Stratigraphical signatures of glacier activity,marine processes and a possible tsunami in the Leirfjorden fjord‐valley system,north Norway

An integrated interpretation of on‐ and offshore stratigraphical records at Leirfjorden, north Norway, reveals new aspects of the area's palaeoenvironmental history. The study is based on marine sparker data and well‐exposed sections on land that were analysed for their sediment facies, mineralogy and fossil assemblages. Existing research and new radiocarbon dates provide a chronological framework for the interpretation. The late Younger Dryas Nordli substage type locality in the Leirfjorden catchment is revised and found to reflect local glacial activity, maybe a collapse of stagnant ice rather than glacier advance, while late Younger Dryas to Preboreal glacier re‐advances south of Leirfjorden and near Ranfjorden are here named the Bardal substage. The stratigraphical record includes pre‐Younger Dryas, valley‐crossing, glacial striae and old till with provenance of resistant bedrock typical of more elevated mountain areas. It differs from younger till units representing topographically controlled glacier movement. Part of the Leirfjorden fjord‐valley system is located between the main glacial and fluvial drainage paths affecting the sediment supply. As a result, highstand deposits are indistinct and fluvial sediments form only a minor part of the forced‐regressive systems tract. Instead, the valley fill overlying till and subtill sediments is dominated by the deglacial transgressive tract and a forced‐regressive systems tract with composite marine deposits and various marine erosion surfaces. A special event bed is interpreted as a possible tsunami deposit caused by seismicity and/or mass‐wasting in the fjord following glacier retreat. The study highlights the stratigraphical complexity of interconnected fjord and sound systems in a low accretion setting.     

A revised stratigraphical framework for the Quaternary deposits of the German North Sea sector: a geological‐geotechnical approach

Using extensive data sets from three separate areas in the German North Sea sector, consisting of seismic grids, cores and in‐situ cone penetration tests (CPT), we have established a revised stratigraphical framework for the mid to late Quaternary deposits of the German North Sea sector. This framework consists of four regional unconformities and 15 other local unconformities derived from seismic profiles. Using these unconformities, along with lithological and geotechnical data, it was possible to define and correlate 14 major units and 21 subunits within the framework. The Quaternary cover in the area is characterized by a variety of environmental settings ranging from glacial terrestrial and fluvial to lacustrine as well as brackish and marine environments with associated erosion, reworking and deposition. The complexity of Quaternary deposits within the area is explained by its history of repeated ice advances interrupted by marine transgressions and exposed periglacial landscapes. Within the framework, eight buried tunnel valleys and two shallow buried river valleys are identified from seismic profiles with four phases of tunnel valley generation inferred. These phases of tunnel valley generation are associated with the Elsterian (three) and Saalian (one) glacial stages. Infill of these tunnel valleys consists of glaciofluvial sands, thick sequences of marine and lacustrine fine‐grained sediments and some reworked till remnants. Elsewhere, extensive tabular units have formed consisting of marine and fluvial sediments. We compare this new stratigraphy with previous stratigraphies for the German North Sea sector, attribute informal stratigraphical names and offer preliminary correlations with established stratigraphies from other sectors of the North Sea.     

Periglacial evidence for a 1.91–1.89 Ga old glacial period at low latitude,Central Sweden

Cryoturbation and slump fold‐like sedimentary structures in ca. 1.9 Ga old dacitic metavolcanic sediments in West Bergslagen, Central Sweden, are recognized as a lowland periglacial environment. This type of environment is comparable with present day tundra in Siberia. Ice‐wedge casts and cryoturbation, together with polygonal frost patterns, are typical geomorphological structures above permafrost in this type of environment. The sedimentary environment could be interpreted as periglacial, broadly comparable to present day tundras. Intensive cryoturbation of the formation and close structural analogy with Quaternary ice‐wedges suggests a cold and humid environment. This discovery is corroborated by a previous report of glacial sediments and structures from NW Australia of ca. 1.8 Ga age. Both occurrences developed at low geographical latitudes, at locations far apart in the Late Palaeoproterozoic supercontinent Columbia. Either suggest the existence of a ca. 100 Ma long epoch of extreme, though possibly intermittent glaciations during the ca. 1.4 Ga long ‘Proterozoic gap’ (～2.2–0.77 Ga) from which no convincing glacial deposits were previously known.     

