31. Brideau, MA; Stead, D; Millard, TH; Ward, BC.Field characterisation and numerical modelling of debris avalanche runout on Vancouver Island, British Columbia, Canada.Landslides, 2019, 16: 875-891 Field characterisation and numerical modelling of debris avalanche runout on Vancouver Island, British Columbia, Canada
Debris avalanches; Field characterisation; Runout modelling
This study presents the results from field characterisation and runout modelling of debris avalanches from Vancouver Island, British Columbia. Information about the terrain attributes at the initiation, transport and deposition zones of 44 debris avalanches (30 to 9000m(3) in volume) is presented. The slope angle at the initiation point of the debris avalanches was found to be independent of the volume of the failure; the termination slope angle did however show a dependence on the debris avalanche volume. Grain size distribution and soil classification were conducted on till and colluvium samples collected from the initiation zones and the failed material classified as well-graded gravels with a low plasticity fine-grained component. Field measurements of the runout path geometry dimensions for 31 slope failures were used to conduct back-analyses. The dynamic analysis code DAN-W was used to determine rheological input parameters for debris avalanche while the modelled runout distance using the empirical-statistical code UBCDFLOW was compared to field observations. The results of the back-analysed rheological parameters were compared against published values for debris and rock avalanches. Based on the DAN-W results, the debris avalanches from Vancouver Island were found to have higher effective friction angle values than the published back-calculated values for large rock avalanches. UBCDFLOW was able to closely model the runout behaviour of most debris avalanches investigated. DOI
30. Wilson, AM; Russell, JK; Ward, BC.Paleo-glacier reconstruction in southwestern British Columbia, Canada: A glaciovolcanic model.Quat. Sci. Rev., 2019, 218: 178-188 Paleo-glacier reconstruction in southwestern British Columbia, Canada: A glaciovolcanic model
Quaternary; Glaciovolcanism; Volcano-ice interactions; Geometric ice model; Paleo ice sheets; Glaciology; Cordilleran Ice Sheet; North America; Radiogenic isotopes
Volcanic rocks erupted within glacial environments offer powerful paleoenvironmental insights. These glaciovolcanoes and their deposits serve as proxies that inform on the paleo-presence, distribution and thickness of past glaciers. We investigate the paleoenvironmental implications of three Mid to Late Pleistocene volcanic deposits in the Garibaldi volcanic belt of southwestern British Columbia, Canada. We use these data to inform a simple geometric model that constrains paleo-glacier distributions in the southern Canadian Cordillera. The three volcanoes are used to recover: i) a coalesced mountain ice sheet in late Marine Isotope Stage (MIS) 4, and possibly into MIS 3 (up to similar to 49.1 +/- 5.5 ka), ii) major and rapid degradation of glaciers during the late, MIS 6 to 5e transition (by 141 +/- 12.9 ka), and, iii) a coalesced mountain ice sheet, or continental ice sheet that existed during MIS 15 (598 +/- 7.5 ka). (C) 2019 Elsevier Ltd. All rights reserved. DOI
29. Roberti, G; Ward, B; de Vries, BV; Friele, P; Perotti, L; Clague, JJ; Giardino, M.Precursory slope distress prior to the 2010 Mount Meager landslide, British Columbia.Landslides, 2018, 15: 637-647 Precursory slope distress prior to the 2010 Mount Meager landslide, British Columbia
Landslide; Mount Meager volcano; Glacial retreat; Slope deformation; Historical airphotos
In 2010, the south flank of Mount Meager failed catastrophically, generating the largest (53 +/- 3.8 x 10(6) m(3)) landslide in Canadian history. We document the slow deformation of the edifice prior to failure using archival historic aerial photographs spanning the period 1948-2006. All photos were processed using Structure from Motion (SfM) photogrammetry. We used the SfM products to produce pre-and post-failure geomorphic maps that document changes in the volcanic edifice and Capricorn Glacier at its base. The photographic dataset shows that the Capricorn Glacier re-advanced from a retracted position in the 1980s then rapidly retreated in the lead-up to the 2010 failure. The dataset also documents 60 years of progressive development of faults, toe bulging, and precursory failures in 1998 and 2009. The 2010 collapse was conditioned by glacial retreat and triggered by hot summer weather that caused ice and snow to melt. Meltwater increased pore water pressures in colluvium and fractured rocks at the base of the slope, causing those materials to mobilize, which in turn triggered several secondary failures structurally controlled by lithology and faults. The landslide retrogressed from the base of the slope to near the peak of Mount Meager involving basement rock and the overlying volcanic sequence. Elsewhere on the flanks of Mount Meager, large fractures have developed in recently deglaciated areas, conditioning these slopes for future collapse. Potential failures in these areas have larger volumes than the 2010 landslide. Anticipated atmospheric warming over the next several decades will cause further loss of snow and glacier ice, likely producing additional slope instability. Satellite- and ground-based monitoring of these slopes can provide advanced warning of future landslides to help reduce risk in populated regions downstream. DOI
28. Menounos, B; Goehring, BM; Osborn, G; Margold, M; Ward, B; Bond, J; Clarke, GKC; Clague, JJ; Lakeman, T; Koch, J; Caffee, MW; Gosse, J; Stroeven, AP; Seguinot, J; Heyman, J.Cordilleran Ice Sheet mass loss preceded climate reversals near the Pleistocene Termination.Science, 2017, 358: 781-784 Cordilleran Ice Sheet mass loss preceded climate reversals near the Pleistocene Termination
