DOCSLIB.ORG

Wrangell-St. Elias National Park and Preserve Natural Resource Condition Assessment

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Wrangell-St. Elias National Park and Preserve Natural Resource Condition Assessment National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Wrangell-St. Elias National Park and Preserve Natural Resource Condition Assessment Natural Resource Report NPS/NRSS/WRD/NRR—2011/406 ON THE COVER. Nabesna River and Glacier Photograph by: Barry Drazkowski, August 2009 Wrangell-St. Elias National Park and Preserve Natural Resource Condition Assessment Natural Resource Report NPS/NRSS/WRD/NRR—2011/406 Barry Drazkowski Kevin Stark Michael Komp Greta Bernatz Chip Brown Courtney Lee Chad Richtman Andrew Robertson Kyle Slifka GeoSpatial Services Saint Mary‘s University of Minnesota 700 Terrace Heights, Box #7 Winona, Minnesota 55987 This report was prepared under Task Agreement J8W07080025 between the National Park Service and Saint Mary‘s University of Minnesota, through the Pacific Northwest Cooperative Ecosystem Studies Unit. June 2011 U.S. Department of the Interior National Park Service Natural Resource Stewardship and Science Fort Collins, Colorado The National Park Service, Natural Resource Stewardship and Science office in Fort Collins publishes a range of reports that address natural resource topics of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Report Series is used to disseminate high-priority, current natural resource management information with managerial application. The series targets a general, diverse audience and may contain NPS policy considerations or address sensitive issues of management applicability. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. Views, statements, findings, conclusions, recommendations, and data in this report do not necessarily reflect views and policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the U.S. Government. Printed copies of this report are produced in a limited quantity, and are only available as long as the supplies last. This report is also available from the Natural Resource Publications Management web site (http://www.nature.nps.gov/publications/nrpm/). Please cite this publication as: Drazkowski, B. , K. J. Stark, M. R. Komp, G. Bernatz, D. Brown, C. Richtman, C. Lee, A. Robertson, and K. Slifka. 2011. Wrangell-St. Elias National Park and Preserve, Natural Resource Condition Assessment. Natural Resource Report NPS/NRSS/WRD/NRR—2011/406. National Park Service, Fort Collins, Colorado. NPS 190/107958, June 2011 ii Contents Page Figures............................................................................................................................................. v Tables ............................................................................................................................................. ix Plates ............................................................................................................................................ xiii Photos .......................................................................................................................................... xvii Acronyms and Abbreviations ...................................................................................................... xix Acknowledgments...................................................................................................................... xxiii Prologue ..................................................................................................................................... xxiii Executive Summary .................................................................................................................... xxv Chapter 1: NRCA Background Information ................................................................................... 1 Chapter 2: Park Resource Setting ................................................................................................... 5 Chapter 3: Study Approach ............................................................................................................. 9 3.1 Preliminary Scoping .......................................................................................................... 9 3.2 NPS Involvement ............................................................................................................... 9 3.2 Framework Development ................................................................................................ 10 3.3 Selection of Reporting Zones .......................................................................................... 15 3.4 Study Methodologies ....................................................................................................... 22 Chapter 4: Component Condition Summaries .............................................................................. 29 4.1 Landcover ........................................................................................................................ 30 4.2 Forest Fires ...................................................................................................................... 43 4.3 Ecosystem and Communities ........................................................................................... 59 4.4 Trumpeter Swans ............................................................................................................. 70 4.5 Bald Eagle ........................................................................................................................ 77 4.6 Moose .............................................................................................................................. 84 iii Contents (continued) Page 4.7 Brown Bear ...................................................................................................................... 96 4.8 Caribou .......................................................................................................................... 104 4.9 Dall’s Sheep ................................................................................................................... 113 4.10 Wolves ......................................................................................................................... 126 4.11 Anadromous Fish ......................................................................................................... 131 4.12 Resident Fish ............................................................................................................... 