Friday, March 30, 2007

Malibu (Iso)STASY

Isostasy is a fun word to say. Isooostaaasy. Isotasy. Isostasy. Try it, you’ll like it.

Isostasy is a fancy word for something we are all familiar with. It is the kissing cousin of buoyancy. It is invoked to explain how we get so many different elevations around the globe.

Think of an iceberg. We all know that what we see above the water is a small percent of the total volume of ice. Let’s say we see 25% of the iceberg above the water. What happens as that iceberg melts? You loose ice, yes. The iceberg gets smaller, yes. But do you see any more than 25% of the iceberg above the water? No. You maintain the ratio of what is above the water to what is below the water even though the total volume of ice is less.

Now take this iceberg analogy and apply it to the Lithosphere.

SIDE NOTE! We talked the other day about what’s going on inside the Earth (see: The tale of Alfred Wegener) and defined the Core, Mantle, and Crust. I should clarify that the difference between what is considered “Crust” and what is considered “Mantle” is a compositional difference. When you hear “Lithosphere” and “Asthenosphere” you are now distinguishing between a phase difference. Lithosphere is solid, Asthenosphere is viscous. You can have chunks of Mantle rocks in the Lithosphere, just as long as those chunks are solid. Everybody cool? Ok, moving on…

Say a mountain is our iceberg. A solid hunk floating around in the viscous Asthenosphere. We can make this mountain smaller by erosion. Erosion breaks down the rocks that comprise our mountain and carries the sediment away via streams, rivers, or wind. Our mountain getting smaller is kinda like our iceberg melting. Just like the iceberg, as our mountain gets smaller, we maintain the ratio of exposed crust to the “root” below it. This can work in the opposite fashion. Say we have a convergent plate boundary where two continental plates are colliding (like the Himalayas) and neither plate wants to subduct beneath the other. The crust has nowhere to go but up. This is how we end up with the tallest mountains in the world. But now you know from the principles of isostasy, those big-ass mountains are supported by a HUGE-ass root underneath. That’s a lot of rocks, folks!

Isostasy can lead to something interesting which is called Isostatic Rebound. Imagine that you are the continental crust during a glacial. You’re grumpy because big, heavy ice sheets have collected on top of you. You are a little depressed and kinda cold. That’s a lot of fucking ice on your back, but wait! Here comes an interglacial. Ahhh, finally. The ice is melting. All that weight is lifted. You stretch out, you bounce back. The continental crust rebounds when all that ice goes away. This happens in places like the Baltic Sea and around Hudson Bay. Scandinavia is uplifting as we speak because of this very process.

So that’s isostasy. Not the most exciting topic in the world, but important to understand none-the-less. The next time you’re in a pool, demonstrate Isostatic Rebound to your friends by holding a beach ball underwater and then letting go so that it pops them in the face. “Isostatic rebound theory, bitch!”

Tuesday, March 27, 2007

The tale of Alfred Wegener

Earth scientists LOVE the story of Alfred Wegener (pronounced Ve-guh-ner) because it’s the ultimate lesson about brilliance and vindication.

About 4.5 billion years before Alfred was born, the Earth as we know it was still a glint in our Solar System’s eye. Planets like the Earth are formed by the collision and amalgamation of many, many pieces of debris floating around in space. Little bitty dust particles start sticking together, then baseball sized globs of rock and metal start sticking together, then chunks the size of cars, then buses, then tall buildings, and so on and so forth until you’ve got yourself a big-ass planet. What happens then is the metallic stuff that was on those billions of itty-bitty chunks wants to sink down, down, down into the center of your new planet. The densest stuff (like iron and other metals) coagulates in the middle and all the really light stuff like silicate rock floats up to the top.

As you can see from the picture above, we’ve got the metallic Core (inner = solid, outer = liquid iron), then the Mantle which behaves like a plastic in the sense that it does indeed flow, but it flows on the timescale of millions of years. Then up on top we’ve got the part of the Earth that we know and love, the Crust. Our Crust is solid, but it floats around on top of the gooey, convecting stuff below it.

