Andrzej TYC. 2006. Marian Pulina (1936-2005), créateur de l’Ecole polonaise de karstologie. p. 1-3
Jean NICOD et Jean-Noлl SALOMON. 2006. Marian Pulina : plus de 40 ans de relations scientifiques entre la Pologne et la France. p. 3-6.
Anne-Sophie Perroux. 2006. Intérêt des sédiments détritiques endokarstiques en tant qu’archive naturelle? Discussion autour des dépôts lacustres souterrains (Grottes de Choranche - Vercors). p. 6-20.
Interest of endokarstic detritic sediments as a natural archive? Discussion on underground lacustrine deposits (Choranche Caves – Vercors).
Among the various natural environmental archives, the underground detritic deposits remained hitherto forgotten, in particular for high resolution analyses and treatments. Through the study of the sedimentary accumulation of the Cathedral Lake (Choranche Caves, Vercors), this paper shows the potential of information which these deposits contain. Sedimentary cores were sampled in the lake, various data are measured (granulometry, spectrocolorimetry, magnetic susceptibility and gray level imagery), then submitted to statistical processing (PCA, Passega images...) and signal treatment (wavelet decomposition). The stratigraphy of charcoal fragments trapped in the sediment and dated by the 14C method, does not appear sufficiently coherent to propose a satisfying age-depth model. Only some dates make it possible to suppose that the sedimentary filling of the lake covers at least the 4000 last years, with an average rate of sedimentation estimated at 1.87 mm/yr. The other results of this work make it possible to understand transport and deposition dynamics of the sedimentary particles in an endokarstic lake, in particular with regard to flooding episodes. The Cathedral lake has a binary functioning, with mainly a fine sedimentation (decantation), punctually stopped by flooding episodes, which on their turn have two different dynamics (brutal or progressive phenomena in sedimentation). Lastly, the study of various signals highlights a great number of sedimentation control factors; these factors seem to act mainly on “small” time scales (more than 80 % of the granulometric signal variation are linked to phenomena with a period inferior to 40 years, according to the chronological framework supposed in the first assumption). This work carried in Choranche shows that endokarstic detritic sediments contain high resolution archives of the environmental evolutions. Subject to a chronological positioning more precise than the one we have today, paleoenvironmental interpretations and reconstitutions will make it possible to go further in their reading.
KEY WORDS: Natural archive, detritic sediments, endokarstic lake, infilling, signal, high resolution, Choranche caves, Vercors.
Laurent Bruxelles, David Colonge et Thierry Salgues. 2006. Morphologie et remplissage des dolines du Causse de Martel d’après les observations réalisées au cours du diagnostic archéologique de l’aérodrome de Brive-Souillac (Corrèze et Lot). p. 21-32
Doline morphology and filling in the Causse of Martel based on the observations realized during the archaeological diagnosis of the Brive-Souillac airfield (Corrиze and Lot, France).
An operation of archaeological diagnosis was led by the INRAP (national institute for preventive archaeological researches) on the Causse de Martel. On this occasion, 610 trenches with bulldozers were done, mainly localized in the bottom of dolines. The morphology of the depressions presents most often a pronounced asymmetry. We observe a gently dipping slope underlain by sandy alterites. On the opposite side, a steep corrosion rim developed in bathonian limestones. The sections show an accumulation of several meters of different sediments. At the base, we find periglacial deposits (stratified scree and yellow silt) which fossilized some archaeological remains of the middle Paleolithic. Just above an erosional unconformity, brown clays with calcareous gravel are found. Thanks to the presence of archaeological material, we date the emplacement of this level to be between the Protohistory and the medieval age. Finally, one or two meters of modern agricultural colluviums end the sequence. These observations put in evidence at least two main periods of infilling of these dolines. They correspond to two major phases of hillside imbalance. The first one has a climatic origin (Periglacial) and the second a human origin (clearings and agriculture). These accumulations are separated from the underlying deposits by distinct erosion surfaces, which can be linked to a reactivation of the karstic undercapture and the erosion of a part of the filling. This functioning corresponds to periods during which the colluviums are less abundant, indicating a certain stability of hillsides. Finally, the morphology of the rock layers and the geometry of the deposits show that the karstic landscape, which was clearly more accentuated before the Periglacial and even before Protohistory, underwent an important filling. Today, the dolines are partially filled and show with a flat bottom.
