The voyage of the ‘Guyot Stone’ from the Swiss Alps to Neuchâtel and Princeton

AbstractIn 1890, former students of Arnold Guyot at the University of Neuchàtel dedicated a ‘large glacial boulder from Neuchâtel’ to his memory, now in front of Guyot Hall at Princeton University. We established that this block originated with all certainty from Upper Carboniferous conglomerates of the Salvan–Dorénaz Basin, the relics of which crop out in the Alps of western Switzerland and eastern France. During the Last Glacial Maximum, the boulder travelled from the lower Rhône Valley on the back of the Pleistocene Rhône Glacier to Neuchâtel from where, later, it crossed the Atlantic and was transported to Princeton. Guyot’s name is familiar to geologists because of the term ‘guyot’, introduced 1946 by Harry Hess for ‘curious flat-topped peaks scattered over millions of square miles in the Pacific basin’, many of which are now known to represent drowned carbonate platforms.

A model of the glacial retreat of upper Rennick Glacier, Victoria Land, Antarctica

Annals of Glaciology ◽

10.3189/172756499781821463 ◽

1999 ◽

Vol 29 ◽

pp. 225-230 ◽

Cited By ~ 8

Author(s):

M. Meneghel ◽

A. Bondesan ◽

M. C. Salvatore ◽

G. Orombelli

Keyword(s):

Last Glacial Maximum ◽

Volcanic Rocks ◽

Depositional Model ◽

Glacial Retreat ◽

The Holocene ◽

The Pacific ◽

Proposed Model ◽

Victoria Land ◽

AbstractThe morphology of the Lichen Hills in the upper section of Rennick Glacier, Victoria Land, Antarctica, is summarised as follows: (a) a top surface on the volcanic rocks with scattered erratic blocks; (b) an exhumed Kukri Peneplain, sculptured with roches moutonnees with striae and crescentic gouges on which lie moraines and patches of drift of mainly volcanic rocks; (c) a granitic bedrock eroded by glaciers into sharp peaks and cirques on top of which there is a glacial drift attributable to ancient blue-ice areas higher than those observed at present and which may be correlated with the Terra Nova drift (Late Wisconsin); (d) various Holocene ice-cored moraines that are pushed to the lee side of the nunataks arid are often banded in strips of different lithology. The bands of the Holocene moraines are related to the rock complexes that became exposed from the ice during the lowering of the surface of the glacier Analysis of the lithology and pattern of the supraglacial debris, as well as of the blue-ice areas, allows us to construct a depositional model for the moraines, and to relate the glacial drift to blue-ice areas existing since the Last Glacial Maximum (LGM).The proposed model shows the different stages of recession of upper Rennick Glacier that are also valid for similar situations observed in northern Victoria Land. A surface lowering of upper Rennick Glacier of several hundred metres shows that significant changes have occurred at the Pacific edge of the East Antarctic ice sheet since the LGM.

Surface geometry of the Last Glacial Maximum (LGM) in the southeastern Swiss Alps (Graubünden) and its paleoclimatological significance

E&G Quaternary Science Journal ◽

10.3285/eg.48.1.03 ◽

1998 ◽

Vol 48 (1) ◽

pp. 23-37 ◽

Cited By ~ 5

Author(s):

Duri Florineth

Keyword(s):

Last Glacial Maximum ◽

Storm Track ◽

Glacial Maximum ◽

Swiss Alps ◽

Geographical Information ◽

Ice Age ◽

Surface Geometry ◽

Last Glacial ◽

Abstract. Using detailed field evidence provided by trimlines on former nunataks, erratic boulders and the orientations of glacial striae, the surface geometry in the accumulation area during the Last Glacial Maximum was reconstructed for the area of SE Switzerland and adjacent Italy. Collectively, the trends of trimline elevations, flowlines deduced from glacial striae and bedrock morphology along the longitudinal valleys and their tributaries indicate that the former accumulation area consisted of an ice dome with the ice divide located over the area enclosed by Schlarignia, Cinuos-chel, Livigno and Piz Bernina. It attained a minimum altitude of approximately 3000 m. Modelling the topography of the ice surface using a Geographical Information System (GIS) is consistent with these results. The paleoclimatological signal included in this surface geometry was used to draw conclusions about the main atmospheric paleocireulation patterns and to outline the principal precipitation areas for the Alps during the last glaciation. It followed from this that ice build-up was principally related to dominating precipitation by southerly circulation (foehn). The prevaleance of foehn circulation most likely reflects a southward shift of the North Atlantic polar atmospheric front and of the accompanied storm track due to the advancing margin of sea ice. There exists good agreement between these assumptions and (a) results of global circulation models for the time of the LGM; (b) estimations of basal shear stress values and flow velocities for Ice Age glaciers; and (c) interpretations of paleowind indicators.