The crust itself is broken up into pieces that we call plates (see above). There are 52 plates in all (1). They range in size from the petite Juan de Fuca plate off the coast of Washington State, to big-mother plates like the Pacific plate which encompasses most of the Pacific Ocean. These plates have been on the move since their very existence – crashing into one another, subducting beneath one another, rifting apart, coming back together, ditching each other for a younger and sexier plate, getting mad and storming off in a huff, cheating on one another with their best friends plate, and…well you get the point.

300 million years ago all the continents were in one gigantic uber-continent: PANGEA (2). But by 180 million years ago the party was over and all the continents started to move into their current positions.

Alfred Wegener took notice of something that seems obvious to most of us now: If you move everything back together, it looked like South America and Africa were totally getting’ it on!

Shame on you, Brazil, taking advantage of the Ivory Coast like that!
Alfred Wegener backed up his new theory of “Plate Tectonics” by pointing out the existence of the same fossils in South America and Southern Africa. He also supported his theory of continental drift by presenting evidence of glaciation found in parts of Africa that are now quite warm. He concluded that Africa must have been closer to the South Pole at some point.

The problem with Alfred’s work was that he didn’t have a mechanism that would explain why the continents would move around in the first place. He proposed a theory suggesting that the continents flung themselves apart via centrifugal force. His claim was that that the inertia of the Earth spinning around was enough to break everything apart and spread it out all over the world like smelly undies in the spin cycle.

As you can imagine, there was plenty of harrumphing and monocle clasping when he presented his ideas in 1912. Nobody bought it. He was scorned and several organizations went out of their way to discredit his work in a very grandiose way. He died at the age of 50, never to see his theory come to fruition.

After WW2, new fangled technology allowed scientists to get a glimpse at what was actually going on under all that fucking water in the oceans. What they saw gave Alfred’s theory of Plate Tectonics the backbone it needed to be widely accepted: sea floor spreading. A paradigm shift ensued and now EVERYBODY believes in plate tectonics, except creationists who are fools. It’s taught in high school, it’s in every Earth Science textbook, it’s on Wikipedia, it’s everywhere. So lets all give props to Alfred Wegener for being ballsy enough to lay it all on the line.

He was awesome.

(1) Bird, P. (2003) An updated digital model of plate boundaries, Geochemistry Geophysics Geosystems, 4(3), 1027
(2) Anderson, D.L. (1990) Planet Earth, pp 65-76 in Beatty, J.K. and A. Chaikin, eds. The New Solar System, 3rd ed., Cambridge Press, Cambridge, 326 pp.

Friday, March 23, 2007

Everyone has their Faults

Let's talk faults. There are 4 types of faults that exist in the entire world: Normal faults, Reverse faults, Strike-Slip faults and Oblique faults. Anyone that tells you otherwise is a liar, a fool, or someone who majored in humanities (both).

The first type of fault is called a Normal Fault. A little bit of history here: all the terminology that deals with fault structures came by way of English miners. England doesn’t see much seismic action now-a-days, but when these miners were digging around for coal n’ stuff, they saw lots of old fault traces in the walls of their suffocating mine shafts. The faults they typically saw looked like this:

Move your eyes from left to right. Follow the yellow layer along until it is broken by the fault. Where does that layer go? Up or down? If you said down, give yourself a gold star! The hunk of rock on the left side of the fault is called the Foot Wall, the right side of the fault (the part that moved down) is called the Hanging Wall. That’s because these poor-ass miners in England, standing in a hole directly on the fault, would hang their lamps above them. Hence, the Hanging Wall. The wall they would be standing on is called the Foot Wall because, you guessed it, their feet were on it! I’m aware that this is totally archaic nomenclature, but it’s the best anyone has come up with. If you have a better idea, please contact your local geologist. They will promptly ignore you because you are not a geologist and shouldn’t go around mucking with precedence. The next kind of fault is a Reverse fault (see above). These types of faults occur where the Earth’s crust is being mashed together. To help you visualize this, picture yourself at a Demolition Derby/Monster Truck rally. Two cars are gunning for one another and there is about to be a SICK collision. POW! They collide, but what happens? Usually one car will pop up over the other. That’s like a reverse fault. One block has to pop up over the other block as they are colliding together.

