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REFERENCES Radiat. Meas., 37, 161-165. Il Quaternario Congresso AIQUA GèiTZE J., PLèiTZE M. & TRAUTMANN T. (2005) - Structure ltalian Joumal of Quaternary Sciences Il Quaternario Italiano: conoscenze e prospettive 24, (Abstract AIQUA, Roma 02/2011 ), 117 - 119 AITKEN M .J. (1985) - Thermo/uminescence Dating. and Juminescence characteristics of quartz from Roma 24 e 25 febbraio 2011 Academic Press, London, 359. pegmatites, Am. Minerai., 90, 13-21. AITKEN M.J. (1998) -An fntroduction to Opticaf Dating. LANG A., LINDAUER S., KUHN R. & WAGNER G.A. (1996) HIGH-ALTITUDE ENVIRONMENTS AND GlACIERS FLUCTUATIONS Oxlord University Press, Oxlord, 267. Procedures used far opticalfy and infrared stimufate IN THE WESTERN SECTOR OF THE AOSTA VALLEY DURING THE HOLOCENE BELL W.T. (1979)- Attenuation factors lo absorbed dose /uminescence dating of sediments in Heidelberg. AncientTL, 14,7-11. in quartz inclusions far thermoluminescence dating. 1 2 LOWICK S.E., PREUSSER F., PINI R. & RAVAZZI C. (2010) Roberta Pini ·, Amelia Aceti', Federica Badino', Valter Ma~gi , AncientTL, 8, 2-13. 2 34 Underestimation of fine grain quartz OSL dating · Giuseppe Orombelli , Luca Raiteri & Cesare Ravazzi BERSEZIO R., PAVIA F., BAIO M., BINI A., FELLETTI F.& 1 RODONDI C. (2004) - Aquifer architecture of the towards the Eemian: Comparison with C.N.R., Istituto per la Dinamica dei Processi Ambientali, Milano 2 Quaternary alluviaf succession of the Southern Lambro pafynostratigraphy from Azzano Decimo, northeastern DISAT, Università di Milano- Bicocca Basin (Lombardy, ftafy}. Il Quaternario, 17 (211), 361- ftafy. Qual Geochr., 5, 583-590. 'Regione Autonoma Valle d'Aosta, Soprintendenza Beni e Attività Culturali, Aosta 378. MURRAY A.S. & WINTLE A.G. (2000) - Luminescence 4Dip. Biologia ed Evoluzione, Università di Ferrara dating of quartz using an improved sing/e-a/iquot BERSEZIO R, CAVALLI E. & CANTONE M. (2010)- Aquifer *Corresponding author: R. Pini
Among the stratigraphical archives yielding on the history of vegetation development, both at information on the structure of ancient natura! and local and regional scale (OROMBELLI, 1998; AcETI, anthropic landscapes, mires are of particular 2006); interest. These habitats, widespread on the Alpine chain, develop well an crystalline bedrock along - the Crotte Basse mire (2365 m asl, southern wide altitudinal transects, extending !rom the slope .. of Mont Fallére, Aosta: Fig. 2). This colline lo the high-alpine bel!. Detailed geologica! stratigraphical sequence was cored in summer and geomorphological surveys in former 2009 and 201 O, retrieving multiple cores a long the glacialized areas nowadays occupied by mires succession of lacustrine - palustrine deposits. provide interesting data on past glacier extent and Pollen and geochernical analysis and 14C fluctuations and help reconciling the chronology of determinations are stili in progress: available da/a local glacial history, trees immigration and forest testify to an early stage of vegetation development development. (before the Holocene onset) and the subsequent This contribution focuses on recent investigations expansion of forests growing well above their carried aut by the authors on high-altitude mires present day altitudinal ranges. This forest and glacial systems in the western sector of the displacement interacted with Mesolithic hunters Aosta Valley. Relevant sites are: and gatherers and Eneolithic farmers seasonally settling on nearby high-altitude areas for - the foreland of the Rutor Glacier (2510 m asl, subsistence purposes (GUERRESCHI et al., 2010). La Thuile Valley: Fig. 1 ). Here a succession of compressed peat, 14C dated lo 7600 - 9200 cal - a 4m - thick tufa bank, outcropping al 1950 m years BP and intercalated within minerogenic asl on Mont Fallére. This deposi!, rich in wood, deposits, outcrops along the proglacial stream and charcoal, needles and eone imprints, testifies to provides information an former phases of glacial the local development of Pinus syfvestris recession during the first hall of the Holocene and woodlands during the Holocene climatic optimum
Ms. received: January 14, 2011 Testo ricevuto il 14 gennaio 2011 R. Pini et al. 118 High-altitude environments and g/aciers fluctuations .. 119
