Original image at http://earthobservatory.nasa.gov/IOTD/view.php?id=47114&src=eorss-iotd
Nevado Coropuna is the highest volcanic peak in Peru The summit elevation is 6,377 m above sea level. Rather than being a single stratovolcano, Coropuna is a complex of numerous summit cones. The complex covers an area of 240 km2 in southeast-central Peru (see map below. While the exact date of the volcano’s last eruption is not known, lava flows along the northern, southern, and western flanks are thought to have been placed during the early Holocene Epoch, which began approximately 12,000 years ago.
Coropuna also hosts several summit glaciers and ice fields that contrast sharply with the dark rock outcrops and surface deposits at lower elevations. Glacial deposits and lateral moraines on the flanks of Coropuna indicate that glaciers once extended to much lower elevations than observed today. Careful mapping and surface exposure age-dating of these deposits and landforms provides data on the timing of ice advances and retreats in the tropics near the end of the Pleistocene Epoch (extending from about 2.5 million to 12,000 years ago). This information can be compared with other paleoclimate records to obtain a better understanding of how Earth’s climate has changed over geologic time.
The Earth observatory article furthermore drew my attention to an interesting paper on glacial events in the central tropical Andes. A prepress pdf copy is available here. Compelling evidence exists for major shifts in tropical temperature and precipitation during the Late Pleistocene challenging the traditional view of tropical climatic stability. However, estimates of the timing and magnitude of these events remain highly variable. Recent glacial-chronologic research in the Andes of central Peru and northern Bolivia suggested that glaciers there reached their maxima as early as 29–35 thousand years ago and were in recession during the global Last Glacial Maximum (17–25 thousand years ago), implying that the tropics were out of phase with global climate during the last glacial cycle.
The mapping and data collected in the mentioned study seem, however, to indicate that glaciers on Nevado Coropuna advanced and retreated broadly in phase with higher latitude glaciers during the Last Glacial Maximum and Late-Glacial period, suggesting that the climate of southern Peru is closely integrated with that of the mid- and high latitudes in both hemispheres. I invite you to read the paper, if you are interested.
Bromley, G.R., et al.,
Relative timing of last glacial maximum and late-glacial events in the central tropical Andes,
Quaternary Science Reviews (2009),