When this collision happens between two oceanic plates, or between an oceanic plate and a continental plate, we get a subduction zone. When it happens between two continental plates – like India and Eurasia, we get big-ass mountains, or OROGENIES as hoity-toity geologists like to call them.

The next kind of fault is called a Strike-Slip or Lateral fault. These faults have all their motion in the horizontal. Our favorite Strike-Slip fault is of course, the San Andreas Fault in western California. There is an analogous fault in Northern Turkey called the North Anatolian Fault. But we aren’t bombing Turkey right now, so who gives a shit what’s going on over there?!

The tricky part with strike-slip faults is determining whether they are a Right Lateral or Left Lateral. I’ll tell you how I do it:

1.) Look at your fault in map view, ie looking down on it from above.

2.) Draw two dots, one on either side of the fault. Imagine one dot is you and the other dot is a friend of yours. Wave hi to your buddy!3.) Now imagine that there is an earthquake. EARTHQUAKE, AHHH! Move your friend over a little bit according to the arrow of motion on his/her side of the fault 4.) From your perspective, your friend should have moved to the right. And from your friend’s perspective, you have moved to his/her right.
5.) You’ve got yourself a right-lateral fault, Chief!

The San Andreas Fault is a right-lateral fault. The Pacific plate is moving northwards at a rate of about 35 mm/yr. Attached to that plate is everything on the west of the red line you see on the map below. That means that in a few million years, Los Angeles will be within spitting distance of San Francisco. And spit we shall.

The last type of fault, an Oblique fault is just a combination of a Dip-Slip fault (either Reverse or Normal) and a Strike-Slip fault. A little bit of vertical motion. A little bit of horizontal motion.

Now you know all about faults! Good for you!

Wednesday, March 21, 2007

So here's the plan. Man.

Sorry kids. No science lesson today. I'm thinking that what I'll do is post 3 or 4 science lessons per week. The days of the week that they come will be a surprise. Awww, don't be sad. I'd love to tell you about the wondrous world of science everyday! But I have papers to grade, classes to attend, excuses to make, and a thesis to ignore.

If it makes you feel better, I put my underwear on backwards this morning. And I still have them on backwards. For inquiring minds, they're boy-shorts so it's a simple mistake to make.

Hanes MY Way, bitch.

Tuesday, March 20, 2007

Science Lesson #4: MAGNITUDES!

Like most things sciency, there is more to reporting an earthquake’s magnitude than meets the eye. When an earthquake happens, all you hear on the news is “Magnitude 6.7 on the Richter scale. Epicenter 2.3 miles from Buttfuck, California”. What you don’t hear is the squabbling between geophysics tribes about the earthquake’s Moment Magnitude, Duration Magnitude, Richter Magnitude, Body Wave Magnitude, and Surface Wave Magnitude. I shit you not: there are that many magnitude scales.

Let’s sort them out together. To make this easier to understand, I will compare each magnitude scale to an actress with the first name of Jessica.

Richter Magnitude = Jessica Lang: The stalwart scale we all know and love. Charles Richter and Beno Guttenberg were fancy-pants geophysicists at CalTech in the early part of the 20th century. Together they built a Wood-Anderson seismograph – a very specific kind of torsion seismograph. Reporting an earthquake’s magnitude on the Richter Scale means that you’ve recorded the earthquake on one of these special seismographs at exactly 100km (about 60 miles) from the earthquake.

The sucky part about a Wood-Anderson seismometer is that it can only record earthquakes up to about a 6.8. Bigger than that and the mechanisms inside go all screwy and you don’t get a good record of the event. You can make all kind of mathematical corrections, but it basically blows your seismogram off scale.


