Mountain glaciation and paleoclimate reconstruction in the Picos de Europa (Iberian Peninsula, SW Europe)

2012 ◽  
Vol 78 (2) ◽  
pp. 303-314 ◽  
Author(s):  
Enrique Serrano ◽  
Juan José González-Trueba ◽  
María González-García
Keyword(s):  
Late Quaternary ◽  
Ice Age ◽  
Equilibrium Line Altitude ◽  
Sedimentary Characteristics ◽  
Geomorphic Mapping ◽  
Stratigraphic Analysis ◽  
History Of ◽  
Northwestern Spain ◽  
The 19Th Century ◽  
Lake Deposits

AbstractGeomorphic mapping and stratigraphic analysis of a lake core document the late Quaternary glacial history of the Central and Eastern Massifs of the Picos de Europa, northwestern Spain. The distribution of glacial deposits indicates that at their most advanced positions glaciers occupied 9.1 km2, extended as far as 7 km down-valley and had an estimated equilibrium-line altitude (ELA) ranging between 1666 and 1722 m. Radiocarbon dating of sediment deposited in a lake dammed by moraines of this advance show that the maximum glacial extent was prior to 35,280 ± 440 cal yr BP. This advance was followed by two subsequent but less extensive late Pleistocene advances, recorded by multiple moraines flanking both massifs and sedimentary characteristics in the lake deposits. The last recognized glacial episode is the 19th-century maximum extent of small Little Ice Age glaciers in the highest cirques above 2200 m.

Late Quaternary vegetation of the Aleutian Islands, southwestern Alaska

1990 ◽  
Vol 68 (6) ◽  
pp. 1320-1326 ◽  
Author(s):  
Calvin J. Heusser
Keyword(s):  
Late Quaternary ◽  
Thickness Distribution ◽  
Patch Dynamics ◽  
Volcanic Eruptions ◽  
Ice Age ◽  
Aleutian Islands ◽  
Fossil Pollen ◽  
History Of ◽  
Tephra Layers ◽  
Radiocarbon Chronology

Late Quaternary vegetational history of the Aleutian Islands is interpreted from fossil pollen and spore stratigraphy and radiocarbon chronology of sections of mires on the islands of Attu, Adak, Atka, and Umnak. Mires postdate the withdrawal of ice-age glaciers between approximately 12 000 and 10 000 years ago with the exception of the mire on Attu Island, where deglaciation apparently began as late as 7000 years ago. No uniform pattern of change in Pacific coastal tundra communities is evident in the fossil assemblages. Pollen assemblages, consisting variably of Gramineae, Cyperaceae, Empetrum, Umbelliferae, Salix, Ranunculaceae, Compositae, Polypodiaceae, and Lycopodium, reflect conditions in effect in different sectors of the Aleutian chain. Climate, soil, topography, volcanism, and seismic activity are noteworthy parameters influencing vegetation composition and distribution. Volcanism has been of major importance, as shown by thickness, distribution, and frequency of tephra layers that number 5 on Attu, 24 on Adak, 17 on Atka, and 5 on Umnak. A repeated condition of patch dynamics, created in the main by recurrent volcanic eruptions with widespread accompanying ashfalls, has apparently overprinted the effects of climatic change. Key words: Aleutian Islands, Quaternary, vegetation, fossil pollen, volcanism.

scholarly journals Late-Quaternary Vegetational and Climatic History of the Yellowstone/Grand Teton Region

1988 ◽  
Vol 12 ◽  
pp. 189-192
Author(s):  
Cathy Barnosky
Keyword(s):  
Environmental History ◽  
Late Quaternary ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Fire Frequency ◽  
Ice Age ◽  
Sediment Chemistry ◽  
History Of ◽  
Climatic History

