Welcome!

Welcome to the blog for the Oberlin College Geomorphology Research Group. We are a diverse team of students working with Amanda Henck Schmidt on geomorphology questions. This blog is an archive of our thoughts about our research, field work travel notes, and student research projects. Amanda's home page is here.

Wednesday, June 21, 2017

Day 10 Dominica Keck Project

6/21/17
Today we split into 3 groups. The geomorphology group went to collect water and sediment samples from rivers while another group collected basalt samples and the final group surveyed the stratigraphy at Fond St. Jean. The group looking for basalts traveled northward and through the middle of the island to attempt to get to the south east, because the road leading directly to Petite Savane was destroyed in 2015 by tropical storm Erika. They found 2 outcrops of basalt on the side of the road and collected samples from one of the outcrops. Since the road into Petite Savane was closed, the group got out of the car and hiked to the outcrop to collect samples. The trail was muddy, but passed some cool cows.

Basalt flows from Fond St. Jean

The group that headed to Fond St. Jean spent the morning looking at the stratigraphy along the side of the road and collecting some samples of basaltic ejecta. This material is believed to be some of the most primitive lava deposited on the island. Back at Springfield, these samples were washed and separated from the dirt encasing them and then heated to dry. Different people then spent the rest of the day labeling, cutting down, and packing up samples to be shipped off later this week, as well as meeting with the project directors to discuss individual projects.
Some stratigraphy visible from the road in Fond St. Jean


-Clarissa and Taryn

Dominica Day 9

Day 9 in Dominica - Tuesday 6/20/17

Today was our first official day off in Dominica. Our professors had interviews with local TV stations scheduled in Roseau, so a small group of students (including the two of us) decided to head into Roseau with them to spend the morning and early afternoon exploring. We were able to try some of the local cuisine at a few different cafes and restaurants and explore the various shopping areas throughout Roseau. A view of Roseau from Morne Bruce is included below.



We headed back to Springfield Guesthouse afterwards, and then each student gave a short presentation about their individual project, what kind of work they plan on doing back at Union College, and what the overall significance of the project is. The water and geomorphology groups have generally been separated from the petrology group throughout our time here, so it was nice to get an idea of what everyone's been working on here during our time apart.


- Justin & Sarah 

Monday, June 19, 2017

Day 2^3

We spent Day 8 split into geomorphology/water and petrology groups, all doing our thing and collecting samples.  It was pretty good weather, cool and breezy, but with some pretty dark clouds, thanks to Tropical Storm Bret.  Thankfully, it's supposed to stay south of us.

The petrology group spent our day in the south end of Dominica in a region known as Foundland. The majority of our group collected samples near the beach town of Font Saint John. Those that stayed in Font Saint John broke into two groups. One group collected pumice clasts and basalt from outcrops found along the main road through the town (Fig. 1). The other group measured layers to construct a stratigraphic column of deposits found along the beach (Fig. 2).
 

Figure 1. Walking the road through Font Saint John.


Figure 2. Measuring deposits found along the coast near Font Saint John.
 A few “hard rock” people went to the northern end of Foundland (Fig. 3) to see the outcrops where samples were collected earlier in the week. While revisiting this area, we found a few more outcrops to sample from.
Figure 3. Outcrop in northern Foundland.
 The group that went to northern Foundland returned to Font Saint John around lunchtime. We split up and joined the two groups that were sampling nearby. Those of us that stayed near the coast had the opportunity to chat with some of the locals. They shared some stories of their lives in Dominica and taught us a few creole words.   

Students in the geomorph/water group, hard at work hunting for sand
Meanwhile, team geomorphology/water chemistry sampled 8 locations, this time on the east coast of the island.  And we were on time for dinner!  At each location, we tested and recorded data about the water, sieved sediments to the two size ranges (<63 and 250-850 micrometers), and took lots of notes and pictures.  Some of the highlights include swimming in one of the rivers, learning why Mazi is so obsessed with the hot dog/sandwich question (he’s in debate club so he apparently just likes arguing), and spotting a sign politely requesting cow owners to tie up their cows (upon seeing that sign, Cole jokingly asked if we could steal a cow, but Amanda immediately shot that down).