Even though Richter magnitude may not be the hot young thing it once was, we all should give props to Chuck and Beno for deciding that magnitudes should be recorded on logarithmic scales. You see, graphically a log scale looks like this

So as numbers get bigger and bigger on the x-axis, they don’t get much bigger on the y-axis. This is great because you can describe an infinite range of magnitudes on a relatively small scale. Theoretically you could have an earthquake with a magnitude of 20 or 100 or infinity, but an earthquake that size would mean that the entire Earth had been torn into two pieces. If that happens I wouldn’t really care if it was a 20.1 or a 22.7, I would be worried about my head exploding a la “Total Recall” in the vacuum of space.

Duration Magnitude = Jessica Alba: Fails to deliver consistent results. This scale deals with how long an earthquake lasts. This can get you into trouble because the duration of an earthquake in any one location depends on what’s going on with the rocks you’re standing on. If you’re in a basin filled with sand (I’m looking at you, Los Angeles) the earthquake is gonna last a lot longer than if you are standing on good, solid bedrock.

Moment Magnitude = Jessica Biel: These days this is the popular magnitude scale. The Moment Magnitude scale relies on something called the seismic moment of an earthquake which incorporates the area of the fault that slipped and how much the fault was displaced. No special kind of seismograph, no instructions on where to record the earthquake. Just quantities that are physically measurable. Nice.

Body/Surface Wave Magnitude = Jessica Simpson: I'm gonna sweep these two scales under the rug for now. It's not that they aren't useful, but they entail some explanation of how earthquake waves travel through the earth. You can live without them.

Monday, March 19, 2007

Science Lesson #3: Fun with Acronyms!

In my years as a budding young scientist, I've encountered innumerable acronyms. Some of them are useful, most of them aren't. I thought I'd share them with you in the event that you yourself encounter a few someday. Who knows, maybe you'll win $20 from your grandma in the event that there is a Jeopardy category with a few of these bad-boys slipped in there. Or say you're kidnapped, bound and gagged and your kidnappers leave a bottle marked BTEX within reach. From this list, you know that BTEX are chemicals in gasoline and gasoline is flammable, so while they're gone to buy sandwiches you kick it over. The next time one of your kidnappers flicks the cigarette he just burned you with onto the ground, BOOM! Jokes on them 'cause you just bought yourself a quick and ideally painless death. Won't you be glad that someone told you what BTEX means when you're sipping margaritas poolside with the big G in Heaven.

SST: Sea Surface Temperature
DO: Dissolved Oxygen
ACC: Antarctic Circumpolar Current
PF: Polar Front
SAF: Sub-Antarctic Front
IGPP: Institute for Geophysics and Planetary Physics
REDOX: Reduction and oxidation
LGM: Last Glacial Maximum
CTD: Conductivity, Temperature and Depth
CCD: Carbonate Compensation Depth
THC: Thermohaline Circulation (not the drug)
OAE: Ocean Anoxia Event
OMZ: Oxygen Minimum Zone
BTEX: Benzene, Toluene, Ethylbenzene, Xylene (chemicals in gasoline)
MCL: Maximum Contamination Level
MCLG: Maximum Contamination Local Goal
HSRAAFAYC: Holy Shit, Run Away As Fast As You Can!
DNAPLS: Dense Non-Aqueous Phase Liquids
LDNAPLS: Low Density Non-Aqueous Phase Liquids
ODP: Ocean Drilling Project
VSMOW: Vienna Standard Mean Ocean Water
PDB: Pee Dee Belemnite
DIC: Dissolved Inorganic Carbon
TCO2: Total CO2
CDT: Canyon Diablo Troilite
DON: Dissolved Organic Nitrogen
ANAMMOX: Anaerobic Ammonium Oxidation (thanks, Mike)
NADW: North Atlantic Deep Water
PPM: Parts Per Million
PPB: Parts Per Billion
PPT: Precipitation or Parts Per Trillion
K/T: Cretaceous-Tertiary Boundary (when all the dinosaurs died)
EPICA: European Project for Ice Coring in Antarctica
LGS: Late Glacial Stage
ENSO: El Nino, Southern Oscillation
PDO: Pacific Decadal Oscillation
DO events: Dansgaard-Oeschger Events (rapid global warming events)
PAGES: Past Global Changes (shouldn’t this be PGC?)
PEP II: Polar Equator-Pole Program
PEEPOLE: I Wish This Was An Acronym
BP: Before Present (actually, before 1950. it's a long story)
MOR: Mid-Ocean Ridge
EPR: East Pacific Rise
SAF: San Andreas Fault

Friday, March 9, 2007

I'm Walkin' On Sunshine!

