DOCSLIB.ORG

Hazard from Himalayan Glacier Lake Outburst Floods

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hazard from Himalayan Glacier Lake Outburst Floods Hazard from Himalayan glacier lake outburst floods Georg Veha,1, Oliver Korupa,b, and Ariane Walza aInstitute of Environmental Science and Geography, University of Potsdam, 14476 Potsdam-Golm, Germany; and bInstitute of Geosciences, University of Potsdam, 14476 Potsdam-Golm, Germany Edited by Andrea Rinaldo, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, and approved November 27, 2019 (received for review August 27, 2019) Sustained glacier melt in the Himalayas has gradually spawned (17). While the distribution and dynamics of moraine-dammed more than 5,000 glacier lakes that are dammed by potentially lakes have been mapped extensively in recent years (12, 18–21), unstable moraines. When such dams break, glacier lake outburst objectively appraising the current Himalayan GLOF hazard has floods (GLOFs) can cause catastrophic societal and geomorphic remained challenging. The high-alpine conditions limit detailed impacts. We present a robust probabilistic estimate of average fieldwork, leading researchers to extract proxies of hazard from GLOFs return periods in the Himalayan region, drawing on 5.4 increasingly detailed digital topographic data and satellite imagery. billion simulations. We find that the 100-y outburst flood has These data allow for readily measuring or estimating the geometry of +3.7 6 3 an average volume of 33.5 /−3.7 × 10 m (posterior mean and ice and moraine dams, the possibility of avalanches or landslides 95% highest density interval [HDI]) with a peak discharge of entering a lake, or the water volumes released by outbursts (9, 18, 20). +2,000 3 −1 15,600 /−1,800 m ·s . Our estimated GLOF hazard is tied to Ranking these diagnostics in GLOF hazard appraisals has mostly the rate of historic lake outbursts and the number of present lakes, relied on expert judgment (18, 22), because triggers and condi- which both are highest in the Eastern Himalayas. There, the esti- tioning factors are largely unknown for most historic GLOFs (23). − mated 100-y GLOF discharge (∼14,500 m3·s 1) is more than 3 times Guided by studies on earthquakes, landslides, wildfires, and that of the adjacent Nyainqentanglha Mountains, and at least an floods, we use the magnitude and frequency of GLOFs in a given order of magnitude higher than in the Hindu Kush, Karakoram, area and period as an objective metric of hazard. GLOFs have − and Western Himalayas. The GLOF hazard may increase in these occurred at an average rate of ∼1.3 y 1 in the Himalayas in the regions that currently have large glaciers, but few lakes, if future past 3 decades (23), although of differing size, which is conven- projected ice loss generates more unstable moraine-dammed lakes tionally described by the released flood volume V0 or the as- Q than we recognize today. Flood peaks from GLOFs mostly attenu- sociated peak discharge p. These parameters are difficult to ENVIRONMENTAL SCIENCES ate within Himalayan headwaters, but can rival monsoon-fed dis- measure during dam failure but can be estimated eventually from charges in major rivers hundreds to thousands of kilometers the surface areas of glacier lakes. We thus scaled the manually downstream. Projections of future hazard from meteorological mapped areas of all 5,184 Himalayan moraine-dammed lakes floods need to account for the extreme runoffs during lake out- (>0.01 km2) to volumes using a Bayesian robust regression of bursts, given the increasing trends in population, infrastructure, maximum lake depth versus area from 24 bathymetrically surveyed and hydropower projects in Himalayan headwaters. lakes (Materials and Methods and SI Appendix,Fig.S2andTable S1). Our approach assumes that all lakes are equally susceptible to atmospheric warming | meltwater lakes | GLOF | extreme-value statistics | outburst and that any incision depth is possible, which is consistent Bayesian modeling with data from Himalayan dam breaks (SI Appendix,Fig.S3). We used a Bayesian variant of a physical dam-break model (24, 25) to Q V onsoonal floods are among the most destructive natural predict peak discharge p from the product of 0 and the breach k Materials and Methods SI Appendix Mhazards in the greater Himalayan region and the adjacent erosion rate ( and ,Figs.S4and mountain ranges of the Hindu Kush, Karakoram, Nyainqentanglha, and Hengduan Shan (Fig. 1). Regional projections for the Significance lower Indus, Ganges, and Brahmaputra rivers hold that flood frequencies will rise noticeably in the 21st century (1, 2), putting Glacier lake outburst floods (GLOFs) have become emblematic the livelihoods of 220 million people at risk (3). In Himalayan of a changing mountain cryosphere. The Himalayas suffered headwaters, such prognoses have disregarded episodic, but po- the highest losses from these sudden pulses of meltwater but tentially destructive, floods from the sudden emptying of