The research underway has focused on two different aspects of the environmental history of the Yellowstone/Grand Teton region. One objective has been to examine the long-term vegetational and climatic history of Jackson Hole, the Pinyon Peak Highlands, and Yellowstone Park since the end of late Pinedale glaciation, about 14,000 years ago. Fossil pollen in sediment cores from lakes in the region is being analyzed to clarify the nature and composition of ice-age refugia, the rate and direction of plant migrations in the initial stages of reforestation, and the long-term stability of postglacial communities. Sedimentary charcoal also is being examined to reconstruct fire frequency during different climatic regions and different vegetation types in the past. This information is necessary to assess the sensitivity of plant communities to environmental change and to understand postglacial landscapes of the northern rocky Mountains. The second objective has been a multidisciplinary investigation of the relationship of climate to sedimentation rates in lakes and ponds in Yellowstone, undertaken with Drs. Wright, D.R. Engstrom and S.C. Fritz of the University of Minnesota. This facet of the research examines the relative importance of climate, fire, hillslope erosion induced by overgrazing, and nutrient enrichment in the last 150 years, as recorded in selected lakes in the northern range of Yellowstone. Populations of elk and bison are known to have fluctuated greatly during this interval, and slight climatic changes are suggested from other lines of research. In this study pollen, diatoms, charcoal, sediment chemistry, and sediment accumulation rates are analyzed in short cores from small lakes.

Late Quaternary evolution of the Upper Paraná River, southeast Brazil: a new geomorphological and chronological database

2021 ◽  
Author(s):  
Stefania C. Oliveira ◽  
Fabiano N. Pupim ◽  
José C. Stevaux ◽  
Mario L. Assine
Keyword(s):  
Late Quaternary ◽  
Morphological Characteristics ◽  
Remote Sensing Data ◽  
Integrated Approach ◽  
Mato Grosso ◽  
Current Configuration ◽  
Sedimentary Characteristics ◽  
Geomorphological Units ◽  
History Of ◽  
River Plain

<p>The Paraná River has being extensively studied in terms of its hydrological and sedimentological aspects, but the geological history of its fluvial plain is still poorly understood due to the lack of geochronological data. Most of the published studies are focused on the low and middle reaches, and the region upstream of the Porto Primavera dam is an area almost unknown in terms of geomorphic evolution. Here, we aim to investigate the succession of geological events responsible for the evolution and current configuration of the Upper Paraná River fluvial system, in the stretch between the Jupiá and Porto Primavera Hydroelectric Plants (São Paulo and Mato Grosso states). Thus, we used an integrated approach including remote sensing data, geomorphology, sedimentology, bathymetric profiles, and chronological methods. Four geomorphological compartments were identified and three of these compartments were dated by Optically Stimulated Luminescence (OSL): Unit 1, raised terrace with circular and semicircular ponds (~150 ka); Unit 2, intermediate terrace with small ponds and waterlogged areas (~60 ka); Unit 3, low terrace with preserved paleochannels (~39–35 ka); and Unit 4, current river plain (>9 ka). The geomorphological units were correlated with previous studies downstream of the studied area and their sedimentary characteristics and depositional ages suggest that their genesis is linked to changes in climatic and hydrological conditions during the Late Quaternary. Units 1, 3, and 4 are considered extensions of the geomorphological units Taquaruçu, Fazenda Boa Vista, and Rio Paraná, respectively. Unit 2 is a compartment with unique morphological characteristics, therefore not correlated with units presented in previous works. Further, two main knickpoints were identified, suggesting an important control in the sedimentation and development of the terrace levels. Thus, this work brings new data on the evolutionary history of the Paraná River, which allows us to understand that the development of the terrace levels and the floodplain of the upper reaches are strongly controlled by the climatic changes that occurred during the Late Quaternary.</p>

scholarly journals The rise and fall of the Refugial Hypothesis of Amazonian speciation: a paleoecological perspective

2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Mark B. Bush ◽  
Paulo E. de Oliveira
Keyword(s):  
Amazon Basin ◽  
Late Quaternary ◽  
Indirect Evidence ◽  
Ice Age ◽  
Data Set ◽  
The Andes ◽  
History Of ◽  
Last Ice Age ◽  
Northern Hemispheric ◽  
Amazonian Forests