Glaciotectonised Quaternary sediments at Cape Shpindler,Yugorski Peninsula,Arctic Russia: implications for glacial history,ice movements and Kara Sea Ice Sheet configuration

The coastal cliffs of Cape Shpindler, Yugorski Peninsula, Arctic Russia, occupy a key position for recording overriding ice sheets during past glaciations in the Kara Sea area, either from the Kara Sea shelf or the uplands of Yugorski Peninsula/Polar Urals. This study on Late Quaternary glacial stratigraphy and glaciotectonic structures of the Cape Shpindler coastal cliffs records two glacier advances and two ice‐free periods older than the Holocene. During interglacial conditions, a sequence of marine to fluvial sediments was deposited. This was followed by a glacial event when ice moved southwards from an ice‐divide over Novaya Zemlya and overrode and disturbed the interglacial sediments. After a second period of fluvial deposition, under interstadial or interglacial conditions, the area was again subject to glacial overriding, with the ice moving northwards from an inland ice divide. The age‐control suggests that the older glacial event could possibly belong to marine oxygen isotope stage (MOIS) 8, Drenthe (300–250 ka), and that the underlying interglacial sediments might be Holsteinian (>300 ka). One implication of this is that relict glacier ice, buried in sediments and incorporated into the permafrost, may survive several interglacial and interstadial events. The younger glacial event recognised in the Cape Shpindler sequence is interpreted to be of Early‐to‐Middle Weichselian age. It is suggested to correlate to a regional glaciation around 90 or 60 ka. The Cape Shpindler record suggests more complex glacial dynamics during that glaciation than can be explained by a concentric ice sheet located in the Kara Sea, as suggested by recent geological and model studies. Copyright © 2003 John Wiley & Sons, Ltd.     

Lacustrine records of post‐glacial environmental change from the Nulhegan Basin,Vermont, USA

The sedimentary records of Nulhegan Pond and Beecher Pond in the Nulhegan Basin of north‐eastern Vermont were analyzed to yield a history of environmental change since the latest Pleistocene. Shoreline landforms indicate that part of the Nulhegan Basin was inundated by Glacial Lake Nulhegan (GLN), which was impounded behind a dam of glacial sediment. Outwash derived from stagnant ice forms the bottom 176 cm of the Nulhegan Pond core. Fine‐grained inorganic sediment deposited between 13.4 and 12.2k cal a BP is interpreted as a deep‐water facies representing GLN, while coarser sediment from 12.2 to 11.8k cal a BP records draining of the glacial lake. Rapid, simultaneous increases in organic matter and biogenic silica signal the onset of productivity following the Younger Dryas. Beecher Pond formed c. 11.3k cal a BP through surface collapse over a buried ice block; buried stagnant ice may have persisted in the vicinity of the pond into the early Holocene. From 8.9 to 5.5k cal a BP, sediment in both lakes became coarser and richer in aquatic organic matter, suggesting a low‐water phase in which previously deposited lacustrine sediments were reworked and the littoral zone shifted basinward. Low water levels at this time are consistent with other records from Maine and southern Quebec, but contrary to records from ～325 km to the south. Copyright © 2012 John Wiley & Sons, Ltd.     

Drivers of ecosystem and climate change in tropical West Africa over the past ∼540 000 years

A paucity of empirical non‐marine data means that uncertainty surrounds the impact of climate change on terrestrial ecosystems in tropical regions beyond the last glacial period. The sedimentary fill of the Bosumtwi impact crater (Ghana) provides the longest continuous Quaternary terrestrial archive of environmental change in West Africa, spanning the last ～1.08 million years. Here we explore the drivers of change in ecosystem and climate in tropical West Africa for the past ～540 000 years using pollen analysis and the nitrogen isotope composition of bulk organic matter preserved in sediments from Lake Bosumtwi. Variations in grass pollen abundance (0?99%) indicate transitions between grassland and forest. Coeval variations in the nitrogen isotopic composition of organic matter indicate that intervals of grassland expansion coincided with minimum lake levels and low regional moisture availability. The observed changes responded to orbitally paced global climate variations on both glacial–interglacial and shorter timescales. Importantly, the magnitude of ecosystem change revealed by our data exceeds that previously determined from marine records, demonstrating for the first time the high sensitivity of tropical lowland ecosystems to Quaternary climate change.

