DOCSLIB.ORG

Physiographic Divisions of Alaska

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Physiographic Divisions of Alaska PHYSI DIVISIONS 0 ALASKA 0 GEOLOGICAL SURVEY PROFESSIONAL PAPER 482 Physiographic Divisions of Alaska By CLYDE WAHRHAFTIG GEOLOGICAL SURVEY PROFESSIONAL PAPER 482 A classification and brief description with a discussion of high-latitude physiographic processes UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1965 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director Library of Congress catalog-card No. GS 65-800 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 CONTENTS Page Abstract------------------------------------------- 1 Description of the physiographic divisions--Continued Introduction ______________________________________ _ 2 Intermontane Plateaus--Continued Acknowledgments _________________________________ _ 3 Western Alaska province-Continued The basis for the classification ______________ ·~--------- 3 Kuskokwim Mountains _________________ _ 30 Summary of the geologic history of Alaska ____________ _ 5 Innoko Lowlands ______________________ _ 30 Details of sculpture-physiographic evolution in the last Nushagak-Big River Hille- _____________ _ 30 million years------------------------------------- 8 Holitna Lowland _______________________ _ 31 Glaciated highlands and mountains ______________ _ 13 Nushagak-Bristol Bay Lowland _________ _ 31 Glaciated lowlands _____________________________ _ 13 Seward Peninsula __________________________ _ 31 U nglaciated uplands ___________________________ _ 14 Bering Shelf ______________________________ _ 32 Unglaciated lowlands ___________________________ _ 16 Yukon-Kuskokwim Coastal Lowland _____ _ 32 Description of the physiographic divisions ____________ _ 18 Bering Piatf orm _______________________ _ 32 Interior Plains_________________________________ _ 18 Ahklun Mountains__ ._ ______________________ _ Arctic Coastal Plain _______________________ _ 33 18 Pacific Mountain System _______________________ _ 33 Rocky Mountain System _______________________ _ 20 Alaska-Aleutian province ___________________ _ 33 Arctic Foothills ____________________________ _ 20 Aleutian Islands _______________________ _ 33 Arctic Mountains province __________________ _ 20 Aleutian Range ________________________ _ 34 De Long Mountains ___________________ _ 20 Alaska Range (southern part) ___________ _ 34 Noatak Lowlands ______________________ _ 21 Alaska Range (central and eastern part) __ _ 35 Baird Mountains ______________________ _ 21 Central and eastern Brooks Range _______ _ Northern Foothills of the Alaska Range __ _ 35 21 Coastal Trough province ___________________ _ Ambler-Chandalar Ridge and Lowland sec- 36 Cook Iniet-Susitna Lowland ____________ _ 36. 22 tion----------------------------~---- Broad Pass Depression _________________ _ Intermontane Plateaus _________________________ _ 22 36 Northern Plateaus province _________________ _ Talkeetna Mountains __________________ _ 37 22 Upper Matanuska Valley _______________ _ Porcupine Plateau _____________________ _ 22 37 Ogilvie Mountains _____________________ _ Clearwater Mountains __________________ _ 38 23 Gulkana Upland _______________________ _ 23 38 Tintina ValleY-------------------------- Copper River Lowland ______ ~ __________ _ Yukon-Tanana Upland _______________ .,. __ 24 38 Northway-Tanacross Lowland ___________ _ Wrangell Mountains ___________________ _ 39 24 Chatham Trough ______________________ _ Yukon Flats section ____________________ _ 39 25 Kupreanof Lowland _______________ ._ ____ _ Rampart Trough ______________________ _ 25 39 Kokrine-Hodzana Highlands ____________ _ 25 Pacific Border Ranges province ______________ _ 39 Western Alaska province ___________________ _ 26 Kodiak Mountains_____________________ _ 40 Kan:uti Flats __________________________ _ 26 Kenai-Chugach Mountains ____ ~ _________ _ 40. Tozitna-Melozitna Lowland _____________ _ 26 St. Elias MOU\ntains ____________________ _ 4i Indian River Upland.,. __________________ _ 26 Fairweather Range ________________ _ 41 Pah River· section ______________________ _ 27 Gulf of Alaska coastal section ___________ _ 41 Koyukuk Flats ________________________ _ 27 Chilkat-Baranof Mountains _____________ _ 42 Kobuk-S'elawik Lowland ____________ ·____ _ 27 Prince of Wales Mountains _____________ _ 42 Selawik Hills _______ - __________________ _ 28 Coast Mountains __________________________ _ 43 Buckland River Lowland _______________ _ 28 Boundary Ranges ______________________ _ 43 Nulato Hills _______ - __________________ _ 28 Coastal Foothills ______________________ _ 43 References cited ___________________________________ _ Tanana-Kuskokwim Lowland ___________ _ 29' 43 Index ____________________________________________ _ Nowitna Lowland______________________ _ 29 51 m IV CONTENTS ILLUSTRATIONS [Plates are 1n pocket] PLATE 1. Maps of physiographic divisions of Alaska. 2. Photographs illustrating minor physiographic features and microrelief in Alaska. 3. Aerial photographs illustrating the physiography of the Rocky Mountain System and Intermontane Plateaus in Alaska. 4. Topographic maps and aerial photographs illustrating the physiography of the Interior Plains, Rocky Mountain System, and Intermontane Plateaus in Alaska. 5. Topographic maps illustrating the physiography of the Pacific Mountain System in Alaska. 6. Aerial photographs illustrating the physiography of the Pacific Mountain System in Alaska. FIGURES 1-6. Map of Alaska showing- Page 1. Location of 1: 250,000 topographic maps ________________________________________________ ~_____ 4 2. Mean daily minimum temperatures in January_________________________________________________ 9 3. Mean daily maximum temperatures in JulY----------------------------·------------------------ 10 4. Average annual precipitation________________________________________________________________ 11 5. Extent of existing glaciers, Pleistocene glaciers, and permafrost regions____________________________ 12 6. Drainage basins of major rivers______________________________________________________________ 19 TABLE Page TABLE 1. The geologic time scale----------------'-------------,----------------- 6 PHYSIOGRAPHIC DIVISIONS OF ALASKA BY CLYDE WAHRHAFTIG ABSTRACT glaciers, permafrost conditions, and geology of each section are Alaslm occupies the great northwestern peninsula of North briefly described. America, which slopes and. drains westward to the Bering and The Rocky Mountain System, Intermontane Plateaus, and Chul{cbi Seas. Most of the State is mountainous or billy al­ Pacific Mountain System together constitute the North Ameri­ though plains 20-100 miles wide abound. The central part, can Cordillera, one of the major physiographic features of the which slopes westward, consists of interspersed plains, plateaus, continent. Throughout most of its history the North American and rounded mountains, extending from beyond the Canadian Cordillera has been the site of geosynclinal sedimentation, border to the west coast ; this part is bordered on the north dominantly miogeosynclinal with interbedded carbonate and and south by high rugged ranges which effectively cut off the well-sorted clastic rocks in the Rocky Mountain System and bulk of the peninsula from the Arctic and Pacific Oceans. The northern . part of the Intermontane Plateaus and dominantly northern range is the Arctic Mountains province of the Rocky eugeosynclinal with interbedded volcanic and poorly sorted Mountain System, dominated by the Brooks Range whose sum­ clastic rocks in the Pacific Mountain System and southern part mit altitudes are 6,000-8,000 feet. North