A sign stating that “ALL COW OWNERS ARE ASK TO TIE YOUR ANIMALS OR SUFFER THE CONSEQUENCES”
At most of the sites, we got in a rhythm and were completely done within half an hour or 45 minutes, but at a few it was harder to find fine enough sand to collect, in which case it took a little longer.  Some of the sites also went faster when it was really easy to get to the river—a few were just off the road and you could casually mosey on down—and it took a little longer when it was more challenging to reach the river—at one of the first sites, we had to climb through a hole in a floodwall to actually get to the water.

Starting our morning off right by scrambling through a hole in a floodwall
In addition to learning about the water, we also learned a little about the island from Pat, who explained that many of the descendants of the indigenous people live on the east side of the island.  She pointed out how the land was slightly different, since they generally farm more than people elsewhere on the island.  At our penultimate stop, she also showed us a little road leading around a bend to a nice view of palm trees and grass overlooking the ocean.

A beautiful ocean view that we enjoyed towards the end of our day
After our geology-filled days, the two groups met back at the guesthouse for dinner (as usual).  The day concluded with some of the best chocolate pudding we’ve ever had, so it was a pretty good day.

Sunday, June 18, 2017

One week In - Dominica Day 7

Hello everyone,
This is Abadie and Marcus here to tell you about day 7 of our time here on the island! After breakfast the group split up into two teams, team geomorph and team petro. Fortunate enough for all you readers, we we're each on different teams so you'll read about everything. 

Team petrology started out the day hunting for enclaves in a quarry on Micotrin, a lava dome in Morne Trois Pitons National Park. We were quite successful, we found a lot and several different types of enclaves that Sarah will be looking at for her project, as well as andesite for Jessie and Abadie to use.
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An enclave from the quarry at Micotrin.
After the quarry, we attempted to hike up Micotrin to find more samples, but didn't get very far. The trail was practically vertical, and we were on all fours on the way up climbing over rocks and roots, so we headed back after about ten minutes.
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The trail up Micotrin.
We visited two ignimbrites in Roseau valley to find pumice clasts, and we ended our day in the Botanical Gardens in Roseau getting more pumice at the top of a short trail. 
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A beautiful ignimbrite in Roseau Valley.
There was a festival going on in the gardens, so we checked that out before heading back to Springfield to relax for the rest of the afternoon.
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The view of Roseau from Jack's Walk Trail in the Botanical Gardens.

Team Geomorphology spent the day along the east coast of the island. Our groups goal was to collect sediment sieved to a specific grain size (less than 63 microns and between 250-850 microns) as well as collecting water samples from different rivers and streams. As Holli has been working in this region for years, these locations have been tested and photographed before, so a side project I've taken up is repeat photography; trying to recreate photos that have been taken in previous field seasons and see the changes. We started the day with high hopes of collecting sediment and water samples from 8 different locations, but unfortunately got rained out after site number six. 

Our first stop was at near a grocery store in the town of Portsmouth, which is in the north-eastern section of the island. It was a fast moving stream with large cobbles covering the banks and stream beds, and smaller to medium sized boulders acting as obstructions and creating rapids. This was a very common setting for most of places we sampled at. Other notable things throughout the day included stopping at a site with two large trees uprooted and integrated into the channel, seeing a small hermit crab scurry along the bank and leaving Amanda's camera at one site without realizing it. Its alright though, we figured out that we were missing it fairly quickly though, and were able to go back and grab it.

One of the repeat photography comparisons. Previous years image on the left, todays on the right. There was a noticeable increase in size and frequency of large rocks as well as much faster moving water. 