147 4.13 Breeding Birds ............................................................................................................. 166 4.14 Kittlitz's Murrelet ......................................................................................................... 173 4.15 Forest Insects and Disease ........................................................................................... 181 4.16 Non-Native Species ..................................................................................................... 200 4.17 Air Quality ................................................................................................................... 219 4.18 Water Quality ............................................................................................................... 231 4.19 Climate ......................................................................................................................... 240 4.20 Glacial Features ........................................................................................................... 260 4.21 Hydrology .................................................................................................................... 264 4.22 Subsurface and Geothermal ......................................................................................... 271 4.23 Soils and Permafrost .................................................................................................... 281 4.24 Consumptive Use ......................................................................................................... 294 4.25 Human Presence .......................................................................................................... 343 4.26 Viewshed ..................................................................................................................... 358 Chapter 5: Discussion ................................................................................................................. 361 Appendices .................................................................................................................................. 363 iv Figures Page Figure 1. Ecoregions of WRST ..................................................................................................... 15 Figure 2. Front and Back Country Areas of Wrangell-St. Elias ................................................... 16 Figure 3. Reporting Zones used in WRST NRCA ........................................................................ 17 Figure 4. Designation symbols used for individual indicator assessments ................................... 24 Figure 5. Example of the final condition graphic used in the component
Load more

Recommended publications
  • Gulkana River
    Fishing the Those who have yet to Gulkana River travel to the Gulkana are missing a rare glimpse of a unique piece ALASKA DEPARTMENT OF FISH AND GAME of Alaska SPORT FISH DIVISION 1300 COLLEGE ROAD FAIRBANKS, ALASKA 99701 (907) 459-7207 GLENNALLEN OFFICE: (907) 822-3309 Contents Fishing the Gulkana River: an Introduction . 1 Roads and lodging . 2 Remote fishing sites: the Middle Fork and the West Fork . 2 The mainstem Gulkana: Paxson Lake to Sourdough . 2 Fishing for grayling in the Gulkana . 3 Fishing for rainbow trout in the Gulkana . 4 The lower Gulkana: Sourdough to the Richardson Highway bridge . 5 Salmon fishing in the Gulkana . 5 Downstream from the Richardson Highway bridge . 6 Lake trout fishing in Summit and Paxson lakes . 6 What to do if you catch a tagged fish . 7 Gulkana River float trips: mileage logs . 8 ADF&G Trophy Fish Program . 10 Catch-and-release techniques . 11 Trophy Fish Affidavit form . 12 Gulkana River area map . back cover he Alaska Department of Fish and Game administers all programs and activities free from discrimination based on race, color, Tnational origin, age, sex, religion, marital status, pregnancy, parenthood, or disability The department administers all programs and activities in compliance with Title VI of the Civil Rights Act of 1964, Section 504 of the Rehabilitation Act of 1973, Title II of the Americans with Disabilities Act of 1990, the Age Discrimination Act of 1975, and Title IX of the Education Amendments of 1972 If you believe you have been discriminated against in any program, activity,
    [Show full text]
  • Geologic Maps of the Eastern Alaska Range, Alaska, (44 Quadrangles, 1:63360 Scale)
    Report of Investigations 2015-6 GEOLOGIC MAPS OF THE EASTERN ALASKA RANGE, ALASKA, (44 quadrangles, 1:63,360 scale) descriptions and interpretations of map units by Warren J. Nokleberg, John N. Aleinikoff, Gerard C. Bond, Oscar J. Ferrians, Jr., Paige L. Herzon, Ian M. Lange, Ronny T. Miyaoka, Donald H. Richter, Carl E. Schwab, Steven R. Silva, Thomas E. Smith, and Richard E. Zehner Southeastern Tanana Basin Southern Yukon–Tanana Upland and Terrane Delta River Granite Jarvis Mountain Aurora Peak Creek Terrane Hines Creek Fault Black Rapids Glacier Jarvis Creek Glacier Subterrane - Southern Yukon–Tanana Terrane Windy Terrane Denali Denali Fault Fault East Susitna Canwell Batholith Glacier Maclaren Glacier McCallum Creek- Metamorhic Belt Meteor Peak Slate Creek Thrust Broxson Gulch Fault Thrust Rainbow Mountain Slana River Subterrane, Wrangellia Terrane Phelan Delta Creek River Highway Slana River Subterrane, Wrangellia Terrane Published by STATE OF ALASKA DEPARTMENT OF NATURAL RESOURCES DIVISION OF GEOLOGICAL & GEOPHYSICAL SURVEYS 2015 GEOLOGIC MAPS OF THE EASTERN ALASKA RANGE, ALASKA, (44 quadrangles, 1:63,360 scale) descriptions and interpretations of map units Warren J. Nokleberg, John N. Aleinikoff, Gerard C. Bond, Oscar J. Ferrians, Jr., Paige L. Herzon, Ian M. Lange, Ronny T. Miyaoka, Donald H. Richter, Carl E. Schwab, Steven R. Silva, Thomas E. Smith, and Richard E. Zehner COVER: View toward the north across the eastern Alaska Range and into the southern Yukon–Tanana Upland highlighting geologic, structural, and geomorphic features. View is across the central Mount Hayes Quadrangle and is centered on the Delta River, Richardson Highway, and Trans-Alaska Pipeline System (TAPS). Major geologic features, from south to north, are: (1) the Slana River Subterrane, Wrangellia Terrane; (2) the Maclaren Terrane containing the Maclaren Glacier Metamorphic Belt to the south and the East Susitna Batholith to the north; (3) the Windy Terrane; (4) the Aurora Peak Terrane; and (5) the Jarvis Creek Glacier Subterrane of the Yukon–Tanana Terrane.
