I am Amy Lally, a fourth year QUADRAT PhD student in Geography. My research study site is Breiðamerkurjökull, an outlet glacier on the southside of the Vatnajökull ice cap (Figure 1). I have been lucky enough to undertake four field trips to this incredible glacier during my project so far. Unfortunately, like all other glaciers around the world it is thinning and retreating at unprecedented rates in response to human induced climate change with retreat rates of up to 500 m since the start of my project in 2020.
It is important for us to understand how glaciers and ice sheets behave in the present day and how they have behaved in the past, so that we can better predict their future behaviour. My research focuses on the glacial drainage system and meltwater processes. Since it is logistically challenging to see into and under the ice, we turn to glacial geomorphology for answers.
What is Glacial Geomorphology?
Glacial geomorphology is the study of processes and landforms produced by glaciers and ice sheets. Each glacial setting will have a specific set of processes that shape distinct landforms, collectively forming a glacial landscape. These landscapes can differ depending on the glaciological conditions. For example, the glacial geomorphology at an Alpine glacier will appear different from marine-terminating sections of the Greenland Ice Sheet, as these have different process-environments. An example of the landscape recently uncovered at Breiðamerkurjökull can be seen in Figure 2.
As I previously mentioned, directly observing processes is logistically challenging, and in the case of ancient ice sheets like the British-Irish Ice Sheet, the environment no longer exists. To reconstruct glaciological conditions and infer process environments, we examine the landscape left behind as the ice retreats, by analysing the type, morphology, and spatial distribution of landforms.
Methods and Data Collection
We use uncrewed autonomous vehicles (UAVs) to collect data across the ice-margin and the associated foreland, from this we create ~ 6cm resolution orthomosaics and digital elevation models which allow us to visualise the topography of the area and map individual glacial landforms in ArcGIS Pro. During each field campaign, detailed field mapping is undertaken to support the interpretations of the remote-sensing data.
To accompany our UAV data, we also conduct ground-penetrating radar (GPR) surveys. GPR is a geophysical method that uses electromagnetic waves to image subsurface features and structures. We collect GPR data across landforms to examine their internal structures, which can provide information on the depositional environment and processes governing their formation. We also collect profiles across the ice (Figure 3) which can help us identify englacial and subglacial features such as meltwater channels and debris-filled fractures.
Research Findings
During my PhD, I repeatedly mapped the glacial geomorphology of the emerging landscape at Breiðamerkurjökull four times over a three-year period, to improve our understanding of landform evolution during rapid ice margin retreat. During the first field trip of my PhD in September 2021, we found an esker melting out of the ice margin. An esker is a sinuous ridge of sand and gravel, deposited by meltwater in a tunnel within or under the ice. We monitored the emergence of this feature over the coming years to examine what controls their formation and preservation potential. This research was recently published and can be read here: https://doi.org/10.1002/esp.5664
My research highlights the value of high-temporal resolution studies, allowing us to capture the evolution of landforms, like englacial eskers, to ground-truth GPR interpretations and improve our understanding of landform process-form relationships.
Upcoming Talk
If you want to hear more about my research, I will be giving a talk as part of the NI Royal Geographical Society Lecture Series on Thursday 16th of November 7-9pm in the Elmwood Building.