of this province are of the Intermontane Plateaus. Orogenic activity, accompanied the Arctic Foothills, also part of the Rocky Mountain System, by the invasion of immense granitic batholiths in the Pacific and the Arctic Coastal Plain, the northwestern extension of Mountain System ·and Intermontane Plateaus, has affected the the Interior Plains. The southern mountain barrier, part of the North American Cordillera almost continuously since early Pacific Mountain System, is a· pair of ridges separated by a Jurassic time. Near the end of Cretaceous time, orogenic ac­ line of discontinuous depressions, the Coastal Trough province. tivity reached its climax; and most of Alaska was converted to The northern ridge of the pair is the Alaska-Aleutian province ; dry land, which has remained ever since. In Cenozoic time and the southern, the Pacific Border Ranges province. The Alaska has been subjected to faulting, warping, and local fold­ highest peal{S of North America, rising to an altitude of more ing. These processes formed highlands, whose erosion pro­ than 20,000 feet, are here; and mountains 8,000-12,000 feet in duced large quantities of poorly consolidated sediments, and altitude are common. basins, in which these sediments were deposited and are now 'l'he part between the Arctic Mountains and the Pacific preserved. Deformation continues and is particularly strong Mountain ·system is a disordered assemblage of flat plains and along the Pacific Coast. Active volcanoes are in the Aleutian rolling uplands, surmounted here and there by groups of low Islands, Alaska Peninsula, and Wrangell Mountains. mountains; the whole region declines in relief and -altitude Alaska has bedrock structure of great variety and complex­ westward. It is divided from east to west into five provinces: ity, which is reflected in the number and types of its moun­ the Northern Plateaus province, having uplands at altitudes of tainlands, uplands,
Load more

Recommended publications
  • Sitka National Historical Park the Archeology of the Fort Unit: Volume I: Results of the 2005-2008 Inventory
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln U.S. National Park Service Publications and Papers National Park Service 2010 Sitka National Historical Park The Archeology Of The Fort Unit: Volume I: Results Of The 2005-2008 Inventory William J. Hunt Jr. National Park Service, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/natlpark Hunt, William J. Jr., "Sitka National Historical Park The Archeology Of The Fort Unit: Volume I: Results Of The 2005-2008 Inventory" (2010). U.S. National Park Service Publications and Papers. 89. https://digitalcommons.unl.edu/natlpark/89 This Article is brought to you for free and open access by the National Park Service at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in U.S. National Park Service Publications and Papers by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. SITKA NATIONAL HISTORICAL PARK THE ARCHEOLOGY OF THE FORT UNIT VOLUME I: RESULTS OF THE 2005-2008 INVENTORY by William J. Hunt, Jr. Midwest Archeological Center Occasional Studies No. 35 Volume 1 NATIONAL PARK SERVICE Midwest Archeological Center United States Department of the Interior National Park Service Midwest Archeological Center Lincoln, Nebraska 2010 This report has been reviewed against the criteria contained in 43CFR Part 7, Subpart A, Section 7.18 (a) (1) and, upon recommendation of the Midwest Regional Office and the Midwest Archeological Center, has been classified as Available Making the report available meets the criteria of 43CFR Part 7, Subpart A, Section 7.18 (a) (1). ABSTRACT In 2005, SITK invited the National Park Service’s (NPS) Midwest Archeological Center (MWAC) to conduct a Systemwide Archeological Inventory Program (SAIP) parkwide inventory at the park’s Fort Site Unit.
