Tag: personal

Categories
Blog Orientation

Writing for this blog

I wrote an assignment for my students yesterday. I ask them to write a blog post (watch for those soon), and give them some guidelines for doing so. I thought it was worth putting up here both for public comment and because I think it’s a nice statement about what I’m trying to do here.

I highly recommend that everyone who goes through my lab learn how to explain their project to the public. This is partially because you’ll have to do it when you get to Senior Seminar (TESC 410). Evan more importantly, it’s because we scientists need to be better about engaging the public with our science. If we don’t, we run the risk of becoming the kind of caricature of a scientist you see in the movies: academics with no connection to the real world.

So, to make that connection with the public, we have a blog. Or rather, I do, since I’m the one who usually writes for it. I try to explain what’s exciting about my science in a way that college students taking an intro class (or any interested people at about that level) might understand. The audience I write for isn’t stupid, but they might not be familiar with the jargon we use as scientists and the kinds of graphs we show each other. They might not care about the details of my work, but they do care about what’s new, exciting, or potentially relevant. Why I do things is much more relevant than how I do them. My audience also cares about stories (I think), including stories about how science works for me.

There are no strict rules about writing a blog post. This is an assignment with no strict page limit or style guidelines. Really, it’s the ideas and how you convey them that matters. I’ve seen a lot of good material on how to run a blog in general. I’m collecting it below. Some of it might be helpful if you’re writing a single post. In the broader sense of communicating your science, I’ve found some useful guidelines in Nancy Baron‘s book Escaping the Ivory Tower. Baron directs an influential program called COMPASS that focuses on preparing scientists to better communicate with the public. Her book has a lot of useful information about how to make sure your science is relevant to different audiences (politicians, journalists, filmmakers, etc.).

One of COMPASS’s signature tools is the Message Box, a scheme for organizing your scientific ideas so you can pitch them to non-scientist readers. Working your ideas into a message box is hard. But it’s good preparation for writing a blog post. Plus it forces you to think about how your science s relevant… which is the whole purpose of doing it! If you want to give the message box a try, there is a template here.

Guidelines:

Aim for about a page of text, with an image. If you don’t have an image, I can help.
You can use informal language, but don’t be sloppy. People will read this.
Have you taken pictures? Drawn comics? Found places on Google Maps? Great! I’m a visual person, and I like having good images on the blog.
Aim to engage people rather than to explain. Stories are good.
Avoid jargon, but don’t dumb it down. Explain it when you have to. I think of my posts as initiating readers into the club of people who understand what I’m talking about.
Look at other blog posts for inspiration.

Categories
Blog Orientation Projects

Lab Equipment on the Drill Ship

I spend about 12 hours in the lab most of the days I’m at sea [1]. So do most of the other scientists on board. Sometimes we get a little silly talking about our lab equipment after (or during) our shifts. Right now the lab is kind of quiet, waiting for cores to come up from our next site, so I have a chance to take pictures of the equipment without getting in anyone’s way.

Photo of lab instrument on track
The Section Half Multi-Sensor Logger

This is an instrument that records the color and magnetic susceptibility of split cores (“section halves”) [2]. It’s actually a robot that slides along a track taking measurements. We call it the Section Half Multi Sensor Logger, or SHMSL (pronounced “schmizzel”). The Germans on board have started calling it the Schnitzel.

The SHMSL isn’t really in our lab, but we use data from it all the time. In fact, there’s a back-and-forth between all of the labs on the ship. Paleontologists use the ages when plankton species appear and disappear from the fossil record to help us narrow down which magnetic reversals we’re measuring. We talk to the sedimentologists about sedimentation rate and what kinds of (magnetic) minerals might be in the sediments. The physical properties scientists help us decipher seismic reflection diagrams – more on those later – and collect most of the magnetic susceptibility data (three of the phys props scientists are paleomagnetists as well!). We collect samples for each other, too – I’ve even collected samples for organic geochemistry!

