Deep beneath the ice of East Antarctica’s Wilkes Land, scientists have identified a vast gravitational anomaly that could mark the site of one of the most dramatic collisions in Earth’s history. What first appeared to be a subtle dip in the planet’s gravitational field has since revealed the hallmarks of a massive buried structure — possibly the scar left by a cataclysmic meteorite impact. New insights from a 2018 study published in Earth, Planets and Space suggest that this feature may represent the largest known impact crater on the planet, hidden for millions of years beneath a mile of ice.
Geological Clues from Earth’s Early Bombardment Period
Studies of the anomaly’s size and structure have drawn comparisons with impact events from the Late Heavy Bombardment, a period between 4.1 and 3.8 billion years ago when the inner solar system experienced frequent collisions with large space rocks. The energy released during such an event would have been sufficient to produce a crater the size of the Wilkes Land anomaly. While direct dating of the structure is not possible due to its location beneath the ice, researchers have modeled its dimensions against known meteorite impacts to estimate the likely energy and origin of the event.
A 2015 study used gravitational mapping to argue that the structure’s profile — especially the mascon — closely resembles those formed by meteorite strikes elsewhere in the solar system. These comparisons strengthen the case for a cosmic origin, although the authors of the study note that alternative explanations, such as ancient volcanic or tectonic activity, cannot yet be entirely ruled out without physical sampling.
Competing Hypotheses Still on the Table
Not all researchers are convinced that the Wilkes Land anomaly is the result of a meteorite impact. Other plausible explanations have been proposed, including a volcanic caldera, a sedimentary basin, or a deeply eroded rift valley formed through purely terrestrial processes. These features can also create gravitational anomalies, although the presence of a central mascon makes such alternatives less likely according to proponents of the impact theory.
The main obstacle to resolving the question definitively is the Antarctic ice sheet itself. At more than 1.6 kilometers thick in this region, it prevents any direct geological exploration of the bedrock below. Until technology or logistics allow for drilling or other forms of subsurface sampling at this depth, conclusions will remain based on remote sensing data and comparative modeling.
Implications for Earth’s History
Should the impact origin be confirmed, the implications would be far-reaching. A collision of this scale could have released enough energy to trigger planet-wide environmental effects, possibly even contributing to mass extinction events or long-term climate change. It would also add a major new chapter to our understanding of Earth’s early bombardment history and the role of extraterrestrial forces in shaping the planet’s evolution.
More broadly, the Wilkes Land anomaly highlights how much remains unknown about subglacial geology and the early tectonic history of Earth’s southern hemisphere. If other craters of similar scale exist beneath ice-covered regions or eroded terrains, they may yet be discovered using increasingly precise gravitational and satellite techniques.