     

Quaternary chronostratigraphy: the nomenclature of terrestrial sequences

There is a long-standing tradition of dividing Quaternary stratigraphical sequences on the basis of climate. This climatostratigraphical approach, begun on terrestrial sequences in the last century, led to the widespread adoption of glacial, interglacial, stadial and interstadial subdivisions as standard. However, the limitations of the approach resulted in its replacement by local sequences of chronostratigraphical stages from the 1950s. The subsequent establishment of the detail and complexity of ocean-core sequences has encouraged increasing use of the terminology developed for these records to the terrestrial and shallow marine succession. The view is expressed that it is advisable to separate and retain regional chronostratigraphies for each sequence-type, and that these should be correlated using event-based stratigraphy where possible. This should ensure both the highest precision and lack of ambiguity and a securely-based synthesis of the relations between the terrestrial and ocean isotope sequences, a synthesis which is fundamental to understanding the nature and detail of regional and global climate change.     

Quaternary glacial records in mountain regions：A formal stratigraphical approach

Glacial deposits in locally-glaciated mountain regions are often expressed through their surface form and the study of these deposits constitutes a major branch of geomorphology. Studies of glacial depositional records in mountain areas have often neglected formal stratigraphical procedure resulting in an ad hoc development of quasi-stratigraphical nomenclature. Here, a formal stratigraphical procedure is recommended, since this enables a systematic approach to the subdivision of glacial deposits in mountain regions. Moreover, such an approach facilitates, in some instances, the development of a formal chronostratigraphy that can be compared to regional and global geological time scales. This is important in locally-glaciated mountain regions where glacial deposits represent one of the most important records of cold stage environments. Given that glacial landforms represent a key component of the Quaternary record, maintaining a formal link between geomorphological and geological stratigraphical procedure is a fundamental requirement of a consistent and comparable stratigraphical framework.     

Glacigenic rafting at Castle Hill,Gardenstown, and its significance for the glacial history of northern Banffshire,Scotland

Reinvestigation of the lower part of the key Quaternary section at Castle Hill, Gardenstown, has shown that the sediments are not in stratigraphical order, but consist chiefly of glaciotectonites, including rafts of soft sediments, which were deposited by ice moving southeastwards from the Moray Firth. Sedimentary structures are preserved in some of the rafts, which are separated by subhorizontal shears. The rafts accreted subglacially under conditions of moderate to high strain, the final glacial event being the deposition of a thin, discontinuous sheet of till, probably derived from a more westerly direction. It is proposed that interbedded dark grey shelly clay, till and sand elsewhere in northern Banffshire were emplaced, at least in part, by a similar mechanism during either the Middle Devensian, or more likely, the Late Devensian. Sand and clay with paired bivalve shells, which were formerly exposed within the Quaternary successions at Castle Hill and inland at King Edward, some 12 km to the south, are interpreted to be within glacigenic rafts, and are not in situ deposits formed during a widespread marine transgression. It is suggested that the alternation of phases of constructional and excavational deformation within a single glacial event rather than discrete glaciations provides a useful model for glacial deposition in northern Banffshire, and more generally in northeast Scotland. © 1997 John Wiley & Sons, Ltd.     

Forced regressive deposits of a deglaciation sequence: Example from the Late Quaternary succession in the Lake Saint‐Jean basin (Québec,Canada)

Differentiating between forced regressive deposits from deglacial periods in high latitude domains and forced regressive deposits from the onset of glacial periods in low latitude domains is fundamental for the accurate interpretation of glacial cycles within the geological record and then for the reconstruction of palaeogeography and palaeo‐climate. A forced regressive deglacial sequence is documented from the Lake Saint‐Jean basin (Québec, Canada). In this area, the Late Pleistocene to Holocene sediments have recorded the Laurentide ice sheet retreat accompanied by the invasion of marine waters (Laflamme Gulf) from ca 12·9 cal kyr bp . Subsequently, fluvio‐deltaic and coastal prograding wedges were deposited; they followed the base‐level fall due to glacio‐isostatic rebound. This succession, representing a transition from glacial to post‐glacial periods within a previously glaciated area, was investigated through recent mapping, preserved landforms, facies analysis, and new optical stimulated luminescence and radiocarbon dates. Three basin‐scale geological sections share a common lower part made of isolated ice‐contact fan deposits overlying bedrock. Throughout the entire basin, ice‐contact fans are capped by glacimarine muds. Above, fluvial and coastal prograding systems were deposited and evolved through four steps: (i) deltaic systems progressively increased in width; (ii) coastal influence on sedimentation increased; (iii) hydrographic drainage systems became more organised; and (iv) deltas graded from steep (Gilbert delta) to low‐angle foresets (mouth‐bar delta). Deposited during the base‐level fall from glacio‐isostatic rebound, the complete succession has been designated as a single falling stage system tract referred to as a deglacial falling stage system tract. It is representative of a deglaciation sequence in areas previously covered by ice during glacial periods (i.e. medium to high latitude domains). Diagnostic criteria are provided to identify such a deglacial falling stage system tract in the geological record, which may aid identification of previously unknown glacial cycles.     

