Mid Semester Updates!

Marcus here,

I’ve been working with Ely to investigate Dominica, an Island in the Caribbean. Over the summer I was fortunate enough to take part in the KECK research project (which you can find posts of if you search through the blog a bit) and this semester has been an extension of that. While I was here in July and August I spent a lot of time in the Geochemistry lab preparing the samples we collected for gamma-spectroscopy. It's a process i’ve talked about before, but essentially we want to create two samples from the original, one with just the coatings of the grain and another with everything else. In this lab we are just concerned with the coatings! This semester has been a little less exciting than previous ones in the lab as we’ve had to overcome a lot of technical and mechanical difficulties.

The first hurdle we had to overcome was a malfunction gamma-spectrometer. Over the summer something fell out of alignment and upon returning to Oberlin in July, we found out that we had been running samples through it but not getting any real results. We tried finding make-shift solutions for this problem several times, but ultimately it seems that the only solution was to send it back and have the manufacturer's repair it. In the meantime, Amanda suggested that we find other ways of collecting data. So we went across the street to the physics department and learned how to use the XRD, or at least tried. An XRD, or x-ray diffractometer, works by shooting x-rays at a solid substance and figuring out how much the refract before returning to another meter. This is useful for figuring out the mineralogy of things as each mineral has a unique structure which diffract rays differently. Ely and I spent several days perfecting our technique on around 20 samples, but hit a small roadblock in understanding what the values we obtained meant. There was software on the computer which identifies possible candidates, but it's hard to narrow down one from a list of hundreds.  There have been lots of conversations with our Mineralogy professor as well as Amanda in how to best choose the right mineral we’re looking at.

The slide for XRD analysis, prepared with Kaolin. We were suppose to make the surface as flat as possible, but we quickly found out that trying to do that was an extremely tedious process!

So, thats kind of where we’re at now--making do with what we’ve got. In the absence of substantial real data Ely and I have been reading a lot of papers to make sense of the diffractograms (thanks for the specificity, Zeb) to try and figure out what exactly is in our samples, but its been a struggle. Amanda suggested that we see if any of the samples we ran through the gamma-spectrometer had meaningful data, and it turns out we have 6 or 7 that did run successfully. I think our plans for the rest of the semester are to continue parsing out the XRD information, even if it's just loose connections / verifications of assumptions and try to analyze the few samples that did make it through Harbin.  I still see a lot of paper reading in our future!

XRD output of one of the samples we ran! This pattern was pretty characteristic of  most of the samples we saw and it is turning out to also be very tricky to work with!

Hi! This is Ely,

This fall has been my first semester in Amanda’s Geomorph lab, and I’ve had a blast learning the ropes from the rest of the lab group, especially from my partner, Marcus. I have joined Marcus in helping him further his Dominica KECK research project. My semester started with some general training on how to perform some of the tasks Marcus and I are responsible for.  These items include operating our gamma-spectrometer, HARBIN; leaching soil samples, and operating the X-Ray Diffractometer (XRD). For a portion of the semester, we ran samples in the XRD, and since then have been trying to decipher the data it produces, which should allow us to understand the composition of the Dominica soil samples. In addition, we leached several samples in order to prepare them for Mae Kate, a recent Obie graduate. She is currently using the samples for her research at University of Vermont. As of right now, Marcus and I are hoping to return to Dominica during winter term to collect more samples, as we believe they could provide great insight as to the before and after effects of a large tropical storm, such as Hurricane Maria, which hit Dominica head-on. I have really enjoyed my time in Amanda’s lab and being able to work alongside a mentor such as Marcus. I have truly learned a lot about the scientific methods used in a lab that is not part of an organized classroom setting, something I have never experienced before.

Thanks for reading!

Ely