Well it’s been a while since I got back from Louisiana and our trip along the Mississippi River and delta so I figured I’d better post something. It’s been a busy few weeks getting ready for our summer campaign in China (international shipping of research equipment is an absolute nightmare I wouldn’t wish upon my worst enemies) so I got nostalgic for our time on the delta. Below is one of my favorite pictures of the group, showing us all sunk into our knees in mud just after we tried catching methane bubbles in a bucket to light them on fire. The photo was taken down on the distributary channels of Cubit’s Gap, a diversion on the Mississippi delta that was blasted ~100 years ago.
The group on the Mississippi delta trip, taken down one of the distributary channels of Cubit’s Gap.
I’m off to Louisiana for a week to spend some time on the Mississippi River and MR delta with my advisor (who spent a lot of time researching there) and some other colleagues. We’ll be spending a week, starting in St. Francisville, LA and driving down as far as Empire, LA where we’ll be for a few days. The Mississippi is a really cool system for so many reasons, and we’re going to be on the river during a moderate-to-high discharge, especially considering recent events across Louisiana (https://www.youtube.com/watch?v=CB-nBhsMiYc).
Below is a map showing roughly where we’ll be going. I’ll be sure to update with some pictures on the return.
Mississippi River trip map
I spent my spring break with an outstanding group of undergrads TAing a course in geological field methods taught by Helge Gonnerman and Monica Erdman at Rice. I had an absolute blast. We mapped the Tierra Amarilla Anticline [HERE] and the surrounding areas. It was really fun to get back in the field, since I spend most of my days behind a computer working with Matlab nowadays. I may digitize my field map a learning project in the next few weeks, so I’m not going to post that yet, but I will share a picture of the whole group (courtesy Jeffery Piccirillo).
The whole group in NM on our last field day…mapping till the sun went down.
I’ve just returned from an 8-day trip to the state of Washington to serve as a field assistant to my colleague Brian Demet and participate in a class field-trip to observe some really cool geomorphology. The field work was primarily on Whidbey Island, a glacial-sediment island northwest of Seattle that has isostatically rebounded about 300 m since LGM. We also worked elsewhere in Island County during our trip.
An outcrop that Brian and I scouted had a large exposure of megabreccias. A breccia is a broadly defined rock type and is essentially a rock that is comprised of smaller angular clasts bound by a fine matrix. Breccias form in a wide variety of high-energy environments that produce similar but distinctly different rocks; the key similarity is proximal and high-energy deposition. Below is an example of a common-looking breccia.
a common-looking breccia rock. Angular clasts (white) are bound by a fine matrix (gray).
The outcrop that I show below is the exposure of a megabreccia (mega- means large scale) within the glacially-derived sediment that the Whidbey Island bluffs are comprised of. Part of Brian’s thesis will be putting this outcrop into a broader context and story, to try and better understand grounding zone wedge deposits under the Antarctic ice sheet — but that’s another post for another time!
The outcrop here is approximately 60 m wide, and 15-20 m tall.
megabreccia deposit within glacially-derived sediment
post-processed image to highlight large angular clasts
I was recently a participant on a field excursion with a crew out of the University of Texas to the Wax Lake Delta where they have ongoing projects. We simply went out to build some platforms that the research group will later place some long-term monitoring equipment on. Below is a satellite image of the Wax Lake Delta.
The WLD is a really interesting location for study because it’s entire history is well documented. The US ACE created a canal for flood control from the Atchafalaya River (really the Wax Lake) to the Gulf of Mexico in 1942, and the entire delta has been built by rapid deposition since then. The delta is therefore the site of numerous delta formation and autogenic process studies.
Below are a few more pictures from the field work, including one of the platforms we built.
me working in the levees of the WLD, near one of the build sites.
one of the four platforms we built. The structure will support an array of data logging equipment and a car battery. Theoretically, the platform is above the 1-5 year flood stage. Each of the four corner poles are driven about 10 feet into the ground. The other two poles are spares and will be used when attaching the monitoring equipment.
periodic rain meant lots of rainbows. Taken from the boat we had for the duration of the work.