moraine- lack a quantitative appraisal of GLOF hazard. We express the dammed lakes. Such glacier lake outburst floods (GLOFs) occur hazard from Himalayan glacier lakes by the peak discharge for largely independently of hydrometeorological floods, but can a given return period. The 100-y GLOF has a mean discharge of − surpass their peak discharges by orders of magnitude in the upper ∼15,600 m3·s 1, comparable to monsoonal river discharges river reaches (4–6). Glacier lakes dammed by abandoned mo- hundreds of kilometers downstream. The Eastern Himalayas raines are susceptible to outburst, triggered by ice or debris falls, are a hotspot of GLOF hazard that is 3 times higher than in any strong earthquake shaking, internal piping, or overtopping waves other Himalayan region. The size of growing glacier lakes and that exceed the shear resistance of the dam (7–9). These triggers the frequency of lake outbursts determine GLOF hazard, which mostly happen unrecorded in remote terrain, eroding the needs to be acknowledged better in flood hazard studies. impounding barriers within minutes to hours, and releasing sediment-laden floods that may travel >100 km downstream (7). Author contributions: G.V. and O.K. designed research; G.V. and O.K. performed research; With little to no warning, communities and infrastructure down- G.V. and O.K. analyzed data; and G.V., O.K., and A.W. wrote the paper. stream have often been caught unprepared, suffering loss of human The authors declare no competing interest. lives and livestock, and damage to roads, buildings, and hydro- This article is a PNAS Direct Submission. power facilities (10–12). An objective and reproducible hazard Published under the PNAS license. assessment of such dam-break floods is key to human safety and Data deposition: All input data are available at Zenodo (http://doi.org/10.5281/zenodo. sustainable development, and is repeatedly emphasized in re- 3523213), and model codes are available at GitHub (https://github.com/geveh/GLOFhazard). search and media coverage of atmospheric warming, dwindling 1To whom correspondence may be addressed. Email: [email protected]. glaciers, and growing meltwater lakes (3, 13, 14). This article contains supporting information online at https://www.pnas.org/lookup/suppl/ GLOFs have gained growing attention in the Himalayas (15, 16), doi:10.1073/pnas.1914898117/-/DCSupplemental. where these disasters have had the highest death toll worldwide First published December 30, 2019. www.pnas.org/cgi/doi/10.1073/pnas.1914898117 PNAS | January 14, 2020 | vol. 117 | no. 2 | 907–912 Downloaded by guest on September 30, 2021 A BC Fig. 1. Moraine-dammed glacier lakes in the Himalayas. (A) Distribution of moraine-dammed lakes in our study region in 1° × 1° bins. Bubbles are scaled to the total lake area, and color-coded to abundance. Reported GLOFs (yellow triangles) have occurred most frequently in the past 8 decades in regions where glacier lakes are largest (23). (B) Location of the Himalayas between the Indian subcontinent and the Tibetan Plateau. (C) Histogram of glacier lake areas. S5). In summary, we obtained 4.6 × 108 and 4.9 × 109 scenarios of Discussion V Q 0 and p, respectively, for all moraine-dammed lakes in the We offer a consistent and reproducible estimate of present Himalayas. These numbers ensure that we have sufficiently ex- GLOF hazard in the Himalayas. Our Bayesian estimates explore plored the physically plausible space for fitting an extreme-value the parameter space of plausible flood volumes and associated distribution to these key flood diagnostics. We further stacked our peak discharges with roughly a million outburst scenarios for any simulations, accounting for contemporary mean annual GLOF −1 given lake. Our approach expands previous hazard appraisals by rates between 0.03 and 0.71 y in 7 subregions of the Himalayas, explicitly accounting for regionally varying GLOF rates. The and estimated GLOF return periods in terms of the 100-y flood V Q Materials and Methods estimated GLOF return periods are consistent with the fre- volume 100 and discharge p100 ( ) (26, 27). quency of reported flood volumes and discharges since 1935 SI Appendix Results (Fig. 3 and , Fig. S6 and Table S2). The 3 largest reported flood volumes of 71.6, 19.5, and 17.2 × 106 m3 from the The predicted flood volumes and peak discharges span more than 7 lakes Sangwang Tsho (1954), Sabai Tsho (1998), and Lugge Tsho orders of magnitude (Fig. 2). Based on a mean posterior rate of 1.26 − GLOFs y 1 over the past 3 decades (23), we estimate a contemporary (1994), respectively, had return periods of 237, 56, and 49 y, +3.7 6 3 −1 +2,000 3 −1 respectively, according to our predictions. The highest reported V of 33.5 /− × 10 m ·s and Q of 15,600 /− m ·s in − 100 3.7 p100 1,800 peak discharge (15,920 m3·s 1) drained from Lake Zhangzangbo the entire study area (Fig. 3). Regionally differing GLOF rates in 1981; we estimate this as a 100-y event in the greater Himalayan cause variation in V100 and Qp100.
