A glacier in disguise
High on Corno Grande, the tallest mountain in the Apennines at 2,912 meters, lies a collection of unusual landforms that look like immense piles of rock debris. These are rock glaciers, slow-moving lobes of angular boulders and soil cemented together by interstitial ice. Unlike the clean ice of a typical glacier, a rock glacier's ice is hidden, insulated by the overlying rock. This stony blanket protects the ice core from summer melt, allowing these features to persist in environments where a traditional glacier would vanish.
Scientists use Ground-Penetrating Radar (GPR) to study these formations. GPR works by sending electromagnetic pulses into the ground and recording the reflections. The speed and strength of the returning signal reveal the subsurface composition—distinguishing between solid rock, loose sediment, and massive ice. Surveys at Corno Grande have detected ice cores up to 20 meters thick inside the rock glaciers. This buried ice is ice, frozen during colder climatic periods like the Little Ice Age and potentially even earlier ice ages. The rock glaciers are in motion, creeping downslope at rates of a few centimeters to a meter per year, driven by the deformation of the ice within.
The disappearing Calderone
Nearby, the Corno Grande massif is where the former as the Calderone Glacier, the southernmost glacier in Europe. Today, its status is more complex. Due to rising temperatures, the Calderone officially fragmented in the summer of 2000 and is now considered two small, debris-covered "glacierets"—a stage between a glacier and a rock glacier. Its lower section is almost completely buried under a layer of debris between 5 centimeters and 1.5 meters thick, which helps insulate the remaining ice.
The transformation of the Calderone provides a visible, real-time example of the processes that formed the larger, more established rock glaciers on the mountain. Scientists closely monitor both the rock glaciers and the Calderone remnants to understand the impact of climate change on high-altitude permafrost in the Mediterranean region. As the ice within these features melts, it can affect the stability of the mountain slopes and alter local water resources. The landscape of Corno Grande, shaped by tens of thousands of years of glacial activity, continues to evolve, showing deep geological time and contemporary climate science.