The refugial hypothesis is treated as the definitive history of Amazonian forests in many texts. Surprisingly, this important theoretical framework has not been based on paleoecological data. Consequently, a model of Amazonian aridity during the northern hemispheric glaciation has been accepted uncritically. Ironically, the Refuge Hypothesis has not been tested by paleobotanical data. We present a revision of the concept of Neotropical Pleistocene Forest Refuges and test it in the light of paleocological studies derived from pollen analysis of Amazonian lake sediments deposited during the last 20,000 years. Our analysis is based primarily on paleoenvironmental data obtained from sites in Brazil and Ecuador. These data are contrasted with those that favor the hypothesis of fragmented tropical forests in a landscape dominated mainly by tropical savannas under an arid climate. The Ecuadorian data set strongly suggests a 5ºC cooling and presence of humid forests at the foot of the Andes, during the last Ice Age. The same climatic and vegetational scenario was found in the western Brazilian Amazon. On the other hand, somewhat drier conditions were observed in the central Amazon, but the landscape remained a forested landscape during the supposedly arid phases of the Late Quaternary. Data obtained from the Amazon Fan sediments containing pollen derived from extensive sections of the Amazon Basin, were fundamental to the conclusion that the predominance of savannas in this region is not supported by botanical data. Our revision of the assumptions derived from the Refuge Hypothesis indicates that it has succumbed to the test now permitted by a larger paleocological data set, which were not available during the golden age of this paradigm, when indirect evidence was considered satisfactory to support it.

scholarly journals Glacier recession on Cerro Charquini (16° S), Bolivia, since the maximum of the Little Ice Age (17th century)

2006 ◽  
Vol 52 (176) ◽  
pp. 110-118 ◽  
Author(s):  
Antoine Rabatel ◽  
Abraham Machaca ◽  
Bernard Francou ◽  
Vincent Jomelli
Keyword(s):  
20Th Century ◽  
Little Ice Age ◽  
17Th Century ◽  
Climatic Conditions ◽  
Ice Age ◽  
Equilibrium Line Altitude ◽  
Glacier Recession ◽  
Recession Rates ◽  
Cordillera Real ◽  
The 19Th Century

AbstractCerro Charquini, Bolivia (Cordillera Real, 5392 ma.s.l.) was selected as a site to reconstruct glacier recession since the maximum of the Little Ice Age (LIA) in the central Andes. Five glaciers, located on differently exposed slopes, present comprehensive and well-preserved morainic systems attributed to former centuries. The moraines were dated by lichenometry and show a consistent organization on the different slopes. The past geometry of the glaciers was reconstructed using ground topography and aerophotogrammetry. Lichenometric dating shows that the LIA maximum occurred in the second half of the 17th century, after which the glaciers have receded nearly continuously. Over the last decades of the 20th century (1983–97), recession rates increased by a factor of four. On the northern and western slopes, glaciers receded more than on the southern and eastern slopes (by 78% and 65% of their LIA maximum area, respectively). The mean equilibrium-line altitude (ELA) rose by about 160 m between the LIA maximum and 1997. Recession rates were analysed in terms of climatic signal, suggesting that glacier recession since the LIA maximum was mainly due to a change in precipitation and that the 19th century may have been drier. For the 20th century, a temperature rise of about 0.6°C appears to be the main cause of glacier recession. Recent climatic conditions from 1983 to 1997 correspond to a mass deficit of about 1.36m w.e.a–1. If such conditions persist, the small glaciers below 5300ma.s.l. in the Cordillera Real should disappear completely in the near future.