Silver bullet magnetometer
The 2-G superconducting rock magnetometer rocks on

This is the superconducting rock magnetometer, or SRM. We use it to measure the record of Earth’s past magnetic field in split cores (“section halves”) [3]. Everybody likes to say “superconducting rock magnetometer” because it makes you sound cool. But it is a mouthful. We sometimes call it the silver bullet. But usually we just call it the SRM (“ess-are-emm”). We used to have one like it in grad school. We named her Flo.

Boxes with flashing lights, connected to SQUIDs
A selection of SQUIDs

At the heart of the SRM are three rings made of superconducting wire. These are part of very precise magnetic field sensors called superconducting quantum interference devices, or SQUIDs. We have the other kind of squid out here, too. They are good on the barbecue.

DTECH D-2000
Alternating field demagnetizer. Don’t put your credit cards in here.

While this looks like the SRM’s little brother, it’s actually a different kind of device. This is the Dtech D-2000 alternating field demagnetizer. Samples that have had their magnetic records partially obscured by big magnetic fields from the drilling process (or by years of growing iron minerals at the bottom of the ocean) need to have those layers of extra magnetic grime scrubbed off by this machine. It works kind of like those old VHS tape erasers, but it’s a lot more precise. It also beeps VERY LOUD.

Box of plastic wrap watching you
Plastic wrap is a hot commodity in the core lab

We love plastic wrap in the core lab. We use it to make a nice flat surface for the SHMSL measurements, and to keep the sand and mud from cores out of our magnetometer. We wrap cores in plastic after we’re done analyzing or describing them. Hendrik, a sedimentologist, loves the boxes, too. He was very disappointed that other people kept throwing them away. Some people here think that you can wrap a core faster without the box. Hendrik disagrees. So there was a wrap-off between Hendrik and another sedimentologist. I don’t know who won. I’m agnostic about the boxes. But I do like to keep my magnetometer clean.

[1] In case you are just starting to read this blog, this post is part of my series of posts from the JOIDES Resolution, where I am participating in IODP Expedition 354 to study turbidites on the Bengal Fan.

[2] The optical sensor on the SHMSL is very similar to one that we have in the physics teaching lab at UW Tacoma. You will use it if you take Physics 3. It measures the visible and near-infrared spectrum of light. Magnetic susceptibility – “mag sus” around here – is a measurement of how much magnetic material is in a sediment core. The susceptibility meter applies a very weak magnetic field to the core, and measures the change in the sediment’s magnetization. We have one like it (and a track system for cores) in the Environmental Geology lab at UW Tacoma. Sorry, no SHMSL, though.

[3] Previous posts about the basics of Earth’s magnetic field are here, here, and here. Watch this blog for more about how we use the geomagnetic polarity time scale, or GPTS, to figure out the age of rocks – coming soon!

 

Categories
Blog Personnel Projects

A map of my typical day

 

Presented without comment.

adayinmyJRlife

Categories
Blog Orientation Projects

How sediments get magnetized

We are currently drilling through a big pile of mud and sand on the seafloor (the biggest such pile of mud and sand in the world), and I’m spending most of my day sitting next to the “silver bullet” in this photo:

paleomag_labIf you can’t see the sign in the photo, this is the superconducting rock magnetometer (SRM) on the JOIDES Resolution. We use it to measure the record of Earth’s ancient magnetic field in rocks and sediments. Right now, we’re running sections of marine sediment cores through the machine. The SRM tells us what direction your compass would have pointed if you were standing here hundreds of thousands – or even millions – of years ago.