Overall, it was a fun day, not as exciting as the Valley of Desolation hike or  going through the Sulfur deposits, but interesting and eventful nonetheless!

Saturday, June 17, 2017

6


Welcome to Dominica Day 6, by Jackie Buskop and Dexter Kopas! Fraught with water sampling, gas sampling and rock collecting. After an hour and a half north along the beautiful coast all three cars arrived at the Picard River to collect water samples. 

Dexter, Mazi, Kira, Cole, and Pat ventured bravely down the river to determine factors like temperature, pH, dissolved oxygen content. The rest of us loitered in the shade, argued about the parameters constituting a sandwich (see graphic below) and stretched our legs to recover from the hike (see day 5 blog post). Meanwhile, Team Rock Smash looked at pumice clasts and lithics in a finely laminated pyroclastic flow. After we gracefully piled back into our vehicles, we drove further north up the coast to Fort Shirley where we feasted on our potato filled bread pockets and gazed up at lava domes. 

Inside the fort, an exhibit retold the story of European colonialism in Dominca. For your extended historical knowledge, after the British colonized the island in the early 1800s, they forced groups of indigenous persons to form a slave regiment to protect Ft. Shirley. After much toil and hardship, the regiment revolted against the English control and fought off ships that were sent in to reclaim the fort. In the end, they were set free and everyone lived happily ever after and there were never any problems on the island from this moment forward. (This interpretation of Dominican history has been slightly dramatized.) Also learned about was the Munchineel tree: do not eat its fruits or burn its wood, for you could die from ingestion or inhalation of its noxious fumes!

Whilst enduring our windy car ride up the mountains, Team Sieve vigorously debated whether a hot dog was a sandwich and whether the definition of sandwich depended on structure or filling. (see: is a wrap a sandwich? is a taco a sandwich?) Other food related debates regarding the differences between  broccoli and broccolini and cheese stuffed crust vs crust stuffed cheese ensued.


After our historical stop, complete with ocean view we drove east into the heart of the peninsula of Morne aux Diables to sample the cold fumaroles at Cold Soufriere. Team Water (Mazi and Dexter) took more samples of the boiling pools, while Team Rotten Egg (Jackie and Pat) sampled gas from fumaroles at Nancy's and Eric's pool. Knees weak, arms spaghetti, they could get close enough to the fumaroles to absorb the delicious sulfur fumes, as the magma chamber is deeper than elsewhere on the island, imparting chemicals (pH of 1.4!) but not heat. 

Jackie and Pat using a funnel connected to a Giggenbach flask via a tube. The funnel is held underwater to collect gas that is bubbling up from the fumarole. Gas bubbles through the NaOH that neutralizes the acidic CO2 and H2S and collects in the headspace within the flask.

Next the group split up. Most of Team Rock Smash headed back to Springfield to process samples and get some much needed rest. 

Meanwhile, Justin sampled andesite banded pumices and enclaves from a quarry at Morne Trois Piton. 

Team Sieve and Team Water had a relaxing afternoon of wading in rivers and sieving for sand. They drove down the east coast to sample sediment and water in three rivers emptying into the ocean. Team Sieve will be backtracking erosion rates of the island's larger rivers using Be10 dating. At one river, the delta margin between the river and an estuary could be easily seen. 



After a long day and a late dinner, the Keck troopers were happy to snooze early, as tomorrow will be another long day. 

Friday, June 16, 2017

Dominica Day 5- The Valley of Desolation

Today, students had to get up at 4:30 am for a grueling trip to the Valley of Desolation. Students hiked through thick jungle and up slippery staircases, crawling over unsteady boulders and through sulfurous streams. At the beginning of the long hike, the students stopped for a break at the Breakfast River.
Afterwards, they trekked onwards and upwards to the Valley of Desolation- a very desolate place. Sulfur fumes wafted through the valley as students collected gas, water, and rock samples.







