Dominica Group is Making Progress!

Hello All! 

We are really getting into the swing of things here and bringing together the Dominica Project. While this project in the past has had a lot of pathways, we are tracking down all of the samples and nailing down what needs to be done. 

As hurricanes are a repetitive part of the erosional processes on the Caribean Islands, we have been interested to see whether a single mass wasting event could be seen in the spatial weathering patterns of the island. We compared the concentrations of fallout radionuclides before and after a single storm event, Hurricane Maria. Fallout radionuclides have different half-life time scales, from millions of years (Be10) to approximately 53 days (Be7). Due to this difference, some will show the influence of the storm and some will not. Our poster that we presented at GSA built on previous research and provided a context of Dominica. This poster showed the results of having an incredibly unique data set of before and after Hurricane Maria samples on the island of Dominica. Since Melinda Quock finished her part of the study on Beryllium10, we had one full set of data to discuss at the conference and a set of beautiful figures. The preliminary Lead210, Cesium137, and Beryllium7 are hoping to be finished within the year to compare to Melindas’s work. 

Here is a current update on our results that we presented at GSA:

 As part of this study, we did GIS analysis which is a mapping tool that allows us to gather high-resolution photos. We found that landslides post-Hurricane Maria tend to be smaller but in higher density around the island and occur at higher elevations. This also leads to the fairly intuitive conclusion that an increase in activity which deforests the island would lead to greater susceptibility to mass-wasting events in the future.

Our main technique at Oberlin is Gamma spectroscopy. This is the part of the study that we are still really working but we do see preliminary data suggest low 137Cs concentration that generally indicates frequent deep landslides.

Melinda’s work at UVM showed us that the 10Be is very important in the story of Dominica but is not influenced by the single storm event.  We do not see systematic variability in the 10Be measurements which suggest that large storms do not affect the long term erosion rates. We also found an interesting result between grain size and location. An increase of 10Bemconcentration seen in coarse-grain samples post-hurricane on the north side of the island indicated that shallow erosion and longer residence time occurred in the southern part of Dominica. Additionally, the lower 10Bem concentration in coarse-grain samples on the southern side suggests lots of gullying and deeply sourced sediment mixed in after the hurricane precipitation ended. Similar north-south trends are seen in 10Bem concentrations in fine-grained sediment but are not as strongly correlated.

We are really excited to keep up with this project and keep discovering fun new elements of Dominica. 

- Liz, Ely and Amelia



 Emily, Paige and Amelia checked out the geology of Phoenix on a hike while at GSA!


Here is our very large Dominica poster!