scholarly journals Vegetation and Climate Around 780 Kyrs BP in Northern Kathmandu Valley, Central Nepal

2018 ◽  
pp. 37-48
Author(s):  
Sima Humagain ◽  
Khum N. Paudayal
Keyword(s):  
Cold Climate ◽  
Middle Pleistocene ◽  
Kathmandu Valley ◽  
Tree Pollen ◽  
Bottom Part ◽  
Central Nepal ◽  
Water Plants ◽  
Palynological Study ◽  
First Time ◽  
Vegetation And Climate

Palynological study from the Dharmasthali Formation exposed in the northern part of Kathmandu valley revealed the composition of forest vegetation that were growing in middle Pleistocene (780 kyrs BP) in this area. In a total fifteen samples were collected from the 46 m exposed section for the palynological study. The profile can be divided into two zones on the basis of pollen assemblages. The lower part (DF-I) is dominated by Pteridophyte spores such as Lygodium, Polypodium, Cyathea and Pteris. The dominance of Pteridophytes indicate that the forest floor was moist and humid. The tree pollen consists of Abies, Pinus, Quercus, Podocarpus and Alnus. Other Gymnosperms such as Picea and Tsuga were represented by very low percentage. Poaceae and Cyperaceae show their strong presence indicating grassland and wetland conditions around the depositional basin. In the upper zone (DF-II) there is increase of Gymnosperms such as Picea and Abies. The subtropical Gymnosperm Podocarpus decreased while Tsuga completely became absent in this zone. Cold climate preferring trees such as Cedrus, Betula, Juglans and Ulmus appeared first time in this zone. The climate became even colder and drier in the upper part of the section. Near water plants such as Cyperaceae and Typha show their dominance in this zone. The plant assemblages from bottom part of the Dharmasthali Formation indicate warm climate condition which was becoming colder after 780 kyrs towards the top part of the sequence. Bulletin of Department of Geology, vol. 20-21, 2018, pp:37-48

scholarly journals Palaeolclimatic significance of palynological assemblages from the Siwalik sediments in the Dudhaura Khola section, central Nepal

2013 ◽  
Vol 46 ◽  
Author(s):  
Khum N. Paudayal
Keyword(s):  
Temperate Forest ◽  
Vegetation Pattern ◽  
Bottom Part ◽  
Nepal Himalaya ◽  
The Past ◽  
Central Nepal ◽  
Palynological Assemblages ◽  
Palynological Study ◽  
Siwalik Group ◽  
Vegetation And Climate

The palynological study of the Rapti Formation and Amlekhganj Formation from the Siwalik Group in the Dudhaura Khola section revealed plethora of information to interpret the past vegetation and climate existed during Late Miocene in the southern margin of the Nepal Himalaya. Altogether 30 samples were collected from Rapti Formation and Amlekhganj Formations exposed in the Dudhaura Khola section for the palynological study. Palynological assemblages recovered from the upper part of Rapti Formation and lower part of Amlekhganj Formation consist of 5 families and 10 genera from monocotyledon, 8 families and 14 genera from dicotyledon, 1 family and 4 genera from Gymnosperm and 5 families from Pteridophytes. High presence of Palm pollen and Ceratopteris spores in the Rapti Formation and Amlekhganj Formation suggests that the climate was warm and humid. The riverine vegetation is documented by the presence of Alnus, Typha, Potamogeton, Liliaceae and Poaceae.The frequency of zygnemataceous spores is common in the Rapti Formation while it is decreases towards the bottom part of the Amlekhganj Formation. There is little gymnosperm pollen in the Amlekhganj Formation but their frequency and distribution is very less. This suggests change of vegetation pattern from tropical-subtropical forest to lower temperate forest during the deposition of Amlekhganj Formation and after wards.

