Bright pink boulders in the Hudson Mountains of West Antarctica have caught the attention of scientists. They’ve uncovered a significant granite formation buried beneath the ice, extending far below the Pine Island Glacier.
These striking rocks stand out against the darker volcanic landscape, sparking curiosity. The big question is: how did granite, typically found deep underground, end up on mountain peaks?
A team from the British Antarctic Survey (BAS) set out to solve this mystery. They combined rock sampling with airborne surveys to dig deeper into what lies beneath the ice.
They discovered that the granite boulders date back to the Jurassic period, around 175 million years ago. This conclusion comes from analyzing the radioactive decay in mineral crystals, indicating that these rocks aren’t connected to the surrounding younger volcanic formations.
The granite must have originated from an older, hidden source. This shifted the team’s focus from surface observations to what’s beneath the ice.
Using airborne surveys, they found large subglacial formations buried underneath the southern Hudson Mountains. These gravity anomalies revealed a structure that measures about 100 kilometers wide and 7 kilometers thick. This subterranean body matches the composition of the pink granite boulders on the surface.
Dr. Tom Jordan, the lead author and geophysicist with BAS, noted that combining geological dating with gravity data allowed them to link the surface rocks to this deep structure. In a recent study published in Nature Communications Earth & Environment, he explained how their findings reveal not only the origin of the boulders but also offer insights into past ice flow patterns.
“It’s remarkable that pink granite boulders spotted on the surface have led us to a hidden giant beneath the ice.”
So, how did these boulders end up where they are? The answer lies in glacial movement. Officially known as “glacial erratics,” these rocks were transported far from their origins by glaciers. While glaciers typically carry debris downhill, shifts in ice thickness and flow can move materials across varied landscapes, even uphill at times.
Dr. Joanne Johnson, a co-author of the study, highlighted that these rocks offer valuable insights into the planet’s changes over time. They serve as records of past ice movements, showing how glaciers have shaped Antarctica.
“Boulders like these contain a wealth of information about what lies deep beneath the ice sheet,” said Dr. Johnson.
Understanding the origin of these granite formations helps scientists learn more about the evolution of the West Antarctic Ice Sheet and its potential future changes due to climate variations.
