough to visit the library.

The Great Science Book Challenge #2

Thanks to those of you who have suggested books, please keep them coming! I now have, and will regularly update, a list of the recommended books on my sidebar, right under the "Latest from the Geoblogosphere." Warning: Actual science post in the making.

The Great Science Book Challenge

So I've recently become inspired by Mrs. Apaprent-dip-but-with-a-different-last name. She has also started blogging, she is a humanities person (humanitite? that sounds like a mineral, I like it), and has become involved with various online challenges, basically reading X number of books from category Y in time amount Z. Considering my recent posts putting forth my belief that geology needs good public outreach folks, she suggested I start a similar sort of challenge. The idea is that I will come up with 5 science books written for non-scientists that I will read and blog about in the space of a year. 5 books in a year, I know, big challenge, it may go more quickly, but I didn't want to make it impossible, and I want as many people to join me as can. 5 books in a year, that's a little under 1 book every two months, which means I can do this at my normal "non work related reading" clip, just that the selections will be more focused. This seems reasonable (even considering my recent pushes to finish up papers and prepare for a field season). What I would like advice on though are books to read. The ground rules:

1. It must not be a text-book or overly technical treatment, it should be something intended for a more general audience, something you could find in a well stocked bookstore.
   
2. At the same time, it can't be lame. I know that word can mean lots of things, but I want works that are "dense," not picture books or coffee table books.
   
3. I'd prefer at least 2 of the 5 to be geology or earth science related, the other 3 could be any other branch of science.
4. I'd like most of them to be relatively recent books, in other words, I don't want this to be a tour of the classic science texts of yesteryear.
5. No biographies. As much as I like those, I want the main purpose of the book to be explaining or exposing some aspect of science.
6. No wilderness manifestos. I love reading Ed Abbey, but it isn't what I am looking for right now.
   

So I have an idea of some books that fit this bill. I have already read them, but they may give you a good idea of what I mean.

1. The Making of the Atomic Bomb by Richard Rhodes. This is one of the best books, let along science books, I have ever read. It is fat and intimidating, but impossible to put down.
2. The Age of the Earth by Brent Dalrymple. This book grew out of material he had prepared for a court case, and therefore aimed at people with no background. Still, as a geochronologist, I found it complete and fascinating.
3. A Beast the Color of Winter by Douglas Chadwick. This is a natural history of mountain goats. In college I was lucky enough to work on a field project in northern British Columbia. We spent a lot of time in remote camps, high in the coast ranges. I was, and still am amazed by Mountain Goats, and how stupid and timid they made me look trekking around in the mountains. This book was a surprising read for me, I originally bought it hoping for good goat pictures, but the way he describes the goats is just amazing. This book also begins with one of my favorite quotes :

"It is only a statement of physical fact to say: Mountains are as close as the surface of our planet reaches towards the heavens. The purest air, the purest water, and the purest light on earth are found among these great uplifted forms."

Excellent, let's see what kind of a list we can generate, pass this along to anyone you can think of, at the very least, even if no one else wants to join the challenge, it would be great for me to compile a list of books that we professional scientists consider to be among the best.

So here is where you come in. First, I solicit volunteers to join me, with a start date of March 1. Second, I need suggestions for books, I don't care what discipline, just let me know what you consider to be the best science writing around.

Watch as thermochronic speeds through the 5 stages of grief after a horrible performance by the Bears in the superbowl.

1. I can't believe the Bears just lost the superbowl, there must be some mistake, this isn't happening! Someone must have paid the refs! The Colts are on steroids! Were those french figure skating refs? Maybe the real game is next week, yeah, this can't be real, must be a dream, I'll wake up soon.

2. What the bleep! The bleeping defense couldn't stop anything, damn them, damn them to hell! And come on, make a fricking tackle! Catch the fricking ball! What, another fumble! Bleeping overpaid donkeys! My rabbit could block better than that! That's it, I am done with these jackasses, done, D-U-N done, I give up on these losers, overpaid crybaby can't tackle losers!

3. OK, come on, I'll trade you, you can let the Cubs not make the playoffs for the next 100 years, let Cal win the big game, let Duke win the NCAA tourney, I don't care, come on, we can make a deal! Here, take my helium lab, I don't care, I'll make you first author on this paper I am writing, you can have my office, let's just go back and end the game 30 seconds into the first quarter. No one will know! We can do this, just a little favor for a friend!

4. I can't believe this, I'll never be able to recover. I think I'll call in sick tomorrow, drink my sorrows away. It is dark outside, like in my soul. Will the sun ever shine again? Not on me it won't. Darkness, sadness, Mazzy Star and Hank Williams, Stan Rogers' First Christmas, that movie "Leaving Las Vegas", Ben Harpers first album..Sniff sniff, how could this happen, and why does this always happen to me !?!? (now picture me with my fists raised up towards the sky cursing the world, then breaking down into a fetal position and crying, just like Jimmy Bakker, in the rain, alone, with people laughing at me, very very sad).

5. It's OK, it's just a game where millionaires run into each other for 60 minutes, and Prince wasn't that bad, and that "Mapasaurus" commercial, that was kind of funny, and hell, it beats picking apatites all day. I can get through this. Next year, Grossman will be better, Urlacher will be back, our defensive line will be healthy.... I'll be OK. March Madness is almost here, things will be OK. It's just a stupid game, right?

Mississippi House Bill 625 Dies!

Woo-hoo! The Mississippi House bill (#625) I blogged about here officially died in committee on January 31st. This bill would have required Incompetent Design to be taught in public schools along with evolution. This bill said nothing of the flying spaghetti monster, probably an oversight by the bill's author, Mike Lott.