The Cordilleran Ice Sheet (CIS) once covered an area comparable to that of Greenland. Previous geologic evidence and numerical models indicate that the ice sheet covered much of westernmost Canada as late as 12.5 thousand years ago (ka). New data indicate that substantial areas throughout westernmost Canada were ice free prior to 12.5 ka and some as early as 14.0 ka, with implications for climate dynamics and the timing of meltwater discharge to the Pacific and Arctic oceans. Early Bolling-Allerod warmth halved the mass of the CIS in as little as 500 years, causing 2.5 to 3.0 meters of sea-level rise. Dozens of cirque and valley glaciers, along with the southern margin of the CIS, advanced into recently deglaciated regions during the Bolling-Allerod and Younger Dryas. DOI PubMed
27. Roberti, G; Friele, P; de Vries, BV; Ward, B; Clague, JJ; Perotti, L; Giardino, M.Rheological evolution of the Mount Meager 2010 debris avalanche, southwestern British Columbia.Geosphere, 2017, 13: 369-390 Rheological evolution of the Mount Meager 2010 debris avalanche, southwestern British Columbia
On 6 August 2010, a large (similar to 50 Mm(3)) debris avalanche occurred on the flank of Mount Meager in the southern Coast Mountains of British Columbia, Canada. We studied the deposits to infer the morphodynamics of the landslide from initiation to emplacement. Structure from motion (SfM) photogram-metry, based on oblique photos taken with a standard SLR camera during a low helicopter traverse, was used to create high-resolution orthophotos and base maps. Interpretation of the images and maps allowed us to recognize two main rheological phases in the debris avalanche. Just below the source area, in the valley of Capricorn Creek, the landslide separated into two phases, one water-rich and more mobile, and the other water-poor and less mobile. The water-rich phase spread quickly, achieved high superelevation on the valley sides, and left distal scattered deposits. The main water-poor phase moved more slowly, did not superelevate, and formed a thick continuous deposit ( up to similar to 30 m) on the valley floor. The water-poor flow deposit has structural features such as hummocks, brittle-ductile faults, and shear zones. Our study, based on a freshly emplaced deposit, advances understanding of large mass movements by showing that a single landslide can develop multiple rheology phases with different behaviors. Rheological evolution and separation of phases should always be taken into account to provide better risk assessment scenarios. DOI
26. Sacco, DA; Ward, BC; Lian, OB; Maynard, DE; Geertsema, M.Quaternary geology of part of the McLeod Lake map area (NTS 093J), central British Columbia: lithostratigraphy, glacial history, and chronology.Can. J. Earth Sci., 2017, 54: 1063-1084 Quaternary geology of part of the McLeod Lake map area (NTS 093J), central British Columbia: lithostratigraphy, glacial history, and chronology
The coalescence and subsequent divergence of glaciers near the McLeod Lake map area during the last (Fraser) glaciation are recorded by landforms, ice-flow indicators, and the distribution of sediments. Ice initially flowed into the study area from the northwest, with at least one fluctuation in the ice-front position. Ice flow during glacial maximum was generally to the northeast and transitioned to the east during deglaciation. The Quaternary stratigraphic record spans the Fraser Glaciation and is represented by a sequence of advance glaciolacustrine sediments, multiple till units, retreat glaciolacustrine and glaciofluvial sediments, and associated postglacial aeolian material. The surficial geology is dominated by thick, streamlined till that thins where relief is high. Glaciofluvial outwash occurs mostly in northeast-and southeast-trending meltwater channels, while ice-contact glaciofluvial deposits and ablation till occur in depressions throughout the region. Extensive glaciolacustrine deposits blanket low-lying regions in the southern parts of the study area. Meltwater and ice-flow features suggest that deglaciation in the region was dominantly frontal retreat and that ice was largely active as it retreated through the study area. Postglacial aeolian activity was brief; optical dating on K-feldspar from aeolian landforms indicates that the landforms had stabilized by between 8.71-10.71 and 12.3-14.3 ka, and provides minimum ages for ice retreat. The data from the study area are evaluated with similar data from adjacent regions to develop an ice-flow history, and refine the conceptual model of deglaciation for the northern Interior Plateau. DOI
25. Plouffe, A; Ferbey, T; Hashmi, S; Ward, BC.Till geochemistry and mineralogy: vectoring towards Cu porphyry deposits in British Columbia, Canada.Geochem.-Explor. Environ. Anal., 2016, 16: 213-232 Till geochemistry and mineralogy: vectoring towards Cu porphyry deposits in British Columbia, Canada
Indicator minerals; chalcopyrite; epidote; till; Cu porphyry
Regional till sampling was completed near four Cu porphyry mineralized zones in south-central British Columbia, Canada: Highland Valley Copper (Cu-Mo), Gibraltar (Cu-Mo), and Mount Polley (Cu-Au-Ag) deposits, and the Woodjam (Cu-Au-Mo) prospect. At all sites, Cu concentrations in the clay-sized fraction and chalcopyrite grains (0.25 - 0.5 mm; >3.2 specific gravity) are found in greater abundance in till near and down-ice from mineralized zones compared to surrounding background regions. At Mount Polley, the abundance of gold grains in till defines a dispersal train extending at least 3 km down-ice (SW and NW) from mineralization. At three sites out of four, epidote in till heavy mineral concentrates occurs in greater percentage near and down-ice from mineralized zones compared to background regions suggesting that this mineral could be an indicator of propylitic alteration associated with porphyry mineralization. The distribution pattern of Cu concentrations and chalcopyrite grains in till is controlled by the distribution of Cu-porphyry mineral occurrences in bedrock and the direction of ice-flow movements which prevailed during the last glaciation. By comparing study sites, there is a positive relationship between the areal extent of bedrock mineralization that was exposed to glacial erosion and the absolute values of Cu concentrations and chalcopyrite grain counts in till. In the Woodjam region where the till is thick (>10 m), eight samples with background Cu concentrations in the clay-sized fraction of till contain >4 grains of chalcopyrite/10 kg which is indicative of mineralization. This study demonstrates that a combination of till geochemistry and mineralogy is an efficient method for mineral exploration for Cu porphyry deposits covered by variable amounts of glacial sediments. DOI
