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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]

This paper proposes an updated approach to incorporating relative sea level rise in the estimation of flood construction levels in British Columbia, which are required in coastal planning and infrastructure development. Initially, current guidelines for British Columbia are outlined, and recent information on projected relative sea level rise is summarized. Then, recognizing the uncertainty in sea level rise projections, a probabilistic model of estimating the contribution of relative sea level rise to the flood construction level is described, relying on an available theoretical formulation that is corroborated by the application of a Monte Carlo simulation method. An updated approach to incorporating relative sea level rise in the estimation of flood construction levels is thereby recommended, relying on available data portals for relative sea level rise. Finally, the estimation of the probability of overtopping is described, and the implications of this for making informed decisions on flood construction levels with respect to risk assessments are indicated. [ABSTRACT FROM AUTHOR]

Controlling air leakage through the building envelope remains a challenge, especially in light of the imperative to transition to a net-zero energy building sector and the increasing importance of indoor air quality during extreme weather events such as wildfires. The British Columbia Energy Step Code is a performance-based compliance option in the British Columbia Building Code which is intended to provide a transition pathway to net-zero energy ready construction by 2032. For small residential buildings, performance targets entail thresholds for the measured air leakage rate through the building envelope. This paper reports on the airtightness of the first 145 single- and two-family dwellings built under the Energy Step Code in Richmond, BC. Although the first phase of the implementation of the Energy Step Code in Richmond entailed no airtightness targets (only testing), results indicate improvement compared to the historical levels of airtightness in the region. [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]

The discharge and stage measurements in a river system are characterized by a number of sources of uncertainty, which affects the accuracy of a rating curve established from measurements. This paper presents a fuzzy set theory based methodology for consideration of different sources of uncertainty in the stage and discharge measurements and their aggregation into a combined uncertainty. The uncertainty in individual measurements of stage and discharge is represented using triangular fuzzy numbers, and their spread is determined according to the International Organization for Standardization (ISO) standard 748 guidelines. The extension principle based fuzzy arithmetic is used for the aggregation of various uncertainties into overall stage-discharge measurement uncertainty. In addition, a fuzzified form of ISO 748 formulation is used for the calculation of combined uncertainty and comparison with the fuzzy aggregation method. The methodology developed in this paper is illustrated with a case study of the Thompson River near Spences Bridge in British Columbia, Canada. The results of the case study show that the selection of number of velocity measurement points on a vertical is the largest source of uncertainty in discharge measurement. An increase in the number of velocity measurement points provides the most effective reduction in the overall uncertainty. The next most important source of uncertainty for the case study location is the number of verticals used for velocity measurements. The study also shows that fuzzy set theory provides a suitable methodology for the uncertainty analysis of stage-discharge measurements. [ABSTRACT FROM AUTHOR]

This paper evaluates the comparative and absolute in-plane seismic performance of rainscreen and nonrainscreen stucco exterior cladding systems for residential wood frame construction in British Columbia. In this study, an experimental program including quasi-static and dynamic tests was implemented, comprised of 18 (in-plane) quasi-static tests and two dynamic tests. The principal parameters investigated in this study were type of strapping, type and length of strapping fastener, and type and length of lath fastener. All rainscreen specimens were constructed with a 20 mm air space. The overall conclusion is that both rainscreen and nonrainscreen stucco comply with the code requirements addressing the permissible drifts. Therefore, both stucco systems were found to improve the structural behaviour when used as the lateral resisting system of residential wood frame buildings. This paper concludes with recommendations for seismic refinements to current construction practices. [ABSTRACT FROM AUTHOR]

Accident prediction models are invaluable tools that have many applications in road safety analysis. However, there are certain statistical issues related to accident modeling that either deserve further attention or have not been dealt with adequately in the road safety literature. This paper discusses and illustrates how to deal with two statistical issues related to modeling accidents using Poisson and negative binomial regression. The first issue is that of model building or deciding which explanatory variables to include in an accident prediction model. The study differentiates between applications for which it is advisable to avoid model over-fitting and other applications for which it is desirable to fit the model to the data as closely as possible. It then suggests procedures for developing parsimonious models, i.e., models that are not over-fitted, and best-fit models. The second issue discussed in the paper is that of outlier analysis. The study suggests a procedure for the identification and exclusion of extremely influential outliers from the development of Poisson and negative binomial regression models. The procedures suggested for model building and conducting outlier analysis are more straightforward to apply in the case of Poisson regression models because of an added complexity presented by the shape parameter of the negative binomial distribution. The paper, therefore, presents flowcharts detailing the application of the procedures when modeling is carried out using negative binomial regression. The described procedures are then applied in the development of negative binomial accident prediction models for the urban arterials of the cities of Vancouver and Richmond located in the province of British Columbia, Canada. [ABSTRACT FROM AUTHOR]