Late-devensian and flandrian vegetational history of Bodmin Moor, Cornwall

1977 ◽  
Vol 276 (946) ◽  
pp. 251-320 ◽  
Keyword(s):  
Bronze Age ◽  
Cold Climate ◽  
Pollen Record ◽  
The North ◽  
Pollen Content ◽  
History Of ◽  
Pollen Taxon ◽  
Palynological Study ◽  
First Time ◽  
Palynological Records

A largely palynological study of new exposures of lake and mire sediments from Bodmin Moor, Cornwall, together with radiocarbon dating of the polliniferous deposits has allowed, for the first time in southwest England, description of dated local and regional pollen assemblage zones which can be correlated with the pollen zones of Godwin and the chronozones of West. Reconstruction of the vegetational history of the Late-Devensian, early and later Flandrian periods is attempted by using, wherever possible, values for the pollen content of sediments to illuminate real pollen taxon percentage fluctuations. Deposition of limnic sediments in the Late-Devensian started shortly before 13000 b.p. when the dominant vegetation, open grass heaths, snow-beds and flushes, reflects the cold climate. Soils at this time were subject to erosion by snow melt-water. Ensuing climatic amelioration permitted invasion by juniper scrub and about 12000 b.p. expansion of tree birches took pace. Climatic recession occurring under strongly oceanic conditions (marked by considerable amorphous solifluction of the upland soils and the development of grass/sedge mires) was initiated about 11000 b.p., but its duration here cannot be accurately estimated. Within this threefold pattern of Late-Devensian deposition 12 distinct pollen assemblages are described from four profiles. Pollen of Artemisia norvegica, Astragalus alpinus and Saxifraga stellaris is confined to the earlier and later colder periods. In the intervening warmer period, but not the colder periods, there is slight pollen and macroscopic fossil evidence of Betula nana. An unexplained unconformity exists at the base of the Flandrian deposits. Early Flandrian vegetation is characterized by the spread of tree birches and Salix in the valleys, with Empetrum and juniper on the hillsides. The two latter genera are replaced before 9000 b.p. by Corylus followed almost immediately by the spread of Quercus. Throughout the Flandrian Quercus , Betula and Corylus , although the dominant woodland genera, probably colonized only the more sheltered sites on the upland. Archaeological and palynological records have been correlated as far as possible, the only substantial pollen record of human activity being that of Plantago , which spread encouraged by Bronze Age pastoralism. There is also pollen evidence of scanty cereal cultivation. Areas on the Atlantic fringes of Europe show a marked similarity in their early Flandrian forest history, particularly with regard to the slight role played by Pirns in relation to Quercus compared with stations further east. This similarity must derive from the proximity of the tempering influences of the North Atlantic Drift.

scholarly journals Directional changes in Levallois core technologies between Eastern Africa, Arabia, and the Levant during MIS 5

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
James Blinkhorn ◽  
Huw S. Groucutt ◽  
Eleanor M. L. Scerri ◽  
Michael D. Petraglia ◽  
Simon Blockley
Keyword(s):  
Homo Sapiens ◽  
Environmental Parameters ◽  
Detailed Comparison ◽  
Eastern Africa ◽  
Middle Pleistocene ◽  
Reduction Activity ◽  
Core Technology ◽  
Geographic Expansion ◽  
First Time ◽  
Mis 5

AbstractMarine Isotope Stage (MIS) 5, ~ 130 to 71 thousand years ago, was a key period for the geographic expansion of Homo sapiens, including engagement with new landscapes within Africa and dispersal into Asia. Occupation of the Levant by Homo sapiens in MIS 5 is well established, while recent research has documented complementary evidence in Arabia. Here, we undertake the first detailed comparison of Levallois core technology from eastern Africa, Arabia, and the Levant during MIS 5, including multiple sites associated with Homo sapiens fossils. We employ quantitative comparisons of individual artefacts that provides a detailed appraisal of Levallois reduction activity in MIS 5, thereby enabling assessment of intra- and inter-assemblage variability for the first time. Our results demonstrate a pattern of geographically structured variability embedded within a shared focus on centripetal Levallois reduction schemes and overlapping core morphologies. We reveal directional changes in core shaping and flake production from eastern Africa to Arabia and the Levant that are independent of differences in geographic or environmental parameters. These results are consistent with a common cultural inheritance between these regions, potentially stemming from a shared late Middle Pleistocene source in eastern Africa.