Here are notes from my Paleoceanography class. It's mostly boring and the teacher is a lunatic. We talk about the same stuff over and over and over ever time we meet. I had "Walkin' on Sunshine" stuck in my head. The boat is the RV Thomspon - the research vessel I do my work on.

Thursday, March 8, 2007

Here's your stapler, Little Girl

You wouldn’t guess it if you knew me now, but I was fucking nuts for stuft animals when I was a kid. I wasn’t allowed a dog until the 3rd grade, so I made due with fuzzy and squishy creatures purchased from Toys R Us. There were bunnies, bears, dogs, cats, frogs, whales, sea otters, monsters, snakes, monkeys, giraffes, koala bears, probably an armadillo, mice, squirrels, pigs, peacocks and anything else you can turn into a fluffy friend. What there were NOT were dolls. I was never interested in human-themed playthings. Kens and Barbies were only shifty-eyed zookeepers that would breeze in and out of the elaborate productions I would choreograph starring Mr. Chetsworth, the gorilla, and Mrs. Ellington, the penguin.

I had one huge bunny when I was real little, like maybe 3 or 4. It was yellow with big eyes and the typical bucktooth bunny smile. I’d drag it around until it was filthy, then it’d get washed and fluffed and the vicious cycle of dragging would continue. The bunny is even in a picture of me taken WITH a person in a bunny suit while I’m in my Easter dress. I look worried. “Too. Many. Bunnies.” I’m thinking. I was practically a baby, it was confusing.

The only reason I remember the bunny is because it met its demise when I caught a really bad flu and threw up all over it. This was very sad because it was the only stuft animal I had that was bigger than me. I’d come close to experiencing such enchantment only one other time in my life.

When I was 7 years old, my elementary school had a raffle at the obligatory “Bi-Annual-Yes-We-All-Have-Parents” barbeque. Raffle prizes were of the typical fare: school supplies, a couple tee-shirts, trapper keepers, gift certificates, and so on. These things were of little interest to me, but behind the table displaying the various sundries that you could win was the most perfect 4-foot stuft polar bear you could possibly imagine. Beautifully clean and white, with big black beads for eyes, and a little red heart between its paws that read “You are berry special!”. It was huge. I had to have it. I just knew I would win it! Jesus, let me win that! Come on dude, be on my side for once. I promise I’ll do everything right from now on, just let me win that giant bear!

I bought raffle tickets. Not too many as I recall, but I was convinced that any one of them was a winner. I was so confident that that bear would be mine, I could just see it looming over all the other animals, smiling at me. I AM berry special, thank you for noticing! He would be named William. William the Polar Bear.

Raffle time comes. Crappy prizes given out. I wasn’t really paying attention, I was thinking about how awesome it will be driving home in my parents Caravan with that bear sitting next to me. Buckle up, William! What’s that, you’re hungry? We’re almost home, I’ll make you mini pizzas when we get back to YOUR new house. You’re rad, William!

Bear, bear, bear, bear. Numbers calling. Look through tickets. No, not that. No, not that one either. Not you. Or you. Or you. Or…

Any of these.

But, no. That’s my bear. William? What’s going on? How could you go with someone else? How could this happen?

I wandered up to the table and showed them my tickets. Surely this was a mistake, ha ha! You see, you didn’t call the numbers on my tickets when giving out that bear! So how about I just take the bear and we call it a day, hmmm? No. But.

Wait, what’s that? I DID win something? Oh my God, what is it? It’s a stapler? A STAPLER!? Is this a joke? No? Anybody? No joke. What a rip-off.

I only realize now that my life took a dramatic turn that night. I felt the chilly embrace of Disappointment for the first time. And she has been my companion ever since.