Glaciology Research Papers - Academia.edu (original) (raw)

A model subglacial drainage system, coupled to an ice-dammed reservoir that receives a time-varying meltwater input, is described and analysed. In numerical experiments an ice-marginal lake drains through a subglacial channel, producing periodic floods, and fills with meltwater at a rate
dependent on air temperature, which varies seasonally with a peak value of Tm. The analysis reveals regions of Tm parameter space corresponding to ‘mode locking’, where flood repeat time is independent of Tm; resonance, where decreasing Tm counter-intuitively increases flood size; and chaotic dynamics,
where flood cycles are sensitive to initial conditions, never repeat and exhibit phase-space mixing. Bifurcations associated with abrupt changes in flood size and timing within the year separate these regions. This is the first time these complex dynamics have been displayed by a glaciohydraulic model
and these findings have implications for our understanding of ice-marginal lakes, moulins and subglacial lakes.

- by
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- Earth Sciences, Environmental Science, Glaciology, Dynamical Systems
- by Chris Rapley
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- Glaciology, Hydrology, Marine Sciences
- by Alia Khan
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- Glaciology, The cryosphere, Snow science, Black Carbon

Гляциология в целом базируется на ложных позициях. Главной ошибкой является утверждение, что ледник может разрушать, поднимать и переносить горные породе. Причем стиль изложения предполагает, что делает он это с легкостью. Производная от этого является утверждение, что морена является надежным показателем существования ледников. Интересно, что эти утверждения не сопровождаются физическими моделями и расчетами. Все это воспринимают на веру почти двести лет.

- by Pazynych Wasyl
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- Geography, Geology, Glaciology

Copyright 2009, Society of Petroleum Engineers This paper was prepared for presentation at the 2009 SPE/EAGE Reservoir Characterization and Simulation Conference held in Abu Dhabi, UAE, 1921 October 2009. This paper was selected for... more

- by Riyaz Kharrat
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- Gemology, Geology, Geochemistry, Geomorphology
- by A. Kepic and +2
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- Gemology, Geology, Geochemistry, Geomorphology
- by Andrea Toffaletti
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- Geography, Glaciology, Alps, Lombardia
- by jean Abi Rizk
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- Glaciology, Hydrogeology, Lebanon, Karst hydrogeology

The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes (MDGLs) in the recent past have increased the risk of glacier lake outburst floods (GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis (LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km 2 , that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and 6800 m above mean sea level (a msl). With a total surface area of 37.9 km 2 , these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.

- by Sazeda Begam
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- Glaciology, Hydrogeology, Hydrology, Watershed Hydrology

Hydropower and water resources management are an important issue in most countries of the world, included Switzerland. The scientific community is currently engaged to produce numerical models and simulations which aim at understanding... more

- by Davide Saurwein
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- Physical Geography, Glaciology, Hydrology

Миссульськие наводнения является одним из важнейших и интереснейших явлений последнего ледникового периода Северной Америки. Его важность обусловлена тем, что впервые гляциологам пришлось признать, что не только лед, но и вода во время оледенения могла быть главной силой в перестройке поверхности. Открыл это явление американский геолог J Harlen Bretz фактически сто лет назад. Формирование рельефа, который он подробно изучал в течение многих лет, не имело и не могло иметь другого объяснения, чем работа воды.

- by Pazynych Wasyl
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- Geography, Geology, Geomorphology, Glaciology

The main objective of this work is the estimation of the speed ice flow on the Upsala Glacier using radar images. The Upsala Glacier is one of the temperate glaciers of high scientific interest in the Southern Patagonian Ice Field that... more

- by Ailin Sol Ortone Lois and +1
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- Glaciology, Remote Sensing, Patagonia

Experimental and theoretical studies on the growth rate of an icicle were carried out as a function of temperature, water-supply rate and wind speed; the relative humidity was also taken into account. The length of an icicle increases by the downward growth of thin dendritic crystals into the supercooled pendant water drop at the tip, and thus the growth is in the crystallographic a-axis direction. The diameter, on the other hand, increases by the freezing of a water film flowing down along the icicle wall. The ratio of measured length-and diameter-growth rates was large, namely 8–32. Both growth rates increased with decreasing temperature and increasing wind speed. The increase in water-supply rate led to the decrease in the length-growth rate but no significant change in the diameter-growth rate. These results could be well described by a numerical model of icicle growth which takes account of the dendritic growth at the tip and the wall and the effective heat transfer within the ...