    [Show full text]
  • Mount Sanford…Errrr, Mount Jarvis. Wait, What?? Mount Who?? It Was Roughly Around Thanksgiving 2016 and the Time Had Come Fo
    Mount Sanford…errrr, Mount Jarvis. Wait, what?? Mount Who?? It was roughly around Thanksgiving 2016 and the time had come for me to book my next IMG adventure. With two young children at home and no family close by, I had settled into a routine of doing a big climb every other year. This year was a bit different, as I normally book my major climbs around September for an April or May departure the following year. However, due to a Mt. Blackburn (Alaska) trip falling through, I had to book another expedition. In 2015, I was on an IMG team that summitted Mt. Bona from the north side, not the original plan (jot that down – this will become a theme in Alaska), and really enjoyed the solitude, adventure, physical challenge, small team, and lack of schedule the Wrangell & St Elias Mountains had to offer. So, I hopped on IMG’s website, checked out the scheduled Alaskan climb for 2017, which was Mt. Sanford, and peppered George with my typical questions. Everything lined up, so I completed the pile of paperwork (do I really have to sign another waiver?!?), sent in my deposit (still no AMEX, ugh…), set my training schedule, and started Googling trip reports about Mt. Sanford. Little did I know that READING about Mt. Sanford was the closest I would ever get to it! Pulling from my previous Alaskan climbing experience, I was better prepared for this trip than for Mt Bona in 2015. Due to our bush pilot’s inability to safely land us on the south side of Bona two years prior, we flew up, around, and over the mountain and landed on the north side.
    [Show full text]
  • Summary Report for the Navigability of the Nabesna River Within the Tanana River Region, Alaska
    United States Departmentof the Interior BUREAU OF LAND MANAGEMENT TAKE PRIDE • Alaska State Office '"AMERICA 222 West Seventh Avenue, #13 Anchorage, Alaska 99513-7504 http://www.blm.gov/ak In Reply Refer to: 1864 (AK9410) Memorandum To: File FF-094614 From: Jack Frost, Navigable Waters Specialist (AK9410) Subject: Summary Report for the Navigability of the Nabesna River within the Tanana River Region, Alaska The State of Alaska (State) filed an application, dated October 3, 2005, for a recordable disclaimer of interest (RDI) for lands underlying the Nabesna River "between the ordinary high water lines of the left and right banks from its origins at the Nabesna Glacier within Township 5 North, Ranges 13 and 14 East, Copper River Meridian, Alaska, downstream to its confluence with the Tanana River in Township 15 North, Range 19 East, Copper River Meridian." 1 The State identified the location of its application on two maps entitled "Nabesna River Recordable Disclaimer of Interest Application," dated October 3, 2005. The maps were submitted with the State's application. The State filed an amended RDI application for the Nabesna River, dated September 16, 2015, "to include only the submerged lands underlying the Nabesna River from its mouth to the Black Hills (Sec. 25, TI IN, Rl 7E, and CRM). The State withdraws its request for an RDI on the submerged lands underlying the Nabesna River from Sec. 25, Tl IN, R17E, CRM and the river's source at the Nabesna Glacier." 2 Clarifying its letter from September 16, 2015, the State submitted an email on October 16, 2015 stating that "the State withdraws its request for an RDI on the submerged lands underlying the Nabesna River from its confluence with the Cheslina River in Section 35, Tl2N, RI 7E, CRM upstream to the river's source at the Nabesna Glacier." 3 The State bases its application for a disclaimer of interest on the Equal Footing Doctrine, the Submerged Lands Act of May 22, 1953, the Alaska Statehood Act, the Submerged Lands Act of 1988, and any other legally cognizable reason.