24. Turner, DG; Ward, BC; Froese, DG; Lamothe, M; Bond, JD; Bigelow, NH.Stratigraphy of Pleistocene glaciations in the St Elias Mountains, southwest Yukon, Canada.Boreas, 2016, 45: 521-536 Stratigraphy of Pleistocene glaciations in the St Elias Mountains, southwest Yukon, Canada
At least five Middle to Late Pleistocene advances of the northern Cordilleran Ice Sheet are preserved at Silver Creek, on the northeastern edge of the St Elias Mountains in southwest Yukon, Canada. Silver Creek is located 100 km up-ice of the Marine Isotope Stage (MIS) 2 McConnell glacial limit of the St Elias lobe. This site contains similar to 3 km of nearly continuous lateral exposure of glacial and non-glacial sediments, including multiple tills separated by thick gravel, loess and tilted lake beds. Infrared-stimulated luminescence (IRSL) and AMS radiocarbon dating constrain the glacial deposits to MIS 2, 4, either MIS 6 or mid-MIS 7, and two older Middle Pleistocene advances. This chronology and the tilt of the lake beds suggest Pleistocene uplift rates of up to 1.9 mm a(-1) along the Denali Fault since MIS 7. The non-glacial sediment consists of sand, gravel, loess and organic beds from MIS 7, MIS 3 and the early Holocene. The MIS 3 deposits date to between 30-36 C-14 ka BP, making Silver Creek one of the few well-constrained MIS 3-aged sites in Yukon. This confirms that ice receded close to modern limits in MIS 3. Pollen and macrofossil analyses show that a meadow-tundra to steppe-tundra mosaic with abundant herbs and forbs and few shrubs or trees, dominated the environment at this time. The stratigraphy at Silver Creek provides a palaeoclimatic record since at least MIS 8 and comprises the oldest direct record of Pleistocene glaciation in southwest Yukon. DOI
23. Utting, DJ; Gosse, JC; Kelley, SE; Vickers, KJ; Ward, BC; Trommelen, MS.Advance, deglacial and sea-level chronology for Foxe Peninsula, Baffin Island, Nunavut.Boreas, 2016, 45: 439-454 Advance, deglacial and sea-level chronology for Foxe Peninsula, Baffin Island, Nunavut
The impact of the Laurentide Ice Sheet (LIS) deglaciation on Northern Hemisphere early Holocene climate can be evaluated only once a detailed chronology of ice history and sea-level change is established. Foxe Peninsula is ideally situated on the northern boundary of Hudson Strait, and preserves a chronostratigraphy that provides important glaciological insights regarding changes in ice-sheet position and relative sea level before and after the 8.2 ka cooling event. We utilized a combination of radiocarbon ages, adjusted with a new locally derived DR, and terrestrial in-situ cosmogenic nuclide (TCN) exposure ages to develop a chronology for early-Holocene events in the northern Hudson Strait. A marine limit at 192 m a.s.l., dated at 8.1-7.9 cal. ka BP, provides the timing of deglaciation following the 8.2 ka event, confirming that ice persisted at least north of Hudson Bay until then. A moraine complex and esker morphosequence, the Foxe Moraine, relates to glaciomarine outwash deltas and beaches at 160 m a.s.l., and is tightly dated at 7.6 cal. ka BP with a combination of shell dates and exposure ages on boulders. The final rapid collapse of Foxe Peninsula ice occurred by 7.1-6.9 cal. ka BP (radiocarbon dates and TCN depth profile age on an outwash delta), which supports the hypothesis that LIS melting contributed to the contemporaneous global sea-level rise known as the Catastrophic Rise Event 3 (CRE-3). DOI
22. Wolter, A; Stead, D; Ward, BC; Clague, JJ; Ghirotti, M.Engineering geomorphological characterisation of the Vajont Slide, Italy, and a new interpretation of the chronology and evolution of the landslide.Landslides, 2016, 13: 1067-1081 Engineering geomorphological characterisation of the Vajont Slide, Italy, and a new interpretation of the chronology and evolution of the landslide
Vajont Slide; Engineering geomorphology; Regional geomorphology; Endogenic processes; Exogenic processes; Sackung; Rock slope damage
Although the 1963 Vajont Slide in Italy has been extensively studied for over 50 years, its regional geological and geomorphological context has been neglected. In this paper, we use field observations and remote sensing data to elucidate the interaction between endogenic and exogenic processes that brought the north slope of Monte Toc to failure. We present the first detailed pre- and post-failure engineering geomorphology maps of the slide area. The maps delineate two main landslide blocks, several sub-blocks, compressional and extensional zones, and secondary failures in the deposit. The maps provide new insights into the kinematics, dynamics and evolution of the slide. Finally, we discuss the origin of Vajont Gorge and a prehistoric failure that occurred at the same location as the 1963 slide. We propose, as part of a newly developed multi-stage landscape evolution sequence, that the prehistoric failure was a deep-seated gravitational slope deformation (sackung) that initiated during deglaciation and continued to slowly move until the catastrophic failure in 1963. We argue that the gorge was created by these deep-seated slow movements. DOI
