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High-resolution topographic modeling has become more accessible due to the development of structure from motion (SfM)-image-matching algorithms in digital photogrammetry. Large archival databases of historical aerial photographs are available in university, public, and government libraries, commonly as paper copies. The photographs can be in poor condition (i.e., deformed by humidity, scratched, or annotated). In addition, the negatives, as well as metadata, may be missing. Processing such photographs using classic stereo-photogrammetry is difficult and, in many instances, impossible. SfM can be applied to these photosets to access the valuable archive of geomorphic changes over the past century. In this paper, we illustrate the utility of the SfM technique using 568 digitized vertical aerial photographs of Mount Meager volcano, located in southwestern British Columbia, Canada. We use the aerial photographs, which span the period from 1947 to 2006, to track glaciers and glacier–landslide interactions on the volcano. Over this period, glaciers have thinned and retreated, interrupted by minor advances in the 1960s and 1970s. Landslides are frequent on the volcano and contribute to debris cover on the glaciers affecting the ablation process. SfM processing of the aerial photographs allowed us to unlock geomorphic information and reconstruct landscape change that would otherwise have been impossible. The results from SfM provide a visually effective way of presenting landscape change to a broad public audience, as a form of virtual geoheritage. The approach can thus be broadly applied in scientific and professional practices for improving land planning and hazard management. [ABSTRACT FROM AUTHOR]

Cryoplanation terraces (CTs) are large (3000–800 000 m2) erosional landforms found in upland periglacial environments. Two hypotheses for the formation of CTs are supported in contemporary literature: (1) CT formation is controlled primarily by geologic structure; and (2) CTs are climatically controlled through nivation, a suite of erosional processes associated with late-lying snowbanks. A persistent question in periglacial geomorphology is whether nivation can produce CT-scale landforms. This paper examines the unusual deglaciation history of "Frost Ridge" on the Cathedral Massif, northwestern British Columbia, to estimate long-term denudation attributable to nivation processes active since the last glacial maximum. Frost Ridge forms one flank of an east–west-oriented glacial valley. During deglaciation, marginal drainage created V-shaped erosional notches on both valley walls. Minimization of solar radiation on the steep north-facing wall (Frost Ridge) allowed snowbanks to accumulate and persist in the marginal drainage features and nivation processes to erode the slope. Today, several large nivation hollows (incipient CTs) are present near the summit of Frost Ridge, while the V-shaped marginal drainage features are preserved at lower elevations and on the opposite, south-facing valley wall. A high-resolution survey using an unmanned aerial vehicle (UAV) allowed volumes of marginal drainage and incipient terrace features to be compared. Based on this volumetric comparison, denudation rates are estimated to range from 4.2 to 125.8 mm/kyr, which are comparable with relatively short-term nivation rates reported from Antarctica and mid-latitude alpine periglacial areas. [ABSTRACT FROM AUTHOR]

The southeastern Omineca Belt of the Canadian Cordillera preserves a record of overlapping Barrovian and Buchan metamorphism spanning 180-50 Ma. This paper documents the timing, character, and spatial relationships that define separate domains of Middle Jurassic, Early Cretaceous, and Late Cretaceous deformation and metamorphism, and the nature of the geological interfaces that exist between them. A domain of Early Jurassic deformation (D1) and regional greenschist-facies metamorphism (M1) is cross-cut by Middle Jurassic (174-161 Ma) intrusions. Associated contact aureoles are divided into lower pressure (cordierite-dominated; ∼2.5-3.3 kbar; 1 kbar = 100 MPa) and higher pressure (staurolite-bearing; 3.5-4.2 kbar) subtypes; contact metamorphic kyanite occurs rarely in some staurolite-bearing aureoles. Jurassic structures are progressively overprinted northwards by Early Cretaceous deformation and metamorphism (D2M2), manifested in a tightening of Jurassic structures, development of more pervasive ductile fabrics, and Barrovian metamorphism. The D2M2 domain is the southerly continuation of the 600 km long Selkirk-Monashee-Cariboo metamorphic belt. Mid-Cretaceous intrusions (118-90 Ma) were emplaced throughout the D2M2 domain, the earliest of which contain D2 fabrics, but cut M2 isograds. The D2M2 domain makes a continuous, southeasterly transition into a domain of Late Cretaceous regional Barrovian metamorphism and deformation (D3M3; 94-76 Ma). The interface between these two domains is obscured by the coaxial nature of the deformation and the apparent continuity of the metamorphic zones, resulting in a complex and cryptic interface. Similarities between the D3M3 domain and the Selkirk Crest of Idaho and Washington suggest that this domain is the northerly continuation of the northward-plunging Priest River Complex. [ABSTRACT FROM AUTHOR]