- by Lasse Makkonen
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- Glaciology, Growth rate

We describe and delimit with integrative taxonomy the new springtail species Desoria calderonis sp. nov. (Collembola: Isotomidae). This cryophilic species is strictly linked to the supraglacial stony debris of the isolated Calderone glacier (Central Apennines, Italy), one of the southernmost glaciers of Europe. Desoria calderonis sp. nov. could belong to the nivalis-complex, a group of European mountain species included in the violacea-group. Genetic analysis (COI mtDNA barcoding) confirms the morphological attribution to the genus Desoria Nicolet in Desor, 1841, but highlights that the genus, in its current definition, is polyphyletic. We specify the peculiar micro-habitat preferences and highlight the threat of extinction for this cryophilic species in the context of the ongoing climate change and subsequent risk of complete disappearance of the glacier.

- by Barbara Valle and +2
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- Entomology, Glaciology, Conservation Biology, Taxonomy

Calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world. Calving rates can increase dramatically in response to increases in velocity and/or retreat of the glacier margin, with important implications for sea level change. Despite their importance, calving and related dynamic processes are poorly represented in the current generation of ice sheet models. This is largely because understanding the 'calving problem' involves several other long-standing problems in glaciology, combined with the difficulties and dangers of field data collection. In this paper, we systematically review different aspects of the calving problem, and outline a new framework for representing calving processes in ice sheet models. We define a hierarchy of calving processes, to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events. The first-order control on calving is the strain rate arising from spatial variations in velocity (particularly sliding speed), which determines the location and depth of surface crevasses. Superimposed on this first-order process are second-order processes that can further erode the ice margin. These include: fracture propagation in response to local stress imbalances in the immediate vicinity of the glacier front; undercutting of the glacier terminus by melting at or below the waterline; and bending at the junction between grounded and buoyant parts of an ice tongue. Calving of projecting, submerged 'ice feet' can be regarded as a third-order process, because it is paced by first- or second-order calving above the waterline. First-order calving can be represented in glacier models using a calving criterion based on crevasse depth, which is a function of longitudinal strain rate. Modelling changes in terminus position and calving rates thus reduces to the problem of determining the ice geometry and velocity distribution. Realistic solutions to the problem of modelling ice flow therefore depend critically on an appropriate choice of sliding law. Models that assume that basal velocities are controlled by basal drag can replicate much of the observed behaviour of calving glaciers with grounded termini, but an important limitation is that they cannot be used to model floating glacier termini or ice shelves. Alternative sliding laws that parameterise drag from the glacier margins provide more flexible and robust ways of representing calving in ice sheet models. Such models can explain a remarkable range of observed phenomena within a simple, unifying framework, including: downglacier increases in velocity and strain rates where basal and/or lateral drag diminishes; flow acceleration in response to thinning through time; the tendency for glaciers to stabilise at 'pinning points' in relatively shallow water or fjord narrowings; the constraints on ice shelf stability; and the contrasts in calving rates between tidewater and freshwater calving glaciers. Many unresolved issues remain, however, including the role played by the removal of backstress in the acceleration of retreating calving glaciers, and the controls on melting at and below the waterline.