21. Hashmi, S; Ward, BC; Plouffe, A; Leybourne, MI; Ferbey, T.Geochemical and mineralogical dispersal in till from the Mount Polley Cu-Au porphyry deposit, central British Columbia, Canada.Geochem.-Explor. Environ. Anal., 2015, 15: 234-249 Geochemical and mineralogical dispersal in till from the Mount Polley Cu-Au porphyry deposit, central British Columbia, Canada
till geochemistry; porphyry indicator minerals; Mount Polley; exploration geochemistry
The Quesnel terrane in the Interior Plateau of British Columbia, Canada, is highly prospective for locating new porphyry deposits; however, the bedrock in this region is obscured by a nearly continuous blanket of till, making mineral exploration challenging. Located within the Quesnel terrane is the Mount Polley deposit. It is an alkaline, silica-undersaturated, Cu-Au porphyry deposit mined by Imperial Metals Corporation. Eighty-six basal till samples were collected for geochemical and mineralogical analyses in the region of this deposit. Ore elements (Ag, Au and Cu), as well as pathfinder element (Hg and Zn) contents in till reflect detrital glacial dispersal from the Mount Polley deposit. The distribution of anomalous mineral counts of andradite garnet, apatite, chalcopyrite, epidote, jarosite and native gold also reflect glacial dispersal from the deposit. Outcrop-scale ice-flow indicators indicate a dominant ice- flow event to the NW that was preceded by a southwestward glacial advance. The element and mineral signatures of the Mount Polley Cu-Au porphyry deposit are dispersed in sub-glacial surface tills up to 12 km in the down-ice (NW) direction. We demonstrate that till geochemistry and mineralogy can serve for mineral exploration of Cu-Au porphyry mineralization in drift covered areas. DOI
20. Sturzenegger, M; Stead, D; Gosse, J; Ward, B; Froese, C.Reconstruction of the history of the Palliser Rockslide based on Cl-36 terrestrial cosmogenic nuclide dating and debris volume estimations.Landslides, 2015, 12: 1097-1106 Reconstruction of the history of the Palliser Rockslide based on Cl-36 terrestrial cosmogenic nuclide dating and debris volume estimations
Palliser Rockslide; Canadian Rocky Mountains; Cl-36 terrestrial cosmogenic nuclide dating; Paraglacial rock failure; Debris volume
This paper presents the results of a combined study, using cosmogenic Cl-36 exposure dating and terrestrial digital photogrammetry of the Palliser Rockslide located in the southeastern Canadian Rocky Mountains. This site is particularly well-suited to demonstrate how this multi-disciplinary approach can be used to differentiate distinct rocksliding events, estimate their volume, and establish their chronology and recurrence interval. Observations suggest that rocksliding has been ongoing since the late Pleistocene deglaciation. Two major rockslide events have been dated at 10.0 +/- 1.2 kyr and 7.7 +/- 0.8 kyr before present, with failure volumes of 40 and 8 Mm(3), respectively. The results have important implications concerning our understanding of the temporal distribution of paraglacial rockslides and rock avalanches; they provide a better understanding of the volumes and failure mechanisms of recurrent failure events; and they represent the first absolute ages of a prehistoric high-magnitude event in the Canadian Rocky Mountains. DOI
19. Stumpf, AJ; Ferbey, T; Plouffe, A; Clague, JJ; Ward, BC; Paulen, RC; Bush, ABG.Discussion: "Streamlined erosional residuals and drumlins in central British Columbia, Canada" by J. Donald McClenagan, (2013) Geomorphology 189,41-54.Geomorphology, 2014, 209: 147-150 Discussion: "Streamlined erosional residuals and drumlins in central British Columbia, Canada" by J. Donald McClenagan, (2013) Geomorphology 189,41-54
Drumlin; Surflcial geology; Glacial dispersal; Subglacial processes; Ice sheet modeling; Glacial flooding
McClenagan (2013) presents a model td explain streamlined erosional residuals or drumlins on uplands and lowlands in the plateau region of central British Columbia, Canada. In this discussion paper, we note that McClenagan (2013) has not adequately discussed previous relevant work in the region, and we argue that additional analyses and evidence are required to substantiate this new model. The hypothesis offered for the origin of the plateau landscape, specifically catastrophic glaciofluvial activity, differs significantly from a model based on glacial erosion and deformation that has been developed from field-based research over the past six decades. We discuss four critical points relating to the proposed model: (1) the current geological model for the plateau region of central British Columbia; (2) theory of glacial dispersal; (3) existing hypotheses for the formation of drumlins and other glacial landforms; and (4) theoretical glacial erosion modeling. We further suggest that the model cannot be substantiated without sedimentological or morphological field evidence for water bodies argued to be the source of the proposed megaflood or megafloods. (C) 2013 Elsevier B.V. All rights reserved. DOI
18. Turner, DG; Ward, BC; Bond, JD; Jensen, BJL; Froese, DG; Telka, AM; Zazula, GD; Bigelow, NH.Middle to Late Pleistocene ice extents, tephrochronology and paleoenvironments of the White River area, southwest Yukon.Quat. Sci. Rev., 2013, 75: 59-77 Middle to Late Pleistocene ice extents, tephrochronology and paleoenvironments of the White River area, southwest Yukon
Dating; Pleistocene; Beringia; Last Interglacial; Paleoenvironments; Tephrochronology; Macrofossil; Pollen