Age of the Most Extensive Glaciation in the Alps

Geosciences ◽

10.3390/geosciences12010039 ◽

2022 ◽

Vol 12 (1) ◽

pp. 39

Author(s):

Catharina Dieleman ◽

Marcus Christl ◽

Christof Vockenhuber ◽

Philip Gautschi ◽

Hans Rudolf Graf ◽

...

Keyword(s):

Last Glacial Maximum ◽

Northern Hemisphere ◽

Depositional Environments ◽

Marine Isotope Stage ◽

Middle Pleistocene ◽

Glaciofluvial Deposits ◽

The Alps ◽

Cosmogenic 10Be ◽

Previous research suggested that the Alpine glaciers of the Northern Swiss Foreland reached their maximum extensive position during the Middle Pleistocene. Relict tills and glaciofluvial deposits, attributed to the Most Extensive Glaciation (MEG), have been found only beyond the extents of the Last Glacial Maximum (LGM). Traditionally, these sediments have been correlated to the Riss glaciation sensu Penck and Brückner and have been morphostratigraphically classified as the Higher Terrace (HT) deposits. The age of the MEG glaciation was originally proposed to be intermediate to the Brunhes/Matuyama transition (780 ka) and the Marine Isotope Stage 6 (191 ka). In this study, we focused on the glacial deposits in Möhlin (Canton of Aargau, Switzerland), in order to constrain the age of the MEG. The sediments from these deposits were analyzed to determine the provenance and depositional environments. We applied isochron-burial dating, with cosmogenic 10Be and 26Al, to the till layer in the Bünten gravel pit near Möhlin. Our results indicate that a glacier of Alpine origin reached its most extensive position during the Middle Pleistocene (500 ± 100 ka). The age of the MEG thus appears to be synchronous with the most extensive glaciations in the northern hemisphere.

Alpine Evidence for Atmospheric Circulation Patterns in Europe during the Last Glacial Maximum

Quaternary Research ◽

10.1006/qres.2000.2169 ◽

2000 ◽

Vol 54 (3) ◽

pp. 295-308 ◽

Cited By ~ 162

Author(s):

Duri Florineth ◽

Christian Schlüchter

Keyword(s):

Atmospheric Circulation ◽

Last Glacial Maximum ◽

Storm Track ◽

Polar Front ◽

Glacial Maximum ◽

Geological Mapping ◽

Last Glacial ◽

The Alps ◽

The configuration of Alpine accumulation areas during the last glacial maximum (LGM) has been reconstructed using glacial–geological mapping. The results indicate that the LGM ice surface consisted of at least three major ice domes, all located south of the principal weather divide of the Alps. This implies that the buildup of the main Alpine ice cover during oxygen isotope stage (OIS) 2 was related to precipitation by dominant southerly atmospheric circulation, in contrast to today's prevalent westerly airflow. Such a reorganization of the atmospheric circulation is consistent with a southward displacement of the Oceanic Polar Front in the North Atlantic and of the associated storm track to the south of the Alps. These results, combined with additional paleoclimate records from western and southern Europe, allow an interpretation of the asynchronous evolution of the different European ice caps during the last glaciation. δ18O stages (OIS) 4 and 3 were characterized by location of the Polar Front north of 46°N (Gulf of Biscay). This affected prevailing westerly circulation and thus, ice buildup in western Scandinavia, the Pyrénées, Vosges, and northern Alps. At the LGM, however, the Polar Front lay at ∼44°N, causing dominating southerly circulation and reduced precipitation in central and northern Europe.

Extensive Early and Middle Wisconsin Glaciation on the Western Olympic Peninsula, Washington, and the Variability of Pacific Moisture Delivery to the Northwestern United States

Quaternary Research ◽

10.1006/qres.2001.2220 ◽

2001 ◽

Vol 55 (3) ◽

pp. 257-270 ◽

Cited By ~ 49

Author(s):

Glenn D. Thackray

Keyword(s):

