bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of tephra fall and environmental change: a 1000 year record from Matakana Island, Bay of Plenty, North Island, New Zealand
Authors: Giles Teresa M. , Newnham Rewi M. , Lowe David J. , Munro Adam J. 
Published: April 2008

Abstract

Palynological evidence was used to determine the development of vegetation communities on Matakana Island, North Island, New Zealand, over the last 1000 radiocarbon years. The pollen record indicates that changes occurred in the vegetation immediately following fallout deposition of the Kaharoa Tephra approximately 100 km from source at
c.
665 years BP. Such changes may be a direct response to the impact of tephra fall, although the possibility of anthropogenic disturbance cannot be discounted. As a result of the eruption some taxa (
Leucopogon fasciculatus
and
Tupeia antarctica
) became at least temporarily extinct from the area. Two phases of anthropogenic influence on the environment are recorded in the pollen record: Polynesian, followed by European inhabitation of the island, giving a detailed history of human influence in the area for the millennium.
The role of tephrachronology in recognizing synchronous caldera-forming events at the Quaternary volcanoes Longonot and Suswa, south Kenya Rift
Authors: Scott Stuart C. , Skilling Ian P. 
Published: April 2008

Abstract
The Quaternary volcanoes Longonot and Suswa, located in the south Kenya Rift, each have a caldera formed by incremental collapse accompanied by airfall, pyroclastic flow and pyroclastic surge activity. To constrain the relative ages of caldera formation at these two closely spaced centres, syn-caldera deposits are correlated using tephrachronology.

Volcanic products from Longonot and Suswa display contrasting Nb/Zr ratios which provide a unique signature for each centre. Early syn-caldera pyroclastics at Suswa contain airfall pumice beds which have Longonot Nb/Zr signatures. Variation of FeO(T) and Al
2
O
3
with Zr is particularly effective at discriminating the various Longonot units in two component space, and has been combined with volcanological evidence to identify the equivalent Longonot deposits as either early syn-caldera or late syn-caldera. In both cases, the correlation indicates synchronous initiation of caldera formation. This suggests that caldera formation is a regional rather than local event in the southern part of the rift, highlighting the potential rôle of regional tectonics as a controlling mechanism.

Major alignments of eruptive vents, fissures and the caldera collapse centre at each volcano are parallel to rift faults, suggesting that rift floor tension fractures or normal faults are utilized as conduits for magma transport. Synchronous caldera formation at Longonot and Suswa may, therefore, be linked to lateral magma withdrawal along rift floor fractures and decompression of the shallow-level magma chambers during a period of rift floor extension.
Eruptive and seismic activity at Etna Volcano (Italy) between 1977 and 1991
Authors: Vinciguerra S. , Garozzo S. , Montalto A. , Patanè G. 
Published: April 2008

Abstract

A review of volcanic and seismic activity at Etna (Sicily, Italy) between 1977–1991 is presented with the purpose of looking for possible relations between the main phases of seismic energy release and the principal eruptive episodes. Flank eruptions are normally preceded by both deep and shallow seismic swarms (0 <
h
<20km) which accompany the opening of fracture systems some hours before the eruption onset. Conversely, summit eruptions usually take place without any immediate change in the seismic patterns, even if moderate seismic activity some months before the onset suggests that magma uprises gradually and might rest within shallow reservoirs during ascent. It is worth noting that in some cases (1981, 1983, 1984 and 1986) significant episodes of seismic energy release occurred during the late phases of the eruptions. The analysis of the temporal evolution of the coefficient
b
of the magnitude-frequency relation suggests that the shallow seismicity of the eastern flank reflects the existence of a high level of geodynamic activity, probably associated with both regional tectonic forces and seaward sliding of this unbuttressed sector of the volcano.
An assessment of discriminant function analysis in the identification and correlation of distal Icelandic tephras in the British Isles
Authors: Charman Daniel J. , Grattan John 
Published: April 2008

