For over 50 yr, the Juneau Icefield Research Program (JIRP) has provided undergraduate students with an 8 wk summer earth systems and glaciology field camp. This field experience engages students in the geosciences by placing them directly into the physically challenging glacierized alpine landscape of southeastern Alaska. Mountain-top camps across the Juneau Icefield provide essential shelter and facilitate the program’s instructional aim to enable direct observations by students of active glacier surface processes, glaciogenic landscapes, and the region’s tectonically deformed bedrock. Disciplinary knowledge is transferred by teams of JIRP faculty in the style of a scientific institute. JIRP staffers provide glacier safety training, facilitate essential camp logistics, and develop JIRP student field skills through daily chores, remote camp management, and glacier travel in small field parties. These practical elements are important components of the program’s instructional philosophy. Students receive on-glacier training in mass-balance data collection and ice-velocity measurements as they ski ~320 km across the icefield glaciers between Juneau, Alaska, and Atlin, British Columbia. They use their glacier skills and disciplinary interests to develop research experiments, collect field data, and produce reports. Students present their research at a public forum at the end of the summer. This experience develops its participants for successful careers as researchers in extreme and remote environments. The long-term value of the JIRP program is examined here through the professional evolution of six of its recent alumni. Since its inception, ~1300 students, faculty, and staff have participated in the Juneau Icefield Research Program. Most of these faculty and staff have participated for multiple summers and many JIRP students have returned to work as program staff and sometimes later as faculty. The number of JIRP participants (1946–2008) can also be measured by adding up each summer’s participants, raising the total to ~2500.

The Coast orogen of western coastal British Columbia and southeastern Alaska is one of the largest batholithic belts in the world. This paper addresses the structure and composition of the crust in the central part of this orogen, as well as the history of its development since the mid-Cretaceous. The core of the orogen consists of two belts of metamorphic and plutonic rocks: the western metamorphic and thick-skinned thrust belt comprising 105–90-Ma plutons and their metamorphic country rocks, and the Coast Plutonic Complex on the east, with large volumes of mainly Paleogene magmatic rocks and their high-temperature gneissic host rocks. These two belts are separated by the Coast shear zone, which forms the western boundary of a Paleogene magmatic arc. This shear zone is subvertical, up to 5 km wide, and has been seismically imaged to extend to and offset the Moho. Lithologic units west of the Coast shear zone record contractional deformation and crustal thickening by thrusting and magma emplacement in the mid-Cretaceous. To the east, the Coast Plutonic Complex records regional contraction that evolves to regional extension and coeval uplift and exhumation after ca. 65 Ma. Igneous activity in the Complex formed a Paleogene batholith and gave rise to high crustal temperatures, abundant migmatite and, as a result, considerable strain localization during deformation. In both belts, during each stage of the orogeny, crustal-scale deformation enabled and assisted magma transport and emplacement. In turn, the presence of magma, as well as its thermal effects in the crust, facilitated the deformation. After 50 Ma, the style of crustal evolution changed to one dominated by periods of extension oriented approximately perpendicular to the orogen. The extension resulted in tilting of large and small crustal blocks as well as intra-plate type magmatic activity across the orogen. Seismic-reflection and refraction studies show that the crust of this orogen is unusually thin, probably due to the periods of orogen-perpendicular stretching. Magmatic activity west of the Coast shear zone in the Late Oligocene and Miocene was related to one period of orogen-parallel transtension along the margin. Small-scale, mafic, mantle-derived volcanic activity continues in the region today. The change from convergence to translation and extension is related to a major plate reorganization in the Pacific that led to a change from subduction of an oceanic plate to northwestward translation of the Pacific plate along the northwest coast of North America. Although it has been proposed that this orogen is the site of major (up to 4000 km) pre-Eocene northward terrane translation, there is little evidence for such large-scale displacement or for the kind of discontinuity in the geological record that such displacement would entail.

Abstract Glaciers are a significant natural resource in Alaska and the Western United States, covering respective areas of ~74,600 and 688 km 2 ( Dyurgerov, 2002 ; Fountain et al., 2007 ). A large percentage of these glaciers exist within the boundaries of lands managed by the U.S. federal government. For example, glaciers in Wrangell-St. Elias National Park and Preserve and Denali National Park and Preserve in Alaska cover a total area of ~20,000 km 2 ( Adema, 2004 ). In contrast to geologic processes that operate on time scales on the order of thousands or even millions of years, significant glacier change can occur within a human lifetime. The dynamic nature of glaciers strongly influences the hydrologic, geologic, and ecological systems in the environments in which they exist. Additionally, the sensitive and dynamic response to changes in temperature and precipitation make glaciers excellent indicators of regional and global climate change ( Riedel and Burrows, 2005 ). Long-term monitoring of glacier change is important because it provides basic data for understanding and assessing past, current, and possible future conditions of the local, regional, and global environment. A basic understanding of local and regional environmental systems is critical for responsible land management and decision-making.