    [Show full text]
  • North American Notes
    268 NORTH AMERICAN NOTES NORTH AMERICAN NOTES BY KENNETH A. HENDERSON HE year I 967 marked the Centennial celebration of the purchase of Alaska from Russia by the United States and the Centenary of the Articles of Confederation which formed the Canadian provinces into the Dominion of Canada. Thus both Alaska and Canada were in a mood to celebrate, and a part of this celebration was expressed · in an extremely active climbing season both in Alaska and the Yukon, where some of the highest mountains on the continent are located. While much of the officially sponsored mountaineering activity was concentrated in the border mountains between Alaska and the Yukon, there was intense activity all over Alaska as well. More information is now available on the first winter ascent of Mount McKinley mentioned in A.J. 72. 329. The team of eight was inter­ national in scope, a Frenchman, Swiss, German, Japanese, and New Zealander, the rest Americans. The successful group of three reached the summit on February 28 in typical Alaskan weather, -62° F. and winds of 35-40 knots. On their return they were stormbound at Denali Pass camp, I7,3oo ft. for seven days. For the forty days they were on the mountain temperatures averaged -35° to -40° F. (A.A.J. I6. 2I.) One of the most important attacks on McKinley in the summer of I967 was probably the three-pronged assault on the South face by the three parties under the general direction of Boyd Everett (A.A.J. I6. IO). The fourteen men flew in to the South east fork of the Kahiltna glacier on June 22 and split into three groups for the climbs.
    [Show full text]
  • Wrangell-St. Elias National Park and Preserve, Denali
    Central Alaska Network Geologic Resources Evaluation Scoping Meeting Summary A geologic resources evaluation (GRE) scoping meeting was held from February 24 through 26, 2004 at the NPS regional office in Anchorage, Alaska to discuss geologic mapping in and around the parks and geologic resources management issues and concerns. The scoping meeting covered the three parks in the Central Alaska Network (CAKN) – Wrangell-St. Elias National Park and Preserve (WRST), Denali National Park and Preserve (DENA), and Yukon Charley Rivers National Preserve (YUCH). A summary of the status of geologic mapping and resource management issues is presented separately for each of these parks. The scoping summary is supplemented with additional geologic information from park planning documents, websites and NPS Geologic Resources Division documents. Purpose of the Geologic Resources Evaluation Program Geologic resources serve as the foundation of the park ecosystems and yield important information needed for park decision making. The National Park Service Natural Resource Challenge, an action plan to advance the management and protection of park resources, has focused efforts to inventory the natural resources of parks. The geologic component is carried out by the Geologic Resource Evaluation (GRE) Program administered by the NPS Geologic Resource Division. The goal of the GRE Program is to provide each of the identified 274 “Natural Area” parks with a digital geologic map, a geologic evaluation report, and a geologic bibliography. Each product is a tool to support the stewardship of park resources and each is designed to be user friendly to non-geoscientists. The GRE teams hold scoping meetings at parks to review available data on the geology of a particular park and to discuss the geologic issues in the park.
    [Show full text]
  • Resedimentation of the Late Holocene White River Tephra, Yukon Territory and Alaska
    Resedimentation of the late Holocene White River tephra, Yukon Territory and Alaska K.D. West1 and J.A. Donaldson2 Carleton University3 West, K.D. and Donaldson, J.A. 2002. Resedimentation of the late Holocene White River tephra, Yukon Territory and Alaska. In: Yukon Exploration and Geology 2002, D.S. Emond, L.H. Weston and L.L. Lewis (eds.), Exploration and Geological Services Division, Yukon Region, Indian and Northern Affairs Canada, p. 239-247. ABSTRACT The Wrangell region of eastern Alaska represents a zone of extensive volcanism marked by intermittent pyroclastic activity during the late Holocene. The most recent and widely dispersed pyroclastic deposit in this area is the White River tephra, a distinct tephra-fall deposit covering 540 000 km2 in Alaska, Yukon, and the Northwest Territories. This deposit is the product of two Plinian eruptions from Mount Churchill, preserved in two distinct lobes, created ca. 1887 years B.P. (northern lobe) and 1147 years B.P. (eastern lobe). The tephra consists of distal primary air-fall deposits and proximal, locally resedimented volcaniclastic deposits. Distinctive layers such as the White River tephra provide important chronostratigraphic control and can be used to interpret the cultural and environmental impact of ancient large magnitude eruptions. The resedimentation of White River tephra has resulted in large-scale terraces, which fl ank the margins of Klutlan Glacier. Preliminary analysis of resedimented deposits demonstrates that the volcanic stratigraphy within individual terraces is complex and unique. RÉSUMÉ Au cours de l’Holocène tardif, des matériaux pyroclastiques ont été projetés lors d’importantes et nombreuses éruptions volcaniques, dans la région de Wrangell de l’est de l’Alaska.
