LATE QUATERNARY GLACIATION OF COSTA RICA AND GUATEMALA, CENTRAL AMERICA

The highest peaks of Costa Rica and the high plateau of the Altos de los Cuchamatanes in Guatemala were glaciated during the late Pleistocene, attesting to a significantly different climate in the Central American isthmus. In Costa Rica, during the last local glacial maximum (LLGM) ice ~35 km2 in extent covered the highest peaks of the Cordillera de Talamanca, an additional ~2 km2 of ice existed around Cerro Kamuk, and ~6 km2 existed on Cerro de la Muerte. In Chirripó Park, three moraine groups define three glacial stages. The Talamanca stage is represented by the most extensive moraines that reach down to 3040 m. The Chirripó stage moraines reach elevations of 3300 m, and the Talari stage moraines formed at around 3300 and 3420 m. Based on moraine elevations and geomorphological evidence, the paleo equilibrium line altitudes (ELAs) during the Talamanca stage were ~3500 m. Cirque floor elevations around Cerro Kamuk of 3300 m suggest a lower (pre-?)LLGM ELA. Radiosonde data from San José place the modern 0°C isotherm at ~5000 m, which suggests a late Pleistocene ELA depression of ~1500 m. In Guatemala, an ice cap of ~60 km2 existed on the high plateau with ice tongues depositing moraines at elevations of 3470 to 3600 m. The Pleistocene ELA was estimated to be ~3600m.