Last Glacial Maximum ◽

Glacial Maximum ◽

Organic Detritus ◽

Last Glacial ◽

Olympic Mountains ◽

The Pacific ◽

Radiocarbon Chronology ◽

Stratigraphic Sequences ◽

AbstractLarge glaciers descended western valleys of the Olympic Mountains six times during the last (Wisconsin) glaciation, terminating in the Pacific coastal lowlands. The glaciers constructed extensive landforms and thick stratigraphic sequences, which commonly contain wood and other organic detritus. The organic material, coupled with stratigraphic data, provides a detailed radiocarbon chronology of late Pleistocene ice-margin fluctuations. The early Wisconsin Lyman Rapids advance, which terminated prior to ca. 54,000 14C yr B.P., represented the most extensive ice cover. Subsequent glacier expansions included the Hoh Oxbow 1 advance, which commenced between ca. 42,000 and 35,000 14C yr B.P.; the Hoh Oxbow 2 advance, ca. 30,800 to 26,300 14C yr B.P.; the Hoh Oxbow 3 advance, ca. 22,000–19,300 14C yr B.P.; the Twin Creeks 1 advance, 19,100–18,300 14C yr B.P.; and the subsequent, undated Twin Creeks 2 advance. The Hoh Oxbow 2 advance represents the greatest ice extent of the last 50,000 yr, with the glacier extending 22 km further downvalley than during the Twin Creeks 1 advance, which is correlative with the global last glacial maximum. Local pollen data indicate intensified summer cooling during successive stadial events. Because ice extent was diminished during colder stadial events, precipitation—not summer temperature—influenced the magnitude of glaciation most strongly. Regional aridity, independently documented by extensive pollen evidence, limited ice extent during the last glacial maximum. The timing of glacier advances suggests causal links with North Atlantic Bond cycles and Heinrich events.

The onset of the Last Glacial Maximum in the southern side of the Alps

Quaternary International ◽

10.1016/j.quaint.2012.08.964 ◽

2012 ◽

Vol 279-280 ◽

pp. 333

Author(s):

Giovanni Monegato

Keyword(s):

Last Glacial Maximum ◽

Glacial Maximum ◽

Last Glacial ◽

Southern Side ◽

The Alps ◽

A Geophysical and Climatological Assessment of New Guinea — Implications for the Origins of Saccharum

10.1101/2020.06.20.162842 ◽

2020 ◽

Author(s):

Dyfed Lloyd Evans

Keyword(s):

Global Climate ◽

New Guinea ◽

North Coast ◽

Tsunami Modelling ◽

The North ◽

The Pacific ◽

Human Colonization ◽

Modern Form ◽

AbstractAny assessment of whether or not Saccharum species are native or introduced in New Guinea require an evolutionary (in a geological sense), geophysical and climatological assessment of the island. Like many of the land masses circling the Pacific (in the volcanically active region known as the ‘ring of fire’) New Guinea is geologically young, with the island in its modern form not pre-dating 2 Ma. Novel modelling of the 74 ka youngest Toba supereruption indicates a potential extinction level tsunami and loss of habitat. The late Pleistocene megafaunal mass extinction and the last glacial maximum (33–16 ka) are two global effects that would have significantly altered the flora on New Guinea; though the implications of these events on New Guinea have not previously been studied. Even if the genus Saccharum was established on the island during pre-historic times the consequences of Toba and other global climate change events means that it would have been eliminated from New Guinea and would have had to be re-introduced during the period of human colonization. Indeed, given the evolution of Saccharum’s immediate ancestors in Africa and Indochina it is most parsimonious to conclude that it was never native to New Guinea, but was introduced by humans relatively recently.Little work has been done on palaeotsunami evidence and ancient tsunami modelling in New Guinea. However, the recent recognition that the Aitape skull (dating to about 6 ka) may have been the victim of a tsunami (Goff et al. 2017) show that, in the past, tsunami have pen etrated significantly (about 10 km in this case) into the interior of the island to have a profound effect on biodiversity. This tsunami would have left the north coast of the island impoverished of plant life for several decades after.

Piecing together the Lateglacial advance phases of the Reussgletscher (central Swiss Alps)

Geographica Helvetica ◽

10.5194/gh-73-241-2018 ◽

2018 ◽

Vol 73 (3) ◽

pp. 241-252 ◽

Cited By ~ 2

Author(s):

Max Boxleitner ◽

Susan Ivy-Ochs ◽

Dagmar Brandova ◽

Marcus Christl ◽

Markus Egli ◽

...