MIS 3时期青藏高原东南部稻城古冰帽冰进事件研究

深海氧同位素3阶段（Marine Isotope Stage 3,MIS 3）是全球气候演化过程中特殊的时期,对深入认识区域古气候、古环境演变具有重要意义。青藏高原东南部稻城古冰帽是第四纪冰川作用历史和古气候研究的理想区域,许多学者在该区进行了冰川地貌学和年代学研究。目前,该区域在MIS 3阶段是否存在冰川前进事件仍存在争论。现着重从洞穴石笋、高原冰芯、海洋沉积、古湖孢粉等记录来总结我国MIS 3阶段的气候环境状况,并搜集高原及周边地区MIS 3阶段冰进事件的记录,结合稻城古冰帽区已发表的MIS 3阶段的年代数据来探讨稻城古冰帽区MIS 3阶段的冰川前进的可能性。结果表明：稻城古冰帽区MIS 3阶段（43~53 ka）发生了大规模冰进事件,这可能是由于该冰帽区处于相对冷湿环境且受到了西南季风的影响。本研究可为区域气候重建与环境演变提供新的依据。     

Late Quaternary glacial history of the central west coast of Jameson Land, East Greenland

The Late Quaternary ( c . 130,000–10,000 BP) glacial history of the central west coast of Jameson Land, East Greenland, is reconstructed through glacial stratigraphical studies. Seven major sedimentary units are described and defined. They represent two interglacial events (where one is the Holocene). one interstadial event and two glacial events. The older interglacial event comprises marine and fluvial sediments, and is correlated to the Langelandselv interglacial, corresponding to oxygen isotope sub-stage 5e. It is followed by an Early Weichselian major glaciation during the Aucellaelv stade, and subsequently by an Early Weichselian interstadial marine and deltaic event (the Hugin Sø interstade). Sediments relating to the Middle Weichselian have not been recognized in the area. The Hugin Sø interstade deposits have been overrun by a Late Weichselian ice advance, during the Flakkerhuk stade, when the glacier, which probably was a thin, low gradient fjord glacier in Scoresby Sund, draped older sediments and landforms with a thin till. Subsequent to the final deglaciation, some time before 10,000BP, the sea reached the marine limit around 70 m a.s.l., and early Holocene marine, fluvial and littoral sediments were deposited in the coastal areas.     

第四纪气候变化机制研究的进展与问题

自从20世纪50年代海洋沉积氧同位素记录被揭示以来,经典的陆地4次冰期理论被新的认识所取代,人们发现第四纪以来冰期—间冰期旋回远远不止4次,并且从深海沉积和陆地黄土获取的古气候变化记录与地球轨道参数变化可以对比,为揭示第四纪古气候变化机制构建了明确的框架。近年来有关末次冰期不稳定气候事件的揭示也为深入认识古气候变化特征提供了新的证据。然而冰期—间冰期旋回机制、南北半球在冰期—间冰期循环过程中的耦合机制以及气候不稳定事件发生机制仍然是困扰古气候研究者的重大问题。     

玉龙雪山冰川沉积序列OSL定年

位于青藏高原东南缘的玉龙雪山分布有欧亚大陆纬度最低的海洋型冰川,其主峰及周边地区保存了大量清晰完整的第四纪冰川遗迹。研究该区第四纪冰川作用遗迹及其冰川作用史,具有重要的理论与实际价值。应用光释光（OSL）测年技术对玉龙雪山冰川沉积物进行了定年,结合前人研究资料,重建玉龙雪山冰川作用史。研究结果表明：玉龙雪山东麓的末次冰期冰碛物主要形成于晚更新世末次冰期最盛时期,其平均年代约在25ka,西麓末次冰期冰碛物形成年代约为50ka,对应于深海氧同位素3阶段中期（MIS3b）。而倒数第二次冰期的年代在240ka左右,处于中更新世晚期,对应于MIS8阶段,当时玉龙雪山存在多条复式山谷冰川。该研究可为玉龙雪山第四纪冰川作用历史的重新认识以及光释光测年技术在该区的应用提供基础资料。     