Abstract
This paper assesses the potential of discriminant function analysis (DFA) for tephrochronology in the UK and Ireland. Current identification and correlation of Holocene tephras relies largely on radiocarbon dating to suggest a likely candidate eruption followed by a geochemical comparison using binary and ternary plots of selected major oxides. As more tephras are discovered, and the patterns of deposition appear increasingly complex, this approach is likely to work less effectively. In addition, the utility of tephra for the establishment of chronozones will be limited by the availability of radiometric dates to constrain the initial candidate eruption. The results of a DFA on some of the limited published geochemical data are presented and it is clear that this statistical technique offers advantages to the application and development of tephrochronology in western Europe. Future work should concentrate on the provision of discriminant functions from a more complete reference dataset, which will enable the identification of unknown tephras with a known probability of misclassification.
Reconstruction of the 1706 Montaña Negra eruption. Emergency procedures for Garachico and El Tanque, Tenerife, Canary Islands
Authors: Solana M. C. , Aparicio A. 
Published: April 2008

Abstract
In May 1706, after several earthquakes, an eruptive fissure opened in the hills of the Garachico district, forming the Montaña Negra Volcano. In < 15 h the village of El Tanque and part of the town of Garachico, including the harbour, were buried under lava flows. A week later, another flow buried the village of San Juan del Reparo and much of the remaining town of Garachico.
Today, over 6700 people live in the immediate vicinity of this former eruption. Although most of the population is concentrated in the main villages, dwellings are located throughout the district and any future eruption will inevitably destroy property. The reconstruction of the 1706 eruption shows that in any future event only a short time will be available to evacuate the population, but it may be possible to try to prevent the effects of the flows.
Evolving models of the Tertiary evolutionary geomorphology of southern England, with special reference to the Chalklands
Authors: Jones David K. C. 
Published: April 2008

Abstract
This paper examines recent advances in understanding of the Tertiary evolutionary geomorphology of the southern England Chalklands, a subject of continuing controversy despite over a century of investigation. It begins by briefly outlining the classic Wooldridge and Linton model and discussing the many lines of criticism. Particular attention is paid to the explanation of discordant drainage and numerous lines of evidence are presented to explain why the ‘superimposition model’ has been rejected in favour of an explanation involving the development of anteconsequents. Attention is then directed to the new models of evolution advanced in the early 1980s which placed heavier emphasis on Palaeogene denudation and pulsed tectonism. These models are compared and contrasted, and attention focused on the growing recognition that the fundamental erosional surface is an etchplanated Summit Surface originating in the Palaeogene rather than a peneplanated surface developed during the Miocene and Pliocene. Significant developments of the last fifteen years are then reviewed — the establishment of inversion tectonics, lithostratigraphical division of the Chalk, apatite fission-track dating of uplift episodes and new information on the extent of the late Pliocene Red Crag incursion — and combined to produce a new evolutionary sequence which differs from previous interpretations in a number of regards. First, the concept of structural compartmentalization into morphotectonic regions removes the need for uniformity of evolution and indicates that uplift could have been variable in time and space, thereby removing the problems caused by continual adherence to the concept of mid-Tertiary tectonism. Second, the growing evidence for Pleistocene differential uplift of at least 200 m is considered. Third, an explanation of the so-called Plio-Pliocene marine bench involving modified etchplanation is advanced. The paper concludes with a discussion of remaining uncertainties.
Chattian and Miocene elements in the modern landscape of western Britain and Ireland
Authors: Walsh Peter , Boulter Michael , Morawiecka Iwona 
Published: April 2008

Abstract
The best preserved denudation surfaces which are benched into the margins of the pre-Permian oldland massifs of western Britain and Ireland are those comparatively close to sea-level. Such surfaces have frequently been regarded as being of late Pliocene or Pleistocene age and of marine origin. Recent discoveries reviewed in this work reinforce a growing view that these low-level planations are much older and may be of terrestrial origin. Evidence from Wales and southwest England suggests that these little-modified planation elements represent landscapes some 15 Ma old. This paper reviews the palaeobotanical, sedimentological and geomorphological evidence for the close association of several bodies of non-marine Chattian and Miocene sediment and saprolite with some of the better known planation features. In these areas, the former vegetation comprised mixed coniferous/deciduous forest, extinct species of modern north temperate genera, well known from contemporaneous deposits in north Europe. Evidently, differential relief in those times was appreciably less than that of the present and it seems probable that much of what is now the western half of the British Isles was then a wide, forested extension of a previous North European Plain, which varied in altitude by no more than a few decametres.
An overview of Pliocene to present-day uplift and denudation rates in the Northern Apennine
Authors: Bartolini Carlo 
Published: April 2008