Keyword(s):

Last Glacial Maximum ◽

Radiocarbon Dating ◽

Younger Dryas ◽

Swiss Alps ◽

Clear Indication ◽

Lake Lucerne ◽

Last Glacial ◽

Exposure Dating ◽

Abstract. Exposure dating has substantially improved our knowledge about glacier advances during the Younger Dryas (YD) and the early Holocene. The glacier development after the Last Glacial Maximum (LGM) and the timing of morphologically evidenced, earlier Lateglacial re-advances is, however, still widely unknown. In this study we used 10Be surface exposure and radiocarbon dating to address these phases and corresponding landforms in the catchment of the former Reussgletscher (central Swiss Alps). We obtained clear indication for moraine deposition prior to the YD. The oldest samples predate the Bølling–Allerød interstadial (>14.6 ka). Morphostratigraphically even older lateral moraines, probably corresponding to terminal positions in the Lake Lucerne, could not be dated conclusively. Due to the geomorphological constraints of the sampling environment, the establishment of a local pre-YD chronology remains a challenge: moraines with adequate numbers of datable boulders were rarely preserved, and age attributions based on few samples are complicated by outliers.

The Alps: glacial landforms prior to the Last Glacial Maximum

10.1016/b978-0-12-823498-3.00008-x ◽

2022 ◽

pp. 283-294

Author(s):

Susan Ivy-Ochs ◽

Giovanni Monegato ◽

Jürgen M. Reitner

Keyword(s):

Last Glacial Maximum ◽

Glacial Maximum ◽

Last Glacial ◽

The Alps ◽

Glacial Landforms ◽

Numerical reconstructions of the flow and basal conditions of the Rhine glacier, European Central Alps, at the Last Glacial Maximum

The Cryosphere ◽

10.5194/tc-12-2515-2018 ◽

2018 ◽

Vol 12 (8) ◽

pp. 2515-2544 ◽

Cited By ~ 7

Author(s):

Denis Cohen ◽

Fabien Gillet-Chaulet ◽

Wilfried Haeberli ◽

Horst Machguth ◽

Urs H. Fischer

Keyword(s):

Last Glacial Maximum ◽

Glacial Maximum ◽

Swiss Alps ◽

Shear Stresses ◽

Last Glacial ◽

Glacier Terminus ◽

Basal Shear ◽

Alpine Valleys ◽

Abstract. At the Last Glacial Maximum (LGM), the Rhine glacier in the Swiss Alps covered an area of about 16 000 km2. As part of an integrative study about the safety of repositories for radioactive waste under ice age conditions in Switzerland, we modeled the Rhine glacier using a thermodynamically coupled three-dimensional, transient Stokes flow and heat transport model down to a horizontal resolution of about 500 m. The accumulation and ablation gradients that roughly reproduced the geomorphic reconstructions of glacial extent and ice thickness suggested extremely cold (TJuly∼0∘C at the glacier terminus) and dry (∼10 % to 20 % of today's precipitation) climatic conditions. Forcing the numerical simulations with warmer and wetter conditions that better matched LGM climate proxy records yielded a glacier on average 500 to 700 m thicker than geomorphic reconstructions. Mass balance gradients also controlled ice velocities, fluxes, and sliding speeds. These gradients, however, had only a small effect on basal conditions. All simulations indicated that basal ice reached the pressure melting point over much of the Rhine and Linth piedmont lobes, and also in the glacial valleys that fed these lobes. Only the outer margin of the lobes, bedrock highs beneath the lobes, and Alpine valleys at high elevations in the accumulation zone remained cold based. The Rhine glacier was thus polythermal. Sliding speed estimated with a linear sliding rule ranged from 20 to 100 m a−1 in the lobes and 50 to 250 m a−1 in Alpine valleys. Velocity ratios (sliding to surface speeds) were >80 % in lobes and ∼60 % in valleys. Basal shear stress was very low in the lobes (0.03–0.1 MPa) and much higher in Alpine valleys (>0.2 MPa). In these valleys, viscous strain heating was a dominant source of heat, particularly when shear rates in the ice increased due to flow constrictions, confluences, or flow past large bedrock obstacles, contributing locally up to several watts per square meter but on average 0.03 to 0.2 W m−2. Basal friction acted as a heat source at the bed of about 0.02 W m−2, 4 to 6 times less than the geothermal heat flow which is locally high (up to 0.12 W m−2). In the lobes, despite low surface slopes and low basal shear stresses, sliding dictated main fluxes of ice, which closely followed bedrock topography: ice was channeled in between bedrock highs along troughs, some of which coincided with glacially eroded overdeepenings. These sliding conditions may have favored glacial erosion by abrasion and quarrying. Our results confirmed general earlier findings but provided more insights into the detailed flow and basal conditions of the Rhine glacier at the LGM. Our model results suggested that the trimline could have been buried by a significant thickness of cold ice. These findings have significant implications for interpreting trimlines in the Alps and for our understanding of ice–climate interactions.