http://www.ncdc.noaa.gov/cdo/f?p=519:1:::::P1_study_id:13057
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VARVE=VARVA=Deposito di limo glaciale in serie di piccoli strati di colore
diverso a seconda della stagione di deposizione, utilizzato per la datazione
del quaternario. (Dizionario Garzanti: Piazzadante)
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Wilhelm, B., F. Arnaud, P. Sabatier, C. Crouzet, E. Brisset, E. Chaumillon,
J.-R. Disnar, F. Guiter, E. Malet, J.-L. Reyss, K. Tachikawa, E. Bard, and
J.-J. Delannoy. 2012. 1400 years of extreme precipitation patterns over the
Mediterranean French Alps and possible forcing mechanisms. Quaternary
Research, Vol. 78, Issue 1, July 2012, pp. 1-12. DOI:
10.1016/j.yqres.2012.03.003

ALPI Francesi

SUMMARY/ABSTRACT: Investigation of Lake Allos sediments revealed ~160 graded
layers, interpreted as flood deposits, over the last 1400 yr. Comparisons
with records of historic floods support the interpretation of flood deposits
and suggest that most recorded flood events are the result of intense
meso-scale precipitation events. As there is no evidence for any major
changes in erosion processes in the catchment since the Medieval Warm Period
(MWP), we interpret the Allos record in terms of repeated intense
precipitation events over the last millennium, with a low flood frequency
during the MWP and more frequent and more intense events during the Little
Ice Age. This interpretation is consistent with the pattern of increasingly
humid conditions in the northwestern Mediterranean region. This long-term
trend is superimposed on high frequency oscillations that correlate with
solar activity and autumnal North Atlantic Oscillation (NAO). Finally, a
comparison of flood records across the northwestern Mediterranean region
showed that intense precipitation events in Allos (east of the Rhône Valley)
were out of phase with events in the Cévennes (west of the Rhône) but in
phase with events in eastern Spain. Supported by meteorological analyses,
this suggests an oscillation in atmospheric circulation patterns over the
northwestern Mediterranean.
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STUDY NOTES:

Annual flood deposit thickness data from Lake Allos, Mediterranean 
French Alps, for the past 1360 years. The Lake Allos sediment sequence 
consists of 160 normally graded beds containing markers indicating 
an allochtonous origin for the sediment (terrestrial macro-remains 
and Ca-enrichment).  These beds are interpreted as flood deposits, 
associated with extreme precipitation events in the northwest 
Mediterranean region. Grain size analysis (Malvern Mastersizer S) 
was conducted on core ALO09P13, retrieved from the northern basin 
of the lake. Sampling was at a continuous interval of 5 mm.  

Lake Allos, Mediterranean French Alps: 
44°14.16'N, 6°42.55'E, 2230m elevation, 20m water depth. 


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