Glacier‐fed lakes as palaeoenvironmental archives

Glaciers show a sensitive and rapid response to climate shifts. Associated changes in ice extent drive variations in the production of rock flour, the suspended product of glacial erosion. These glacigenic sediments may accumulate in downstream lakes, continuously recording glacier history. Consequently, the lacustrine sediment records of such glacier‐fed lakes represent valuable palaeoenvironmental archives that help constrain past climate variability. In this paper, we discuss the multi‐disciplinary methodological toolbox that is applied to fingerprint a glacier signal from such lake sediments. Special emphasis is placed on dating methods, which transform stratigraphical data into climate time series, allowing us to distinguish leads and lags between archives. We also elaborate on techniques that are used to validate sediment‐based glacier signals and resolve their climate signature. Finally, we conclude with a brief outlook on new research avenues such as proxy data–climate model comparisons.     

OSL‐based chronostratigraphy of river terraces in mountainous areas,Dunajec basin,West Carpathians: a revision of the climatostratigraphical approach

The technique of optically stimulated luminescence (OSL) dating applied to fluvial sediments provided a geochronological framework of river terrace formation in the middle part of the Dunajec River basin – a reference area for studies of evolution of river valleys in the northern part of the Carpathians (West Carpathians). Fluvial sediments at 18–90 m above valley bottoms were dated in the valleys of the Dunajec River and one of its tributaries. The resulting ages range from 158.9±8.3 to 12.2±1.3 ka. This indicates that some of the terrace sediments were deposited much later than previously assumed on the grounds of a combined morphostratigraphical and climatostratigraphical approach. The OSL‐based chronostratigraphy of terrace formation consists of seven separate phases of fluvial aggradation, separated by periods of incision and lateral erosion. Some of the ages determined correspond to warm stages of the Pleistocene – Marine Isotope Stage 3 (MIS 3) and MIS 5 – demonstrating that some terraces were formed during interstadial or interglacial periods. The results provide a key for evaluating rates of neotectonic uplift, allowing us to decipher the response of a fluvial system to climate change within the context of the glacial–interglacial scheme.     

Sedimentary architecture of a glaciolacustrine braidplain delta: proxy evidence of a pre‐Middle Wisconsinan glaciation (Grimshaw gravels,Interior Plains,Canada)

The erosional nature of glacial systems commonly results in removal of direct evidence of previous glaciation (e.g. till and moraine). Therefore, reconstruction of former ice‐margin positions may rely, in part, on indirect (proxy) evidence from the sedimentary record. This study examines the facies and sedimentary architecture of a pre‐Middle Wisconsinan sand and gravel deposit (the ‘Grimshaw gravels’), which is positioned between areas where previous stratigraphical investigations have identified single (Late Wisconsinan) and multiple (pre‐Middle to Late Wisconsinan) glaciation by the Laurentide Ice Sheet. Five facies associations (FAs) are characterized within the deposit, which, together with the sedimentary architecture, record a transition from a braided river environment in the west (FA1‐3) to a gravelly braidplain delta front in the east (FA4 and 5). We propose that the Grimshaw gravels braid delta formed at the margin of a body of water that occupied the ancestral Peace River valley, probably impounded by the LIS; hence, the Grimshaw braid delta provides proxy evidence of the presence of an ice margin (previously unrecognized) in the Peace River lowland prior to the Middle Wisconsinan. This study provides further understanding of the origin of the Grimshaw gravels deposit, allowing re‐evaluation of previous models of formation. These findings offer insight into the glacial history of the southwestern margin of the LIS, and may help to refine ice‐sheet reconstructions spanning the Wisconsinan glaciation.     