Sedimentary deposits from two Middle to Late Pleistocene glaciations and intervening non-glacial intervals exposed along the White River in southwest Yukon, Canada, provide a record of environmental change for much of the past 200 000 years. The study sites are beyond the Marine Isotope stage (MIS) 2 glacial limit, near the maximum regional extent of Pleistocene glaciation. Non-glacial deposits include up to 25 m of loess, peat and gravel with paleosols, pollen, plant and insect macrofossils, large mammal fossils and tephra beds. Finite and non-finite radiocarbon dates, and twelve different tephra beds constrain the chronology of these deposits. Tills correlated to MIS 4 and 6 represent the penultimate and maximum Pleistocene glacial limits, respectively. The proximity of these glacial limits to each other, compared to limits in central Yukon, suggests precipitation conditions were more consistent in southwest Yukon than in central Yukon during the Pleistocene. Conditions in MIS 5e and 5a are recorded by two boreal forest beds, separated by a shrub birch tundra, that indicate environments as warm or warmer than present. A dry, treeless steppe-tundra, dominated by Artemisia frigida, upland grasses and forbs existed during the transition from late MIS 3 to early MIS 2. These glacial and non-glacial deposits constrain the glacial limits and paleoenvironments during the Middle to Late Pleistocene in southwest Yukon. (c) 2013 Elsevier Ltd. All rights reserved. DOI
17. Brideau, MA; Sturzenegger, M; Stead, D; Jaboyedoff, M; Lawrence, M; Roberts, N; Ward, B; Millard, T; Clague, J.Stability analysis of the 2007 Chehalis lake landslide based on long-range terrestrial photogrammetry and airborne LiDAR data.Landslides, 2012, 9: 75-91 Stability analysis of the 2007 Chehalis lake landslide based on long-range terrestrial photogrammetry and airborne LiDAR data
Terrestrial photogrammetry; LiDAR; Distinct element; Limit equilibrium
On December 4th 2007, a 3-Mm(3) landslide occurred along the northwestern shore of Chehalis Lake. The initiation zone is located at the intersection of the main valley slope and the northern sidewall of a prominent gully. The slope failure caused a displacement wave that ran up to 38m on the opposite shore of the lake. The landslide is temporally associated with a rain-on-snow meteorological event which is thought to have triggered it. This paper describes the Chehalis Lake landslide and presents a comparison of discontinuity orientation datasets obtained using three techniques: field measurements, terrestrial photogrammetric 3D models and an airborne LiDAR digital elevation model to describe the orientation and characteristics of the five discontinuity sets present. The discontinuity orientation data are used to perform kinematic, surface wedge limit equilibrium and three-dimensional distinct element analyses. The kinematic and surface wedge analyses suggest that the location of the slope failure (intersection of the valley slope and a gully wall) has facilitated the development of the unstable rock mass which initiated as a planar sliding failure. Results from the three-dimensional distinct element analyses suggest that the presence, orientation and high persistence of a discontinuity set dipping obliquely to the slope were critical to the development of the landslide and led to a failure mechanism dominated by planar sliding. The three-dimensional distinct element modelling also suggests that the presence of a steeply dipping discontinuity set striking perpendicular to the slope and associated with a fault exerted a significant control on the volume and extent of the failed rock mass but not on the overall stability of the slope. DOI
16. Jackson, LE; Nelson, FE; Huscroft, CA; Villeneuve, M; Barendregt, RW; Storer, JE; Ward, BC.Pliocene and Pleistocene volcanic interaction with Cordilleran ice sheets, damming of the Yukon River and vertebrate Palaeontology, Fort Selkirk Volcanic Group, west-central Yukon, Canada.Quat. Int., 2012, 260: 3-20 Pliocene and Pleistocene volcanic interaction with Cordilleran ice sheets, damming of the Yukon River and vertebrate Palaeontology, Fort Selkirk Volcanic Group, west-central Yukon, Canada
Neogene volcanism in the Fort Selkirk area began with eruptions in the Wolverine Creek basin ca. 4.3 Ma and persisted to ca. 3.0 Ma filling the ancestral Yukon River valley with at least 40 m of lava flows. Activity at the Ne Ch'e Ddhawa eruptive center overlapped with the last stages of the Wolverine Creek eruptive centers. Hyaloclastic tuff was erupted between ca. 3.21 and 3.05 Ma. This eruption caused or was coincident with damming of Yukon River. The first demonstrable incursion of a Cordilleran ice sheet into the Fort Selkirk area was coincident with a second eruption of the Ne Ch'e Ddhawa eruptive center ca. 2.1 Ma. The Ne Ch'e Ddhawa subglacial mound was erupted beneath at least 300 m of glacial ice (Ne Ch'e Ddhawa Glaciation). The Eruption of the Fort Selkirk center occurred between the last eruption of Ne Ch'e Ddhawa and Fort Selkirk Glaciation (ca. 2.1-1.5 Ma). Till and outwash from Fort Selkirk Glaciation are conformably overlain by nonglacial sediments that contain the Fort Selkirk tephra (fission track dated at ca. 1.5 Ma). These nonglacial sediments also preserve a short magnetic reversal (reversed to normal) identified as the Gilsa polarity excursion. Temporal control and sedimentology constrain Fort Selkirk Glaciation and the Fort Selkirk Local Fauna to marine isotope stage 54. Rapid and extensive eruption of the Pelly eruptive center filled the Yukon River valley with 70 m of lava which buried these glacial and nonglacial sediments and dammed Yukon River. Local striations and erratic pebbles occur on the last of these lava flows. They document a subsequent incursion of glacial ice during the last 500 ka of the Matuyama Chron (Forks Glaciation). The last major eruption of mafic lava occurred in the middle Pleistocene west of (early Holocene) Volcano Mountain in basin of Black Creek: lava flowed down the valley presently occupied by Black Creek and dammed Yukon River in the area of the Black Creek confluence. This eruption predated the middle Pleistocene Reid Glaciation. Minor volcanism has continued in this area since the middle Pleistocene at Volcano Mountain. (C) 2011 Elsevier Ltd and INQUA. All rights reserved. DOI
