Mt. Breccioso (1,974 m) is on the southern side of Vai Roveto (the upper valiey of the Liri River) at the Valleionga watershed in Abruzzo (centra! Italy). Near the top six glacial cirques are present: three out of six are oriented to the NE and are part of the southern slope of Valleionga, whereas the other three are oriented towards the west and north-west and lie on Val Roveto. To the West of the three cirques found in Val Roveto, a moraine apparatus is present. It is composed of three different moraines belonging to as many periods of stasis or of glacier re-advance during the retreat phases of the Late Pleistocene last glacial maximum. The two oldest moraines are cut by a small valley. Among the material partially filling this valley there is a sandy tephra, identified as the "Cerchio Tephra" and found also elsewhere , as for instance within the lacustrine sediments of the nearby Fucino Plain. The tephra fall dates to some time before 19,100±650 years B.P, which implies that the moraine of the second retreat phase is older than this date and that the retreat phases of the last glacial maximum advance began before 19,100±650 years B.P., that is well before the period assumed in the literature up to now. The glacial maximum advance would probably be reached before 20,000 years B.P. The Mt. Breccioso last stadial morainic deposits are covered by a loess datable to around 14-15,000 years B.P. Part of these deposits appear to have been involved in movements of the rockglacier type, triggered by the presence of a discontinuous permafrost in the glacial sediments. Because eolian silt is present in even small depressions, it can be assumed that the movement took place in a time just before 14-15,000 years ago. The glacial deposits left by the Mt. Breccioso last glacial episode would therefore be older than this date.
First report on the Mt. breccioso glacial apparatus (Val Roveto, Abruzzo): A contribution for the chronology of the late pleistocene glacial phases [Prima segnalazione dell'apparato glaciale di M. Breccioso (val roveto-abruzzo): Un contributo all'inquadramento cronologico delle fasi glaciali tardo-pleistoceniche]
Giraudi, C.
1997-01-01
Abstract
Mt. Breccioso (1,974 m) is on the southern side of Vai Roveto (the upper valiey of the Liri River) at the Valleionga watershed in Abruzzo (centra! Italy). Near the top six glacial cirques are present: three out of six are oriented to the NE and are part of the southern slope of Valleionga, whereas the other three are oriented towards the west and north-west and lie on Val Roveto. To the West of the three cirques found in Val Roveto, a moraine apparatus is present. It is composed of three different moraines belonging to as many periods of stasis or of glacier re-advance during the retreat phases of the Late Pleistocene last glacial maximum. The two oldest moraines are cut by a small valley. Among the material partially filling this valley there is a sandy tephra, identified as the "Cerchio Tephra" and found also elsewhere , as for instance within the lacustrine sediments of the nearby Fucino Plain. The tephra fall dates to some time before 19,100±650 years B.P, which implies that the moraine of the second retreat phase is older than this date and that the retreat phases of the last glacial maximum advance began before 19,100±650 years B.P., that is well before the period assumed in the literature up to now. The glacial maximum advance would probably be reached before 20,000 years B.P. The Mt. Breccioso last stadial morainic deposits are covered by a loess datable to around 14-15,000 years B.P. Part of these deposits appear to have been involved in movements of the rockglacier type, triggered by the presence of a discontinuous permafrost in the glacial sediments. Because eolian silt is present in even small depressions, it can be assumed that the movement took place in a time just before 14-15,000 years ago. The glacial deposits left by the Mt. Breccioso last glacial episode would therefore be older than this date.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