    [Show full text]
  • Ecological Subsections of Glacier Bay National Park & Preserve, Sitka National Historic Park, Klondike Gold Rush National Historic Park
    ECOLOGICAL SUBSECTIONS OF GLACIER BAY NATIONAL PARK & PRESERVE, SITKA NATIONAL HISTORIC PARK, KLONDIKE GOLD RUSH NATIONAL HISTORIC PARK Mapping and Delineation by: Gregory Nowacki, Michael Shephard, William Pawuk, Gary Fisher, James Baichtal, David Brew, Evert Kissinger and Terry Brock, USDA Forest Service Photographs by: USDA Forest Service Alaska Region Inventory and Monitoring Program 2525 Gambell Anchorage, Alaska 99503 Alaska Region Inventory & Monitoring Program 2525 Gambell Street, Anchorage, Alaska 99503 (907) 257-2488 Fax (907) 264-5428 Ecological Subsections of Glacier Bay National Park & Preserve Klondike Gold Rush National Historic Park Sitka National Historic Park 2001 Excerpts from Ecological Subsections of Southeast Alaska and Neighboring Areas of Canada Gregory Nowacki, Michael Shephard, William Pawuk, Gary Fisher, James Baichtal, David Brew, Evert Kissinger and Terry Brock USDA Forest Service, Alaska Region Technical Publication R10-TP-75 October 2001 Table of Contents TABLE OF CONTENTS ..............................................................................1 ECOLOGICAL SUBSECTION DELINEATION CRITERIA AND MAPPING..2 HIERARCHICAL ARRANGEMENT AND FINAL CORRECTION..................4 GLACIER BAY NATIONAL PARK AND PRESERVE ...................................1 Icefields...................................................................................................1 SAINT ELIAS—FAIRWEATHER .....................................................................1 Recently Deglaciated Areas .................................................................3
    [Show full text]
  • Norway and Its Marine Areas - a Brief Description of the Sea Floor
    No.3 2003 IN FOCUS Norway and its marine areas - a brief description of the sea floor From the deep sea to the fjord floor Norwegian waters comprise widely differing environments - from the Bjørnøyrenna deep sea via the continental slope and continental shelf to the coastal zone with its strandflat, archipelagos and fjords.This constitutes a geologi- cal diversity that is unique in a European context. An exciting geological history lies Trænadjupet behind this diversity - a development that has taken place over more than 400 million years.The continents con- Vøringplatået sist of plates of solidified rock that float on partially molten rock, and these plates move relative to one another.Where they collide, the Earth's crust is folded and mountain chains are created.Where they drift apart, deep oceans form and new sea Storegga floor is created along rifts because molten rock (magma) streams up from below. A good example is the Mid-Atlantic Ridge, including Iceland, a which is a result of Greenland and n n e Europe drifting from each other at a r e rate of about 2 cm a year. k s r o The plates on which Norway and N Greenland rest collided more than 400 million years ago and formed mountain chains on either side of a Skagerrak shallow sea. Both Greenland and Norway are remnants of worn down mountain chains. Between these mountain chains, the shallow sea Figure 1.Norway and its neighbouring seas. gradually filled with sediments derived from the erosion of the chains.These sedi- ments became transformed into sandstones, shales and limestones and it is in these rocks we now find oil and gas on the Norwegian continental shelf.
    [Show full text]
  • SW CASC Science Agenda 2013-2018
    Department of the Interior U.S. Geological Survey Southwest Climate Science Center 2013 Strategic Science Agenda Contents Introduction .................................................................................................................................................. 3 Relation of the Southwest Climate Science Center to the Stakeholder Advisory Committee and Partners 5 Climatic Context of the Southwest ............................................................................................................... 6 Vision ........................................................................................................................................................... 13 Guiding Principles ....................................................................................................................................... 13 Goals of the Southwest Climate Science Center ......................................................................................... 14 Leadership goal ............................................................................................................................ 14 Research goal ............................................................................................................................ 14 Synthesis goal ............................................................................................................................ 15 Critical Information Needs .........................................................................................................................