Load more

Recommended publications
  • (1987): "Tectonomagmatic Evolution of Cenozoic Extension in the North American Cordillera"
    Downloaded from http://sp.lyellcollection.org/ by Frances J Cooper on January 21, 2013 Geological Society, London, Special Publications Tectonomagmatic evolution of Cenozoic extension in the North American Cordillera Brian P. Wernicke, Philip C. England, Leslie J. Sonder and Robert L. Christiansen Geological Society, London, Special Publications 1987, v.28; p203-221. doi: 10.1144/GSL.SP.1987.028.01.15 Email alerting click here to receive free e-mail alerts when service new articles cite this article Permission click here to seek permission to re-use all or request part of this article Subscribe click here to subscribe to Geological Society, London, Special Publications or the Lyell Collection Notes © The Geological Society of London 2013 Downloaded from http://sp.lyellcollection.org/ by Frances J Cooper on January 21, 2013 Tectonomagmatic evolution of Cenozoic extension in the North American Cordillera B.P. Wernicke, R.L. Christiansen, P.C. England & L.J. Sonder SUMMARY: The spatial and temporal distributions of Cenozoic extension and magmatism in the Cordillera suggest that the onset of major crustal extension at a particular latitude was confined to a relatively narrow belt (< 100 km, pre-extension) and followed the onset of intermediate and silicic magmatism by no more than a few million years. Extension began in early Eocene time in southern British Columbia, northern Washington, Idaho and Montana. Farther S, extension began at about the Eocene- Oligocene boundary in the Great Basin and slightly later in the Mojave-Sonora Desert region. The intervening area, at the latitude of Las Vegas, remained quiescent until mid- Miocene time. Compositional and isotopic characteristics of most pre-Miocene magmas are consistent with their containing major components of melted continental crust.
    [Show full text]
  • Brief Overview of North American Cordilleran Geology by Cin-Ty Lee Topography Map of North America
    Brief overview of North American Cordilleran geology by Cin‐Ty Lee Note: make sure to take notes as I will talk or sketch on the board many things that are not presented explicitly in these slides Topography map of North America Topography map How does the NthNorth AiAmerican Cor dillera fit itinto a glbllobal contt?text? Dickinson 2004 P‐wave tomography: Seismic structure beneath western USA Burdick et al. 2008 Crustal provinces of North America (Laurentia) ‐Proterozoic and Archean terranes were already assembled by 1.6 Ga Hoffman, 1988 Crustal provinces in southwestern USA Hoffman, 1988 Bennett and DePaolo, 1987 Some examples of tectonic margins for your reference Dickinson and Snyder, 1978 1.1 Ga = Rodinia Super‐continent (Grenvillian age) Neo‐Proterozoic = Rodinia breaks up “western” margin of Laurentia represents a passive margin due to opening of the Panthalassan ocean 700‐400 Ma Western margin of Laurentia represents a passive margin Dickinson and Snyder, 1978 400‐250 Ma Passive margin is interrupted in Devonian times by the accretion of island arcs Antler and Sonoma orogenies Accretion of allochthonous terranes to the western margin of the NhNorth AiAmerican craton Antler/Sonoma orogenies result in the accretion of Paleozoic island arc terranes to western North America Permian Formation of Pangea “”“western” margin of NhNorth AiAmerica now didominate d by subduct ion zone 250‐50 Ma Subduction results in continued accretion of fringing island arcs and the generation of continental magmatic arcs Sierra Nevada batholith Sevier and
    [Show full text]
  • OPPOSITE THRUST-VERGENCIES in the PRECORDILLERA and WESTERN CORDILLERA in NORTHERN CHILE and Structurally LINKED CENOZOIC PALEOENVIRONMENTAL EVOLUTION