15. Zazula, GD; Turner, DG; Ward, BC; Bond, J.Last interglacial western camel (Camelops hesternus) from eastern Beringia.Quat. Sci. Rev., 2011, 30: 2355-2360 Last interglacial western camel (Camelops hesternus) from eastern Beringia
Western camel; C. hesternus; Beringia; Fauna; Yukon; Pleistocene; Stratigraphy; Last interglacial; Sangamonian; Rancholabrean
Western camel (C. hesternus) fossils are rare from Eastern Beringia, thus there is little available information on their chronology, paleoecology, and biogeography in this region. In August of 2010, a partial proximal phalanx of a western camel was recovered from a sedimentary exposure along the White River, in the formerly glaciated terrain of southwest Yukon, northwest Canada. The fossil specimen was recovered in situ from sediments that are correlated by stratigraphic, tephra and radiocarbon data to the Marine Isotope Stage (MIS) 5 interglacial period (Sangamonian). Associated paleoenvironmental data indicates that this western camel inhabited a shrub tundra ecosystem that did not include spruce trees or boreal forest during a relatively cold interval between MIS Se and 5a. This is the oldest reliably dated western camel fossil from Eastern Beringia and supports the model of range expansion for this species to the high latitudes of northwest North America during the last interglacial (sensu lato). Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved. DOI
14. Riedel, JL; Clague, JJ; Ward, BC.Timing and extent of early marine oxygen isotope stage 2 alpine glaciation in Skagit Valley, Washington.Quat. Res., 2010, 73: 313-323 Timing and extent of early marine oxygen isotope stage 2 alpine glaciation in Skagit Valley, Washington
Alpine glaciation; Geochronology; Cascades; Skagit valley; Washington; Evans Creek stade
Twenty-two new radiocarbon ages from Skagit valley provide a detailed chronology of alpine glaciation during the Evans Creek stade of the Fraser Glaciation (early marine oxygen isotope stage (MIS) 2) in the Cascade Range, Washington State. Sediments at sites near Concrete, Washington, record two advances of the Baker valley glacier between ca. 30.3 and 19.5 cal ka BP, with an intervening period of glacier recession about 24.9 cal ka BP. The Baker valley glacier dammed lower Skagit valley, creating glacial Lake Concrete, which discharged around the ice dam along Finney Creek, or south into the Sauk valley. Sediments along the shores of Ross Lake in Upper Skagit valley accumulated in glacial Lake Skymo after ca. 28.7 cal ka BP behind a glacier flowing out of Big Beaver valley. Horizontally laminated silt and bedded sand and gravel up to 20 m thick record as much as 8000 yr of deposition in these glacially dammed lakes. The data indicate that alpine glaciers in Skagit valley were far less extensive than previously thought. Alpine glaciers remained in advanced positions for Much of the Evans Creek stade, which may have ended as early as 20.8 cal ka BP. Published by Elsevier Inc. on behalf of University of Washington. DOI
13. Vickers, KJ; Ward, BC; Utting, DJ; Telka, AM.Deglacial reservoir age and implications, Foxe Peninsula, Baffin Island.J. Quat. Sci., 2010, 25: 1338-1346 Deglacial reservoir age and implications, Foxe Peninsula, Baffin Island
Foxe Basin, 8.2 cal. ka event; Laurentide Ice Sheet; macrofossils; marine reservoir age; radiocarbon
Marine reservoir age is reported for Foxe Basin, Canada, during deglaciation of the Laurentide Ice Sheet. Radiocarbon (C-14) measurements were made on pairs of contemporaneous molluscs and Salix (willow) macrofossils, yielding a mean marine reservoir age of 985 +/- 10 C-14 a. Mean regional Delta R is calculated to be 615 +/- 20 C-14 a relative to a mean global reservoir age of ca. 400 C-14 a. Previous studies in the Canadian Arctic that have been conducted on modern pre-bomb molluscs give Delta R values of ca. 100-300 C-14 a. The difference between modern and deglacial reservoir ages indicates that Delta R in Foxe Basin has changed over time, which has implications for the reconstruction of past events based on marine C-14 dates. We recalculate the timing of deglaciation of Hudson Strait with this new reservoir age and relate this to the 8.2 cal. ka event. We recommend that local Delta R be determined for the time period being examined whenever possible, and that in cases where this is impossible a Delta R value of 615 C-14 a be applied when calibrating marine samples from Foxe Basin and vicinity during deglaciation. Copyright (C) 2010 John Wiley & Sons, Ltd. DOI
12. Wolter, A; Ward, B; Millard, T.Instability in eight sub-basins of the Chilliwack River Valley, British Columbia, Canada: A comparison of natural and logging-related landslides.Geomorphology, 2010, 120: 123-132 Instability in eight sub-basins of the Chilliwack River Valley, British Columbia, Canada: A comparison of natural and logging-related landslides
Chilliwack; Surficial landslides; Logging impacts; Terrain attributes