    [Show full text]
  • WEST NORWEGIAN FJORDS UNESCO World Heritage
    GEOLOGICAL GUIDES 3 - 2014 RESEARCH WEST NORWEGIAN FJORDS UNESCO World Heritage. Guide to geological excursion from Nærøyfjord to Geirangerfjord By: Inge Aarseth, Atle Nesje and Ola Fredin 2 ‐ West Norwegian Fjords GEOLOGIAL SOCIETY OF NORWAY—GEOLOGICAL GUIDE S 2014‐3 © Geological Society of Norway (NGF) , 2014 ISBN: 978‐82‐92‐39491‐5 NGF Geological guides Editorial committee: Tom Heldal, NGU Ole Lutro, NGU Hans Arne Nakrem, NHM Atle Nesje, UiB Editor: Ann Mari Husås, NGF Front cover illustrations: Atle Nesje View of the outer part of the Nærøyfjord from Bakkanosi mountain (1398m asl.) just above the village Bakka. The picture shows the contrast between the preglacial mountain plateau and the deep intersected fjord. Levels geological guides: The geological guides from NGF, is divided in three leves. Level 1—Schools and the public Level 2—Students Level 3—Research and professional geologists This is a level 3 guide. Published by: Norsk Geologisk Forening c/o Norges Geologiske Undersøkelse N‐7491 Trondheim, Norway E‐mail: [email protected] www.geologi.no GEOLOGICALSOCIETY OF NORWAY —GEOLOGICAL GUIDES 2014‐3 West Norwegian Fjords‐ 3 WEST NORWEGIAN FJORDS: UNESCO World Heritage GUIDE TO GEOLOGICAL EXCURSION FROM NÆRØYFJORD TO GEIRANGERFJORD By Inge Aarseth, University of Bergen Atle Nesje, University of Bergen and Bjerkenes Research Centre, Bergen Ola Fredin, Geological Survey of Norway, Trondheim Abstract Acknowledgements Brian Robins has corrected parts of the text and Eva In addition to magnificent scenery, fjords may display a Bjørseth has assisted in making the final version of the wide variety of geological subjects such as bedrock geol‐ figures . We also thank several colleagues for inputs from ogy, geomorphology, glacial geology, glaciology and sedi‐ their special fields: Haakon Fossen, Jan Mangerud, Eiliv mentology.
    [Show full text]
  • University Micrdfilms International 300 N
    INFORMATION TO USERS This was produced from a copy of a document sent to us for microfilming. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help you understand markings or notations which may appear on this reproduction. 1. The sign or “target” for pages apparently lacking from the document photographed is "Missing Page(s)”. If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure you of complete continuity. 2. When an image on the film is obliterated with a round black mark it is an indication that the film inspector noticed either blurred copy because of movement during exposure, or duplicate copy. Unless we meant to delete copyrighted materials that should not have been filmed, you will find a good image of the page in the adjacent frame. If copyrighted materials were deleted you will find a target note listing the pages in the adjacent frame. 3. When a map, drawing or chart, etc., is part of the material being photo­ graphed the photographer has followed a definite method in “sectioning” the material. It is customary to begin filming at the upper left hand corner of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued again—beginning below the first row and continuing on until complete.
    [Show full text]
  • Sitka Area Fishing Guide
    THE SITKA AREA ................................................................................................................................................................... 3 ROADSIDE FISHING .............................................................................................................................................................. 4 ROADSIDE FISHING IN FRESH WATERS .................................................................................................................................... 4 Blue Lake ........................................................................................................................................................................... 4 Beaver Lake ....................................................................................................................................................................... 4 Sawmill Creek .................................................................................................................................................................... 5 Thimbleberry and Heart Lakes .......................................................................................................................................... 5 Indian River ....................................................................................................................................................................... 5 Swan Lake .........................................................................................................................................................................
    [Show full text]
  • Major Landforms and Their Economic Significance MODULE - 2 Changing Face of the Earth 7 Notes MAJOR LANDFORMS and THEIR ECONOMIC SIGNIFICANCE
    Major Landforms and their Economic Significance MODULE - 2 Changing face of the Earth 7 Notes MAJOR LANDFORMS AND THEIR ECONOMIC SIGNIFICANCE You have learnt in the previous lesson that the landforms found on the earth’s surface are the result of interplay between internal and external forces. The soft rocks are easily worn down by these forces. While the relatively harder rocks are not so easily worn down. Therefore, rocks have a great influence on the landforms developed in an area. The internal forces are perpetually elevating the earth’s surface and the external forces about which you will study in the next lessons are constantly wearing down such elevations to make ,the surface level. This is how various landforms are formed by constant action of agents of gradation. These landforms are not only the physical features of the earth’s surface but also the basis of human civilization. The major landforms found on the earth’s surface are mountains, plateaus and plains. In this lesson, we will study the major landforms of the earth and their economic importance for us. OBJECTIVES After studying this lesson you will be able to : differentiate among the three major landforms found on the earth’s surface; explain the process of formation of various landforms with the help of illustrations; classify mountains on the basis of their mode of formation; discuss the usefulness of mountains to man; list different types of plateaus and describe their economic significance; GEOGRAPHY 121 MODULE - 2 Major Landforms and their Economic Significance Changing face of the Earth enumerate major types of plains and explain their influence on human life; locate major mountains, plateaus and plains on the outline map of the world.