KEY WORDS: doline, filling, Quaternary, archaeology, Palaeolithic, Protohistory, anthropisation, Causse of Martel, Quercy, France.
Stéphane Héritier. 2006. Phénomènes karstiques et tourisme dans les parcs nationaux de l’Ouest canadien : la mise en valeur progressive d’un patrimoine naturel. p. 33-48.
The karst phenomenon and tourism in western canadian national parks: the progressive promotion of a natural heritage.
Canadian national parks located in the Rockies and in the Selkirk range (Alberta and British Columbia) can be considered as places of major interest to focus research on the Canadian parks. Since the beginning of the National Park System in 1885, transcontinental railway companies have promoted tourism activities within national parks based on scenery and natural sites. With more than 10 millions visitors per year, these parks have become a favorite tourist destination for many Canadian and Americans. Nature and different natural processes, such as falls, lakes, canyons and caves, karst springs, glacial processes and postglacial landforms, are thus considered as tourist resources [Sanguin & Gill, 1990]. The present paper analyzes how karst landscapes have become a significant part of the tourist dynamics within the Canadian national parks. These landforms and processes seem to be involved in a tourism process based on the promotion of the entire environment, its dynamics and its mechanisms. The final point will be to interrogate the way in which karst processes and landforms have become « subjects » that offer opportunities for tourism development through the terms and conditions of their promotion as a support for parks attractivity. A century of tourism development has enlarged the scientific opportunities for visitors, introducing the latter to the geomorphologic as well as the human heritage. Since the end of the 1960s, coordinated regional programs have been developed (tourism management, interpretation, etc.) between the mountain parks and the tourism sector (railway companies, private interpreters, businesses, etc.). The use and the promotion of karst has been gradually developed, especially for endokarstic and hydrokarstic forms and processes, like mountain scenery, karst lansdcapes have become a foundation for nature tourism. As parts of national parks, the hydrokarst and the canyons… are geomorphosites [Reynard & Panizza, 2005] which are protected for their ecological value. Nowadays, they are also preserved for their scientific and esthetic values but also because they are considered as significant parts of the tourism industry. Since the 1960s, scientific studies have incited actors to develop a global approach in environment management that converges on « ecological integrity », a major concept for Parks Canada. In the end, the differing values (aesthetic, cultural, economic, ecological, scientific) identified by Reynard [2005] converge in the concept of «heritage value», understood as the synthesis of the identified values for geomorphosites, based either on a mathematic evaluation or on a synthetic analysis. Regarding the history of karst sites promotion within the Canadian mountain parks, and the recent proposal concerning a restrictive karst policy [Horne, 2004-b], it seems the karst phenomenon has obtained a genuine economic, touristic and heritage status.
KEYWORDS: national parks, Canada, protected areas, karst, heritage value, heritage promotion.
Jean SESIANO. 2006. Evolution actuelle des phénomènes karstiques dans la Cordillera de la Sal (Atacama, Nord Chili). p. 49-54
New observations about the very slow present-day evolution of karstic phenomena in the Cordillera de la Sal (Atacama, Chile).
A second visit to the salt diapir in the Cordillera de la Sal, on the western margin of the Salar de Atacama was conducted 9 years after the first one. We noticed practically no change in the landscape morphology in that very arid region. A stainless steel piton driven at the base of a small cliff of rock salt was used to measure the salt dissolution rate. It did not show any extra thickness loss. A new passage system, partly underground, was discovered and mapped. Several swallow holes were observed, most of them half-filled with eolian sand. Undoubtedly they become active as soon as enough rain is collected at the surface. The underground water flows probably in the direction of the Salar in order to feed the water-table in the post evaporitic sediments, following the prominently N 140o oriented fracture system of the Cordillera de la Sal. Under the present climatic conditions, which are hyper-arid, observations on a time scale longer than the decade are essential to see changes in morphology.
KEY-WORDS: salt diapir, karst, Atacama, Chile. |
