Francisco Hervé

We present an interpretation of how natural geological and meteorological events influenced the cosmovision of the Mapuche people from south-central Chile. These events resulted from the geodynamic conditions and related processes occurring along the South American active continental margin and the climatic conditions in the region. Their influence on the Mapuche cosmovision is clearly reflected in the most important myths and legends of the Mapuche acquired knowledge. One particularly illustrative myth refers to the combat between two huge snakes, Trentrén and Kaikai. Kaikai, representing the ocean, continuously tries to encroach upon the earth, and Trenten, representing the earth, opposes Kaikai by uplifting the ground to save the inhabitants. This is interpreted as an allegory for what happens during earthquakes when the back-and-forth movement of tsunami waves makes it appear as if the earth sinks and uplifts. Several hills named Trentrén are topographic heights that people can climb to be safe from the effects of the tsunamis. Other myths and legends refer to other characteristic geological phenomena in this particularly active tectonic environment. This article illustrates how the mythical interpretation of geological events configured the understanding of the surrounding world and produced the exquisite body of myths and legends in the Mapuche culture.

El Profesor Johannes Brüggen Messtorff (1887-1953) fue quien, con el libro Fundamentos de Geología de Chile (1950), trazó una primera visión integrada de la geología chilena, que refunde el conocimiento adquirido en 40 años de investigación. A ello deben agregarse unas 60 publicaciones sobre la geología y recursos naturales de Chile y textos didácticos: ?Geología? y ?Tablas para la Enseñanza de la Mineralogía?. El Prof. Brüggen creó el Instituto de Geología en la Facultad de Ciencias Físicas y Matemáticas, primer centro académico de la disciplina en la Universidad de Chile y el país. Allí se formaban los Ingenieros de Minas con mención en Geología. Sus alumnos, los Ingenieros Jorge Muñoz Cristi y Héctor Flores Williams, crearon, junto con Don Humberto Fuenzalida Villegas, la carrera de Geología en esa facultad. Su trascendencia ha sido reconocida con el ?Premio Juan Brüggen?, del Instituto de Ingenieros de Minas, a alumnos destacados de Ingeniería de Minas y el ?Premio Nacional de Geología-Medalla Juan Brüggen?, del Colegio de Geólogos de Chile, a geólogos destacados. Un glaciar en el Campo de Hielo Patagónico Sur y un mineral, brüggenita [Ca(IO3)2·H2O)], llevan su nombre. En 1942, al retirarse, la universidad le rindió un homenaje con la presencia de autoridades del área de la Ingeniería de Minas, egresados y estudiantes de esa carrera y el destacado geólogo argentino Don Horacio J. Harrington. Sin lugar a dudas, el Profesor Johannes Brüggen es el padre de la geología en Chile.

A succession of marine and continental strata on the southern flank of Cerro Cono in the Sierra Baguales, northeast of Torres del Paine, can be correlated with stratigraphic units exposed along the southern border of the Lago Argentino region in Santa Cruz Province, Argentina. These include the Estancia 25 de Mayo Formation and the basal part of the Santa Cruz Formation. The lithological correlation is also confirmed by detrital zircon ages (maximum age of 18.23±0.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a post-Colhuehuapian, pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to 17.8 Ma. Similar ages have been obtained from the basal part of the Santa Cruz Formation at Estancia Quién Sabe in southwestern Argentina, supporting the assumption of a regional continuity between these deposits. A measured lithostratigraphic column is presented and the depositional environment is interpreted as a coastal plain with small, meandering rivers and ephemeral floodplain lakes. The sedimentation coincides with intensified uplift of the Patagonian Andes during the ‘Quechua Phase’ of Andean tectonism, which is reflected by a change in paleocurrent directions from northwest to east-northeast.

Very little work has been done on the stratigraphy and sedimentology of the upper Oligocene-Lower Miocene Río Baguales Formation in the Magallanes Province of southern Chile since its original definition in 1957. A detailed stratigraphic section of the upper part of the formation exposed west of the Baguales River is presented, with an interpretation of depositional environments. This indicates a prograding shoreline in which estuary mouth, middle estuary (lagoon) and bay head delta facies are represented. Large-scale delta slope foresets indicate progradation towards the north and northwest, whereas southeast-directed cross-beds on the delta front probably suggest wave action. The general sequence reflects a gradual sea-level fall largely counteracted by tectonic subsidence, which provided the necessary accommodation space for thick tidal flat and subtidal deposits to accumulate. A longer period of transgression towards the top of the succession may be related to a rise in sea-level or accelerated tectonic subsidence, whereas a major regression commencing at around 23.3 Ma probably coincides with the opening of the Drake Passage and the growth of the East Antarctic Ice Sheet.