Lummi and Eliza Islands form the northeast part of the San Juan Island group in northwest Washington. Lummi is a long, narrow island characterized by a rocky, mountainous southern half and a low, northern half. Eliza is a small T-shaped island southeast of Lummi Island. Lummi Island is underlain by igneous, metamorphic, and sedimentary rocks of Paleozoic to Lower Cenozoic age. The oldest rocks are believed to be those of the Lummi Island Metamorphic and Igneous Complex which form a small, isolated knob in the middle of the island. These are hornblendic rocks, intruded by quartz-albite rocks and cut by numerous aplite and lamprophyric dikes. The age and origin of these rocks is unknown but they may be older "basement" rocks brought to their present position through faulting. Shale, graywacke and granule conglomerate of the Carter Point formation (Paleozoic or Mesozoic) underly most of southern Lummi Island. These rocks show all the characteristics of the typical "graywacke suite" such as great thickness, clastic character, rhythmic bedding, and graded bedding. The only fossils found were a few carbonized plant stems imbedded in fine-grained graywacke. The rocks forming the bedrock of Eliza Island may be a more metamorphosed equivalent of these. Overlying the Carter Point formation on the southeast side of Lummi Island and directly underlying the sandstone at the northern end are the Reil Harbor volcanics. Although they occur in five isolated outcrops these rocks are grouped together on the basis of lithology and outcrop features. In contrast to an earlier intrusive interpretation these occur as submarine (pillow) lavas and interbedded breccia with tuffaceous - argillaceous rocks rather than as dikes or sills. The lavas of some of the outcrops are spilitic and in most cases are extremely altered. The breccias are dominantly volcanic - clastic types which show some reworking. The age of the volcanics and underlying Carter Point formation is unknown; however, interbedded sedimentary rocks contain radiolarian tests suggestive of Mesozoic age. Northern Lummi Island is underlain by plant-bearing lithic-feldspathic arenites and conglomerates of the Chuckanut formation (Paleocene). These are believed to have a continental fluviatile origin on the basis of: absence of marine fossils; conspicuous amounts of hematite imbedded in the sandstone; moderate sorting and rounding; apparent large-scale heterogeneity evidenced by internal structures such as prominant cross bedding and cut - fill structures, and the dominance of sandstone and conglomerate facies. The Carter Point formation and the overlying volcanics on the southeast side of Lummi Island strike N 40 W and dip 45 degrees NW. Drag folds suggest that southern Lummi Island represents the eastern limb of a northwest plunging anticline. The Chuckanut formation and the underlying Reil Harbor vol-canics at the north end of the island have been folded into three synclines which strike northwest-southeast and plunge gently northwest. During the Pleistocene, northern Lummi Island was blanketed with glacial drift while the higher knobs here and the rocks of southern Lummi were grooved, polished or eroded by the glaciers. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Fur trapping, for generations the chief source of income for native people in northern Canada, has seriously declined in recent years. An outstanding exception is the community of Sachs Harbour, Banks Island, N. W. T., where several thousand white fox pelts are harvested annually by 15 to 20 trappers. The thesis analyzes two topics: the cultural ecology of the colonization of Banks Island as a trapping frontier, and the economic geography of trapping and hunting there. Its purposes are to investigate the ecological, economic and social basis of trapping, to understand trapping as an adaptive strategy in particular historical circumstances, and to analyze it as a viable resource system. The study is based on 14 months of field research in the Western Arctic, chiefly at Sachs Harbour, N.W.T. The primary research method was participant observation, although most quantitative data were obtained through semi-formal interviews. Archival research provided additional historical information and statistics. The relative success of the various groups of settlers was strongly related to their previous orientation to white fox trapping, and hence to their place of origin within the Western Arctic. The development of inland trapping was critical to the successful exploitation of the Island, and despite subsequent centralization of settlement, the trappers have expanded their resource hinterland. This is in contrast to developments in other parts of the north. The ecology of the Arctic fox on Banks Island is discussed, and a means of measuring areal exploitation in trapping is devised. The relationship between effort inputs and trapping success are examined. The number of trap checks is the input factor most strongly correlated with the number of foxes caught, with the number of traps set showing the second best correlation. Tentative predictor equations for trapping success are derived for various levels of fox abundance within the population cycle, and for the cycle as a whole. Quantitative analyses of seal, caribou, polar bear and other types of hunting show how these activities are integrated with the total resource system, and provide data for comparison with other Arctic regions. Methods are developed for the calculation of production costs of fur pelts and animal foods (and hence the profitability of trapping and hunting), as well as for the calculation of income in kind. The discussion includes the role of marketing, credit and savings. In conclusion, the resource system on Banks Island is discussed in terms of its ecologic, economic, and social viability - both in relation to the future of trapping on Banks Island itself and to the possibility of this system as a generic type being instituted elsewhere. There is no evidence of overharvesting of any major biological resources on Banks Island, and the number of trappers and the spatial arrangement of their activities appear to be optimal. Trapping provides a good standard of living on Banks Island, and reasonable stability of income seems assured. The Banks Island resource system would thus be ecologically stable and economically viable in other parts of the Arctic with similar resources. Social forces however make such a development unlikely. Social values and occupational aspirations are rapidly changing, especially among young people, and trapping is increasingly devalued as a life style despite its economic potential. The difficulties of recruiting young trappers at Sachs Harbour are noted, and the trapping system is seen as one of decreasing social acceptability all across the north. / Arts, Faculty of / Geography, Department of / Graduate