and allows for comparisons with the 9100 years ca l BP. palaeobotanical information obtained from the Generally speaking, glaciological and palaeobotanical Grotte Basse mire. lnterestingly, this is not the only data from the western Alps are in good agreement tula deposi! found on Mont Fallére: the slopes with those from the Centrai ltalian, the Swiss actually host several tula layers, displaying (HORMES el al., 2001) and the Austrian Alps massive to porous texture and varying in thickness (NICOLUSSI & PATZELT, 2000) and speak for severa) from a few centimeters to several decimeters. phases of climatic optimum during the first hall of the Holocene, characterized by recessional glacier DISCUSSION phases and development of woody vegetation well above the modern treeline. Further studies are The stratigraphic section at the foreland of the needed lo understanding and characterize such Rutor Glacier testifies to prolonged phases of phases and for a better definition of their timing glacier recession framed between the early and and extent: are they short-lived, centennial phases the middle Holocene. Deposition of fine-grained or longer periods of climatic optimum? materia! (lacustrine silt overlied by peat) above glacial sediments can be related to a phase of REFERENCES sudden glacier retreat dated to ca. 9500 years cal BP. The glacier maintained a reduced extent at AcETI A. (2006) - La variabilità climatica least up to ca. 6500 years cal BP, possibly up to neii'Oiocene: studio di torbiere e ambienti d'alta 4900 years cal BP (considering the age of other quota nelle Alpi italiane. Unpublished PhD Thesis peat layers found dislocated nearby the studied in Geologica! Sciences, Univ. Milano - Bicocca, section). Forests never reached the proglacial 115 Rutor area; palaeobotanical data indeed suggest GUERRESCHI A., RAITERI L., DI MAlO P., RAVAZZI C., that Abies alba was widespread along the valley PINI R., GABRIELE P. & BASTER l. (2010)- A new Fig. 1, Panoramic view of the western and centrallobes of the Rutor Glacier. The white li ne indicates the position of the slopes possibly up to an altitude of ca. 2000 - high-altitude Mesolithic sile on Mont Fallére moraine related to the 1980's advance; an arrow shows the outcrop of compressed peat discussed in the text (photo: 2200 m asl, while Pinus cembra developed at (Aosta, northern ltaly). First results on Amelia Aceti, summer 2005). higher altitudes. archaeology, environmental and landscape Panorama dei lobi occidentale e centrale del Ghiacciaio del Rutor. La linea bianca indica la posizione della morena The same chronological interval is testified at the evolution. Convegno MESO 201 O - The s'h deposta dopo l'avanzata degli anni 'BO; la freccia mostra la posizione dell'affioramento di torbe compresse discusse nel Grotte Basse mire. Palaeobotanical and lnternational Conference on Mesolithic in Europe testo {foto: Amelia Aceti, estate 2005). chronological data indicate the local occurrence of (Santander, Spain). Abstract volume. dense conifer forests dominated by Pinus cembra HORMES A., MOLLER B.U. & SCHLOCHTER C. (2001) as early as ca. 8800 years cal BP, accompanied - The Alps with little ice: evidence for eight by Abies alba starting at ca. 8600 years cal BP. Holocene phases of reduced glacier extent in the The full sun aspect enabled the growth of dense Centra/ Swiss Alps. The Holocene, 11, 255-265. conifer forests up to an exceptional altitude (at NICOLUSSI K. & PATZELT G. (2000) - Oiscovery of least up to 2365 m asl). The widespread deposition early Holocene wood and peat on the forefield of of tula at an unusual altitude (1900 - 2150 m asl) the Pasterze G/acier, Eastern Alps, Austria. The on Mont Fallére may represent an evidence for Holocene, 10, 191-199. phases of climatic optimum. In particular, OROMBELLI G. (1998) - Le torbe del Rutor: una radiocarbon dating of the huge carbonatic bank successione significativa per la storia olocenica found on the southern mountain slope established dei ghiacciai e del clima nelle Alpi. Mem. Soc. that tula accumulated quickly between 5800 - Geogr. lt., 55, 153-165.
\
Fig. 2, The Grotte Basse mire: this stratigraphic sequence provides information far the reconstruction of the vegetation and climate history of the area from the last part of the Late Glacial to the present (photo: Diego De Nis·i, summer 2009). La torbiera delle Grotte Basse: questa sequenza stratigrafica illustra la storia della vegetazione e del clima dell'area in esame a partire dalla fine del Tardoglaciale fino ai giorni nostri (foto: Diego De Nisi, estate 2009).