    [Show full text]
  • USGS Professional Paper 1739-A
    Studies by the U.S. Geological Survey in Alaska, 2006 U.S. Geological Survey Professional Paper 1739–A Blue Mountain and The Gas Rocks: Rear-Arc Dome Clusters on the Alaska Peninsula By Wes Hildreth, Judy Fierstein, and Andrew T. Calvert Abstract pal nearby town) and 15 to 20 km behind (northwest of) the volcanic-front chain, which is locally defined by Kejulik and Behind the single-file chain of stratovolcanoes on the Peulik stratovolcanoes (fig. 1). The Gas Rocks form a knobby Alaska Peninsula, independent rear-arc vents for mafic mag- peninsula at the south shore of Becharof Lake, and Blue mas are uncommon, and for silicic magmas rarer still. We Mountain is a group of rounded hills a few kilometers west of report here the characteristics, compositions, and ages of two Upper Ugashik Lake (fig. 2). Both dome clusters rise abruptly andesite-dacite dome clusters and of several nearby basaltic above a nearly flat (virtually treeless and roadless) plain of units, all near Becharof Lake and 15 to 20 km behind the late Pleistocene glacial deposits (Detterman and others, 1987a, volcanic front. Blue Mountain consists of 13 domes (58–68 b), consisting largely of till and outwash, supplemented by the bog and lacustrine deposits of hundreds of ponds and by weight percent SiO2) and The Gas Rocks of three domes (62–64.5 weight percent SiO ) and a mafic cone (52 weight beach and terrace deposits along the lakeshores. The enor- 2 mous moraine-dammed lakes (fig. 2) are generally shallower percent SiO2). All 16 domes are amphibole-biotite-plagio- clase felsite, and nearly all are phenocryst rich and quartz than 5 m, and their surfaces are barely 10 m above sea level.
    [Show full text]
  • Where We Found a Whale"
    ______ __.,,,,---­ ....... l-:~-- ~ ·--~-- - "Where We Found a Whale" A -~lSTORY OF LAKE CLARK NATlONAL PARK AND PRESERVE Brian Fagan “Where We Found a Whale” A HISTORY OF LAKE CLARK NATIONAL PARK AND PRESERVE Brian Fagan s the nation’s principal conservation agency, the Department of the Interior has resposibility for most of our nationally owned public lands and natural and cultural resources. This includes fostering the wisest use of our land and water resources, protect- ing our fish and wildlife, preserving the environmental and cultural values of our national parks and historical places, and providing for enjoyment of life Athrough outdoor recreation. The Cultural Resource Programs of the National Park Service have respon- sibilities that include stewardship of historic buildings, museum collections, archaeological sites, cultural landscapes, oral and written histories, and ethno- graphic resources. Our mission is to identify, evaluate, and preserve the cultural resources of the park areas and to bring an understanding of these resources to the public. Congress has mandated that we preserve these resources because they are important components of our national and personal identity. Published by the United States Department of the Interior National Park Service Lake Clark National Park and Preserve ISBN 978-0-9796432-4-8 NPS Research/Resources Management Report NPR/AP/CRR/2008-69 For Jeanne Schaaf with Grateful Thanks “Then she said: “Now look where you come from—the sunrise side.” He turned and saw that they were at a land above the human land, which was below them to the east. And all kinds of people were coming up from the lower country, and they didn’t have any clothes on.