Students then hiked towards the Boiling Lake, a hydrothermal lake that boils at 90 degrees celsius with a pH of 3.5. Students stood far away from the lake for fear of falling in. The air was filled with steam, and that was about all that could be seen.



The hike back was long and difficult, but everyone made it back alive. It was an epic adventure that none of the students will forget.


Thursday, June 15, 2017

Dominica Day 4

While Mazi is all for muffin hands, I feel strongly corduory would make a great alternative for skin. However, we both agree that sulfur stained skin is a no-no. Sadly, that is what the Hyrdogeology guys got today. Wotten Waven had two hot tubs in the ground that were filled with sulfur and high in pH.  They sampled the whole area and got one or two extra sample areas than needed. Luckily, after dividing and conquering they have sampling down to a science now. At Micotrin, Mazi used his three syringe method to bring the stop to a quick finish.


The Geomorph guys tagged along and got their first sediment samples. Ankle deep in water, they sieved for sediment, which they will later use for Be-10 dating.

The petrology crew had an adventurous day, beginning with an introduction to the massive Grand Bay Ignimbrite, a pyroclastic deposit sourced from the collapse of an eruption column.


Half of the group then headed to Foundland on a scavenger hunt for plutonic nodules, while the other half sought to tackle the brainteaser that is Fond St Jean.  The Fond St Jean Ignimbrite (pictured below, Karl and Nolan for scale) has been lumped in with the Grand Bay Ignimbrite in the past, but key difference raise skepticism.


Walking the length of the outcrop raise only more questions.  We found distinct lava flows with brecciated margins and laminated eruptive deposits!  The excitement continued as we walked up-section to find a mess of lava flows, lapilli-rich deposits, and scoria, further complicating the story of Fond St Jean.  The day finished on the beach sieving sand, acquiring both zircons and a wee sunburn.
Also, doggos!


Wednesday, June 14, 2017

6/14/17 Dominica Day 3

6/14/17 Dominica Day 3

Would you rather have muffins for hands or corduroy skin? Normally we ponder more scientific inquiries, but today, as we took shelter inside the Trafalgar Falls welcome center, hoping to wait out the torrential downpours that ended up following us for the rest of the day, our attention was focused toward the more implausible. The rain let up and we marched on to the falls where Amanda explained how different materials (in this case welded tuff) weather at different rates, resulting in 125 ft and 75 ft falls. Aftrr team Hydro took samples in a nearby stream, we split into two groups (Hydro/Geomorphology and Petrology) and set off towards more samples.



The Petrology group ventured up the winding roads to Morne Micotrin to hit rocks with hammers, and despite a buffeting wind and substantial rains were successful in collecting unaltered rocks from which thin sections will be made. Team Geomorph braved Dominica's mountainous roads in attempt to finally get some samples. But unfortunately when we arrived on site, locals warned us against the dangerous river conditions and the sieves remained dry and in the car. Both teams headed back early today to start researching literature and have a productive afternoon planning individual projects.

Wohoo!

-Kira & Nolan

Day 2 Dominica Keck Project

6/13/17

Today we headed to Roseau to obtain permits, and everyone got a chance to explore the city and chat with the locals. Then we drove to sulfur springs and took a steep uphill hike through the tropical forest. On the way up, Holli taught us the procedure for collecting water samples. The first stream we stopped at had sediment that was a deep brown reddish color due to hydrothermal alteration, and warm water. After that we moved to a site with lots of hydrothermally altered rocks that contained beautiful sulfur crystals that emitted a strong aroma. We continued hiking upwards to take additional water samples, have a lunch break, and collect gas samples.

Sampling gas from a furmarole. 

After hiking down from sulfur springs, we moved to a hydrothermally altered debris flow scar to collect additional gas samples and discuss potential research project directions for other students. After that, we moved to Scotts head where we had a refreshing dip in the water and took in the view. On the way back, we stopped at an outcrop of lava, which is different from the typical block and ash outcrops that we usually see, and collected some hand samples to wrap up the day.

