For years, scientists have been intrigued by pink granite boulders scattered in the Hudson Mountains of West Antarctica. A recent study, published in October 2025, might have cracked the case. Researchers discovered these boulders come from a massive granite formation buried beneath the Pine Island Glacier, measuring nearly 100 kilometers wide and 7 kilometers thick.
Led by the British Antarctic Survey, the team used a technique called U-Pb zircon geochronology. This method reveals the age of rocks by analyzing the radioactive decay of zircon crystals. They found that the granite boulders formed around 175 million years ago during the Jurassic Period.
Back then, Antarctica was not the icy land we see today. It was a warm, forested region home to various dinosaurs, like the 7-meter-long Cryolophosaurus, a relative of the famed T.rex, and Glacialisaurus, a long-necked dinosaur that could also walk on two legs.
Today, only a few hardy lichens, mosses, and the occasional snow petrel inhabit the area.
While dating the boulders gave some clues, the real breakthrough came from aerial surveys conducted by the BAS. These surveys revealed gravity anomalies above the Pine Island Glacier. By analyzing the density of rocks beneath the ice, researchers could confirm the presence of the granite body, revealing where the pink boulders originated.
Tom Jordan, the study’s lead author, noted the significance of this discovery: “It’s remarkable that pink granite boulders led us to a hidden giant beneath the ice.” This not only solves the mystery of the boulders but also enhances our understanding of the glacier’s past and its potential future changes.
This study opens a window into how the Pine Island Glacier has moved over time, likely picking up and moving these rocks during periods when the ice sheet was thicker. Understanding these processes is crucial as this area has seen some of the fastest ice loss in Antarctica.
The geological features beneath the Pine Island Glacier influence how it slides over bedrock and how meltwater drains underneath. The insights from this study will improve models predicting changes in the West Antarctic Ice Sheet, which are critical for understanding sea level rise linked to rapid glacial melting.
Joanne Johnson, a co-author and geologist at BAS, emphasized the importance of these rocks: “They record major changes in Earth’s systems over time.” Such boulders are vital for grasping how Antarctica’s landscape has evolved.
The study is published in Nature Communications Earth and Environment. This discovery not only unravels the mystery of the pink boulders but also underscores the significance of geological research in understanding our planet’s history and future.