Late Quaternary Glacial History of George VI Sound Area, West Antarctica

1982 ◽  
Vol 18 (3) ◽  
pp. 243-267 ◽  
Author(s):  
Chalmers M. Clapperton ◽  
David E. Sugden
Keyword(s):  
Amino Acid ◽  
Late Quaternary ◽  
Ice Age ◽  
Dry Valleys ◽  
West Antarctica ◽  
Ice Shelf ◽  
Ice Caps ◽  
Climatic Control ◽  
Acid Ratio ◽  
History Of

AbstractDuring the last glacial maximum in West Antarctica separate ice caps developed on Alexander Island and on Palmer Land, became confluent in George VI Sound, and discharged northward from latitude 72° S. Radiocarbon (>32,000 yr) and amino acid (approximately 120,000 yr) age determinations on shell fragments (Hiatella solida) found in basal till suggest a Wisconsin age for the glaciation that incorporated them. The pattern of ice flow differed from that deduced for this area in the CLIMAP reconstruction. Following the maximum stage, there was a stadial event when outlet valley glaciers flowed from smaller ice caps into George VI Sound. More widespread recession permitted the George VI ice shelf to deposit Palmer Land erratics on eastern Alexander Island before isostatic recovery raised them to final elevations of about 82 m. The ice shelf may have been absent at about 6500 yr B.P., when large barnacles (Bathylasma corolliforme) were living in the sound. Small glaciers readvanced to form at least two terminal moraines before the ice shelf re-formed and incorporated the barnacle shells into its moraine on Alexander Island. The shells gave a 14C age (corrected for Antarctic conditions) of about 6500 yr B.P. and an amino acid ratio consistent with a Holocene age. Valley glaciers readvanced over the ice-shelf moraine before oscillations of both valley glaciers and the ice shelf led to the formation of the present sequence of contiguous ice-cored moraines, probably during the Little Ice Age. Such oscillations may represent a climatic control not yet observed in the dry valleys of Victoria Land, the only other part of Antarctica studied in detail for glacier fluctuations.

scholarly journals Little Ice Age climate reconstruction from ensemble reanalysis of Alpine glacier fluctuations

2014 ◽  
Vol 8 (2) ◽  
pp. 639-650 ◽  
Author(s):  
M. P. Lüthi
Keyword(s):  
Atlantic Multidecadal Oscillation ◽  
Ice Age ◽  
Macroscopic Model ◽  
Radiative Cooling ◽  
Equilibrium Line Altitude ◽  
Alpine Glacier ◽  
Mountain Glaciers ◽  
Glacier Terminus ◽  
History Of ◽  
The Alps

Abstract. Mountain glaciers sample a combination of climate fields – temperature, precipitation and radiation – by accumulation and melting of ice. Flow dynamics acts as a transfer function that maps volume changes to a length response of the glacier terminus. Long histories of terminus positions have been assembled for several glaciers in the Alps. Here I analyze terminus position histories from an ensemble of seven glaciers in the Alps with a macroscopic model of glacier dynamics to derive a history of glacier equilibrium line altitude (ELA) for the time span 400–2010 C.E. The resulting climatic reconstruction depends only on records of glacier variations. The reconstructed ELA history is similar to recent reconstructions of Alpine summer temperature and Atlantic Multidecadal Oscillation (AMO) index, but bears little resemblance to reconstructed precipitation variations. Most reconstructed low-ELA periods coincide with large explosive volcano eruptions, hinting at a direct effect of volcanic radiative cooling on mass balance. The glacier advances during the LIA, and the retreat after 1860, can thus be mainly attributed to temperature and volcanic radiative cooling.

scholarly journals Little Ice Age glacier history of the Central and Western Alps from pictorial documents

2018 ◽  
Vol 44 (1) ◽  
pp. 115 ◽  
Author(s):  
H.J. Zumbühl ◽  
S.U. Nussbaumer
Keyword(s):  
Little Ice Age ◽  
Western Alps ◽  
Ice Age ◽  
European Alps ◽  
Huge Number ◽  
Valley Bottom ◽  
Valley Glacier ◽  
History Of ◽  
The Alps ◽  
The 19Th Century

