- Email: [email protected]
Holocene Environmental and Cultural Dynamics in the Mountain Valley of Stymphalia (NE-Peloponnese, Greece)
198
Abstracts / Quaternary International 279-280 (2012) 121–232
THE “GREAT LATERAL MORAINE”: PROBLEMS OF READING LATE QUATERNARY GLACIER CHANGE IN LANDFORMS AND SEDIMENTS, KARAKORAM MOUNTAINS, INNER ASIA Kenneth Hewitt. Wilfrid Laurier University, Canada E-mail address: [email protected]
Pronounced trimlines, observed along the ablation zones of most Karakoram glaciers, have been grouped together as the Great Lateral Moraine (GLM), formerly equated with the “1850 moraines” in the Alps. Emerging evidence points to diverse glacial and non-glacial origins of these features. The Little Ice Age and subsequent thinning created an appearance of uniformity and climatic relations that break down on analysis. Examples are shown to involve a longer term and more complex series of events. They are part of a range of problematic readings in late Quaternary reconstructions that include questionable assumptions about, or misidentification of, “glacial lakes”, moraines and tills, glacitectonic deformation, basal tillites, sediment fans, paraglacial sedimentation and tectonically controlled river terraces. Issues of sediment diagnostics, agedeterminations, form and process are critical for glaciation chronologies and put a number of them in doubt. A complicating factor is the role of hundreds of recently identified large, post-glacial landslides and related geomorphic developments. A revised approach to the ‘GLM’ and other Holocene landforms is developed.
geomorphological map of the plain reveals three main Karkheh (palaeo) channel belts (Kh1, Kh2, Kh3) corresponding to successive shifts. To the south, the Karkheh floodplain is bordered by a Karun megafan. Geological investigation showed that the latter played an important role in the Holocene development of the Lower Mesopotamian Plain through its relation with the Shatt el-Arab outlet of the rivers Tigris and Euphrates. Two Karkheh river shifts are documented in our datasets, both taking place within the last 1500 years. The first avulsion regards a shift from channel belt Kh1, once a tributary of the Karun, to the straight riverbed Kh2, taking place at least after 1240-1310 cal BP according to geological data. This is in agreement with the distribution of archaeological sites, which suggests that the palaeochannel belt Kh2 was active at least from the Early Islamic period (640 AD). The second avulsion, from Kh2 to Kh3, is documented in historical sources and happened in a single night event in the year 1837. The historical date of this avulsion event fits well with the geological data, showing that sedimentation by palaeochannel belt Kh3 started at the earliest in 150 cal BP. Both river shifts were strongly influenced by human activity, whereby an artificial irrigation canal took over the entire river flow from the main channel belt. Satellite imagery shows that reactivation of the Kh2 riverbed and its irrigation canals can be attributed to the construction of an artificial canal bypassing the second avulsion point some time after 1968. HUMAN IMPACT ON ALLUVIAL FAN DEVELOPMENT IN A SEMI-ARID REGION
HOLOCENE ENVIRONMENTAL AND CULTURAL DYNAMICS IN THE MOUNTAIN VALLEY OF STYMPHALIA (NE-PELOPONNESE, GREECE)
Vanessa M.A. Heyvaert. Geological Survey of Belgium, Belgium
Christian Heymann. GS Human development in landscapes - Kiel Universi, Germany
Alluvial fans are cone-shaped depositional landforms, typically located at mountain fronts where rivers are released from their confinement and discharge conditions promote frequent avulsions. This paper discusses the development of a series of alluvial megafans deposited by the Karun, Jarrahi and Diyala rivers along the piedmont of the Zagros Mountains in Iran and Iraq. Data derived from geological (facies interpretation of undisturbed boreholes) and archaeological surveys, remote sensing (notably CORONA and Landsat imagery) and historical sources are combined to study these (palaeo) fans on different timescales. A present-day equivalent is the active Jarrahi fan. It is characterised by a ‘true’ distributary channel network (all channels are simultaneously active), which is an unlikely situation under natural conditions. Radiocarbon dating of marsh deposits underlying the fan deposits reveal a date of 1520-1600 AD. This date thus sets a maximum age for the onset of fluvial deposition and suggests rapid progradation. Recent high sedimentation rates are confirmed by the analysis of a sequence of satellite images, revealing a fan progradation rate of 2.6 km2 a 1 over the last 68 years. Remote sensing data also show that levee breaks are key locations for the construction of inlets to irrigation canals on the fan. It is suggested that the management of these levee breaks by humans initiate rapid fan progradation through preventing avulsions and facilitating deposition along extremely low gradients. Judging from the presence of extensive irrigation patterns, human activities must also have played an important role in the development of the other (palaeo) fans in the region.