This paper presents a study describing the effect of various hydrological variables in stochastic dynamic programming (SDP) for solving the optimization problem of managing a hydropower system. We will show how choosing the best hydrological variables can strongly affect management policies. This is especially true for the system studied here, namely the Kemano hydroelectric system located in British Columbia, Canada, which is subject to large streamflow volumes due to significant snow cover during winter. Real-time snow water equivalent (SWE) data can be used directly as a variable in SDP management policies. Results indicate that for the system in this study, the maximum SWE (i.e., highest level of SWE observed from the start of winter to the current decision period) is the best among the methods investigated for effective, safe management, compared with Markov or order p autoregressive models when forecasts are not available. [ABSTRACT FROM AUTHOR]

Expansion and densification of urbanized areas can lead to increased pressure on an area's water and wastewater infrastructure. This paper presents an optimization model using geographic information systems to locate potential sources and sinks of reclaimed water within an urbanized area. A mathematical solver then maximizes the water reuse using a set of constraints on mass balance, water quality, and electricity used for pumping. Three variations of the model are applied to Vancouver, British Columbia. The first scenario identifies a number of potential industrial sources and sinks for direct cascading with a total potential water savings of 133 400 m3/year. With the implementation of a satellite water reclamation facility in scenario 2, water recycling potential is increased to a maximum of 613 800 m3/year. Scenario 3 expands to include the non-industrial water users and the potential for water reuse is increased to a maximum of 969 200 m3/year. [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]

This paper describes a study of the seismic behaviour of taller eccentrically braced frames (EBFs). Chevron-type EBFs with shear-critical links are designed for 14-, 20-, and 25-storey buildings in Montreal and Vancouver. For each location the importance of different design criteria is discussed and an appropriate design sequence is proposed. It was found that ductility requirements did not control design. For Vancouver, buildings member selection was mostly influenced by the inelastic inter-storey drift requirements whereas for Montreal ensuring the global frame stability was critical. The seismic response of these frames to the sets of earthquake records calibrated to match design spectra is described. The seismic performance for Vancouver frames was found to be adequate, except that in the upper storeys the inelastic link deformations and shear forces exceeded values anticipated in design. For the Montreal structures, all global and local response indicators remained well below the design limits. [ABSTRACT FROM AUTHOR]

Canadian Wooden Dome (CWD) is an innovative orthotropic, monolithic modular sectional building system. The main frame of these structures is built using mill trim ends that are normally chipped or used for finger-jointing. The structure, in comparison to conventional wood-frame single-family housing, has a rapid manufacturing process, and quick, on-site assembly attempts to reduce overall construction time. Presented with these advantages and the uniqueness of the wooden-dome system, a technical study was initiated to investigate the structural performance of the modular wooden dome in earthquake-prone areas and to examine its load resistance to heavy snow. This paper describes the results from a series of static and dynamic load tests conducted on the CWD as part of this study. The test results generally indicated that based on the structural performance of the CWD under static and dynamic loads, the CWD could be an alternative to the conventional wood-frame construction system. The test results are then compared with those obtained from the tests conducted on conventional single-family wood-frame houses as part of the Earthquake 99 (EQ-99) Woodframe House Project at The University of British Columbia. The seismic performance of the CWD was superior to that of the nonengineered housing system and comparable to that of the engineered wood-frame housing system. Le système de construction « Canadian Wooden Domes (CWD) » est un système modulaire novateur de construction sectionnelle, monolithique et orthotrope. Le cadre principal de ces structures est bâti en utilisant des éboutures qui sont normalement mises en copeaux ou utilisées pour des aboutages. La structure, par rapport à celle des maisons unifamiliales conventionnelles à ossature de bois, se fabrique rapidement et l’assemblage rapide sur le site tend à diminuer le temps de construction global. En tenant compte de ces avantages, une étude technique a été lancée pour examiner le rendement de cette structure unique de dôme en bois modulaire dans les zones sujettes aux séismes et sa résistance à une charge de neige abondante. Le présent article décrit les résultats d’une série d’essais en charge statique et dynamique effectués sur les dômes en bois dans le cadre de cette étude. En se basant sur le rendement structural de ces dômes en bois sous des charges statiques et dynamiques, les résultats indiquent généralement que les dômes en bois pourraient être une solution de remplacement au système traditionnel de construction à ossature de bois. Ces résultats ont ensuite été comparés à ceux obtenus lors d’essais effectués sur des maisons unifamiliales à ossature de bois traditionnelles dans le cadre du projet « Earthquake 99 Woodframe House Project » réalisé antérieurement à l’Université de la Colombie-Britannique. Par rapport aux structures à ossature de bois traditionnellement mises à l’épreuve, le dôme en bois présentait un rendement sismique supérieur à celui des systèmes non techniques et un rendement sismique similaire à celui des systèmes techniques à ossature de bois. [ABSTRACT FROM AUTHOR]