- by Ruth Mottram
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- Earth Sciences, Glaciology, Strain Rate, First-Order Logic
- by Dr.N Sukumar
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- Mathematics, Glaciology, Physics, Philosophy

The aim of this study was to improve our understanding of Quaternary glaciations in Tasmania, and to assess their climatic significance. During the Quaternary, Tasmania experienced ice cap development in the West Coast Range and Central Plateau, with smaller cirque and valley glaciers developing on surrounding mountains. Geomorphic evidence indicates at least four glacial advances occurred. A 500 m resolution, three-dimensional thermomechanical ice-sheet model was used to reconstruct and simulate these glacier fluctuations. The model, while a simplification of reality, provided a framework in which to understand the genesis of contemporary landforms and former glacial climate conditions in Tasmania. Input specifications of basal topography, temperature and precipitation were required, with the latter two interpolated from present-day datasets. Numerous experiments were carried out, involving systematic alterations to temperature and precipitation, basal sliding and atmospheric tempe...

- by Rebecca O'Donnell
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- Geomorphology, Glaciology, Paleoclimatology, Text
- by Dominic Hodgson
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- Glaciology, Phylogeography, Biomass, Endemism

The melting of ice and the subsequent production of regelation ice from the melt water in a large-scale closed system beneath sub-polar and polar glaciers produces progressive fractionation between the melt water and the regelation ice derived from it. A theory is developed which predicts the change of isotopic composition in regelation ice in a subglacial zone of freezing and in the water from which it is derived. The theory is tested against data from the Byrd Station bore hole in West Antarctica, and applied to explain features of the isotopic composition in several other glaciers where thick sequences of regelation ice have formed. The principal conclusions are: 1. Basal isotopic profiles can be used to reconstruct important features of a glacier’s hydrological system. 2. Isotopic profiles in basal regelation ice do not simply reflect isotopic characteristics of ancient atmospheres but also, by using the theory, some of the isotopic characteristics of the normal glacier ice whic...

- by Ulrich Spring
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- Glaciology, Fusion, Glacier, Melting

Holocene glacier fluctuations in College Fjord in south-central Alaska provide an integrated proxy record of climatic and related environmental changes through this critical geologic epoch. During the early Holocene around 10,000 yr BP, ice was receding from lower Port Wells but was still present in College Fjord. With the beginning of the Holocene Climatic Optimum, recession increased and the ice front reached the Golden Moraine site 1 by 7680 cal yr BP, starting its long early to middle Holocene retreat to the head of tidewater. An ice-free fjord existed between 7680 cal yr BP and about 5190 yr BP. A middle Holocene advance started between approximately 5190 and 4470 yr BP with ice arriving at the mouth of the fjord before 2470 cal yr BP. The late Holocene was characterized by various standstills and minor readvance positions as the glacier fell back and by significant Little Ice Age expansions and retreats of individual glaciers present in the fjord. During the late Holocene, the glacier built four large and distinctive moraines all representative of at least four standstill positions of College Fjord Glacier before 2470, 2060, 1330, and approximately 1120 cal yr BP.

- by Lúcio Cunha
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- Glaciology, Glacial Geomorphology, Holocene, College Fjord

A NEW DISCOVERY, CALLED TODAY "THE ICE FLOW THEORY."

- by John Delano
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- Geography, Prehistoric Archaeology, Earth Sciences, Geology

Krasno polje is one of the less typical karst poljes within the Dinaric Mountains. It is situated within Velebit Mountain. Our research utilized morphographic, morphostructural and morphometric analysis of the polje to present its mor phogenetic characteristics. It is completely filled with gravel and lacking any surface flows. Slopes above the polje were severely altered by glacial action during the colder periods of the Pleistocene. As a result, proglacial fans filled the karst depression, creating a piedmont type polje. Glacial evidence suggests that there were at least two separate phases of in tense proglacial deposition within the polje.

- by Uroš Stepišnik
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- Glaciology, Karst Environments, Karst Geomorphology, Glacial Geomorphology
- by Régis Braucher
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- Geology, Geomorphology, Glaciology, Structural Control
- by Andrey F Glazovsky
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- Glaciology
- by Riccardo Scotti
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- Glaciology, Climate Change, Alps

Computerized evaluation of Vibroseis similarity test data is the logical consequence of the increasing quality requirements for signal reproducibility and for synchronization of vibrators. The differences in start time and phase as well as an indication of local phasing problems between any two Vibroseis signals can be obtained from an analysis of the difference of their respective phase spectra. This method appears to be accurate and stable with respect to harmonics which usually plague the signals from transducers monitoring the motion of the vibrators'base plates.