Weichselian sediments at Foss‐Eikeland,Jæren (southwest Norway): sea‐level changes and glaciation history

The Jæren area in southwestern Norway has experienced great changes in sea‐levels and sedimentary environments during the Weichselian, and some of these changes are recorded at Foss‐Eikeland. Four diamictons interbedded with glaciomarine and glaciofluvial sediments are exposed in a large gravel pit situated above the post‐glacial marine limit. The interpretation of these sediments has implications for the history of both the inland ice and the Norwegian Channel Ice Stream. During a Middle Weichselian interstadial, a large glaciofluvial delta prograded into a shallow marine environment along the coast of Jæren. A minor glacial advance deposited a gravelly diamicton, and a glaciomarine diamicton was deposited during a following marine transgression. This subsequently was reworked by grounded ice, forming a well‐defined boulder pavement. The boulder pavement is followed by glaciomarine clay with a lower, laminated part and an upper part of sandy clay. The laminated clay probably was deposited under sea‐ice, whereas more open glaciomarine conditions prevailed during deposition of the upper part. The clay is intersected by clastic dykes protruding from the overlying, late Weichselian till. Preconsolidation values from the marine clay suggest an ice thickness of at least 500 m during the last glacial phase. The large variations in sea‐level probably are a combined effect of eustasy and glacio‐isostatic changes caused by an inland ice sheet and an ice stream in the Norwegian Channel. Copyright © 2002 John Wiley & Sons, Ltd.     

Reinterpreting Rotherslade,Gower Peninsula: implications for Last Glacial ice limits and Quaternary stratigraphy of the British Isles

Rotherslade on the Gower Peninsula in south Wales has been viewed as a key site for the reconstruction of Quaternary depositional environments in the British Isles. Since the early 20th century, and certainly since the 1980s, the accepted view has been that Rotherslade is the most westerly location on the south Gower coast where there is in situ basal till exposed and that, logically, this location marks the position of the LGM ice limit. However, reinvestigation of the sediments and their architecture, and analysis of clast fabrics and thin sections of critical sedimentary units, show that none of the exposed sediments has properties diagnostic of subglacial deposition or deformation. We postulate here that LGM ice terminated at the western side of Swansea Bay, a few kilometres to the north‐east of Rotherslade, and propose that the sedimentary sequence comprises Early to Middle Devensian periglacial sediments, overlain by a complex of Late Devensian, ice‐proximal outwash fan deposits, an assemblage of paraglacial debris and, finally, periglacial mass movement deposits. The proposed repositioning of the Late Devensian ice limit and the associated new subaerial interpretation of the sediments suggest that a reassessment of sedimentary sequences (Hunts Bay, Western Slade) and landforms (Paviland Moraine) farther west on Gower, which have attained similar stratigraphical status, is now warranted. Copyright © 2008 John Wiley & Sons, Ltd.     

Sedimentology and depositional model for glaciolacustrine deposits in an ice-dammed tributary valley, western Tasmania, Australia

Quaternary sedimentary successions are described from the Linda Valley, a small valley in western Tasmania that was dammed by ice during Early and Middle Pleistocene glaciations. Mapping and logging of exposures suggest that an orderly sequence of deposits formed during ice incursion, occupation and withdrawal from tributary valleys. Four principal sediment assemblages record different stages of ice occupation in the valley. As the glacier advanced, a proglacial, lacustrine sediment assemblage dominated by laminated silts and muds deposited from suspension accumulated in front of the glacier. A subglacial sediment assemblage consisting of deformed lacustrine deposits and lodgement till records the overriding of lake-bottom sediments as the glacier advanced up the valley into the proglacial lake. As the glacier withdrew from the valley, a supraglacial sediment assemblage of diamict, gravel, sand and silt facies formed on melting ice in the upper part of the valley. A lacustrine regression in the supraglacial assemblage is inferred on the basis of a change from deposits mainly resulting from suspension in a subaqueous setting to relatively thin and laterally discontinuous laminated sediments, occurrence of clastic dykes, and increasing complexity of the geometry of deposits that indicate deposition in a subaerial setting. A deltaic sediment assemblage deposited during the final stage of ice withdrawal from the valley consists of steeply dipping diamict and normally graded gravel facies formed on delta foresets by subaqueous sediment gravity flows. The sediment source for the delta, which prograded toward the retreating ice margin, was the supraglacial sediment assemblage previously deposited in the upper part of the valley. A depositional model developed from the study of the Linda Valley may be applicable to other alpine glaciated areas where glaciers flowed through or terminated in medium- to high-relief topography.