Abstract

Quaternary, Holocene and present denudation rates in the Northern Adriatic basin and sedimentary supply rates, formerly to the Northern Apennine Foredeep and at present to the Adriatic Sea, are approximately consistent. The Quaternary denudation rate, based on sediment feeding to the foredeep is 0.45 mm a
−1
. This value is congruous with a mean exhumation rate since the Early Pliocene, deduced from apatite fission track dating, of 0.5 mm a
−1
in the Apuan Alps. The Quaternary supply rate to the foredeep (0.047 km
3
a
−1
) is over twice as fast as that of the Pliocene (0.021 km
3
a
−1
), and reflects an increased denudation rate due to higher energy relief and a slightly larger catchment basin. The Pleistocene increase in uplift/denudation rates is emphasized by the onset of fast prograding sedimentation pattern since 1.0 to 0.8 Ma on both the Padan and the Tyrrhenian side of the Apennines. Pleistocene uplift also had a considerable impact on Apennine morphology and drainage pattern evolution.
Landscape evolution and the preservation of tectonic landforms along the northern Yammouneh Fault, Lebanon
Authors: Butler R. W. H. , Spencer S. 
Published: April 2008

Abstract

The Yammouneh Fault is commonly considered to be the principal active strand of the Dead Sea Transform in Lebanon — an inference reached primarily from interpretations of the geomorphological expression of the fault on satellite images. However, new geological field observations show the Yammouneh Fault to be sealed stratigraphically by the Homs Basalt, dated using new K-Ar ages at 5.2–6.5 Ma. Drainage systems which link to the pre-Homs Basalt palaeosurface show evidence of fault disruption. Those valleys incised into the basalt show no evidence for transcurrent offsets. The inferred left-lateral displacement of
c.
45 km on the Dead Sea Transform that post-dates the Homs Basalt is presumed to have bypassed to the west of Mount Lebanon. These linked geological and geomorphological studies indicate that landscape evolution can be exceptionally slow in northern Lebanon. Faceted spurs, poljes and offset drainage along the Yammouneh Fault across Mount Lebanon, evident on satellite images, are interpreted as being of Miocene age and are not indicative of Plio-Quaternary displacements on the fault. Much of the Lebanese tectonic landscape has thus remained stable for many millions of years, although locally incised during large-scale uplift of the Mount Lebanon range. Presumably landscape insensitivity reflects the arid climatic conditions together with inhibited run-off due to the regional karst system.
Influence of crustal movements on landforms, erosion and sediment deposition in the Irangi Hills, central Tanzania
Authors: Eriksson Mats G. 
Published: April 2008

Abstract

The influence of crustal movements on landforms, erosion and sediment deposition has been analysed in the severely eroded Irangi Hills in Kondoa District, central Tanzania. Field observations, in combination with satellite imagery, aerial photographs, and topographical and geological maps have been used. The Irangi Hills, which are uplifted relative to the vast Maasai Plain, consist of several tectonic blocks, with each block being tilted to the west. Frequent earthquakes indicate that relative uplift, faulting and tilting of the Irangi Hills are still taking place. The drainage pattern of the area and the deposition of river sediments are directly influenced by the morphotectonics. Where fault scarps occur, large rivers have cut into the bedrock across the fault scarps and follow antecedent stream courses, while small streams have been dammed, forming swamps or lakes. The denudation rate for a small catchment (33.4km
2
) has been calculated to 2.7mm a
−1
for the years 1836–1992 by using a dated sediment record. This is considered to be an accelerated denudation rate. The soil erosion of the Irangi Hills is a long-term natural stripping of regolith, accelerated by anthropogenic causes, probably in combination with crustal uplift and the tilting of tectonic blocks.
Uplift and landscape stability at Taroko, eastern Taiwan
Authors: Petley David N. , Reid Sharon 
Published: April 2008