Logging causes increased landslide frequency in British Columbia. In this study, the slope, type, initiation location, aspect, rate, bedrock geology, and size of mass movements located in eight logged tributary valleys of the Chilliwack River Valley are investigated. A landslide inventory was created by digitizing landslides identified on aerial photographs dating from 1941 to 2002. This database was analysed using qualitative observations and simple statistical tests, and a comparison between natural and logging-related landslides was made. Slope tests displayed a significant difference between natural and logging-related events, indicating that, on average, logging-related landslides require lower slope gradients to initiate than natural events. Although aspect, initiation location, and landslide type did not show a significant relationship between natural and logging-related landslides, they do suggest subtle differences. Landslide rate was calculated and compared for natural and logging-related landslides. It was significantly higher for logging-related events, attaining a maximum of 31 times the natural rate in 1978 and an overall average increase of nine times the natural rate. Logging-related landslides were on average smaller than natural landslides but this nevertheless resulted in a 3.1 times increase in area affected by logging-related landslides compared to natural landslides. Geology may influence landslide frequency as well; it appears to be higher over the less resistive sedimentary rocks of the Cultus Formation and Chilliwack Group and lower in granodioritic areas. Finally, roads affected slope stability more than clearcuts in the early decades of the study, but this effect decreased over time, suggesting a correlation with improved road construction. (C) 2010 Elsevier B.V. All rights reserved. DOI
11. Utting, DJ; Ward, BC; Little, EC.Genesis of hummocks in glaciofluvial corridors near the Keewatin Ice Divide, Canada.Boreas, 2009, 38: 471-481 Genesis of hummocks in glaciofluvial corridors near the Keewatin Ice Divide, Canada
Glaciofluvial corridor hummocks (GCHs) within the Walker Lake map area, Canada, were examined in order to determine the character and genesis of these geomorphic features and their associated deposits. Located south of the Chantrey Moraine and north of the Keewatin Ice Divide, these corridors occur within a belt extending approximately 120 km east-west and approximately 60 km north-south. They are spaced 5-10 km apart and are hundreds of metres to several kilometres in width. They have undulating longitudinal profiles, abrupt material boundaries with the surrounding till and occur in valleys and over interfluves. Hummocks were investigated using longitudinal and perpendicular ground-penetrating radar (GPR) surveys in conjunction with pit excavations. From these analyses, the hummocks comprise a single lithofacies consisting of coarsely stratified, matrix-supported gravely sand to a depth of approximately 10 m. This sediment is similar to that of a 'sliding bed facies' observed in esker sediments and hyperconcentrated flow deposits, both of which are attributed to high meltwater discharges. Therefore, we hypothesize that the Walker Lake GCHs formed from sedimentation in cavities at the base of the ice sheet by a rapid influx of meltwater. DOI
10.Ward, BC; Bond, JD; Froese, D; Jensen, B.Old Crow tephra (140+/-10 ka) constrains penultimate Reid glaciation in central Yukon Territory.Quat. Sci. Rev., 2008, 27: 1909-1915 Old Crow tephra (140+/-10 ka) constrains penultimate Reid glaciation in central Yukon Territory
Old Crow tephra (140 +/- 10 ka) is closely associated with deposits from the penultimate Reid glaciation along the Pelly River in central Yukon Territory. The elevation of the tephra above present base level and association with deglacial sediments Suggests a close minimum age estimate, confirming a MIS 6 age for the Reid glaciation. This is in contrast to a MIS 4 age for the penultimate Gladstone glaciation in Southwest Yukon. This study demonstrates that the assumed synchrony of the penultimate advance of the Cordilleran Ice Sheet has little support, and regional controls on the mass balance of source regions of the ice sheet are more important than previously considered. (C) 2008 Elsevier Ltd. All rights reserved. DOI
9.Ward, BC; Bond, JD; Gosse, JC.Evidence for a 55-50 ka (early Wisconsin) glaciation of the Cordilleran ice sheet, Yukon Territory, Canada.Quat. Res., 2007, 68: 141-150 Evidence for a 55-50 ka (early Wisconsin) glaciation of the Cordilleran ice sheet, Yukon Territory, Canada
Cordilleran ice sheet; glacial extent; cosmogenic nuclides; dating; precipitation
Cosmogenic Be-10 ages on boulders of 54-51 ka (n = 4) on a penultimate Cordilleran ice sheet (CIS) drift confirm that Marine Oxygen Isotope Stage (MIS) 4 (early Wisconsin) glaciation was extensive in parts of Yukon Territory, the first confirmed evidence in the Canadian Cordillera. We name the glaciation inferred from the mapped and dated drift the Gladstone. These results are in apparent contrast to the MIS 6 (Illinoian) age of the penultimate Reid glaciation to the east in central Yukon but are equivalent to exposure ages on MIS 4 drift in Alaska. Contrasting penultimate ice extents in Yukon requires that different source areas of the northern CIS in Yukon responded differently to climatic forcing during glaciations. The variation in glacier extent for different source areas likely relates to variation in precipitation during glaciation, as the northern CIS was a precipitation-limited system. Causes for a variation in precipitation remain unclear but likely involve the style of precipitation delivery over the St. Elias Mountains possibly related to variations in the Aleutian low. (c) 2007 University of Washington. All rights reserved. DOI
8. Al-Suwaidi, M; Ward, BC; Wilson, MC; Hebda, RJ; Nagorsen, DW; Marshall, D; Ghaleb, B; Wigen, RJ; Enkin, RJ.Late Wisconsinan Port Eliza Cave deposits and their implications for human coastal migration, Vancouver Island, Canada.Geoarchaeology, 2006, 21: 307-332 Late Wisconsinan Port Eliza Cave deposits and their implications for human coastal migration, Vancouver Island, Canada
