Models of how the #Antarctic ice sheet may have looked over the past 20 kyrs helped us track where the cobbles came from.

Knowing ice flow paths and what rocks lie underneath Antarctic glaciers today (e.g. how rough or smooth they are) helps us improve models of future sea level rise. 6/6

Our results revealed a negative gravity anomaly under Pine Island Glacier 👉a lower density rock must extend to the edge of the Hudson Mountains.

We had wondered if this gravity anomaly indicated a granite - the presence of granite cobbles confirmed our hunch!
5/n #geology

We studied composition of the cobbles & used geophysics to find out more about what lies under the glacier.

👀Geophysics detects properties of rocks and "sees" through ice. Radar, gravity and magnetics detectors on @bas.ac.uk #aircraft reveal if they contain magnetic minerals. 4/n #geophysics 🧪

We found lumps of the same pink granite 🪨embedded in the bedrock of one of the mountains. 👉 So there must be lots of granite nearby, but under the ice where we can't see it! 🤔 3/n #geology 🧪❄️🥼

Pink and grey granite cobbles lie all over the Hudson Mountains next to Pine Island Glacier in remote West #Antarctica👇 They were carried there by flowing rivers of ice - glaciers🧊 - that then retreated around 8,000 years ago. 2/n #geology