The Lower Grindelwald Glacier (Bernese Oberland, Switzerland) consists of two parts, the Ischmeer in the east (disconnected) and the Bernese Fiescher Glacier in the west. During the Little Ice Age (LIA), the glacier terminated either in the area of the “Schopffelsen” (landmark rock terraces) or advanced at least six times (ten times if we include early findings) even further down into the valley bottom forming the “Schweif” (tail). Maximal ice extensions were reached in 1602 and 1855/56 AD. The years after the end of the LIA have been dominated by a dramatic melting of ice, especially after 2000. The Mer de Glace (Mont Blanc area, France) is a compound valley glacier formed by the tributaries Glacier du Tacul, Glacier de Léschaux, and Glacier de Talèfre (disconnected). During the LIA, the Mer de Glace nearly continuously reached the plain in the Chamonix Valley (maximal extensions in 1644 and 1821 AD). The retreat, beginning in the mid-1850s, was followed by a relatively stable position of the front (1880s until 1930s). Afterwards the retreat has continued until today, especially impressive after 1995. The perception of glaciers in the early times was dominated by fear. In the age of Enlightenment and later in the 19th century, it changed to fascination. In the 20th century, glaciers became a top attraction of the Alps, but today they are disappearing from sight. With a huge number of high-quality pictorial documents, it is possible to reconstruct the LIA history of many glaciers in the European Alps from the 17th to the 19th centuries. Thanks to these pictures, we get an image of the beauty and fascination of LIA glaciers, ending down in the valleys. The pictorial documents (drawings, paintings, prints, photographs, and maps) of important artists (Caspar Wolf, Jean-Antoine Linck, Samuel Birmann) promoted a rapidly growing tourism. Compared with today’s situations, it gives totally different landscapes – a comparison of LIA images with the same views of today is probably the best visual proof for the changes in climate.

scholarly journals Little Ice Age climate reconstruction from ensemble reanalysis of Alpine glacier fluctuations

2013 ◽  
Vol 7 (5) ◽  
pp. 5147-5175 ◽  
Author(s):  
M. P. Lüthi
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Macroscopic Model ◽  
Volume Changes ◽  
Equilibrium Line Altitude ◽  
Alpine Glacier ◽  
Mountain Glaciers ◽  
Glacier Terminus ◽  
History Of ◽  
The Alps

Abstract. Mountain glaciers sample a combination of climate parameters – temperature, precipitation and radiation – by their rate of volume accumulation and loss. Flow dynamics acts as transfer function which maps volume changes to a length response of the glacier terminus. Long histories of terminus positions have been assembled for several glaciers in the Alps. Here I analyze terminus position histories from an ensemble of seven glaciers in the Alps with a macroscopic model of glacier dynamics to derive a history of glacier equilibrium line altitude (ELA) for the time span 400–2010 C.E. The resulting climatic reconstruction depends only on records of glacier variations. The reconstructed ELA history is similar to recent reconstructions of Alpine summer temperature and Atlantic Meridional Oscillation (AMO) index. Most reconstructed low-ELA periods coincide with large explosive volcano eruptions, hinting to mass balance reduction by volcanic radiative cooling. The glacier advances during the LIA, and the retreat after 1860 are thus explained by temperature and volcanic cooling alone.

The California Ice-Age Refugium and the Rancholabrean Extinction Problem

1977 ◽  
Vol 8 (2) ◽  
pp. 149-153 ◽  
Author(s):  
Donald Lee Johnson
Keyword(s):  
Environmental Impact ◽  
Environmental Change ◽  
Late Quaternary ◽  
Ice Age ◽  
Glacial Refugium ◽  
Principal Agent ◽  
Extinction Event ◽  
History Of

The question of what caused the late Quaternary extinction of the Rancholabrean fauna in the California glacial refugium is examined. In the absence of significant climatic and other natural environmental change, man was probably the principal agent of extinction in California. This extinction event marked the beginning of a long history of environmental impact in the area by humans.

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