Keck participants collecting water samples.


-Taryn and Clarissa

Tuesday, June 13, 2017

Day 1 in Dominica - Monday 6/12/17

After our early breakfast, we spent the morning at Springfield learning about the geologic setting and geography of Dominica (Check out the rainbow photo taken from the back veranda). After lunch, we set out for the first day in the field.


We first set out for the Grand Savanne ignimbrite. An ignimbrite is a deposit of a pyroclastic flow, resulting from a collapsed eruption column of an explosive volcanic eruption (see image below). We characterized the stratigraphy exposed along a beach on Dominica's west coast. The bottom layer, characterized by angular fragments, is a block and ash flow, overlain by a fossil soil known as a paleosol. This paleosol exhibited a distinct orange color which is a "baked contact". This baked contact was a result of the transition of ferrous iron to ferric iron, a form of oxidation. The paleosol is overlain by a welded tuff, a compacted ash deposit. Overlying the welded tuff is a pyroclastic flow and ashfall deposit, indicative of numerous eruptions in the area. 


We then traveled to "surprise beach" with an employee from the Office of Disaster Management of Dominica (see below). The principal of the local school shared her first hand account with us of how Surprise Beach had formed. The original coast at this location was a cobble to boulder sized rock beach with no sand. A river less than three kilometers away had experienced a landslide that effectively dammed the river. As the water accumulated behind the loose sediment of the dam, the pressure of the water eventually broke through the dam and washed the sediment into the ocean. Over the course of months sand began to accumulate along the coast, creating a brand new beach for the island of Dominica.



















- Justin & Sarah

Wednesday, May 24, 2017

A Year in Review

Hi, it’s Casey and this is my first blog post in this wonderful group. I just graduated two days ago which is pretty crazy. This year working in the Geomorphology lab has been great. I really enjoyed the variety of tasks that I have done. Prior to this year, I went on a whirlwind of a China trip for research—I got stuck in Beijing for 48 hours on my way to Jiuzhaigou, then flew first class to Chengdu, had a great time in Jiuzhaigou National Park surveying and collecting charcoal samples, and then travelled on my own in Chengdu for a bit and got to see some Pandas at the breeding center. Here is a picture of some terraces in Jiuzhaigou that I have been researching all semester.
I spent last semester working in GIS and mapping the locations of the samples and figuring out what data we had, and what questions about Jiuzhaigou we could solve. Unfortunately, all of the GPS points we took in the field this summer were wrong and didn’t match up with the map so we couldn’t use any of them—but that’s field work for you! Here is a picture of a figure I made last semester with some of the sample points we have.
Originally, Amanda and I were trying to figure out if the terraces are anthropogenic in origin or caused by natural geological processes, but that proved to be too big of a problem to figure out with the data we have. Instead, we have tried to figure out where the loess in Jiuzhaigou came from—the Chinese Loess Plateau, the Chengdu Basin, or the Tibetan Loess Plateau.

The data we have available are OSL, grain size, color, and radiocarbon data. The color data we have are very similar to other areas and didn’t tell us much. The OSL data told us that we have early Holocene ages (ranging approximately 9.53-1.20) thousand years ago. What became really key was the grain size data.  

The past few weeks, I was working with grain size data to create figures modeled after the grain size distribution curves and depth profiles from the 2010 paper “Timing and provenance of loess in the Sichuan Basin, southwestern China” by Yang & Fang et al..
Here’s an example of what most of the grain size data looks like all on one graph:

It has been really exciting because it seems pretty certain that the loess in Jiuzhaigou is coarser than the loess in the Chinese Loess Plateau and in the Chengdu basin which means it must have come from the Tibetan Plateau.
Even though the semester (and my time at Oberlin) has ended, there is still more work to be done on this project. This includes sieving a sample that had a double peaked grain size distribution curve and writing a paper on loess provenance in Jiuzhaigou, China. 
Signing off for the first and last time,Casey