Pollen record of early- to mid-Holocene vegetation and climate dynamics on the eastern coast of the Yellow Sea, South Korea

The Holocene ◽  
2018 ◽  
Vol 28 (6) ◽  
pp. 1011-1022 ◽  
Author(s):  
Bing Song ◽  
Sangheon Yi ◽  
Wook-Hyun Nahm ◽  
Jin-Young Lee ◽  
Limi Mao ◽  
...  
Keyword(s):  
South Korea ◽  
Yellow Sea ◽  
Asian Summer Monsoon ◽  
Climate Dynamics ◽  
Cold Climate ◽  
The Yellow Sea ◽  
Eastern Coast ◽  
Pollen Record ◽  
Vegetation And Climate ◽  
Humid Period

To understand the early- to mid-Holocene vegetation and climate dynamics on the eastern coast of the Yellow Sea, we obtained a sedimentary core with high-resolution accelerator mass spectrometry (AMS) carbon 14 (14C) data from the Gunsan coast in South Korea. The palynological analysis demonstrated that the riverine wetland meadow from 12.1 to 9.8 cal. kyr BP changed to temperate deciduous broad-leaved forest in 9.8–2.8 cal. kyr BP. In addition, the cold climate from 12.1 to 9.8 cal. kyr BP became warmer from 8.5 to 7.3 cal. kyr BP. This was followed by another relatively cold period from 7.3 to 2.8 cal. kyr BP. The temperature change was mainly in response to solar factors. However, there are two relatively humid periods from 12.1 to 9.8 and 8.5 to 7.3 cal. kyr BP, which arose for different reasons. The earlier humid period resulted from strong westerlies and a rapidly rising sea level. The later humid period was produced mainly by the strong East Asian summer monsoon (EASM) and may also be linked to La Niña–like activity. The cold ‘Younger Dryas’ event from 12.0 to 11.4 cal. kyr BP recorded in this study may have been produced by a North Atlantic meltwater pulse. This would have reduced temperatures that were already low because of weak insolation, and the strong winter monsoons would have increased the precipitation.

scholarly journals Vegetation and climate from Late Quaternary Thimi Formation (Phaidhoka Section), Bhaktapur, Nepal

2015 ◽  
Vol 50 (1) ◽  
pp. 1-12
Author(s):  
Deepak Banjade ◽  
Kabir Sharma ◽  
Khum N. Paudayal
Keyword(s):  
Late Quaternary ◽  
Middle Part ◽  
Temperate Climate ◽  
Silty Clay ◽  
Pollen Diagram ◽  
Formation Zone ◽  
Palynological Study ◽  
Deltaic Deposit ◽  
Warm Temperate ◽  
Vegetation And Climate

The Thimi Formation is fluvio-deltaic deposit that constitutes the uppermost part of the sedimentary sequence in the Kathmandu Basin, and is featured by carbonaceous and diatomaceous clay, silty clay, silt, fine to medium grained sand beds, and thin to medium lignite beds. The Phaidhoka Section is located on the way to Nala from Chyamasingh, and is one of the major exposures of the Thimi Formation. Forty four samples were collected from 25 m thick surface exposure for palynological study. The study revealed the dominance of gymnosperm over the angiosperm and herbaceous members. The pollen diagram suggested Pinus, Picea and Quercus as the most dominant trees whereas Poaceae is other dominant among the grasses. Three major pollen assemblage zones were marked in the Thimi Formation. Zone P-I indicated warm temperate climate, whereas zone P-II and P-III indicated cold temperate climate. Molluscan operculum in the upper part indicated shallow water condition. The Bovid molars, limb and pelvic bones from the middle part of the section confirm the early findings of molar bones in this area.

scholarly journals Luminescence dating of a late Middle Pleistocene glacial advance in eastern England

2021 ◽  
Vol 100 ◽  
Author(s):  
Philip L. Gibbard ◽  
Mark D. Bateman ◽  
Jane Leathard ◽  
R.G. West
Keyword(s):  
Previous Investigation ◽  
Alluvial Fan ◽  
Luminescence Dating ◽  
Marine Isotope Stage ◽  
Middle Pleistocene ◽  
Eastern Margin ◽  
First Time ◽  
Late Middle Pleistocene ◽  
Glacial Advance