- by Eike Rietsch
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- Gemology, Geology, Geochemistry, Geomorphology

Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (∼42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (∼5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.

- by Pierre Pitte and +2
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- Glaciology, Climate Change, Glacier fluctuations

Timely for a "Lexicon for an Anthropocene Yet Unseen"

- by Cymene Howe
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- Geology, Glaciology, Anthropology, Metaphysics of Time

Investigations have been made of the geomorphology, internal structure, and till fabric of small drumlins in a drumlin field exposed in front of the retreating northern part of Mýrdalsjökull, Iceland. The drumlins either comprise irregular drumlin complexes or they show clearly the shape of typical drumlins with their highest points at the up-glacier ends of streamlined hills. The core of each drumlin consists either of undisturbed glacio-fluvial deposits or glacio-dynamically deformed drift. The distribution of the first type often has a characteristic en échelon arrangement, similar to the interstream areas in the upper reaches of outwash fans. The second type forms a pattern with a predominant trend conforming to the glacier margin; this type is superimposed on overridden ice-margin push-moraine ridges. It is shown that the material in the drumlin cores is only slightly eroded by the glacier that formed the drumlins. The core is mantled by subglacial lodgement till about 0.1–1.5 ...

- by Johannes Krüger
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- Geology, Glaciology, Morphology, Drumlins
- by ana maria gauza
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- Gemology, Geology, Geochemistry, Geomorphology

La mayor parte de la población de Perú se concentra en ciudades localizadas en la estrecha franja comprendida entre la costa del Océano Pacífico y los Andes Centrales. Se trata de una de las regiones más áridas de la Tierra, donde la precipitación total anual apenas alcanza unas decenas de mm. Por ese motivo las reservas hídricas de la población y sus actividades económicas dependen en gran medida de los glaciares que se conservan en la cordillera. Esas masas de hielo forman parte de la criosfera, junto con la nieve, los glaciares rocosos y las capas de suelo helado (permafrost), que también están adquiriendo gran importancia como reservas de agua debido a la marcada tendencia a la reducción de la superficie y el volumen de los glaciares observada durante las últimas décadas. El proceso de deglaciación implica además un incremento de los peligros geológicos asociados a la criosfera, como aludes, avalanchas y otros tipos de movimientos en masa. El riesgo es mayor si cabe en las vertientes de la cordillera como consecuencia de su fuerte desnivel. En ese contexto la Autoridad Nacional del Agua (ANA); el Instituto Geológico Minero y Metalúrgico (INGEMMET); el Grupo de Investigación en Geografía Física de Alta Montaña de la Universidad Complutense de Madrid (GFAM) y la ONG Guías de Espeleología y Montaña (GEM), con el auspicio de la Organización de las Naciones Unidas para la Educación, la Ciencia y la Cultura (UNESCO), han acordado impulsar un proyecto denominado CRYOPERU, con dos metas principales: 1) Contribuir a la comprensión de los efectos del cambio climático en la criosfera de los Andes Centrales, en relación con dos problemas que afectan a Perú: la reducción de las reservas hídricas sólidas y el incremento de los peligros geológicos asociados al proceso de deglaciación. 2) Proporcionar instrumentos de análisis a las instituciones que deben planificar y ejecutar las políticas de adaptación y mitigación de la sociedad a los efectos del cambio climático. Para alcanzar los objetivos previstos el proyecto analizará 10 geoindicadores del cambio climático y 4 geoindicadores de peligros geológicos en 8 áreas de estudio distribuidas de norte a sur de la cordillera occidental y la cordillera oriental de los Andes Centrales. Se ha previsto el desarrollo de un software para automatizar, sistematizar y recopilar los resultados. El software será la plataforma tecnológica online de un Observatorio de la Criosfera.

