Colluvial deposits – proxies for climate change and cultural chronology. A case study from Tigray, Ethiopia
Changement climatique ; Chronostratigraphie ; Colluvions ; Ethiopie ; Géoarchéologie ; Holocène ; Paléo-environnement ; Paléosol ; Phytolithe ; Tigray ; Utilisation du sol ; Zone intertropicale
Chronostratigraphy ; Climatic change ; Colluvium ; Ethiopia ; Geoarchaeology ; Holocene ; Land use ; Palaeo-environment ; Palaeosol ; Phytolith ; Tropical zone
, paleosols and phytoliths in Yeha illustrate existing links between ancient land-use being part of the Ethio-Sabaean culture and different stratigraphic units. While the study of colluvial deposits provide answers on cultural chronology and land-use-changes
, the study of paleosols buried by or formed within these colluvial deposits makes it possible to demonstrate Holocene climate change along the intertropical convergence zone (ITCZ)
Changing mountain permafrost from the 1970s to today – comparing two examples from Niwot Ridge, Colorado Front Range, USA
Années 1970-2009 ; Changement climatique ; Colorado ; Etats-Unis ; Exposition de versant ; Gélifluxion ; Modèle ; Montagne ; Niwot Ridge ; Pergélisol ; Périglaciaire ; Rocky Mountains ; Température du sol ; Tomographie de résistivité électrique
Climatic change ; Colorado ; Electrical resistivity tomography ; Gelifluction ; Model ; Mountain ; Periglacial features ; Permafrost ; Rocky Mountains ; Slope exposure ; Soil temperature ; United States of America
at 3600 m during 1970, if so, permafrost degradation on south facing slopes on Niwot Ridge was not driven by recent climate change. However, north-facing slopes do cover permafrost, and certainly did in the 1970s, they are most probably affected by climate
warming as already documented by a changing hydro-chemical signal in nearby streams.
The bolsas mostly are accompanied by a large number of Quaternary reef terraces in East Cuba. Raised beaches are not only the result of eustatic changes but also of isostatic or tectonic processes. Tectonic uplifts occurred frequently during
the Cainozoic era in Cuba and in the Caribbean as well. Both of these processes – uplifts and sea-level changes – involve a particular problem closely linked with the reconstruction of bolsa stages. That means it is necessary to differentiate not only regionally
but also chronologically. Evidence suggests that the sediments of the bolsas keep records of a long landscape history and even of eustatic medium-term sea-level changes. The AA. assume that the conditions of the sedimentation changed gradually during
, the study area might have experienced repeated phases of landscape stability and initial soil development during the latest phase of the Upper Pleistocene before a change in hydrological conditions initiated a distinctive erosional period that prevailed
from Central Saxony. The AA. obtained information about a climatic shift from more humid to more arid conditions during the late Pleniglacial, due to changes in the landscape dynamics of the study area : At ca. 30 ka, braided river floodplain