The highest peak outside Asia shows glacial erosion patterns at extreme altitude. Ice core studies from its glaciers track Andean climate changes over 10,000 years in unprecedented detail.
Bjørn Christian Tørrissen, CC BY-SA 4.0, via Wikimedia Commons
The Sculpted Giant
Cerro Aconcagua, the highest mountain in the Western Hemisphere, is not a volcano, a common misconception. It is a massive up-thrust block of rock, created by the subduction of the Nazca Plate beneath the South American Plate around 8 to 10 million years ago. Its composition is a mix of volcanic rocks like lavas and breccias, layered with older marine sediments from a Triassic-era basin. This complex geology has been sculpted by ice for millennia.
The mountain has several significant glaciers. The largest is the Ventisquero Horcones Inferior, which flows for about 10 kilometers down the south face to an elevation of 3,600 meters. Other major glacier systems include the Ventisquero de las Vacas Sur and the Glaciar Este/Ventisquero Relinchos system, each about five kilometers long. The most famous, however, is the Ventisquero de los Polacos, or Polish Glacier. It covers the northeastern face and is a well-known climbing route, first ascended by a Polish expedition in 1934.
During the Pleistocene, glaciers were far more extensive, carving out the deep, U-shaped valleys seen today. Evidence from the Last Glacial Maximum suggests a massive ice stream network existed, with some glaciers stretching over 112 kilometers. Today, a different type of ice feature dominates many areas: rock glaciers. In the arid climate of the Dry Andes, the area of debris-covered glaciers and rock glaciers is similar in size to that of uncovered "clean" ice glaciers. These masses of frozen rock and ice are significant water sources for the region.
An Icy Archive
The glaciers of the high Andes are natural archives of past climate. By drilling deep into the ice and extracting cores, scientists can analyze trapped air bubbles, dust, and chemical isotopes to reconstruct past atmospheric conditions. While the oldest continuous ice cores from Antarctica reach back 800,000 years, Andean glaciers provide high-resolution records of regional climate changes.
Studies of past glaciations on and around Aconcagua reveal a complex history. Geochronological analysis indicates significant glacial advances occurred during the Late Glacial period, between approximately 14,700 and 11,600 years ago. A much larger glaciation event is dated to around 32,000 years ago, pre-dating the global Last Glacial Maximum. These findings suggest that climate shifts in the Andes were driven by factors like changes in tropical circulation and summer precipitation, and global temperature.
The ice holds records of temperature and other data. Layers of ash correspond to volcanic eruptions, and pollen and dust reveal changes in vegetation and wind patterns. This detailed stratigraphy allows researchers to build a timeline of environmental shifts with remarkable precision. The ongoing study of these ice cores helps understand the mechanics of climate change in South America and for modeling future scenarios in a warming world.
💡Fun Facts
Aconcagua is not a volcano, but its structure is composed of volcanic rocks from a period when it was active, millions of years ago.
The mountain has two summits, a north and south peak, connected by a one-kilometer-long ridge called the Cresta del Guanaco.
In 1985, the mummified remains of a seven-year-old Inca boy were discovered at an elevation of 5,167 meters, a ritual sacrifice site.
A Polish expedition made the first ascent of the eastern face in 1934, giving the now-famous Polish Glacier its name.
Aconcagua Provincial Park is open year-round, but the main climbing and trekking season is from mid-November to March.
Admission
A permit is required to enter the park for any activity. Fees vary based on the length of stay (one-day, three-day, seven-day, or full ascent) and nationality.
Accessibility
The terrain is rugged, high-altitude, and strenuous. Trails are unpaved and steep. It is not accessible for individuals with mobility impairments.