    Fourth /SAG. Goettingen (Germany), 04 - 06//0//999 155 OPPOSITE THRUST-VERGENCIES IN THE PRECORDILLERA AND WESTERN CORDILLERA IN NORTHERN CHILE AND STRUCTURALLy LINKED CENOZOIC PALEOENVIRONMENTAL EVOLUTION Reynaldo CHARRIER(I-7), Gérard HERAIL(2-7), John FLYNN(3), Rodrigo RIQUELME(I-7), Marcelo GARCIA(4-7), Darin CROFf(5) and André WYSS(6) (1) Departamento de Geologfa, Universidad de Chile; [email protected]. (2) IRD, 209-213, Rue La Fayette, 75010 Paris,[email protected]. (3) The Field Museum of Natural History, Chicago, USA. [email protected]. (4) SERNAGEOMIN. Av. Sta. Maria 0104, Providencia, Santiago, Chile. [email protected]. (5) The Field Museum of Natural History, Chicago, and University of Chicago, USA. (6) Department of Geological Sciences, University of California Santa Barbara, USA [email protected]. (7) Convenio IRD-Departamento de Geologïa, Universidad de Chi le. KEY WORDS: Altiplano, Chile, syntectonic sedimentation, Cenozoic paleoenvironment. INTRODUCTION Morphologie units in the northern Chilean Andes parailei one another and the offshore trench. These units are, from west to east: Coastal Cordillera, Central Depression, Precordillera, Western Cordillera and Altiplano (Fig. i). The development of the west part of the Western Cordillera (Chapiquifia-Belén Ridge), in the Chilean Altiplano, was controlled by two diverging, trench-parallel systems of thrusts and folds, one located along the Precordil1era and the other along the eastern side of the Western Cordillera. Although total shortening associated with these systems is only 12 to 14 km, their activity determined the development of fluvial and lacustrine basins which recorded the synorogenic paleoenvironmental evolution of this region. We describe here facies, geometry and chronology of the deposits associated with both systems and provide an explanation for the differing depositional environments developed on the Precordillera and the Western Cordillera.
    [Show full text]
  • Plate Tectonic Setting of the Andean Cordillera
    183 by Victor A. Ramos Plate tectonic setting of the Andean Cordillera Laboratorio de Tectónica Andina, Universidad de Buenos Aires, Argentina. E-mail: [email protected] The Andes are a natural laboratory for the study of the acterize the different segments are widely variable. The present interaction between subduction of the oceanic plate and overview will focus on the major geological differences among these segments, based on today’s plate-tectonic knowledge of this moun- active geological processes. Inter- and intraplate seis- tain chain. micity, volcanic activity, thick- and thin-skinned fold and thrust belts, and foreland basin subsidence, in con- junction with space geodetic observations, contribute to Major geological provinces characterize the present plate tectonic setting of discrete The Andes north of the Golfo de Guayaquil are unique, as estab- segments of the Andes. The inherited geological history, lished by Gansser (1973). The Northern Andes record an important as well as the present tectonic setting, is responsible for accretion of oceanic crust during Jurassic, late Cretaceous, and Pale- the unique geology of the Northern, Central, and South- ogene times. As a result, the Western Cordillera of Colombia and Ecuador is mainly constituted of an oceanic basement that during ern Andes. The Northern Andes are the result of Meso- accretion was related to ophiolite obduction, important penetrative zoic and Cenozoic collisions of oceanic terranes, prior deformation and metamorphism, in cases up to blue schist facies. to the present Andean-type setting. The Central Andes Further north, the emplacement of the Caribbean nappes was related to the collision of an island arc system, the Bonaire block, during have a long history of subduction and volcanic arc Paleogene times (Bosch and Rodríguez, 1992, Kellogg and Bonini, activity, while the Southern Andes record the closing of 1982).