Anybody need $10,000?

I am by no means an expert when it comes to climate change, so I will leave the more technical posts for my fellow geoblogofolks (see the sidebar). What I would like to point out is something Mrs. Apparent-Dip-but-with-a-different-last-name (mad props) told me about and was reported on CNN Money. Turns out that in response to the IPCC report, ExxonMobil has offered some climate scientists $10,000 for critiques of the conclusions (which, for the bajillionth time in the past decade state very clearly that humans are causing climate change). Now of course oil industry funding in the earth sciences is nothing new, after all, geologists do plenty of oil finding. What I think is unique in this case, and disturbing, is the predetermination of the outcome. I know plenty of people doing industry funded studies, I am sure it is common in other branches of science as well, but when is that conditional on the outcome. Sounds very wild west to me, "Look, there's a bounty on that thar climate report! Wanted, dead or alive!" But, on the plus side, if funding is tight, perhaps I can convince them that apatite (U-Th)/He thermochronology proves the earth is cooling, out of control cooling, my latest data says we are heading to runaway global cooling, straight into snowball earth! OK, it doesn't, but 10 grand could set me up at a sweet hotel for GSA. This is disappointing news considering recent good signs from the same company.

San Francisco, the city that waits to die!

This post is intended to honor one of the great geology films of all time. Really a classic. It is amazing how many people I know who at some time in their career have seen this film, but yet how little information exists about it. I actually think that Apparent Dip will become the most informative site relating to this film, at least that I can find. The movie is a BBC documentary from 1971 called "San Francisco, the city that waits to die." I first saw this in college, it was brought out during the last lab of my intro course. I remember the impression I got at the time was kind of patronizing, "oh look how silly those old geologists were, how much smarter we are now." Truth is, over the last 10 years or so I have watched this film dozens of times, and every time I do I get a greater appreciation for it.




The only part of the movie that I still think is a little absurd is the tone with which it is narrated (by Paul Vaughan). Basically, Americans are idiots, look how stupid they are, man, no one else in the world is as stupid as those bloody Americans. Although the tone is kind of annoying, what gets me about this film is that I can imagine, 30 years from now, watching something similar but this time dealing with global warming. Scientist after scientist is trotted out and basically says "we know it is dangerous, we know we put buildings where we shouldn't, we know many of the buildings aren't safe, but there isn't much we can do about it." Politics and real estate dollars rule. Some notables that make appearances include

Louis C. Pakiser, the first director of the U.S.G.S. earthquake center at Menlo Park and 1996 recipient of the Geological Society of America Distinguished Service Award


CalTech Geophysicist Clarence Allen



Geothechnical engineer, Cal Professor, and alleged outstanding soccer player Harry Seed. Here he is demonatrating liquefaction. If you look closely, you can see a small yellow house perched on a column of wet sand, that is then shook until the house sinks. Incidentaly, this house is roughly the same size as my last apartment in California.


CalTech Professor Emeritus George Housner, one of the original earthquake engineers (distinct from the O.G.'s)


David Evans, one of, if not the first person to demonstrate the relationship between pore fluid pressure and induced seismicity (see Evans, D.M. (1969), Fluid Pressure and Earthquakes, Eos, Transaction, Amer. Geophys. Union, 50, 5, p. 387-388.)



And who demonstrates the famous beer can experiment



and Darrell Wood (sp?), sitting in front of "one of the largest computers in the world," at Stanford's linear accelerator.



There are a few fantastic statements about earthquake prediction, guaranteed to bring some chuckles, including, "if the [next] San Francisco earthquake does not occur within the next 5 years it is my opinion that we will be able to predict it." I remember actually being kind of struck by some of footage. I remember especially the discussion of the numerous buildings, including schools, hospitals, and police stations, that sit right above the Hayward fault. Like the home of the second best college football team in the bay area (below)


Or my favorite, an old school for the deaf in Berkeley, which is now the Clark Kerr campus (where at the time I first saw this film I had a friend living)


Also footage of the creeping part of the fault system in Hollister


And footage of a USGS led project to monitor slip across a strand of the fault by using geodolites. The footage below is from Mount Diablo where they were making measurements




Perhaps the oddest thing though is the soundtrack for the movie. It is "California Earthquake" by Mama Cass. The full on song blares in the beginning and end of the movie, when the motorcycles are cruising all over the place, over the bay bridge, through the streets of the city, catching major air... I am not sure what the connection is between the motorcycles, Mama Cass, and earthquakes. During the more reflective parts of the film, we are treated with a tuned down instrumental version of the song. Truth is, without this soundtrack, I don't think the movies would really have stuck in my head, it would have just been a normal old boring class film strip. Well, except for the predictions about predicting earthquakes and the narrators apparent excitement about the prospect of using nuclear weapons to trigger earthquakes. Fortunately none of the geologists interviewed supported the idea of intentionally triggering earthquakes with H-bombs.



This movie was released in 1971, filmed in 1970. This is really at the beginning of the acceptance of plate tectonics as a field. Tectonics is referred to at a few points in the film, mainly the ideas of plates, but it certainly doesn't play a large role, and there are some definite factual errors. But really, for the state of the field, the information isn't really that bad. I also am thankful that no one is asking me on tape to make predictions, because my track record....well, err..

Prof. Advisor "Hey Thermo, when is this alleged lab you've been building going to be up and running?"
PhD Candidate Thermochronic, "Well, assuming that turbo pump is ready for me to pick up Friday, I'll be pumping out data by spring of 2002, easy."

Is this movie standard fare at other schools? I see it in many library holdings, small liberal arts school had a copy, is it pervasive? Am I crazy to think with a better editor and less annoying soundtrack this movie might be excellent?