    [Show full text]
  • Wrangellia Flood Basalts in Alaska, Yukon, and British Columbia: Exploring the Growth and Magmatic History of a Late Triassic Oceanic Plateau
    WRANGELLIA FLOOD BASALTS IN ALASKA, YUKON, AND BRITISH COLUMBIA: EXPLORING THE GROWTH AND MAGMATIC HISTORY OF A LATE TRIASSIC OCEANIC PLATEAU By ANDREW R. GREENE A THESIS SUBMITTED iN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Geological Sciences) UNIVERSITY OF BRITISH COLUMBIA (Vancouver) August 2008 ©Andrew R. Greene, 2008 ABSTRACT The Wrangellia flood basalts are parts of an oceanic plateau that formed in the eastern Panthalassic Ocean (ca. 230-225 Ma). The volcanic stratigraphy presently extends >2300 km in British Columbia, Yukon, and Alaska. The field relationships, age, and geochemistry have been examined to provide constraints on the construction of oceanic plateaus, duration of volcanism, source of magmas, and the conditions of melting and magmatic evolution for the volcanic stratigraphy. Wrangellia basalts on Vancouver Island (Karmutsen Formation) form an emergent sequence consisting of basal sills, submarine flows (>3 km), pillow breccia and hyaloclastite (<1 1cm), and subaerial flows (>1.5 km). Karmutsen stratigraphy overlies Devonian to Permian volcanic arc (—‘380-355 Ma) and sedimentary sequences and is overlain by Late Triassic limestone. The Karmutsen basalts are predominantly homogeneous tholeiitic basalt (6-8 wt% MgO); however, the submarine part of the stratigraphy, on northern Vancouver Island, contains picritic pillow basalts (9-20 wt% MgO). Both lava groups have overlapping initial and ENd, indicating a common, ocean island basalt (OIB)-type Pacific mantle source similar to the source of basalts from the Ontong Java and Caribbean Plateaus. The major-element chemistry of picrites indicates extensive melting (23 -27%) of anomalously hot mantle (‘—1500°C), which is consistent with an origin from a mantle plume head.
    [Show full text]
  • Climate Change in Selawik, Alaska Strategies for Community Health
    Climate Change in Selawik, Alaska Strategies for Community Health ANTHC Center for Climate and Health Funded by Report prepared by: Michael Brubaker, MS Prithviraj Chavan, P.E. James Berner, MD Mike Black John Warren, P.E. ANTHC recognizes all of our technical advisors for this report. Thank you for your support. LeeAnn Ayres, Selawik National Wildlife Reserve Eric Hanssen, ANTHC Tanya Ballot, Native Village of Selawik Millie Hawley, Maniilaq Association James Beylund, City of Selawik Lucy Snyder, Native Village of Selawik Susan Clark, Native Village of Selawik Allison Woodward, University of Alaska Fairbanks Paul Eaton, Maniilaq Association © Alaska Native Tribal Health Consortium (ANTHC), May 2012. Through adaptation, negative health effects can be prevented. TABLE OF CONTENTS Summary 1 Introduction 7 Community 9 Climate 11 Land 15 River 17 Water 19 Waste Water 21 Solid Waste 23 Transportation 25 Housing 27 Energy 29 Food 31 Conclusion 33 Figures 1. Map of Maniilaq Service Area 8 2. Google Maps view of Selawik and region 10 3. Mean Monthly Temperature Selawik (SNAP) 12 4. Mean Monthly Precipitation Selawik (SNAP) 13 5. Circulating Water, Vacuum Sewer Systems 29 6. Climate Change Health Assessment Findings, Selawik Alaska 34 Appendices A. Selawik Participants 35 B. Selawik Climate and Health Web Resources 36 C. General Climate Change Adaptation Guidelines 37 References 38 Cover Art: Whale Bone Mask by Larry Adams Rural Arctic communities are vulnerable to climate change and residents seek adaptive strategies that will protect public health. In the Inupiat community of Selawik, climate change is impacting the weather, land, river, wildlife, plants, and the lives of the people who live there.
    [Show full text]