This paper presents a comparison of the two main regional damage estimation methodologies currently in use, namely the modified Mercalli intensity (MMI) based approach and the spectral parameter based approach. In the first methodology, expected damage is related to ground shaking intensity in terms of MMI through damage probability matrices. In the second methodology, the ground motion intensity is described in terms of spectral acceleration (SA), and building response in terms of spectral displacement (SD). Both methodologies were applied to buildings in Vancouver of three different construction types: single-family wood-frame houses, low-rise unreinforced masonry buildings, and high-rise concrete frame structures with concrete shear walls. The two methodologies predict damage that lies in the same general damage categories of light and moderate, which are defined by fairly broad ranges in mean damage factors. The specific mean damage factors predicted by the two methods for a given location are significantly different, however. The significant differences in mean damage factors imply significant differences in damage costs and hence in seismic risk. [ABSTRACT FROM AUTHOR]

This paper presents the results of regional seismic risk assessment studies that were carried out for two cities in southwestern British Columbia, Vancouver and Victoria. Ground shaking intensity in the area was obtained using the seismic source zones delineated by the Geological Survey of Canada for a probability level of 10% chance of exceedance in 50 years. Building inventories were compiled by aggregating data from sidewalk surveys as well as municipal databases. Modified Mercalli intensity-based damage matrices that relate the level of ground shaking to the amount of damage expected in different types of structures were used to estimate damage to structural and non-structural components of buildings. Estimated damage and loss distributions were mapped on a block-by-block basis. The historic sections of the cities were estimated to have damage levels between 10% and 30% of the replacement cost, while in the rest of the cities the estimated damage was generally in the 5% to 10% range. The results show the estimated economic loss distribution is considerably different from the damage distribution. Although the older neighbourhoods of the cities are expected to suffer highest amount of damage, the highest amount of economic loss is estimated to occur in areas with concentration of concrete high-rise buildings. [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]

The paper presents the results of laboratory triaxial compression tests to study the stiffness of very loose Fraser River sands. The stiffness has been shown to be very dependent on the time of confinement prior to shearing and the stress ratio at which the sample is aged. Higher stress ratios resulted in very low initial moduli with no ageing, but the moduli increased by several hundred percent during the first 1000 min of ageing. For ageing at a stress ratio of 1.0 (i.e., isotropic ageing), the initial moduli were higher than those for ageing at high stress ratios, but the stiffness increased by only about 60% during the first 1000 min of ageing. The rate of stiffness increase was approximately linear with the logarithm of time up to ageing times of 10 000 min (>1 week). Ageing at any stress ratio resulted in reduced contractive volumetric strain during subsequent shearing, reflecting a change in soil structure during ageing. The dℇ[sub v] /dℇ[sub a] ratio under triaxial compression loading decreased as the ageing stress ratio increased. The results suggest that close attention must be paid to the age of laboratory samples prepared to study the stress–strain response of sands at strains up to about 0.1%, particularly in studies on loose sand.Key words: sands, ageing, creep, modulus.Cet article présente les résultats d'un programme d'essais en laboratoire pour étudier la rigidité de sables très lâches du fleuve Fraser au moyen d'essais de compression triaxiale. On a montré que la rigidité était très dépendante du temps de confinement antérieur au cisaillement et du rapport des contraintes sous lequel l'échantillon a vieilli. Des rapports de contraintes plus élevés ont donné des modules initiaux très faibles sans vieillissement, mais les modules ont augmenté de plusieurs 100 % au cours des mille premières minutes de vieillissement. Sous un vieillissement isotrope, les modules initiaux étaient plus élevés que pour des rapports de contraintes plus élevés mais la rigidité a augmenté de seulement environ 60 % durant les 1000 premières minutes de vieillissement. La vitesse d'augmentation de la rigidité était approximativement linéaire en fonction du logarithme du temps jusqu'à des temps de vieillissement de 10 000 minutes (>1 semaine). Le vieillissement sous n'importe quel rapport de contraintes a donné des déformations volumétriques de contraction réduites durant le cisaillement subséquent, ce qui indiquait un changement dans la structure du sol durant le vieillissement. Le rapport dℇ[sub v] /dℇ[sub a] sous chargement triaxial en compression a diminué lorsque le rapport de contraintes de vieillissement augmentait. Les résultats suggèrent que l'on doit porter un attention particulière à l'âge des échantillons préparés en laboratoire pour étudier la réponse contrainte-déformation des sables jusqu'à des déformations de 0,1 %, particulièrement dans les études sur le sable lâche.Mots clés : sables, vieillissement, fluage, module.[Traduit par la Rédaction] [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]