    [Show full text]
  • Birch Defoliator Yukon Forest Health — Forest Insect and Disease 4
    Birch Defoliator Yukon Forest Health — Forest insect and disease 4 Energy, Mines and Resources Forest Management Branch Introduction The birch leafminer (Fenusa pusilla), amber-marked birch leafminer (Profenusa thomsoni), birch leaf skeletonizer (Bucculatrix canadensisella) and the birch-aspen leafroller (Epinotia solandriana) are defoliators of white birch (Betula papyrifera) in North America. Of the four, only the Bucculatrix is native to North America, but it is not currently found in Yukon. The other three species, as invasives, pose a far greater threat to native trees because their natural enemies in the form of predators, parasites and diseases are absent here. The birch leafminer was accidently introduced from Europe in 1923 and is now widely distributed in Canada, Alaska and the northern United States, though it has not yet been found in Yukon. The amber-marked birch leafminer was first described in Quebec in 1959 but is now found throughout Canada, the northern contiguous U.S., and Alaska. The amber-marked birch leafminer has proven to be, by far, the more damaging of the two species. Both species are of the blotch mining type as opposed to the skeletonizing Bucculatrix and the leafrolling Epinotia. Amber-marked leafminer damage is typically found along road systems. Infestations along roadsides are often greater in areas of high traffic, or where parked cars are common, suggesting that this pest will hitchhike on vehicles. It was first identified in Anchorage, Alaska in 1996 and has since spread widely to other communities. In areas of Alaska, efforts to control the spread of the amber-marked birch leafminer have been underway since 2003 with the release of parasitic wasps (Lathrolestes spp.).
    [Show full text]
  • P1616 Text-Only PDF File
    A Geologic Guide to Wrangell–Saint Elias National Park and Preserve, Alaska A Tectonic Collage of Northbound Terranes By Gary R. Winkler1 With contributions by Edward M. MacKevett, Jr.,2 George Plafker,3 Donald H. Richter,4 Danny S. Rosenkrans,5 and Henry R. Schmoll1 Introduction region—his explorations of Malaspina Glacier and Mt. St. Elias—characterized the vast mountains and glaciers whose realms he invaded with a sense of astonishment. His descrip­ Wrangell–Saint Elias National Park and Preserve (fig. tions are filled with superlatives. In the ensuing 100+ years, 6), the largest unit in the U.S. National Park System, earth scientists have learned much more about the geologic encompasses nearly 13.2 million acres of geological won­ evolution of the parklands, but the possibility of astonishment derments. Furthermore, its geologic makeup is shared with still is with us as we unravel the results of continuing tectonic contiguous Tetlin National Wildlife Refuge in Alaska, Kluane processes along the south-central Alaska continental margin. National Park and Game Sanctuary in the Yukon Territory, the Russell’s superlatives are justified: Wrangell–Saint Elias Alsek-Tatshenshini Provincial Park in British Columbia, the is, indeed, an awesome collage of geologic terranes. Most Cordova district of Chugach National Forest and the Yakutat wonderful has been the continuing discovery that the disparate district of Tongass National Forest, and Glacier Bay National terranes are, like us, invaders of a sort with unique trajectories Park and Preserve at the north end of Alaska’s panhan­ and timelines marking their northward journeys to arrive in dle—shared landscapes of awesome dimensions and classic today’s parklands.