Muck in the oceans builds up, layer upon layer, so that older mud eventually gets covered with younger stuff. If you look closely at the muck, you’d see it was composed of lots of tiny particles. These are pieces of clay, silt, and sand formed from the detritus of eroded mountain ranges, the decaying bodies and shells of tiny fossil creatures, dust from the air, tiny crystals that form in the oceans, and even microscopic meteorites. Some of those particles are magnetic. For the most part, those contain the magnetic iron oxide magnetite [1], which can be part of the dregs of continental erosion, or it can be made by bacteria in the ocean, or by a number of other things. As the tiny magnetic particles fall through the water, they turn so that they are magnetized in line with Earth’s magnetic field – just like little compasses [2]. After they fall into the sediment accumulating on the seafloor, the magnetic particles get buried, “locked” in position by the other particles surrounding them. If Earth’s magnetic field switches polarity, the “tiny compasses” in new sediment being deposited will align with Earth’s new magnetic field, but the ones already locked in the sediment will stay as they were.

At least, that’s how the typical story goes about how sediment records the direction of Earth’s magnetic field. In reality, it’s not so simple. For one thing, all kinds of creatures live in the sediment – like whoever lived in this burrow:

Burrow in sediment core from Bengal Fan

This sediment core is actually full of fossil burrows. But sediments full of burrows can record Earth’s magnetic field just fine. We think it might be because the creatures burrowing in the sediment stir up the muck just enough that it settles back in line with Earth’s magnetic field again. It’s just that the sediment “locks in” the record of the magnetic field after the burrows themselves get buried. That seems reasonable until you realize that this burrow and others like it did not record a magnetic field in the same direction as the sediment around it [3]. This burrow is filled with pyrite, which, though iron-bearing, is not itself magnetic in the same way as magnetite [4]. Some geologists think that something happened to make new magnetic materials form or old ones dissolve around burrows like this one.

To make things even more complex, the area we are looking at on the Bengal Fan was not formed by sediments settling out in quiet water. Instead, much of the sand and mud deposited here was dumped very quickly from places close to land [5]. Do the magnetic particles in these tremendous currents full of churning sand and mud even have time to be pulled by Earth’s magnetic field, or are the forces in the currents too great? It looks like, at least in the muddy parts of deposits like the ones we’re studying, the sediment does keep a mostly faithful record of Earth’s magnetic field.

In the end, the story we tell about how sediments become magnetized is probably fundamentally OK, but there are parts of it we still don’t fully understand. Those parts of the story we’re still curious about are what keep us doing science!

[1] Magnetite is Fe3O4. To a certain extent, hematite (Fe2O3) and goethite (FeOOH) can also be incorporated into marine sediments, along with other magnetic minerals that can grow there.

[2] Unlike in igneous rocks, where the magnetic minerals “lock in” a record of Earth’s magnetic mineral as they cool. The minerals in igneous rocks DO NOT move.

[3] See Abrajevitch, A., Van Der Voo, R., and Rea, D., 2009. Variations in abundances of goethite and hematite in Bengal Fan sediments: Climatic vs. diagenetic signals, Marine Geology 267:191-206.

[4] Pyrite is paramagnetic, meaning that it can be magnetized only in the presence of a magnetic field, not after the field is gone; magnetite is ferromagnetic, meaning that it can be permanently magnetized.

[5]This is called a turbidity current, and the sand and mud deposits it leaves behind are called turbidites.

 

 

Categories
Blog Orientation

Basics of Magnetism 1: Compasses

When I tell people that I study the history of Earth’s magnetic field, I get a bit self-conscious – as if I just told someone I specialize in Santa Claus. Geologists call us “paleomagicians” for a reason. You can’t see magnetic fields. You can’t touch them. Unlike most geological stuff, nothing obvious happens if you hit a magnetic field with a hammer. Once you understand a few things about Earth’s magnetic field, though, it becomes a bit less mystical. In the next few articles, I’ll try to bring Earth’s magnetic field … um … down to Earth.

Number 1: Compasses line up with magnetic fields. Although you can’t see a magnetic field, you can see its effects. In the pre-GPS days, when we still used maps and compasses, we used those effects all the time. Compass needles (which are themselves magnets) line up with magnetic fields. One end of the compass needle is the “north seeking” end, which points toward Earth’s North Magnetic Pole [1]. But wait: Earth’s North Magnetic Pole is not its North Pole! And the North Magnetic Pole moves from year to year. Here is a movie showing the angle your compass would point (relative to True North… as in North Star North) at different places on Earth, over the past 400 years more or less. Scientists made this animation in part by looking through old navigation logs, matching ships’ compass readings with the same ships’ positions based on speed estimates (dead reckoning) and star sightings [2]. Keep an eye on the North Magnetic Pole – where the lines converge in the Northern Hemisphere – as it drifts aimlessly around the Arctic. How random is this drift?