Current methodologies for estimating the number of waste sorts require prior information on statistics (mean and standard deviation) for specific waste categories. The methods often require an iterative procedure or computer software to estimate the number of sorts required and the required statistics may change both spatially and temporally. To overcome the need for prior statistical information and avoid the need for iterative effort, a real-time methodology is developed to determine the required number of waste sorts for a waste category while sampling in the field for solid waste characterization. The information on required numbers of waste sorts is field-based and evolves during the sampling by utilizing real-time data to characterize the means and standard deviations. The proposed approach does not require prior information. The application of proposed methodology is demonstrated using the data from the Greater Vancouver Regional District (GVRD) for the primary categories of paper, glass, and secondary category glass-beverage. [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]

This paper synthesizes data extracted from the literature and data collected in various studies by the author on the quantity, characteristics, and functional importance of coarse woody debris (CWD) in the old-growth forests of British Columbia (B.C.). There is little agreement in the literature about the minimum diameter of CWD or the number of decay classes recognized. In western North America, five decay classes are commonly used, but recent studies suggest fewer decay classes are preferable. Comparisons among decay classes and biogeoclimatic zones and subzones in B.C. reveal that quantities and volumes are greatest (up to approximately 60 kg/m[sup 2] and approximately 1800 m[sup 3] /ha, respectively), and CWD persists the longest (sometimes in excess of 1000 years) in the Coastal Western Hemlock (CWH) biogeoclimatic zone. The quantity and ground cover of CWD increase with forest productivity. Persistence of CWD has varied from less than 100 to over 800 years in two coastal (CWH and Mountain Hemlock (MH)) and three interior (Interior Douglas-fir (IDF), Interior Cedar–Hemlock (ICH), and Engelmann Spruce – Subalpine Fir (ESSF)) biogeoclimatic zones. Trends in CWD quantity with forest age in managed coastal B.C. forests suggest a U-shaped curve, with greater quantities occurring in recent cutovers than in old-growth forests, and lowest quantities occurring in middle-aged forests. This may be the normal trend in CWD with forest age, with departures from this trend resulting from disturbance- or environment-specific factors. Relatively large amounts of data exist on the characteristics of CWD in the CWH, IDF, ICH, ESSF, and Boreal White and Black Spruce (BWBS) biogeoclimatic zones, but such data for the Coastal Douglas-fir, Sub-Boreal Pine–Spruce, Sub-Boreal Spruce (SBS), and Spruce–Willow–Birch biogeoclimatic zones appear relatively sparse. There have been few studies of the functional role of CWD in B.C. forests, but those studies that have been completed indicate that CWD is an important habitat component for some plant and animal species. A total of 169 plant species, including >95% of all lichens and liverworts, were found to grow on CWD in old-growth forests in the CWH, MH, IDF, ICH, and ESSF biogeoclimatic zones. One third of these species were restricted to CWD. Studies in several biogeoclimatic zones have found that CWD provided preferred habitat for and was associated with higher populations of some small animal species, such as shrews, some voles, and some salamanders, in old-growth forests, but the effects varied with species and biogeoclimatic zone. The nutrient cycling role of CWD is not yet well known, but it currently appears to be relatively insignificant in B.C. old-growth forests. Although it has been considered that CWD could increase mineral soil acidification and eluviation, no evidence for this was found in a study of the CWH, MH, IDF, ICH, ESSF, BWBS, and SBS biogeoclimatic zones. Future studies of the functional role of CWD should consider both scale (square metre vs. hectare) and temporal (changes in CWD with forest age) issues, as studies including these are sparse and both may be important. Key words: biogeoclimatic zones, British Columbia, coarse woody debris, old-growth forests.Cette communication résume les données tirées de la littérature et celles recueillies par l'auteur dans diverses études sur la quantité, les caractéristiques et l'importance fonctionnelle des débris ligneux grossiers (DLG) dans les forêts anciennes de la Colombie-Britannique (C.