Gastropods are described from Ludlow-age strata of the Heceta Limestone on Prince of Wales Island, southeast Alaska. They are part of a diverse megabenthic fauna of the Alexander terrane, an accreted terrane of Siberian or Uralian affinities. Heceta Limestone gastropods with Uralian affinities include Kirkospira glacialis , which closely resembles “ Pleurotomaria ” lindströmi Oehlert of Chernyshev, 1893 , Retispira cf. R. volgulica ( Chernyshev, 1893 ), and Medfracaulus turriformis ( Chernyshev, 1893 ). Medfracaulus and similar morphotypes such as Coelocaulus karlae are unknown from rocks that are unquestionably part of the North American continent (Laurentia) during Late Silurian time. Beraunia is previously known only from the Silurian of Bohemia. Pachystrophia has previously been reported only from western North American terranes (Eastern Klamath, York, and Farewell terranes) and Europe. Bathmopterus Kirk, 1928 , is resurrected and is only known from the Silurian of southeast Alaska. Newly described taxa include Hecetastoma gehrelsi n. gen. and n. sp. and Baichtalia tongassensis n. gen. and n. sp.

The Heceta Formation of southeastern Alaska (Alexander terrane) comprises a 3000-m-thick limestone-siliciclastic deposit of Early–Late Silurian age. The limestones record the first widespread evidence of carbonate platform development in this ancient island arc. Interbedded polymictic conglomerates represent interruption in platform evolution during onset of the Klakas orogeny, an arc-continent collisional event that occurred in the Late Silurian–Early Devonian. Conglomerates grade upward into finer-grained siliciclastics capped by shallow-marine limestones in sequences that are 200–300 m thick. Clasts range in diameter from 2 to 30 cm, are subangular to well rounded, poorly to moderately sorted, and densely packed in disorganized, poorly stratified beds. Most of the clasts are volcanic (basaltic-andesitic), but limestone clasts predominate in some sections; rare fragments of volcaniclastic, plutonic, and indeterminate rocks also occur. Clast compositions match the lithology of rocks in the underlying Heceta and Descon formations, and sedimentary attributes indicate redeposition of recycled material by debris flows and rivers in a coastal alluvial fan complex. This evidence—together with affinities of marine fossils, paleomagnetic and detrital zircon data, associated Old Red Sandstone-like facies, and coincidence in timing of tectonism—suggests the Klakas orogeny was a Caledonide event that is manifest in Alaska's Alexander terrane.

Study of Late Triassic biofacies and associated paleoecology reveals new silicified shallow-water corals and other fossils from new and previously known localities within the Alexander terrane (Keku Strait and Gravina Island, southeast Alaska) and Wrangellia (Wrangell Mountains, Alaska, and Vancouver Island, British Columbia). Twenty-five species of coral are identified from eight localities within the Alexander terrane and 34 species are identified from four localities in Wrangellia. Distributions of silicified shallow-water marine fossils contribute to Late Triassic (Norian–Rhaetian) paleoecology, biotic diversity, and terrane paleogeography. Depositional environments establish the conditions in which these organisms lived as well as provide evidence for lithological correlation between tectonically separate fragments. This study also confirms the presence of biostrome reef buildups in the southern Alexander terrane (Gravina Island), indicating warm, clear, and nutrient-free water with lots of sunlight; this differs from the central Alexander terrane (Keku Strait) and northern Wrangellia (Wrangell Mountains), where corals grow as individual colonies, not in a structured, reef-like buildup, and are accompanied by filter- and detritus-feeding organisms indicating warm, cloudy and nutrient-rich water in a back-reef environment. Paleobiogeographic results from silicified Upper Triassic corals show faunal similarity between Gravina Island and Keku Strait (Alexander terrane) and no similarity between northern and southern Wrangellia. Likewise, no similarity was found between the Alexander terrane and either northern or southern Wrangellia.

Upper Triassic rocks in the Keku Strait area of southeast Alaska record a variety of facies in an intra-arc setting. The Hyd Group consists of the Burnt Island Conglomerate, Keku sedimentary strata, Cornwallis Limestone, Hamilton Island Limestone, and the Hound Island Volcanics. The Burnt Island Conglomerate represents initial infill of the basin and underlies the Hamilton Island Limestone, which is coeval with the Cornwallis Limestone and Keku sedimentary strata. Volcanic and sedimentary rocks of the Hound Island Volcanics overlie the entire area. An improved biostratigraphic framework indicates deposition from early Carnian through late Norian time. Conodonts originating in the late Carnian include Metapolygnathus polygnathiformis , Metapolygnathus carpathicus , Metapolygnathus nodosus , Metapolygnathus sp. cf. M. reversus , Metapolygnathus sp. aff. M. zoae , Metapolygnathus sp. aff. M. nodosus , and Metapolygnathus primitius . Early Norian conodonts include Epigondolella quadrata , Epigondolella triangularis , Epigondolella sp. aff. E. triangularis , and the longer-ranging Neogondolella sp. and Misikella longidentata . Middle Norian conodonts include Epigondolella spiculata , Epigondolella transitia , Epigondolella matthewi , Epigondolella postera , and Neogondolella steinbergensis . Late Norian conodonts include Epigondolella bidentata , Epigondolella englandi , Epigondolella sp. aff. E. mosheri , and Epigondolella tozeri . This study resulted in three major accomplishments. Reworked Paleozoic conodonts in Upper Triassic rocks, combined with geologic evidence, suggest major preLate Triassic uplift due to compressional tectonics. Late Carnian and early Norian ages support the correlation between the Keku sedimentary strata, shallow-marine limestone of the Cornwallis Limestone, and deeper-water limestone of the Hamilton Island Limestone. Precise conodont biostratigraphy establishes the base of the Hound Island Volcanics as late early Norian, within the Epigondolella triangularis Zone.