- by Jose Ubeda
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- Geomorphology, Glaciology, Climate Change, Glacial Geomorphology
- by Muneer Qureshi
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- Glaciology, Remote Sensing, Climate Change, Climatology

Необхідність написання передмови до дисертації робота над якою була завершена ще у 2010 році пов’язана з кількома причинами. Головною є та обставина, що у той час, на підставі аналізу змін будови долини середньої течії Дніпра, було зрозуміло, що перебудова відбулася в наслідок кількох потужних катастрофічних післяльодовикових потоків. Цій проблемі було присвячено досить значний об’єм роботи. Десь біля 60 сторінок.

- by Pazynych Wasyl
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- Geography, Geology, Geomorphology, Glaciology
- by M. Krabbendam and +1
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- Earth Sciences, Geology, Geomorphology, Glaciology

На сайті Academia біля п’яти років розміщена робота "Льодовики, давня людина та палеогеографія України", а також її версія "Давня людина і палеогеографічні умови України" (З книжки: "Природна та етнокультурна спадщина України"). За цей час кількість читачів подолала 1000. Ці роботи були написані по матеріалам до 2010 року. Читачі, напевно, помітили, що вони базуються на принципово інших підходах до оцінки подій, які мали місце на території України, ніж в офіційних виданнях. Перш за все це стосується зледеніння.
Коли писалися роботи, тоді вже була впевненість, що Україна не зазнала зледеніння. З одного боку, це базувалася на фактичному матеріалі, а з іншого на результатами фізичного аналізу природних процесів. Але, у той час ще не було загальної фізичної оцінки. Зараз вона завершена і треба сказати, що зараз "впевненість" підкріплена "доказами". А це єдиний критерій для визначення реальності подій. Не стандартна для сучасної науки фраза: "Як вважає якийсь авторитет….", а реальна фізика. Далі буде показане, як народжувалися без знання об’єкту досліджень "наукові" теорії, які можна оцінювати, як дитячі казки. На жаль наука в Україні не тільки залишилася на тому рівні, але можна констатувати, що її вже просто немає.
Тому для узгодження й кращого розуміння попередніх текстів було вирішено додати до них результати теоретичних досліджень. Тут вони вміщені не повністю, а тільки в об’ємі, який стосується нашої території та подій, що тут відбувалися.

- by Pazynych Wasyl
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- Geography, Geomorphology, Glaciology, Hydrology
- by Hilario Bezerra
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- Gemology, Geology, Geochemistry, Geomorphology
- by Sergio Foghin-Pillin
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- History, Botany, Glaciology, Climatology

Выполненные ранее исследования особенностей распространения Полесских озер, послеледниковых озер Северной Америки и современных приледниковых озер Гренландии показали, что в основе механизма их формирования лежат вихревые системы, возникающие в краевых частях ледников или при поступлении значительного количества талой воды на поверхность промерзших приледниковых озер. После того, как в ходе воспоминаний с коллегами, о проблемах советской геоморфологии, в которые были упомянуты и Чарские пески, аналогичный поход был имплементирован и по отношению к ним. Результаты исследований были такими же, как и в предыдущих работах. Источником песка стали твердые горные породы, которые были перемолоты вихревыми системами в условиях горного озера, которое во время деградации горных ледников превратилось в ледоем.
Естественно, что следующим объектом исследований автоматически стали тукуланы Якутии. Они, как и Чарские пески, песчаные арены Аляски и Канады, до сегодняшнего дня остаются необъяснимыми природными феноменами. В среде естествоиспытателей обеих континентов издавна прижилось мнение об их эоловом происхождении. Всех эта версия устраивала, несмотря на то, что для ее подтверждения не был выполнен элементарный анализ климатических условий этих территорий на предмет их соответствия физическим условиям, при которых начинается эоловая активность. Наблюдения, естественно, были. Ими фиксировались перемещение песчаного материала в современных условиях. По наличию погребенных почв и органики выделялись периоды активизации эоловой деятельности. При этом упускались из виду очень важные аспекты.