Abstract
The Taroko area of Taiwan represents an extremely dynamic environment, of rapid geological and geomorphological change. The location of the area on the collision zone between the continental Eurasian plate and the oceanic Philippine Sea plate leads to a high frequency of seismic activity, intense internal deformation and high rates of tectonic uplift. The rate of uplift, which is believed to be one of the highest measured, is approximately 5.5mm per annum, with higher rates inferred for the last million years. In consequence, the area, which consists predominantly of relatively weak, intensely deformed marble and schist, has a high potential energy providing ideal conditions for rapid landform evolution.
In addition to high rates of uplift, high rates of denudation are also favoured by the extreme climatic conditions. In particular, the area is seasonally affected by tropical cyclones (typhoons); an average of 16 of these occur in the northwest Pacific per annum, about three of which affect Taiwan. The passage of a typhoon is marked by heavy rainfall which may reach intensities of 100mm per hour and 1500mm in 24 hours. The high rainfall intensities generate intense fluvial activity, including extensive overland flow, high peak discharges, the mobilization of debris channels, landslides and rockfalls.
Intense tectonic and geomorphological activity provide the ideal environment for studying the rapid evolution of landscapes. In this paper, uplift data are combined with daily hydrological records from a major river for the last fifteen years. The hydrological records, which include discharge, mean flow rates and sediment volumes, are used to estimate the sediment budget for the river and hence to estimate denudation rates. It is demonstrated that average aerial denudation rates approximately equal uplift rates. These data are then used to generate a simple computer model for the evolution of Taroko Gorge, which demonstrates that current landforms may be created without substantial changes in the rate of uplift.
The landscape evolution of Nemegt Uul: a late Cenozoic transpressional uplift in the Gobi Altai, southern Mongolia
Authors: Owen Lewis A. , Cunningham W. Dickson , Windley Brian F. , Badamgarov J. , Dorjnamjaa D. 
Published: April 2008

Abstract
The geomorphology and structural geology of Nemegt Uul, Southern Mongolia, is examined as an example of a mountain range that has formed within a restraining bend along a major intracontinental strike-slip fault system, the Gobi-Tien Shan fault system. Structural and geomorphological analysis demonstrates that the mountain belt is young and has been differentially tilted and eroded. A geomorphological model is developed showing that uplift and erosion have resulted in the formation of deeply incised mountains, alluvial fans, badlands, desert pavements and dunes.
Hydrodynamics of a floodplain recirculation zone investigated by field monitoring and numerical simulation
Authors: Nicholas A. P. , McLelland S. J. 
Published: April 2008

Abstract

Results are presented from a combined field monitoring and numerical modelling study of flow dynamics within a floodplain recirculation zone. An array of four acoustic Doppler velocimeters (ADVs) was employed to monitor 3D flow velocities within a backwater site on the River Culm, Devon, UK. Patterns of measured mean velocity and turbulent kinetic energy are compared with the results of a numerical simulation of 3D flow carried out using the computational fluid dynamics software package
fluent
. Simulation results illustrate the presence of flow recirculation within the backwater zone, which is consistent with lateral flow convergence monitored in the field along the upstream portion of the channel-backwater interface. Both the simulation results and ADV data highlight the existence of a free-shear layer at the mixing interface between these flows, which is characterized by high levels of turbulent kinetic energy. However, simulated turbulent kinetic energy levels are significantly lower than those monitored in the field. In addition, ADV data illustrate deviations from isotropic turbulence that may not be simulated using a two-equation
k
-ɛ turbulence model. These results provide quantitative evidence of the hydraulic mechanisms responsible for promoting high rates of suspended sediment deposition in such backwater recirculation zones, and highlight several modelling issues that require further attention.
Variations in the quality of the thatching reed
Phragmites australis
from wetlands in East Anglia, England
Authors: Boar R. R. , Kirby J. J. H. , Leeming D. J. 
Published: April 2008