    [Show full text]
  • The Cordillera of the Andes Boundary Case (Argentina, Chile)
    REPORTS OF INTERNATIONAL ARBITRAL AWARDS RECUEIL DES SENTENCES ARBITRALES The Cordillera of the Andes Boundary Case (Argentina, Chile) 20 November 1902 VOLUME IX pp. 37-49 NATIONS UNIES - UNITED NATIONS Copyright (c) 2006 37 AWARD BY HIS MAJESTY KING EDWARD VII IN THE ARGENTINE- CHI LE BOUNDARY CASE, 20 NOVEMBER 1902 x WHEREAS, by an Agreement dated the 17th day of April 1896, the Argentine Republic and the Republic of Chile, by Their respective Representatives, determined: THAT should differences arise between their experts as to the boundary-line to be traced between the two States in conformity with the Treaty of 1881 and the Protocol of 1893, and in case such differences could not be amicably settled by accord between the two Governments, they should be submitted to the decision of the Government of Her Britannic Majesty; AND WHEREAS such differences did arise and were submitted to the Govern- ment of Her late Majesty Queen Victoria; AND WHEREAS the Tribunal appointed to examine and consider the differences which had so arisen, has — after the ground has been examined by a Com- mission designated for that purpose — now reported to Us, and submitted to Us, after mature deliberation, their opinions and recommendations for Our consideration ; Now, WE, EDWARD, by the grace of God, King of the United Kingdom of Great Britain and Ireland and of the British Dominions beyond the Seas King, Defender of the Faith, Emperor of India, etc., etc., have arrived at the following decisions upon the questions in dispute, which have been referred to Our arbitration, viz. : 1.
    [Show full text]
  • Present Knowledge of the Magmatic Evolution of the Eastern Cordillera of Peru
    Earth-Science Reviews, 18 (1982) 253-283 253 Elsevier Scientific Publishing Company, Amsterdam-Printed in The Netherlands Present Knowledge of the Magmatic Evolution of the Eastern Cordillera of Peru G. Carlier', G. Grandin', G. Laubacher', R. and F. M6gard2 ' ORSTOM, Mission Peru, Apartado 270, Lima 18 (Peru) and 2'4 rue Bayard75008 Paris (France) ' Institut Francais #Etudes Andines, Apartado 278, Lima I8 (Peru) Pontificia Universidad Catdica del Perú, Avda S. Boliuar, Lima 27 (Peru) ABSTRACT Carlier, G., Grandin, G., Laubacher, G., Marócco, R. and Mégard, F., 1982. Present knowledge of the magmatic evolution of the Eastern Cordillera of Peru. Earth-Sci. Rev., 18: 253-283. The studies which have been carried out in the Eastern Cordillera of Peru over the past 20 years prove the existence of at least three orogenic cycles: the Late Precambrian, the Hercynian and the Andean, each one accompanied by a more or less abundant magmatism. (1) The Precambrian. Leaving aside the prasinites, possibly derived from synsedimentary , volcanites, Precambrian magmatism (in the Huanuco region) consists of: a meta-igneous ultramafic to mafic association (serpentinites, meta-gabbros, meta-diorites); syntectonic meta-tonalites; and post-tectonic dioritic and granitic intrusive bodies. (2) The Hercynian (550 to 220 my.). From the Cambrian to the Upper Devonian the existence of a synsedimentary magmatism is known. Syntectonic granites were emplaced during the Eohercynian phase, but the major part of magmatism is of a Late Permian to Early Trias age, and is characterized by the intrusion of granitoids and by volcanism of calc-al- kaline tendency. It appears that the nepheline syenite of Macusani may belong to a terminal episode of this magmatic period.
    [Show full text]
  • The American Cordillera: a Long Journey Through Time & Space
    The American Cordillera: A Long Journey Through Time & Space Part III:The North American Taphrogen Lecture 25: April 25, G. Zandt An overview of the collapse of the American Cordillera 1 Some of the Big Questions • What caused the extreme inboard migration of deformation and magmatism during the Laramide? [Flat Slab] • What caused the mid-Tertiary extensional collapse and ignimbrite flareup? [Slab Rollback] • Why is the extension and associated magmatisn separated into two domains with different spatial-temporal evolutions? • How did the Colorado Plateau escape significant deformation and magmatism during both periods? Major questions we want to address today. 2 North American Cordillera Topography is the first-order expression of orogeny, and high topography extends half way across the continent (>1000 km). And it remains high despite significant extension which normally leads to subsidence. 3 Western US today We will follow Dickinson (2002) in this review of the Cordilleran taphrogen. He follows Sengor in dividing the Basin and Range taphrogen into the Numic and Piman subtaphrogens. Black bodies are core complexes with arrows indicating direction of vergence (movement of upper plate). We will focus today on the relationship between the subtaphrogens and the Colorado Plateau–Laramide Rocky Mountains. Dickinson, W. R., The Basin and Range Province as a Composite Extensional Domain, Int. Geol. Rev., 44, 1-38, 2002. 4 The tectonic evolution of the Cordillera can be divided into 7 frames (Coney): 1) Formation of the continental margin in late Precambrian time and development of the Cordilleran passive margin. 2) Mid- to late Paleozoic brief orogenic events (Antler, Ancestral Rockies, Sonoma orogenies).