Georgia Depression is a major northwest-trending structural trough that lies between the Coast Mountains and Vancouver Island, along the western boundary of the Coast Plutonic Complex. Field work on a part of this boundary on Hardwicke and West Thurlow Islands in Johnstone Strait established it as an intrusive contact between an Upper Jurassic quartz diorite and stratified rocks of the Vancouver Group. The Vancouver Group in the vicinity of the contact is broken by two major west-northwest trending preplutonic faults. Contact metamorphic conditions determined from basic and carbonate assemblages are P ,-3 kb. total and T . = (650 - 720°C . Post-plutonic fractures and dikes maximum trend northeast. The main result of the field study was to confirm for a particular area that the western margin of the Coast Plutonic Complex is essentially a magmatic front. Georgia Depression began to subside in the Upper Cretaceous as the Coast Plutonic Complex rose. It is proposed that the initial subsidence of Georgia Depression was complementary to the uplift of the Coast Mountains. Georgia Depression is part of the Coastal Trough of western North America, an elongate depression that lies between a series of colinear magmatic arcs (the Coast Plutonic Complex, the Cascades, and the Sierra Nevada) and the western margin of the North American plate. The various sub-basins of the Coastal Trough formed at different times, from the Upper Jurassic to the Late Tertiary, that correspond to the times of uplift of the adjacent igneous complexes. This coincidence suggests that the subsidence of the whole Coastal Trough, including Georgia Depression, was coupled to the uplift of the magmatic arcs of North America. The Coastal Trough may be analogous to the marginal synclines developed in Ramberg's (1967) diapir experiments. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Economically important Mississippi Valley type zinc-lead deposits exist in a late Proterozoic dolomite, the Society Cliffs Formation, at north Baffin Island, District of Franklin, N.W.T., Canada. The Society Cliffs Formation ranges from 1,000 to 2,000 feet in thickness and is underlain by up to 2,000 feet of black, organic-rich shale, the Arctic Bay Formation, and overlain by either black shale and limestone of the Victor Bay Formation or by red, fine- to coarse-grained clastic rocks of the Strathcona Sound Formation. Disconformities exist between each of the formations. Society Cliffs Formation has undergone at least four temporally distinct episodes of karstification since its deposition. The most important karst episode, with respect to the formation of the zinc-lead deposits, occurred during the hiatal interval between the deposition of the Victor Bay Formation and the deposition of the Strathcona Sound Formation. During this hiatal interval a holokarst developed in Society Cliffs Formation and a large integrated cave system of the Mammoth Cave-Flint Ridge Cave System type was formed; i.e. long, nearly horizontal, tubular passages were formed during initial periods of base-level stabilization, followed by the development of sub-vertical canyons beneath the tubes when the base-level dropped. After this karst episode the Society Cliffs Formation was deeply buried and the cave system was partially or completely filled with sulphide and carbonate minerals. The zinc-lead deposits are characterized by banded structure which comprises pyrite, relict marcasite, sphalerite and galena interlayered with sparry dolomite. The zinc-lead deposits contain several sedimentary structures that were formed by a chemical deposition-chemical corrosion process. These include cross-stratification, cut-and-fill and onlap. Onlap indicates the paleocaves were filled from the floor up. The meteoric waters which formed the caves did not form the zinc-lead deposits because the temperature of ore deposition was between 200°C and 150°C, the calculated oxygen isotope composition of the ore fluid is +12.8 per mil, and mineral stability and isotopic data indicate the oxygen fugacity decreased during ore deposition. The sulphide sulphur isotope composition of the zinc-lead deposits has a relatively narrow range about +26 per mil, similar to that of sulphate evaporite (+23.7 per mil) which exists locally within the Society Cliffs Formation. Lead isotope data indicate the lead in the deposits was derived by at least a two-stage process from a source with a uniform uranium-thorium ratio. The ore fluid and contained metals are postulated to have been derived from the Arctic Bay Formation during a late-stage dewatering of the shale. Sulphide deposition may have been caused by the chemical reduction of sulphate which existed in the ore fluid when the ore fluid entered hydrocarbon-filled caves. The hydrocarbons were probably expelled from the Arctic Bay Formation shale during an earlier stage of thermal metamorphism and dewatering. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Aim: Mammals on islands often undergo remarkable evolutionary changes. The acquisition of ‘low gear’ locomotion, namely short and robust limb elements, has been typically associated with the island syndrome in large mammals and, especially, ruminants. Here we provide an investigative framework to examine biotic and abiotic selective factors hypothesized to influence evolution of this peculiar type of gait. Location: Islands worldwide. Taxon: Bovidae. Methods: We calculated response variables associated with ‘low gear’ locomotion in 21 extinct and extant insular bovids. We assembled data on the physiography of 11 islands and on life history and ecological traits of the focal taxa. We estimated 10 predictors (island area and four topographic indices, body mass, body size divergence, number of predators and competitors, large mammal richness) and used multiple regressions, regression trees, and random forests to assess their contextual importance. Results: The acquisition of ‘low gear’ locomotion generally happens on islands with a small number of competitors. However, the roughness of the island terrain appears to be also important, without being a main driver. Finally, although the most extreme cases of ‘low gear’ locomotion occurred on islands with no mammalian predators, our models show a non-significant relationship with this factor. Main conclusions: The evolution of ‘low gear’ locomotion in insular ruminants does not simply result from phyletic dwarfing and predatory release. Variation in morphological responses within Bovidae to ecological and topographic traits suggests, instead, a complex interplay of biotic and abiotic factors. Current understanding on the main drivers of species evolutionary pathways and biogeographic patterns are disproportionally based on few taxa, mainly vertebrates, and in some extreme cases (like this one) even on few species. Here we show how adding more data, even within the same taxonomic group, can challenge historically accepted macroevolutionary and macroecological concepts.

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