Infestation by the mountain pine beetle, Dendroctonus ponderosae, decimated the forests of central British Columbia from 1999 to 2012, severely impacting the forest industry of the Nechako-Chilcotin plateau. In response, all levels of government recognized the value in developing other areas of economic activity, such as hydrocarbon and mineral exploitation, to support local economies. Exploration for resources beneath the Nechako-Chilcotin plateau has historically been constrained by Tertiary volcanic sequences and Quaternary glacial deposits that obscure the underlying geology and limit geophysical imaging. Thus, a coordinated program comprising additional geological mapping, borehole data analysis, and modern geophysical surveys of the area was initiated in 2006, with the objective of better defining the subsurface geology, solving problems of imaging through the complex near-surface, and developing improved regional geological and tectonic models. An initial set of papers arising from this fieldwork, which focused on issues relevant to mineral and hydrocarbon exploration, was published in June 2011 in a Special Issue of the Canadian Journal of Earth Sciences. This Introduction to the second 'Mountain Pine Beetle' Special Issue summarizes a set of scientific papers that focus on topics more related to hydrocarbon exploration and the large-scale structure of the crust. The papers deal with the development, thickness, and present distribution of the most prospective Cretaceous sedimentary rocks, as well as characterizing the physical properties of the near-surface volcanic units. [ABSTRACT FROM AUTHOR]

Mineral and petroleum exploration in the Cariboo-Chilcotin region of British Columbia is hampered by widespread and extensive cover of Pleistocene glacial deposits and Tertiary volcanic successions. Seeing through this geological cover is critical to reducing exploration risk and enhancing exploration activity. Also critical to exploration is effective community engagement, hopefully resulting in endorsement and support for exploration initiatives. The forests in the Cariboo-Chilcotin region have been extensively destroyed by an infestation of the mountain pine beetle, , disrupting established communities and greatly affecting economic activity in the region. Governments of all levels recognized that geological exploration activity could provide a ready and appreciable stimulus to economic activity, but only if local communities endorsed such programs. Relatively little oil and gas exploration and research has taken place in the region, and its effects have been poorly understood locally. Consequently, an extended effort was undertaken to establish an integrated geoscience program for the Cariboo-Chilcotin region, focused on mineral and petroleum exploration-related research and coupled with engagement with local communities to inform them of exploration benefits and risks. This Introduction to the 'Mountain Pine Beetle' Special Issue of Canadian Journal of Earth Sciences provides a brief overview of the scientific papers included in the issue and also a review of the community engagement process that was undertaken to establish working relationships with First Nations and other communities in the region. [ABSTRACT FROM AUTHOR]

The south-central Intermontane belt of British Columbia has a complex architecture comprising late Paleozoic to Mesozoic volcanic and plutonic arc magmatic suites, marine and nonmarine clastic basins, high-grade metamorphic complexes, and accretionary rocks. Jurassic and Cretaceous clastic basins within this framework contain stratigraphy with hydrocarbon potential. The geology is complicated by Cretaceous to Eocene deformation, dismemberment, and dislocation. The Eocene to Neogene history of the southern Intermontane belt is dominated by non-arc volcanism, followed by Pleistocene to Recent glaciation. The volcanic and glacial cover makes this a difficult region to explore for resources. Much recent work has involved re-evaluating the challenges that the overlying volcanic cover has historically presented to geophysical imaging of the sedimentary rocks in this region in light of technological advances in geophysical data collection and analysis. This paper summarizes the lithological and stratigraphic framework of the region, with emphasis on description of the sedimentary units that have been the targets of hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

A giant short-faced bear (Arctodus simus) ulna fragment was found at the base of exposed Quaternary sediments at Cowichan Head, southern Vancouver Island, British Columbia. In this paper, the ulna fragment and its geological context are described and a reasonable taphonomic trajectory is presented. The radiocarbon age of 22 750 ±140 BP on the bone indicates that these bears were on Vancouver Island during the late Wisconsinan. A likely source for the Cowichan Head A. simus was from the mainland to the southeast. [ABSTRACT FROM AUTHOR]