    [Show full text]
  • Profiles of Colorado Roadless Areas
    PROFILES OF COLORADO ROADLESS AREAS Prepared by the USDA Forest Service, Rocky Mountain Region July 23, 2008 INTENTIONALLY LEFT BLANK 2 3 TABLE OF CONTENTS ARAPAHO-ROOSEVELT NATIONAL FOREST ......................................................................................................10 Bard Creek (23,000 acres) .......................................................................................................................................10 Byers Peak (10,200 acres)........................................................................................................................................12 Cache la Poudre Adjacent Area (3,200 acres)..........................................................................................................13 Cherokee Park (7,600 acres) ....................................................................................................................................14 Comanche Peak Adjacent Areas A - H (45,200 acres).............................................................................................15 Copper Mountain (13,500 acres) .............................................................................................................................19 Crosier Mountain (7,200 acres) ...............................................................................................................................20 Gold Run (6,600 acres) ............................................................................................................................................21
    [Show full text]
  • Wrangell-St. Elias National Park and Preserve Visitor Study Summer 1995
    Wrangell-St. Elias National Park and Preserve Visitor Study Summer 1995 Report 77 Visitor Services Project Cooperative Park Studies Unit Visitor Services Project Wrangell-St. Elias National Park and Preserve Visitor Study Margaret Littlejohn Report 77 January 1996 Margaret Littlejohn is VSP Coordinator, National Park and Preserve Service based at the Cooperative Park Studies Unit, University of Idaho. I thank Diane Jung, Maria Gillette, Glen Gill and the staff of Wrangell-St. Elias National Park and Preserve for their assistance with this study. The VSP acknowledges the Public Opinion Lab of the Social and Economic Sciences Research Center, Washington State University, for its technical assistance. Visitor Services Project Wrangell-St. Elias National Park and Preserve Report Summary • This report describes part of the results of a visitor study at Wrangell-St. Elias National Park and Preserve during July 12-18, 1995. A total of 531 questionnaires were distributed to visitors. Visitors returned 444 questionnaires for an 84% response rate. • This report profiles Wrangell-St. Elias visitors. A separate appendix contains visitors' comments about their visit; this report and the appendix include a summary of visitors' comments. • Fifty-five percent of the visitors were in family groups; 20% were in groups of friends. Forty-nine percent of Wrangell-St. Elias visitors were in groups of two. Most visitors (56%) were aged 26- 55. • Among Wrangell-St. Elias visitors, 11% were international visitors. Forty percent of those visitors were from Germany. United States visitors were from Alaska (31%), California (7%), Florida (5%) and 43 other states. • Almost two-thirds of Wrangell-St.
    [Show full text]
  • Insar Observations of the 1993-95 Bering Glacier (Alaska, U. S. A
    Journal ofGlaciology, Vo l. 48, No.162,2002 InSAR observations of the 1993^95 Bering Glacier (Alaska, U.S.A.)surge and a surge hypothesis Dennis R. FATLAND,1 Craig S. LINGLE2 1Vexcel Corporation, Boulder,Colorado 80301-3242, U.S.A. E-mail: [email protected] 2Geophysical Institute, University ofAlaska Fairbanks, Fairbanks, Alaska 99775-7320, U.S.A. ABSTRACT. Time-varying accelerations were observed on Bagley Icefield during the 1993^95 surge of Bering Glacier, Alaska, U.S.A., using repeat-pass synthetic aperture radar interferometry. Observations were from datasets acquired during winter 1991/92 (pre-surge), winter 1993/94 (during the surge) and winter 1995/96 (post-surge).The surge is shown to have extended 110km up the icefield from Bering Glacier to within 15km or less of the flow divide. Acceleration and step-like velocity profiles are strongly associated with an along-glacier series of central phase bull's-eyes with diameters of 0.5^4 km.These bull's-eyes are interpreted to represent glacier surface rise/fall events of 3^30 cm during 1^3 day observation intervals and indicate possible migrating pockets of subglacial water. We present a surge hypothesis that relates late-summer climate to englacial water storage and thence to the subglacial water dynamics ö pressurization, hydraulic jacking, depres- surization and migration ö suggested by our observations. INTRODUCTION with floods of sediment-laden water at the glacier terminus onVariegated and West Fork Glaciers, Alaska (Harrison and Bering Glacier, together with Bagley Icefield, its associated others, 1986, 1994). This work demonstrated that large-scale accumulation area, and smaller tributaries, covers an area of 2 disruption of the basal drainage system results in large 5200 km in the Chugach^Saint Elias Mountains of south- volumes of subglacially stored water and bed separation central Alaska, U.S.A.
    [Show full text]