Abstract

Phragmites australis
(Cav.) Trin. ex Steud. (common reed) is an emergent grass that grows in a wide belt across the wetlands of North America and Europe. In many European wetlands, dead stems of
P. australis
are harvested annually to supply the roof thatching industry. This study has measured and compared the quality, in terms of mechanical strength and decay rate, of a reed harvest from 12 marshes in the floodplains of the Rivers Bure, Ant, Thurne Waveney and Blythe in East Anglia, UK. The marshes varied from fresh-water peat to marine alluvium and were in floodplains that have been managed traditionally to supply thatching reed. The decay rate of stems varied more within the floodplains than between them. Mechanical properties, however, varied between the different floodplains, with stems of greatest tensile strength from brackish reedbeds not flooded directly by sea water. As neither the mechanical properties, nor the shape and size of reed stems varied with their decay rate, the quality of roof thatch originating from particular growing areas cannot be predicted easily.
Biotic response to late Holocene floodplain evolution in the River Irthing catchment, Cumbira
Authors: Cotton J. A. , Heritage G. L. , Large A. R. G. , Passmore D. G. 
Published: April 2008

Abstract

This paper presents some results of a geomorphological and palaeoecological evaluation of late Holocene floodplain evolution at a site in the middle reaches of the River Irthing, a tributary of the River Eden, near Brampton, Cumbria, UK. Geomorphological mapping and survey have identified a minimum of seven Holocene alluvial terraces in this reach, each with well-defined palaeochannels developed on their surfaces. Sediment coring and radiocarbon dating of selected channel fills indicate that a large proportion of the Holocene valley floor has been deposited during and after the 3rd millennium
bc
. Detailed sedimentological and macrofossil analyses undertaken on late Holocene channel fill sediments reveal spatial and temporal variability in patterns of local vegetation development within palaeochannel environments. These reflect local changes in hydrology, the character and rates of sedimentation, and levels of disturbance. Results are interpreted in the context of regional records of Holocene climate and land-use change, as well as existing models of floodplain vegetation succession. The advantages of taking a holistic approach to palaeoenvironmental reconstruction and the utilization of macrofossils are discussed.
Historical background to floodplain morphology: examples from the East European Plain
Authors: Panin A. V. , Sidorchuk A. Yu. , Chernov A. V. 
Published: April 2008

Abstract
Floodplain morphology is described in relation to channel pattern changes in the past. The oldest segments of the present-day floodplains were formed in the Late Valdai (Weichselian). Their morphology is inherited from large palaeomeanders (macromeanders) formed under extremely high discharge conditions. A map of the spatial distribution of Late Valdai macromeander relics on the East European Plain is given. Various floodplain segments have a spectrum of ages that may reflect only selected portions of the river history. The most widespread morphological units correspond to the periods when the river was undergoing its widest lateral migration. Periods of stable channel position may result in a gap in the floodplain age spectrum. The channel pattern and rates of river migration are controlled both by hydrological conditions and by valley floor morphology inherited from the preceding river regime. Heterogeneity of floodplains is illustrated from three key sites: the Khoper River (Southern Russia), the Protva River (Central Russia) and the Vychegda River (Northern Russia).
Palaeochannels and ground-water storage on the North China Plain
Authors: Zhao Yingkui , Wu Chen , Zhang XiuQing 
Published: April 2008

Abstract
The North China Plain, on which there are many palaeochannels as a result of frequent river channel changes, consists of a complex of floodplains formed by the Yellow, the Haihe and the Luanhe rivers. The palaeochannels act as a significant store of fresh ground water. Most of the storage is within sand and gravel layers. The buried depth of these layers varies among palaeochannels formed in different periods. For example, those formed between the last principal stage of glaciation and early Holocene time are buried 20–40 m deep. Those formed in mid-Holocene time are found at a depth of 10–20 m and those formed in late Holocene time at 0–10 m depth. Ground-water storage and palaeochannel discharge was calculated for the North China Plain. Ground-water in palaeochannels is recharged mainly by rainfall. With good management practice, the water withdrawn can be balanced against recharge to achieve a sustainable level of use. In addition, the shallow-buried palaeochannels provide a suitable environment for water regulation and storage and can be used to develop underground reservoirs.