We want to how Magnetic North changes through time because it helps us navigate. But that’s really not the main issue now that we have GPS. We want to know how Magnetic North wanders because it’s a puzzle, and because it brings up some even more fundamental puzzles about the Earth. Why does Magnetic North wander? Where has it wandered in the past? If we were to watch a compass for, say, a million years, would it point at the true North Pole on average? And what, if anything, does that wandering tell us about the Earth?

[1] Physicists (and geophysicists) represent magnetic field lines in a few different ways: as arrows that line up the way compasses would (field vectors), as lines that connect those arrows (field lines), or, confusingly, as lines that illustrate the strength of the magnetic field (contour lines). You can play around with some of these representations here.
[2] If you want to see the original work, it’s by Finlay and Jackson (2003) and Jackson et al. (2000). These are not meant to be entry-level papers.

Categories
Blog Projects

How to go to sea as a paleomagnetist, part 2

What? You really wanted to know how I got picked to go to sea?

You might say it was Facebook.

Last spring, the Facebook page for the drillship JOIDES Resolution (“the JR”) posted a call for a paleomagnetist from the US to sail on an expedition to the Bengal Fan. Since that description fits me (and not that many other people), I sent in an application soon after. A few months later I heard that I got the position.

But that would be unfair: one does not simply apply for a position on the JR. I had to read up on what the chief scientists were planning to study, consider what my own contribution might be to the project, write a proposal to convince The Powers that Be that I was the real deal, and back that up with a list of all of my relevant academic work (my CV). To even get to that point, it took me all of college and several years of grad school to know what the JR was, and to be able to call myself a paleomagnetist. Honestly, though, I’m still sometimes not even sure I’m qualified to go on this cruise.

On the other hand, there is a lot you can learn about the JR, our cruise, and what it means to be a paleomagnetist with very little investment. The JR’s blog and website are an excellent way to start. Right now, the ship is not too far from where we’ll be drilling, on a different part of the Bengal Fan. There will be posts about our cruise when we are at sea. I’ll be posting some background here about Earth’s magnetic field and why it’s important for this particular cruise. I’m also planning to write a few posts about the rise of the Himalaya, the collision of India and Eurasia, and the Asian Monsoon.

And then, when the cruise is over, if you’re a UW student and would like to kick your involvement up a notch, you can work with me on samples that we bring home from the drill sites. You don’t need much training – most of the students who work in my lab start just after taking their first geology class. But being involved in research as a college student is a great way to work toward going to sea on a research vessel like the JR!

Categories
Blog Projects

How to go to sea as a paleomagnetist

Starting late next month, I’ll be at sea in the middle of the Bay of Bengal as part of IODP Expedition 354. Going to sea for months at a time is something new and exciting for me. I’m going to be blogging here about my experience, starting with preparations for the cruise. I hope that you, the reader, will find something here that excites you as much as it does me. I’m a paleomagnetist, which means that part of what excites me about this cruise is the chance to track Earth’s magnetic field through geologic time. So if I want you to follow me, I’ll have to explain why I think geological magnets are freaking awesome.

I’m also secretly hoping that you, reader, will hear me out when I make a fool of myself in front of my colleagues or get seasick (wait – do I get seasick?), because, frankly, I’m also a little terrified. The cruise is TWO MONTHS long. I’ve never been away from my wife and kids for this long before. I’ve never been to this part of the world. Research-wise, working with magnetism of sedimentary rocks is relatively new to me. I may be a scientist, but I’m a human being, too, and I may at times just need to connect with you people in the outside world.