Abstract Previous investigation of isolated landforms, on the eastern margin of the East Anglian Fenland, England, has demonstrated that they represent an ice-marginal delta and alluvial fan complex deposited at the margin of an ice lobe that entered the Fenland during the ‘Tottenhill glaciation’ (termed the ‘Skertchly Line’). They have been attributed, based on regional correlations, to a glaciation during the Late Wolstonian (i.e. Late Saalian) Substage (Drenthe Stadial, early Marine Isotope Stage (MIS) 6). This paper aimed to test this correlation by directly optically luminescence dating, for the first time, sediments found within the Skertchly Line at Shouldham Thorpe, Norfolk, and Maidscross Hill, Suffolk, together with those in associated kame terrace deposits at Watlington, Norfolk. Ages ranged from 244 ± 10 ka to 12.8 ± 0.46 ka, all the results being younger than MIS 8 with some clearly showing the landforms have been subsequently subjected to periglacial processes, particularly during the Late Devensian Substage (∼MIS 2). Most of the remainder fall within the range 169–212 ka and could be assigned to MIS 6, thus confirming the previously proposed age of the glaciation. The local and regional implications of these conclusions are discussed, the maximum ice limit being linked to that of the Amersfoort–Nijmegen glaciotectonic ridge limit in the central Netherlands.

scholarly journals Pull-Out Capacity and Failure Mechanisms of Strip Anchors in Clay

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3853
Author(s):  
Fernando Cañizal ◽  
Jorge Castro ◽  
Jorge Cañizal ◽  
César Sagaseta
Keyword(s):  
Failure Mechanisms ◽  
Cohesive Soils ◽  
Finite Element Analyses ◽  
Bottom Part ◽  
Pull Out ◽  
Shallow Failure ◽  
Plate Anchors ◽  
Floating Platforms ◽  
First Time ◽  
Analytical Limit

Plate anchors are a well-established solution for supporting the efforts of floating platforms for wind and marine renewable energies. The behavior of ultrathin rigid plate anchors buried in purely cohesive soils under undrained and plane-strain conditions is analyzed. As already known, a dimensional analysis shows that the pull-out capacity of the anchor may be expressed using a weightless break-out factor (Nc0) that only depends on the ratio between the depth and the anchor width (H/B). Using finite element analyses, tabulated values of the weightless break-out factor are provided in this paper and three different failure mechanisms are identified, namely very shallow (quasi-vertical), shallow or intermediate (semi-vertical), and deep (rotational). For very shallow failure mechanisms, the studied problem is completely equivalent to the trapdoor problem because immediate breakaway at the bottom part of the anchor is considered (vented conditions). The existing analytical solutions for the very shallow (Nc0 = 1.956 H/B) and deep cases (Nc = 3π + 2) using the slip-line method are reviewed and an analytical limit is proposed for the first time for the very shallow mechanism (H/B = 1.314). For shallow (intermediate) cases, the failure mechanism is identified and the angle of the main slip lines is numerically evaluated.

scholarly journals First nearly complete skull of Gallotia auaritae (lower-middle Pleistocene, Squamata, Gallotiinae) and a morphological phylogenetic analysis of the genus Gallotia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Penélope Cruzado-Caballero ◽  
Carolina Castillo Ruiz ◽  
Arnau Bolet ◽  
Juan Ramón Colmenero ◽  
Julio De la Nuez ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Cranial Morphology ◽  
Middle Pleistocene ◽  
Phylogenetic Position ◽  
Fossil Species ◽  
La Palma ◽  
Computed Microtomography ◽  
X Ray Computed ◽  
Cranial Osteology ◽  
First Time

Abstract The Canary Islands are an Atlantic archipelago known for its high number of endemic species. Among the most known endemic vertebrate species are the giant lizards of the genus Gallotia. We describe the cranial osteology of the first almost complete and articulated fossil skull of the taxon Gallotia auaritae, recovered from the lower-middle Pleistocene of the La Palma island. In this work, X-ray computed microtomography images were used to perform an exhaustive phylogenetic analysis where most of the extant and fossil species of the genus Gallotia were included for first time. This analysis recovered a monophyletic Gallotia clade with similar topology to that of molecular analyses. The newly described specimen shares some characters with the group formed by G. bravoana, G. intermedia and G. simonyi, G. auaritae, and its position is compatible with a referral to the latter. Our study adds new important data to the poorly known cranial morphology of G. auaritae, and the phylogenetic analysis reveals an unexpected power of resolution to obtain a morphology-based phylogeny for the genus Gallotia, for inferring the phylogenetic position of extinct species and for helping in the identification of fossil specimens.

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