E-mail address: [email protected]
Known from the ancient Heracles myth of the Zeus’ son slaying the Stymphalian birds, the mountainous region of Stymphalia (22 27’E/ 37 51’N) is an ideal site to study the environmental history of the area by combining the climate archive of lake sediments with the historical and archaeological record of the nearby ancient settlement of Stymphalos. Above all, we aim to distinguish the natural versus human-induced environmental change and compare the results to other regions in the Northern Peloponnese. At Lake Stymphalia a 15.52 m long sediment core (STY-1) was retrieved during a first field campaign in March 2010 using a piston coring device on a floating platform. The upper, Holocene part of the core (0-8.68 m) is characterized by light gray to gray clays/carbonate mud interpreted as open water facies that is intercalated with fine- to coarse sand units representing debris flows from adjacent slopes and/or input from torrential rivers. Late Holocene reddish gray to brown clay units indicate intense erosion of red soils in the catchment area. Since organic content is low throughout the core, radiocarbon dates on bulk sediment samples were determined. Sample KIA-42912 from a black ash layer in the upper part of the core (1.495 m) was dated to an age of 1608-1570 cal BC. This black ash layer might be of volcanic origin as it is indicated from magnetic susceptibility. Further environmental analyses include geochemical methods (i.a., X-ray fluorescence, loss-on-ignition, CNS). The climatic and environmental variability of the ancient Arcadian region, as it is documented in the lacustrine sediment core STY-1, is connected with human development in the karst polje of Stymphalia. Historical sources and archaeological findings indicate settlement activity since at least the 5th century BC at Stymphalos. Hence, the spatiotemporal patterns of land use and water management and the effect of climate on the environmental development of the region are reconstructed. HUMAN-TRIGGERED AVULSION IN A SEMI-ARID REGION (KARKHEH RIVER, LOWER KHUZESTAN, IRAN) Vanessa M.A. Heyvaert. Geological Survey of Belgium, Belgium E-mail address: [email protected]
In this paper, the role of human interference on the floodplain history of the river Karkheh, located in the Lower Khuzestan plain is investigated by combining geological with historical and archaeological data. The
E-mail address: [email protected]
BRITISH ICE SHEET DYNAMICS INFERRED FROM NORTH ATLANTIC ICERAFTED DEBRIS RECORDS SPANNING THE LAST 175 000 YEARS Fiona Hibbert. University of St Andrews, United Kingdom E-mail address: [email protected]
Sediment core MD04-2822 from the Rockall Trough, northeast Atlantic, provides lithological evidence for the expansion of the British Ice Sheet (BIS) onto the Hebridean margin during both the penultimate (Marine Isotope Stage (MIS) 6/Wolstonian/Saalian) and last glaciation (Devensian/ Weichselian). A composite chronology is constructed using: (i) the benthic foraminiferal oxygen isotope record, matched to an orbitally tuned stacked record of global ice volume (SPECMAP); (ii) the synchronisation of the planktonic foraminiferal (Neogloboquadrina pachyderma (sinistral)) and ITRAX XRF Ca records to the Greenland ice core (NGRIP) back to ca. 123 ka; and (iii) the synchronisation of the same N. pachyderma (sinistral)) and ITRAX XRF Ca records to the atmospheric methane record of the Antarctic
Abstracts / Quaternary International 279-280 (2012) 121–232
THE “GREAT LATERAL MORAINE”: PROBLEMS OF READING LATE QUATERNARY GLACIER CHANGE IN LANDFORMS AND SEDIMENTS, KARAKORAM MOUNTAINS, INNER ASIA Kenneth Hewitt. Wilfrid Laurier University, Canada E-mail address: [email protected]