    [Show full text]
  • Eastern Cordillera Real Oriental Paramos and Montane Forests
    ECORREGIONAL ASSESSMENT: EASTERN CORDILLERA REAL ORIENTAL PARAMOS AND MONTANE FORESTS The Nature Conservancy, EcoCiencia y Fundación AGUA. 2005. Evaluación Ecorregional de los Páramos y Bosques Montanos de la Cordillera Real Oriental. Quito-Ecuador. The ecoregional assessment of Eastern Cordillera Real Paramos and Montane Forests was implemented to design a network of conservation areas that can maintain successfully in the long-term characteristic biodiversity of the region, as well as ecological processes. The Tropical Andes region located in northern South America is gifted with an impressive array of biodiversity. The Nature Conservancy (TNC) has worked for several years in collaboration with local organizations implementing conservation actions on this region. Within the Tropical Andes the Eastern Cordillera Real Paramos and Montane Forests are found, which have been identified as strategic areas for directing conservation efforts.The Nothern Andes Program of the World Fund for Nature (WWF), in the biodiversity vision for the Northern Andes, identified 65 priority areas for conservation on this region that groups several ecoregions. This process identified the Eastern Cordillera Real Montane Forests ecoregion as a priority within the ecoregional complex. With this background, the former Ecuador Program (now Northern Tropical Andes Conservation Program) in collaboration with EcoCiencia and Fundación AGUA, decided to develop an ecoregionall assessement on this ecoregion to refine the results and data produced by WWF. The objective
    [Show full text]
  • Extensional Collapse of the Tibetan Plateau: Results of Three-Dimensional Finite Element Modeling Mian Liu and Youqing Yang Dept
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. 8, 2361, doi: 10.1029/2002JB002248, 2003 Extensional collapse of the Tibetan Plateau: Results of three-dimensional finite element modeling Mian Liu and Youqing Yang Dept. of Geological Sciences, University of Missouri-Columbia, MO 65211 Received 17 October 2002; revised 7 April 2003; accepted 12 May 2003; published 1 August 2003. [1] Following their initial collision 50-70 Myr ago, the Indian and Eurasian plates have been continuously converging toward each other. Whereas the regional stress field is predominately compressive, the Late Cenozoic tectonics within the Tibetan Plateau features widespread crustal extension. Numerous causes of the extension have been proposed, but their relative roles remain in debate. We have investigated the major factors contributing to the Tibetan extension in a three-dimensional viscoelastic model that includes both lateral and vertical variations of lithospheric rheology and relevant boundary conditions. Constrained by the present topography and GPS velocity field, the model predicted predominately extensional stress states within the plateau crust, resulting from mechanical balance between the gravitational buoyancy force of the plateau and the tectonic compressive stresses. The predicted stress pattern is consistent with the earthquake data that indicate roughly E-W extension in most of Tibet and nearly N-S extension near the eastern margin of the Tibetan Plateau. We explored the parameter space and boundary conditions to examine the stress evolution during the uplift of the Tibetan Plateau. When the plateau was lower than 50% of its present elevation, strike-slip and reverse faults were predominate over the entire plateau, and no E-W crustal extension was predicted.
