Survey of Cryogenic Processes, Periglacial Forms and Permafrost Conditions in South America

DARIO TROMBOTTO

Revista do Instituto Geológico

Winner Graph

Lugar: São Paulo; Año: 2000 vol. 21 p. 33 - 55

0100-929X

This geocryological inventory contributes to the state of the art and to recent advances of Geocryology in the countries of South America with  permafrost occurrence or seasonally frozen ground, where this field of research is of scientific interest. The aim is to increase the knowledge about the areas of the present cryosphere being modified by man and/or suffering changes due to climatic factors. A brief climatic analysis helps to understand the main South American cryogenic regions still poorly known and lacking the corresponding geomorphological  cartography. The survey also emphasizes the fact that very few data are available on altitudinal Andean permafrost degradation caused by global warming processes, which should be monitored for hydrological and other reasons. The main cryogenic processes observed such as cryometeorization, nivation, solifluction, cryoturbation and sorting are described in different lithologies. Some quantifications are given, such as data on solifluction movements and sedimentological methods applied to detect cryogenic phenomena. The latest data of Andean permafrost are summarized. They have recently been obtained with the help of different methodologies, including geophysics and/or through borehole with ground temperature measurements. The most common  Andean cryogenic forms are presented: microforms, patterned ground, felsenmeer, cryoturbation structures, thufurs in moors and solifluction lobes. Characteristic mesoforms of the Central Andes rock glaciers or important elements of a periglacial environment such as sedimentary cryogenic slopes, cryoplanation surfaces or asymmetrical valleys are also described.