-B.). Dans la littérature, on ne s'entend pas sur le diamètre minimum des DLG, ou le nombre de classes de décomposition. Dans l'ouest de l'Amérique du Nord, on emploie le plus souvent cinq classes, mais des études récentes portent à croire qu'un nombre de classes inférieur serait préférable. Les comparaisons entre les classes de décomposition et les zones et sous-zones biogéoclimatiques de la C.-B. révèlent que les DLG sont plus abondants (pouvant atteindre environ 60 kg/m[sup 2] et 1800 m[sup 3] /ha) et persistent le plus longtemps (parfois pendant plus de 1000 ans) dans la zone biogéoclimatique cótière de la pruche de l'Ouest (CWH). L'abondance des DLG et la superficie de sol qu'ils couvrent augmentent avec la productivité de la forêt. La persistance des DLG varie de moins de 100 ans à plus de 800 ans dans cinq zones biogéoclimatiques : deux zones côtières (la CWH et la zone de la pruche subalpine (MH)) et trois zones intérieures (celle du douglas taxifolié de l'intérieur (IDF), celle des cèdres et des pruches de l'intérieur (ICH) et celle de l'épinette d'Engelmann et du sapin subalpin (ESSF)). Dans les forêts côtières aménagées de la C.-B., l'abondance des DLG en fonction de l'âge de la forêt suivrait une courbe en U, les débris étant plus abondants sur les parterres de coupe récents que dans les forêts anciennes, et moins abondants dans les forêts d'âge moyen. Cette relation entre les DLG et l'âge de la forêt est peut-être la tendance normale, et les écarts par rapport à celle-ci pourraient être le résultat de facteurs propres à chaque perturbation ou milieu. Il existe beaucoup de données sur les caractéristiques des DLG dans la CWH, la IDF, la ICH, la ESSF et la zone boréale des épinettes blanche et noire (BWBS), mais il en existe relativement peu pour la zone côtière du douglas taxifolié, la zone subboréale des pins et des épinettes, la zone subboréale de l'épinette (SBS) et la zone de l'épinette, du saule et du bouleau. Peu d'études ont été consacrées au rôle fonctionnel des DLG dans les forêts de la Colombie-Britannique, mais d'après celles qui ont été réalisées, les DLG constitueraient une composante importante de l'habitat de certaines espèces végétales et animales. On a recensé 169 espèces végétales poussant sur ces débris, dont plus de 95 % de tous les lichens et hépatiques, dans les forêts anciennes de la CWH, de la MH, de la IDF, de la ICH et de la ESSF. Le tiers de ces espèces ne poussent que sur les DLG. D'après des études effectuées dans plusieurs zones biogéoclimatiques, ces débris constituent l'habitat préféré de certains petits animaux présents dans les forêts anciennes, tels que les musaraignes, certains campagnols et certaines salamandres, et sont associés à de plus fortes populations de ces animaux, mais les effets varient selon l'espèce et la zone biogéoclimatique. Le rôle des DLG dans le recyclage des éléments nutritifs n'est pas bien connu, mais il semble qu'il soit relativement négligeable dans les forêts anciennes de la C.-B. Il a été avancé que les débris ligneux grossiers pourraient accroître l'acidification et le lessivage des sols minéraux, mais de tels effets n'ont pas été mis en évidence dans une étude de la zone CWH, de la MH, de la IDF, de la ICH, de la ESSF, de la BWBS et de la SBS. À l'avenir, les études sur le rôle fonctionnel des DLG devraient tenir compte des aspects liés à l'échelle (m[sup 2] ou ha) et temporels (modifications des DLG avec le vieillissement de la forêt) puisque les études impliquent ces paramètres potentiellement importants sont rares. Mots clés : zones biogéoclimatiques, Colombie-Britannique, débris ligneux grossiers, forêts anciennes. [Traduit par la rédaction] [ABSTRACT FROM AUTHOR]