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Detrital zircon from three coarse-grained marine siliciclastic rocks was analyzed for U–Pb, Lu–Hf, and trace element compositions to constrain the timing of deposition and sediment provenance of the Cunningham Lake formation (formerly siliciclastic unit of the Sitlika assemblage) in north-central British Columbia. This strategy tests previously proposed sedimentary linkages between the Cache Creek terrane and the westerly rocks of the Stikine terrane. All three samples indicate maximum depositional ages at ca. 205–202 Ma (Rhaetian). The samples contain a predominant ca. 225–215 Ma detrital population, sourced from proximal contemporaneous volcanic arcs, and minor Permian to Middle Triassic and Carboniferous arc-derived detrital populations. The absence of Precambrian grains is consistent with the strongly suprachondritic zircon compositions (εHf(t) = +7 to +20), and indicates exclusively juvenile sources for the Cunningham Lake formation. Late Triassic sources of zircon are not known in the Cache Creek terrane and, except within western Stikine terrane, are uncommon among the Intermontane terranes that amalgamated with the Cache Creek terrane during Late Triassic–Early Jurassic. The Stikine suite (ca. 230–214 Ma) and coeval volcanic rocks in western Stikinia are the most probable sources of Late Triassic detritus for the Cunningham Lake formation. Stikinia's Paleozoic basement is the probable source of Carboniferous detrital zircon. Volcanic arc–backarc complexes in the Cache Creek terrane are the most likely sources of Permian to Middle Triassic detritus in the Intermontane terranes. Accordingly, the siliciclastic rocks of the Cunningham Lake formation represent an overlap sedimentary succession that links Stikinia to the Cache Creek terrane by the latest Triassic. [ABSTRACT FROM AUTHOR]

Indigenous oral traditions of the Líl̓wat Nation recount observations of Qw̓elqw̓elústen (Mount Meager), a Garibaldi Volcanic Belt volcano in southwestern British Columbia, Canada; and associated eruptive activity, mass-wasting, and outburst flooding. We present Líl̓wat observations relating to Qw̓elqw̓elústen's ∼2360 cal year B.P. eruption and its aftermath, a devastating outburst flood down the Lillooet valley. The Copper Canoe story correlates with the event sequence of pyroclastic damming of the Lillooet River and an outburst flood traveling far downstream, interrupting salmon runs and displacing people. Other stories suggest an eruptive plume and fumaroles. Recounted valley-floor changes, with proximal scouring and downstream filling of marshes allowing human resettlement, closely parallel and augment geological evidence, showing that oral traditions are equally important in holding landscape history. Oral traditions portray dramatic landscape changes, some by the Transformers, said to have traveled this land to make imperfect things right. Geologically documented debris-flow delta progradation and infill of the upper 50 km of Lillooet Lake since ∼12 000 cal B.P. underscore the land's dynamism and the need for both sources to inform planning for future eruptive, mass-wasting, and flooding events. Traditional landscape knowledge, like Western science, is observational and evidence-based, though interpretations can differ given Indigenous belief in a sentient landscape, capable of acting with intention. Binding of stories to geographical locations has functioned as a powerful mnemonic device to preserve orally transmitted information across many generations. [ABSTRACT FROM AUTHOR]

Dinosaur skeletal material from the mid-Cretaceous of Canada is rare; however, the Cenomanian-aged Dunvegan Formation of northeastern British Columbia and northwestern Alberta is rich with ichnofossils attributed to nodosaurid ankylosaurs. A long bone (Hudson's Hope Museum specimen HH 2017.010.002) collected in 1993 from the Murray River of northeastern British Columbia is identified here as an ankylosaur femur. Femoral measurements of the bone plotted against femoral measurements of major dinosaur clades, combined with observations on femoral features, indicate that the bone belongs to an ankylosaur. The specimen is too damaged to assign to Nodosauridae or Ankylosauridae. HH 2017.010.002 represents the first limb bone material recovered from the Dunvegan Formation; previous ankylosaur material described from the Dunvegan Formation includes associated vertebrae and ribs from British Columbia and osteoderms from Alberta, as well as the presumed nodosaurid footprints Tetrapodosaurus borealis Sternberg, 1932. The Cenomanian is a time of great ecological change in North America, including the possible extirpation of ankylosaurid ankylosaurs. Fossils from the Dunvegan Formation can thus yield important insight into the responses of fauna to this major transition. [ABSTRACT FROM AUTHOR]