During the decay of the Cordilleran Ice Sheet 10 000 – 13 000 BP, glacial lakes developed within valleys that dissect the Interior Plateau of British Columbia. In this paper, we (1) illustrate a procedure for assessing paleo water planes that has general application, (2) document lake paleogeography and evolution in the Thompson Valley, (3) provide new data on the glacio-isostatic response of the central Cordillera, and (4) present new evidence of its late-glacial environment. We employ geomorphology and sedimentology, digital elevation models, and new technologies (differential global positioning systems, ground penetrating radar, and geographic information systems) to refine paleogeographic reconstructions of glacial lakes. Glacial Lake Thompson and Glacial Lake Deadman were ribbon-shaped (width to length ratio ≈ 3:100), deep (>>140 to ~50 m) lakes that contained significant water volumes (84–24 km3). They lengthened to the west and their water level lowered as ice decayed. Final ice dam failure resulted in an ~20 km3 jökulhlaup that eroded bedforms and deposited flood eddy bars within the lake basin, travelled ~250 km along the Fraser River system, and may have deposited exotic mud offshore between 10 190 and 11 940 BP. Glacio-isostatic tilts of water planes are among the highest in the world (1.7–1.8 m km–1). Their orientations suggest that ice sheet loads were greater or longer- lived to the north-northwest of the study area, lending support to the notion of an ice divide centred on the Fraser Plateau. [ABSTRACT FROM AUTHOR]

Holocene lateral moraines in the Coast Mountains of British Columbia are commonly composed of multiple drift units related to several glacier advances. In this paper, we document lateral moraine stratigraphy at Lillooet Glacier in the southern Coast Mountains. Five tills, separated by laterally extensive paleosols and layers of large woody debris, were found in three cross-sectional exposures through the northeast lateral moraine and two shallow gullies incised into its steep proximal face. Eighteen new radiocarbon ages constrain the timing of five separate advances of Lillooet Glacier: (1) prior to 3000 14C years BP; (2) ~3000 14C years BP; (3) ~2500 14C years BP; (4) ~1700 to 1400 14C years BP; and (5) during the Little Ice Age (LIA), after 470 14C years BP. The Lillooet Glacier chronology is broadly synchronous with other glacier records from the Coast Mountains. These records collectively demonstrate climate variability at higher frequencies during the late Holocene than is apparent from many paleoecological reconstructions. Reconstructions of glacier fluctuations are often hampered by poor preservation of landforms that predate the extensive LIA advances of the latest Holocene. Our results highlight the potential of lateral moraine stratigraphy for reconstructing these earlier events. [ABSTRACT FROM AUTHOR]