    [Show full text]
  • CORDILLERA DEL CÓNDOR John L
    CORDILLERA DEL CÓNDOR John L. Clark John L. Clark BOTANICAL TREASURES BETWEEN THE ANDES AND THE AMAZON DAVID NEILL y four botanical companions us carry the gear, food for 10 days and the stature of an adult Shuar warrior. The and I had been hiking uphill plant-collecting supplies. waterfall before us had been the site for Mfor two days, ascending the initiation rites for several generations of steep slopes through epiphyte-laden Raúl Pitiur, the leader of Tinkimints vil- Shuar from Tinkimints. cloud forests, toward the crest of the lage, pointed to a waterfall that emerged Cordillera del Cóndor in south-eastern from the vertical sandstone cliff face The thunderous waterfall was truly an Ecuador near the border with Peru. We below the summit, and plunged 50 m impressive sight, but my gaze drifted up emerged into the sunshine on a ridge into a pool below. “We have been to this to the summit of the mountain above. with low shrubby vegetation. A thousand waterfall many times before”, said Raúl, “What is above the waterfall?” I asked metres below us lay the Shuar village of and he explained the significance of Raúl. “We have never been above the Tinkimints, on the banks of the rushing waterfalls in the traditional Shuar male waterfall”, he replied. So, with the help of Coangos River, with its palm-thatched initiation rites. When a boy reached man- our Shuar hosts, our group of botanists – houses surrounding the village’s grass hood, he was led by the elders to a place José Manzanares, Paul Berry, Lou Jost, airstrip, soccer field and one-room beside a powerful waterfall, where he was schoolhouse.
    [Show full text]
  • Chapter 7 Australasia
    Chapter 7 Australasia Three large islands east of Timor Trough and Aru and Allen 1988). The prominent peaks are the Basin constitute Asia’s farthest region of Australa- Puncak Jaya (Mt. Victory at 5,029m) in the west sia. Australia, its main bulk, can be described as and Mount Wilhelm (4,697m) in the east. The the world’s largest island and smallest continent. former, originally called Mount Carstenz after a The other two island groups are New Guinea in Dutch navigator, is high enough to support some the north and New Zealand in the south-east. small glaciers. The western section in Indonesia, Australia and New Guinea are only separated by Pegunungan Maoke, has three other peaks over the shallow Arafura Sea but present a contrast in 4,500m in elevation. The eastern section in Papua geological structure. Australia is mostly founded New Guinea extends from Thurnwald through the on Precambrian stable shield related to Gondwana Bismarck to Owen Stanley Ranges in the extreme land. New Guinea, on the other hand, has east- east. As a general pattern, the highlands have the west axes of Tertiary folding. New Zealand is simi- steepest slopes towards the south. Along the north- larly built on a folded structure but aligned south- ern coast are a chain of lower ranges that trend west/north-east (Figure 8 and Annex F). parallel to the main range. These are the Van Rees in the west, Torricelli in the middle, and Finisterre 7.1 New Guinea in the east. The main highlands are composed of Archaean schists and massive crystallines with lava The island of New Guinea is comprised of the In- effusives in the central part.
    [Show full text]
  • Dickinson2004.Pdf
    7 Apr 2004 20:19 AR AR211-EA32-02.tex AR211-EA32-02.sgm LaTeX2e(2002/01/18) P1: GCE 10.1146/annurev.earth.32.101802.120257 Annu. Rev. Earth Planet. Sci. 2004. 32:13–45 doi: 10.1146/annurev.earth.32.101802.120257 Copyright c 2004 by Annual Reviews. All rights reserved First published online as a Review in Advance on November 10, 2003 EVOLUTION OF THE NORTH AMERICAN CORDILLERA William R. Dickinson Department of Geosciences, University of Arizona, Tucson, Arizona 85721; email: [email protected] Key Words continental margin, crustal genesis, geologic history, orogen, tectonics ■ Abstract The Cordilleran orogen of western North America is a segment of the Circum-Pacific orogenic belt where subduction of oceanic lithosphere has been under- way along a great circle of the globe since breakup of the supercontinent Pangea began in Triassic time. Early stages of Cordilleran evolution involved Neoproterozoic rifting of the supercontinent Rodinia to trigger miogeoclinal sedimentation along a passive continental margin until Late Devonian time, and overthrusting of oceanic allochthons across the miogeoclinal belt from Late Devonian to Early Triassic time. Subsequent evolution of the Cordilleran arc-trench system was punctuated by tectonic accretion of intraoceanic island arcs that further expanded the Cordilleran continental margin during mid-Mesozoic time, and later produced a Cretaceous batholith belt along the Cordilleran trend. Cenozoic interaction with intra-Pacific seafloor spreading systems fostered transform faulting along the Cordilleran continental margin and promoted incipient rupture of continental crust within the adjacent continental block. INTRODUCTION Geologic analysis of the Cordilleran orogen, forming the western mountain system of North America, raises the following questions: 1.
    [Show full text]