Ms. received: January 14, 2011 Testo ricevuto if 14 gennaio 2011 R. Pini et al. 118 High-altitude environments and g/aciers fluctuations .. 119
and allows for comparisons with the 9100 years ca l BP. palaeobotanical information obtained from the Generally speaking, glaciological and palaeobotanical Grotte Basse mire. lnterestingly, this is not the only data from the western Alps are in good agreement tula deposi! found on Mont Fallére: the slopes with those from the Centrai ltalian, the Swiss actually host several tula layers, displaying (HORMES el al., 2001) and the Austrian Alps massive to porous texture and varying in thickness (NICOLUSSI & PATZELT, 2000) and speak for severa) from a few centimeters to several decimeters. phases of climatic optimum during the first hall of the Holocene, characterized by recessional glacier DISCUSSION phases and development of woody vegetation well above the modern treeline. Further studies are The stratigraphic section at the foreland of the needed lo understanding and characterize such Rutor Glacier testifies to prolonged phases of phases and for a better definition of their timing glacier recession framed between the early and and extent: are they short-lived, centennial phases the middle Holocene. Deposition of fine-grained or longer periods of climatic optimum? materia! (lacustrine silt overlied by peat) above glacial sediments can be related to a phase of REFERENCES sudden glacier retreat dated to ca. 9500 years cal BP. The glacier maintained a reduced extent at AcETI A. (2006) - La variabilità climatica least up to ca. 6500 years cal BP, possibly up to neii'Oiocene: studio di torbiere e ambienti d'alta 4900 years cal BP (considering the age of other quota nelle Alpi italiane. Unpublished PhD Thesis peat layers found dislocated nearby the studied in Geologica! Sciences, Univ. Milano - Bicocca, section). Forests never reached the proglacial 115 Rutor area; palaeobotanical data indeed suggest GUERRESCHI A., RAITERI L., DI MAlO P., RAVAZZI C., that Abies alba was widespread along the valley PINI R., GABRIELE P. & BASTER l. (2010)- A new Fig. 1, Panoramic view of the western and centrallobes of the Rutor Glacier. The white li ne indicates the position of the slopes possibly up to an altitude of ca. 2000 - high-altitude Mesolithic sile on Mont Fallére moraine related to the 1980's advance; an arrow shows the outcrop of compressed peat discussed in the text (photo: 2200 m asl, while Pinus cembra developed at (Aosta, northern ltaly). First results on Amelia Aceti, summer 2005). higher altitudes. archaeology, environmental and landscape Panorama dei lobi occidentale e centrale del Ghiacciaio del Rutor. La linea bianca indica la posizione della morena The same chronological interval is testified at the evolution. Convegno MESO 201 O - The s'h deposta dopo l'avanzata degli anni 'BO; la freccia mostra la posizione dell'affioramento di torbe compresse discusse nel Grotte Basse mire. Palaeobotanical and lnternational Conference on Mesolithic in Europe testo {foto: Amelia Aceti, estate 2005). chronological data indicate the local occurrence of (Santander, Spain). Abstract volume. dense conifer forests dominated by Pinus cembra HORMES A., MOLLER B.U. & SCHLOCHTER C. (2001) as early as ca. 8800 years cal BP, accompanied - The Alps with little ice: evidence for eight by Abies alba starting at ca. 8600 years cal BP. Holocene phases of reduced glacier extent in the The full sun aspect enabled the growth of dense Centra/ Swiss Alps. The Holocene, 11, 255-265. conifer forests up to an exceptional altitude (at NICOLUSSI K. & PATZELT G. (2000) - Oiscovery of least up to 2365 m asl). The widespread deposition early Holocene wood and peat on the forefield of of tula at an unusual altitude (1900 - 2150 m asl) the Pasterze G/acier, Eastern Alps, Austria. The on Mont Fallére may represent an evidence for Holocene, 10, 191-199. phases of climatic optimum. In particular, OROMBELLI G. (1998) - Le torbe del Rutor: una radiocarbon dating of the huge carbonatic bank successione significativa per la storia olocenica found on the southern mountain slope established dei ghiacciai e del clima nelle Alpi. Mem. Soc. that tula accumulated quickly between 5800 - Geogr. lt., 55, 153-165.
\
Fig. 2, The Grotte Basse mire: this stratigraphic sequence provides information far the reconstruction of the vegetation and climate history of the area from the last part of the Late Glacial to the present (photo: Diego De Nis·i, summer 2009). La torbiera delle Grotte Basse: questa sequenza stratigrafica illustra la storia della vegetazione e del clima dell'area in esame a partire dalla fine del Tardoglaciale fino ai giorni nostri (foto: Diego De Nisi, estate 2009).
Ms. received: January 14, 2011 Testo ricevuto if 14 gennaio 2011