New bedrock mapping completed as part of the Nechako NATMAP Project indicates that the area between Babine and Takla lakes in central British Columbia is underlain by rocks of the Early Permian Asitka, Late Triassic Takla, and Early to Middle Jurassic Hazelton volcanic-arc assemblages of the Stikine Terrane. These are cut by large composite stocks of quartz diorite, granodiorite, and quartz monzonite previously mapped as the Late Triassic to Early Jurassic Topley intrusions. New U/Pb (n = 6) and laser [sup 40] Ar/[sup 39] Ar (n = 10) isotopic age dates reported in this paper suggest there are two distinct ages of plutons: the Topley intrusive suite with isotopic ages between 218 and 193 Ma; and, east of Babine Lake, the new Spike Peak intrusive suite with isotopic ages ranging from 179 to 166 Ma. West of the main plutonic belt is a thick volcanic succession of subaerial, porphyritic andesite flows, volcanic breccias, and rhyolitic ash-flow tuffs that have isotopic ages between 185 and 174 Ma. These rocks are assigned to the Saddle Hill Formation of the Hazelton Group. The plutonic roots of this proximal arc assemblage are most likely the coeval and compositionally similar plutons of the Spike Peak intrusive suite that have been unroofed in the area east of the Takla Fault. Major oxide and trace element data support the interpretation that the Topley and Spike Peak granitic rocks formed in a juvenile volcanic-arc environment and that magmatism is related to melts generated above a long-lived subduction zone of unknown orientation.Une nouvelle cartographie effectuée dans le cadre du projet NATMAP Nechako indique que la région entre les lacs Babine et Takla au centre de la Colombie-Britannique est recouverte de roches des assemblages d'arcs volcaniques du terrane de Stikine, soit Asitka du Permien précoce, Takla du Trias tardif et Hazelton du Jurassique précoce à moyen. Ces assemblages sont recoupés par des petits massifs intrusifs composites de diorite quartzique, de granodiorite et de monzonite quartzique qui avaient auparavant été cartographiés en tant que les intrusions Topley, du Trias tardif au Jurassique précoce. De nouvelles datations U-Pb (n = 6) et isotopes laser [sup 40] Ar/[sup 39] Ar (n = 10) présentées dans cet article suggèrent deux âges distincts de plutons, soit la suite intrusive de Topley avec des âges isotopiques entre 218 et 193 Ma et, à l'est du lac Babine, la nouvelle suite intrusive de Spike Peak dont les âges isotopiques varient de 179 à 166 Ma. À l'ouest de la ceinture plutonique principale se trouve une séquence volcanique épaisse d'écoulements subaériens d'andésite porphyrique, des brèches volcanique et des tufs d'écoulement de cendre rhyolitique dont les âges isotopiques varient entre 185 et 174 Ma. Ces roches sont assignées à la Formation de Saddle Hill du Groupe Hazelton. Les racines plutoniques de cet assemblage d'arc proximal sont fort probablement les plutons contemporains et à composition similaire de la suite intrusive de Spike Peak qui ont été décapés dans la région à l'est de la faille de Takla. Les données sur les principaux oxydes et les éléments traces corroborent l'interprétation que les roches granitiques de Topley et de Spike Peak se sont formées dans un environnement d'arc volcanique juvénile et que le magmatisme est relié aux fusions qui se sont produites au-dessus d'une ligne de subduction de longue durée mais dont l'orientation est inconnue.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

This special issue reports on some of the results of a multi-disciplinary research program conducted in the Boreal Plains of northwest Alberta and northeast British Columbia. Several innovative approaches to conducting geoscientific research in this remote drift-covered region are presented, including geochemical analysis of bentonites for evaluating kimberlite potential, the use of electromagnetic surveys for mapping buried aggregate deposits, and paleo-topographic mapping techniques to define buried channels. Results of the program include the discovery of several large aggregate deposits, the first kimberlite indicator minerals in northeast British Columbia, a significant sphalerite dispersal train in northwest Alberta, the first documented report of kimberlite-sourced bentonites, and numerous previously unknown interglacial sites. Together these papers provide a greatly enhanced understanding of the glacial history, Quaternary stratigraphy, and kimberlite geology of northwest Alberta and northeast British Columbia and provide an improved framework for resource exploration in the region. Ce numéro spécial fait le point sur quelques résultats d’un programme de recherche multidisciplinaire effectué dans les plaines boréales du nord-ouest de l’Alberta et du nord-est de la Colombie-Britannique. Plusieurs approches innovatrices de recherche géoscientifique dans cette région éloignée recouverte de sédiments glaciaires sont présentées, incluant l’analyse géochimique des bentonites pour l’évaluation du potentiel kimberlitique, l’utilisation de relevés électromagnétiques pour cartographier des dépôts enfouis d’agrégats et des techniques de cartographie paléotopographique dans le but de définir des chenaux enfouis. Les résultats du programme comprennent la découverte de plusieurs grands dépôts d’agrégats, des premiers minéraux indicateurs de kimberlite dans le nord-est de la Colombie-Britannique, une traînée importante de dispersion glaciaire de sphalérite dans le nord-ouest de l’Alberta, la première documentation de bentonites dont la source est une kimberlite et de nombreux sites interglaciaires inconnus à ce jour. Ensemble, ces articles fournissent une bien meilleure compréhension de l’historique glaciaire, de la stratigraphie du Quaternaire et de la géologie des kimberlites dans le nord-ouest de l’Alberta et le nord-est de la Colombie-Britannique; ils fournissent aussi un meilleur encadrement d’exploration pour les ressources dans cette région. [ABSTRACT FROM AUTHOR]