- by Pazynych Wasyl
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- Geography, Geology, Glaciology, Glacial Geology

It is no longer possible to maintain that the ancient economy completely escapes any possibility of quantification over the long run. There are good indicators to measure development of the economy in general: atmospheric pollution by lead for the production of silver coinages, copper for the bronze, and shipwrecks for levels of trade. The convergence of these graphs clarifies an increased activity during the last centuries BC and the first three centuries AD. Of the three, the wrecks is the most spectacular with its peak in the period 200 BC-AD 200. This kind of periodization also seems to agree best with monetary affairs.

- by Francois de Callatay
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- History, Ancient History, Glaciology, Roman History

Случилось так, что после публикации в Интернете первой версии этой статьи в ходе короткой дискуссии с коллегой, главным вопросом была проблема профессиональной оценки. Возражение моего коллеги было следующим: «Я закончил гидрографию, и опубликованная работа охватывает более широкий круг проблем. Большинство из них я знаю только в общих чертах. Как я могу оценить результаты в целом?» Мое возражение было коротким, но оно Была сосредоточена на сущности исследования. Физическая география изучает природу и процессы, которые постоянно изменяют Землю, особенно ее рельеф. Все естественные процессы основаны на физических законах, особенно на механике, поэтому они являются производными от законов физики. Таким образом, понимание «географических законов» требует знания физики, особенно механики. Этот ответ был упрощен. Необходимы также некоторые знания о электричестве и магнетизм.
Основной вывод, вытекающий из этого подхода, очень категоричен. Физическая география в ее нынешнем виде - это не наука. Сегодня это коллекция догадок, идей, догм и тому подобного. Напоминается, что физическая география в прошлом была отраслью физики. Отделенная от физики, география потеряла научную основу и превратилась в псевдонауку. В действительности для понимания основных процессов и явлений нам нужны знания только элементарной физики. Остальная часть, включая географическую терминологию, является мусором. Каждый географический термин можно объяснить повседневным языком. Но интересно, что это, к сожалению, даже физика не понимает.

- by Pazynych Wasyl
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- Geography, Geology, Geomorphology, Glaciology

Geodesy, the oldest science, has become an important discipline in the geosciences, in large part by enhancing Global Positioning System (GPS) capabilities over the last 35 years well beyond the satellite constellation's original design. The ability of GPS geodesy to estimate 3D positions with millimeter-level precision with respect to a global terrestrial reference frame has contributed to significant advances in geophysics, seismology, atmospheric science, hydrology, and natural hazard science. Monitoring the changes in the positions or trajectories of GPS instruments on the Earth's land and water surfaces, in the atmosphere, or in space, is important for both theory and applications, from an improved understanding of tectonic and magmatic processes to developing systems for mitigating the impact of natural hazards on society and the environment. Besides accurate positioning, all disturbances in the propagation of the transmitted GPS radio signals from satellite to receiver are mined for information, from troposphere and ionosphere delays for weather, climate, and natural hazard applications, to disturbances in the signals due to multipath reflections from the solid ground, water, and ice for environmental applications. We review the relevant concepts of geodetic theory, data analysis, and physical modeling for a myriad of processes at multiple spatial and temporal scales, and discuss the extensive global infrastructure that has been built to support GPS geodesy consisting of thousands of continuously operating stations. We also discuss the integration of heterogeneous and complementary data sets from geodesy, seismology, and geology, focusing on crustal deformation applications and early warning systems for natural hazards.

- by Diego Melgar and +1
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- Geodesy, Glaciology, Hydrology, Space Physics
- by Matt Westoby
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- Glaciology, Computer Vision, Photogrammetry, Digital Elevation Models

The relationship between climate change at the Pleistocene-Holocene Boundary (ca. 12,600-10,200 cal B.P.) and cultural responses to attendant shifts in the environment remains a vexing issue for archaeologists. This study compiles and analyzes glacial, palynological, faunal, and stratigraphic/geomorphological proxy datasets for climate change in the Pacific Northwest of North America and compares them to the coeval archaeological record. The primary purpose of this exercise is to consider the potential ways in which climate change at the Pleistocene-Holocene Boundary affected cultural development for Late Paleoindian-Early Archaic peoples in the Pacific Northwest. Results indicate that climatic and environmental change at this interval was rapid or abrupt, and of a magnitude that likely produced varying adaptational responses by peoples of different cultural traditions who appear across the region at this period. Transformations in tools and technology, shifts in dietary habits, migration and regionalization, and trade intensification are all elements of Late Paleoindian-Early Archaic cultural responses to rapid climate change.