Pronounced trimlines, observed along the ablation zones of most Karakoram glaciers, have been grouped together as the Great Lateral Moraine (GLM), formerly equated with the “1850 moraines” in the Alps. Emerging evidence points to diverse glacial and non-glacial origins of these features. The Little Ice Age and subsequent thinning created an appearance of uniformity and climatic relations that break down on analysis. Examples are shown to involve a longer term and more complex series of events. They are part of a range of problematic readings in late Quaternary reconstructions that include questionable assumptions about, or misidentification of, “glacial lakes”, moraines and tills, glacitectonic deformation, basal tillites, sediment fans, paraglacial sedimentation and tectonically controlled river terraces. Issues of sediment diagnostics, agedeterminations, form and process are critical for glaciation chronologies and put a number of them in doubt. A complicating factor is the role of hundreds of recently identified large, post-glacial landslides and related geomorphic developments. A revised approach to the ‘GLM’ and other Holocene landforms is developed.
geomorphological map of the plain reveals three main Karkheh (palaeo) channel belts (Kh1, Kh2, Kh3) corresponding to successive shifts. To the south, the Karkheh floodplain is bordered by a Karun megafan. Geological investigation showed that the latter played an important role in the Holocene development of the Lower Mesopotamian Plain through its relation with the Shatt el-Arab outlet of the rivers Tigris and Euphrates. Two Karkheh river shifts are documented in our datasets, both taking place within the last 1500 years. The first avulsion regards a shift from channel belt Kh1, once a tributary of the Karun, to the straight riverbed Kh2, taking place at least after 1240-1310 cal BP according to geological data. This is in agreement with the distribution of archaeological sites, which suggests that the palaeochannel belt Kh2 was active at least from the Early Islamic period (640 AD). The second avulsion, from Kh2 to Kh3, is documented in historical sources and happened in a single night event in the year 1837. The historical date of this avulsion event fits well with the geological data, showing that sedimentation by palaeochannel belt Kh3 started at the earliest in 150 cal BP. Both river shifts were strongly influenced by human activity, whereby an artificial irrigation canal took over the entire river flow from the main channel belt. Satellite imagery shows that reactivation of the Kh2 riverbed and its irrigation canals can be attributed to the construction of an artificial canal bypassing the second avulsion point some time after 1968. HUMAN IMPACT ON ALLUVIAL FAN DEVELOPMENT IN A SEMI-ARID REGION
HOLOCENE ENVIRONMENTAL AND CULTURAL DYNAMICS IN THE MOUNTAIN VALLEY OF STYMPHALIA (NE-PELOPONNESE, GREECE)
Vanessa M.A. Heyvaert. Geological Survey of Belgium, Belgium
Christian Heymann. GS Human development in landscapes - Kiel Universi, Germany
Alluvial fans are cone-shaped depositional landforms, typically located at mountain fronts where rivers are released from their confinement and discharge conditions promote frequent avulsions. This paper discusses the development of a series of alluvial megafans deposited by the Karun, Jarrahi and Diyala rivers along the piedmont of the Zagros Mountains in Iran and Iraq. Data derived from geological (facies interpretation of undisturbed boreholes) and archaeological surveys, remote sensing (notably CORONA and Landsat imagery) and historical sources are combined to study these (palaeo) fans on different timescales. A present-day equivalent is the active Jarrahi fan. It is characterised by a ‘true’ distributary channel network (all channels are simultaneously active), which is an unlikely situation under natural conditions. Radiocarbon dating of marsh deposits underlying the fan deposits reveal a date of 1520-1600 AD. This date thus sets a maximum age for the onset of fluvial deposition and suggests rapid progradation. Recent high sedimentation rates are confirmed by the analysis of a sequence of satellite images, revealing a fan progradation rate of 2.6 km2 a 1 over the last 68 years. Remote sensing data also show that levee breaks are key locations for the construction of inlets to irrigation canals on the fan. It is suggested that the management of these levee breaks by humans initiate rapid fan progradation through preventing avulsions and facilitating deposition along extremely low gradients. Judging from the presence of extensive irrigation patterns, human activities must also have played an important role in the development of the other (palaeo) fans in the region.