Canoe Reach is a region of high geothermal potential on a segment of the Southern Rocky Mountain Trench fault (SRMTF) with highly metamorphosed and structurally complex wall rocks, near Valemount, British Columbia. This study contains analyses of magnetotelluric data collected at Canoe Reach accounting for electrical anisotropy, which is not often considered during geothermal exploration. Isotropic and anisotropic 3D inversions are used due to signs of electrical anisotropy in the Canoe Reach magnetotelluric data and the presence of visibly anisotropic geological structure. At Canoe Reach North, the anisotropic model is preferred for its simpler structure and consistency with the mapped geology. An anisotropic feature in the footwall of the steeply southwest-dipping SRMTF has a low resistivity in the fault-perpendicular direction and a high resistivity in the vertical direction, which is more easily explained by conductive minerals than by fluids in the highly metamorphosed gneiss. An exploration well in the SRMTF footwall encountered two graphite seams with thicknesses ≥1 m, supporting the interpretation of anisotropic resistivity due to conductive minerals. A strong resistivity contrast across the SRMTF suggests juxtaposition of different lithologies, challenging existing interpretations of SRMTF displacement at Canoe Reach. At Canoe Reach South, anisotropic features near the Canoe River thermal spring with a high resistivity in the fault-perpendicular direction and low resistivity in the vertical direction are consistent with fault core and damage zone models. Magnetotelluric data may be sensitive to permeability anisotropy of fault zones, and the use of electrically anisotropic inversions should be considered for these settings. [ABSTRACT FROM AUTHOR]

We assessed 28 Canadian volcanoes in terms of their relative threats to people, aviation, and infrastructure. The methodology we used was developed by the United States Geological Survey for the 2005 National Volcano Early Warning System. Each volcano is scored on multiple hazard and exposure factors, producing an overall threat score. The scored volcanoes are assigned to five threat categories, ranging from Very Low to Very High. We developed a knowledge uncertainty score to provide additional information about assessed threat levels; this does not affect the threat scoring. Two Canadian volcanoes are in the Very High threat category (Mt. Garibaldi and Mt. Meager). Three Canadian volcanoes are in the High threat category (Mt. Cayley, Mt. Price, and Mt. Edziza) and one volcano is in the Moderate threat category (Mt. Silverthrone). We compare the ranked Canadian volcanoes to volcanoes in the USA and assess current levels of monitoring against internationally recognized monitoring strategies. We find that even one of the best-studied volcanoes in Canada (Mt. Meager) falls significantly short of the recommended monitoring level and is currently monitored at a level commensurate with a Very Low threat edifice. All other Canadian volcanoes are unmonitored (apart from falling within a regional seismic network). This threat ranking has been used to prioritize hazard and risk assessment targets and to help select monitoring activities that will most effectively address the undermonitoring of Canadian volcanoes. [ABSTRACT FROM AUTHOR]

The Texas Creek rock avalanche is a prehistoric deposit in the Fraser River Canyon, 17 km south of Lillooet, southwestern British Columbia, Canada. Original mapping suggested that the debris consisted of two landslides: a 45 Mm3 event deposited after the Mazama tephra but before about 2 ka ago, and a 7.2 Mm3 event about 1.1 ka ago. The proposed timing of the younger landslide was correlated with a decline in the First Nations population and was proposed as an agent of cultural collapse driven by its impact on salmon returns vital to the population's sustenance. We provide six surface exposure ages using 10Be from boulder tops, with three samples from each surface that were originally posited to be older and younger debris. The six samples yielded similar ages suggesting the landslide deposit represents a single event with an average age of 2.28 ± 0.19 (2σ external error) ka before 1950 AD. Evidently, the landslide played no role in the cultural collapse. Fraser River Holocene incision rates, estimated pre- and post-landslide are between 13 and 24 mm/yr, consistent with previous estimates for the mid-Fraser River region. Landslide timing is coincident with the explosive eruption of Mount Meager, 120 km to the northwest, and with a possible landslide at Mystery Creek 85 km to the west and 65 km south of Mount Meager. The landslide may have been seismically triggered, but attribution is speculative. [ABSTRACT FROM AUTHOR]

Kitasu Hill and MacGregor Cone formed along the Principe Laredo Fault on British Columbia's central coast as the Wisconsinan ice sheet withdrew from the Coast Mountains. These small-volume Milbanke Sound Volcanoes (MSV) provide remarkable evidence for the intimate relationship between volcanic and glacial facies. The lavas are within-plate, differentiated (low MgO < 7%) Ocean Island Basalts, hawaiites, and mugearites that formed from ∼1% decompression melting of asthenosphere with residual garnet. Kitasu Hill, on glaciated bedrock, formed between 18 and 15 cal ka BP. Dipping, poorly stratified, admixed hyaloclastite, and glacial diamicton with large plutonic clasts and pillow breccia comprise its basal tuya platform (0–43 masl). Subaerial nested cinder cones, with smaller capping lava flows, sit atop the tuya. New marine samples show McGregor Cone formed subaerially but now sits submerged at 43–200 mbsl on an eroded moraine at the mouth of Finlayson Channel. Seismic data and cores reveal glaciomarine sediments draping the cone's lower slopes and show beach terraces. Cores contain glaciomarine diamictons, ice-rafted debris, delicate glassy air fall tephra, and shallow, sublittoral, and deeper benthic foraminifera. Dates of 14.1–11.2 cal ka BP show volcanism spanned ∼2000 years during floating ice shelf conditions. The MSV have similar proximal positions to the retreating ice sheet, display mixed volcano-glacial facies, and experienced similar unloading stresses during deglaciation. The MSV may represent deglacially triggered volcanism. The dates, geomorphic and geological evidence, constrain a local relative sea level curve for Milbanke Sound and show how ice gave way to fire. [ABSTRACT FROM AUTHOR]