- by Tiffany J. Fulkerson
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- Native American Studies, Archaeology, Prehistoric Archaeology, Geology

Shoreline and shelf-edge trajectories describe the migration through time of sedimentary systems, using geomorphological breaks-in-slope that are associated with key changes in depositional processes and products. Analysis of these trajectories provides a simple descriptive tool that complements and extends conventional sequence stratigraphic methods and models. Trajectory analysis offers four advantages over a sequence stratigraphic interpretation based on systems tracts: (1) each genetically related advance or retreat of a shoreline or shelf edge is viewed in the context of a continuously evolving depositional system, rather than as several discrete systems tracts; (2) subtle changes in depositional response (e.g. within systems tracts) can be identified and honoured; (3) trajectory analysis does not anticipate the succession of depositional events implied by systems-tract models; and (4) the descriptive emphasis of trajectory analysis does not involve any a priori assumptions about the type or nature of the mechanisms that drive sequence development. These four points allow the level of detail in a trajectory-based interpretation to be directly tailored to the available data, such that the interpretation may be qualitative or quantitative in two or three dimensions. Four classes of shoreline trajectory are recognized: ascending regressive, descending regressive, transgressive and stationary (i.e. nonmigratory). Ascending regressive and high-angle (accretionary) transgressive trajectories are associated with expanded facies belt thicknesses, the absence of laterally extensive erosional surfaces, and relatively high preservation of the shoreline depositional system. In contrast, descending regressive and low-angle (nonaccretionary) transgressive trajectories are associated with foreshortened and/or missing facies belts, the presence of laterally extensive erosional surfaces, and relatively low preservation of the shoreline depositional system. Stationary trajectories record shorelines positioned at a steeply sloping shelf edge, with accompanying bypass of sediment to the basin floor. Shelf-edge trajectories represent larger spatial and temporal scales than shoreline trajectories, and they can be subdivided into ascending, descending and stationary (i.e. nonmigratory) classes. Ascending trajectories are associated with a relatively large number and thickness of shoreline tongues (parasequences), the absence of laterally extensive erosional surfaces on the shelf, and relatively low sediment supply to the basin floor. Descending trajectories are associated with a few, thin shoreline tongues, the presence of laterally extensive erosional surfaces on the shelf, and high sediment supply to basin-floor fan systems. Stationary trajectories record near-total bypass of sediment across the shelf and mass transfer to the basin floor.

- by William Helland-Hansen
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- Earth Sciences, Gemology, Geology, Geochemistry

A global overview of glacier advances and retreats (grouped by regions and by millennia) for the Holocene is compiled from previous studies. The reconstructions of glacier fluctuations are based on 1) mapping and dating moraines defined by 14 C, TCN, OSL, lichenometry and tree rings (discontinuous records/time series), and 2) sediments from proglacial lakes and speleothems (continuous records/ time series). Using 189 continuous and discontinuous time series, the long-term trends and centennial fluctuations of glaciers were compared to trends in the recession of Northern and mountain tree lines, and with orbital, solar and volcanic studies to examine the likely forcing factors that drove the changes recorded. A general trend of increasing glacier size from the earlyemid Holocene, to the late

- by V. Jomelli and +4
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- Glaciology, Paleontology, Glacial Geomorphology
- by Gerard C. van de Bruinhorst
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- Glaciology, Social Identity
- by Neil Glasser and +1
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- Earth Sciences, Glaciology, Photogrammetry, Natural Hazards