E-mail address: [email protected]
Known from the ancient Heracles myth of the Zeus’ son slaying the Stymphalian birds, the mountainous region of Stymphalia (22 27’E/ 37 51’N) is an ideal site to study the environmental history of the area by combining the climate archive of lake sediments with the historical and archaeological record of the nearby ancient settlement of Stymphalos. Above all, we aim to distinguish the natural versus human-induced environmental change and compare the results to other regions in the Northern Peloponnese. At Lake Stymphalia a 15.52 m long sediment core (STY-1) was retrieved during a first field campaign in March 2010 using a piston coring device on a floating platform. The upper, Holocene part of the core (0-8.68 m) is characterized by light gray to gray clays/carbonate mud interpreted as open water facies that is intercalated with fine- to coarse sand units representing debris flows from adjacent slopes and/or input from torrential rivers. Late Holocene reddish gray to brown clay units indicate intense erosion of red soils in the catchment area. Since organic content is low throughout the core, radiocarbon dates on bulk sediment samples were determined. Sample KIA-42912 from a black ash layer in the upper part of the core (1.495 m) was dated to an age of 1608-1570 cal BC. This black ash layer might be of volcanic origin as it is indicated from magnetic susceptibility. Further environmental analyses include geochemical methods (i.a., X-ray fluorescence, loss-on-ignition, CNS). The climatic and environmental variability of the ancient Arcadian region, as it is documented in the lacustrine sediment core STY-1, is connected with human development in the karst polje of Stymphalia. Historical sources and archaeological findings indicate settlement activity since at least the 5th century BC at Stymphalos. Hence, the spatiotemporal patterns of land use and water management and the effect of climate on the environmental development of the region are reconstructed. HUMAN-TRIGGERED AVULSION IN A SEMI-ARID REGION (KARKHEH RIVER, LOWER KHUZESTAN, IRAN) Vanessa M.A. Heyvaert. Geological Survey of Belgium, Belgium E-mail address: [email protected]
In this paper, the role of human interference on the floodplain history of the river Karkheh, located in the Lower Khuzestan plain is investigated by combining geological with historical and archaeological data. The
E-mail address: [email protected]
BRITISH ICE SHEET DYNAMICS INFERRED FROM NORTH ATLANTIC ICERAFTED DEBRIS RECORDS SPANNING THE LAST 175 000 YEARS Fiona Hibbert. University of St Andrews, United Kingdom E-mail address: [email protected]
Sediment core MD04-2822 from the Rockall Trough, northeast Atlantic, provides lithological evidence for the expansion of the British Ice Sheet (BIS) onto the Hebridean margin during both the penultimate (Marine Isotope Stage (MIS) 6/Wolstonian/Saalian) and last glaciation (Devensian/ Weichselian). A composite chronology is constructed using: (i) the benthic foraminiferal oxygen isotope record, matched to an orbitally tuned stacked record of global ice volume (SPECMAP); (ii) the synchronisation of the planktonic foraminiferal (Neogloboquadrina pachyderma (sinistral)) and ITRAX XRF Ca records to the Greenland ice core (NGRIP) back to ca. 123 ka; and (iii) the synchronisation of the same N. pachyderma (sinistral)) and ITRAX XRF Ca records to the atmospheric methane record of the Antarctic