Sediments of Port Eliza Cave provide a record of the Last Glacial Maximum (LGM) on Vancouver Island that has important implications for human migration along the debated coastal migration route. Lithofacies changes from nonglacial diamict to glacial laminated silt and clay and till, then a return to nonglacial conditions with oxidized clay, colluvial block beds, and speleothems, along with radiocarbon and U/Th dates, define glacial-nonglacial transitions. Scanning electron microscope studies and clay mineralogy confirm that the laminated fines represent glaciation. Preglacial faunal evidence shows a diverse range from small species, including birds, fish, vole, and marmot, to larger species, such as mountain goat. Pollen data from the same unit show a cold, dry tundra environment with sparse trees. Deglaciation occurred prior to an age of 12.3 ka B.P. based on dated mountain goat bone. These data support the viability of the coastal migration route for humans prior to similar to 16 ka B.P. and then as early as similar to 13 ka B.P. (c) 2006 Wiley Periodicals, Inc. DOI
7. Huscroft, CA; Ward, BC; Jackson, LE; Tarnocai, CE.Investigation of high-level glaciofluvial terraces and re-evaluation of the established soil stratigraphy for Early and Middle Pleistocene surfaces, central Yukon, Canada.Boreas, 2006, 35: 96-105 Investigation of high-level glaciofluvial terraces and re-evaluation of the established soil stratigraphy for Early and Middle Pleistocene surfaces, central Yukon, Canada
Palaeosols developed on the highest Yukon River glaciofluvial terraces were investigated in order to reconstruct the Plio-Pleistocene evolution of the river valley beyond Late Pleistocene glacial limits. A record of at least two pre-Reid (> 311 kyr) glaciations is chronicled by the presence of two populations of glaciofluvial terraces within the study area. The populations of pre-Reid terraces were identified based on their degree of soil development and elevation. Pre-Reid terraces 200-250 m above river level have preserved morphological and mineralogical features of the Wounded Moose palaeosol, a palaeosol previously associated with pre-Reid surfaces in central Yukon. Clay mineralogy and colour indicate that the Wounded Moose palaeosol developed in part during warm and sub-humid as well as temperate and humid interglacials. A second set of pre-Reid terraces between 110 and 30 m above river level are characterized by the presence of the less-developed Diversion Creek palaeosol, a palaeosol previously associated with only Reid-aged (< 311 kyr) surfaces in central Yukon. In contrast to the Wounded Moose palaeosol, the Diversion Creek palaeosol developed during comparatively cool and humid interglacial conditions. The presence of Diversion Creek palaeosols on pre-Reid outwash terraces suggests that a transition from dominantly warmer to cooler interglacial conditions occurred prior to 311 kyr in Yukon Territory. In addition, the presence of a Diversion Creek palaeosol cannot be used to differentiate stable Reid and stable pre-Reid surfaces across central Yukon. DOI
6. Huscroft, CA; Ward, BC; Barendregt, RW; Jackson, LE; Opdyke, ND.Pleistocene volcanic damming of Yukon River and the maximum age of the Reid Glaciation, west-central Yukon.Can. J. Earth Sci., 2004, 41: 151-164 Pleistocene volcanic damming of Yukon River and the maximum age of the Reid Glaciation, west-central Yukon
Stratigraphic, paleomagnetic, and radioisotope investigations of the Selkirk Volcanic Group have identified a new eruptive period and constrained the age of the Reid Glaciation, the most extensive middle Pleistocene cordilleran advance recognized in central Yukon. Downstream from Fort Selkirk, a complex of valley-filling compound pahoehoe basalt flows and pillow basalt is exposed for 10 km along the Yukon River and is overlain by outwash deposited during the Reid Glaciation. The flows have an Ar-40/Ar-39 age of 311 +/- 32 ka. This age is consistent with the normal magnetization of the flows and their termination below the level of the contemporary Yukon River flood plain. Taken with the ca. 190 ka Sheep Creek tephra, which overlies Reid drift elsewhere in Yukon Territory, the Reid Glaciation is constrained to oxygen isotope stage 8, not stage 6 as previously thought. The presence of thick foreset-bedded pillow breccia units intercalated with the subaerial flows indicates that this eruption caused damming of the Yukon River. Reevaluation of the stratigraphy of early Pleistocene basalt flows and pillow lavas in the Fort Selkirk area indicates that volcanic damming of the Yukon River has occurred at least once previously. DOI
5. Roberts, B; Ward, B; Rollerson, T.A comparison of landslide rates following helicopter and conventional cable-based clear-cut logging operations in the Southwest Coast Mountains of British Columbia.Geomorphology, 2004, 61: 337-346 A comparison of landslide rates following helicopter and conventional cable-based clear-cut logging operations in the Southwest Coast Mountains of British Columbia
landslide rates; logging impact; yarding; helicopter logging; conventional logging; clear-cut logging
A comparison of landslide rates following helicopter and conventional, cable-based, clear-cut logging was carried out using results from two independent terrain attribute studies in the Eldred and Lois River watersheds in the Southwest Coast Mountains of British Columbia. Landslides initiating from directly within a road prism were excluded from the study in order to focus the comparison on landslides related primarily to conventional versus helicopter yarding methods. A landslide rate of 0.02 landslides/ha was observed in 162 terrain polygons logged by helicopter similar to8 years prior to this study. Landslide rates in 38 gullied polygons were 0.06 landslides/ha. No landslides were observed in 124 open-slope polygons. Over a similar 8-year average period, 0.03 landslides/ha were observed in 142 cable-yarded terrain polygons; 0.06 and 0.02 landslides/ha occurred in gullied and open-slope polygons, respectively. t-Tests indicate that total landslide rates are not significantly different following helicopter and conventional logging; however, a dichotomy exists between gullied and open-slope terrain polygons. Landslide rates are not significantly different in gullied terrain but are significantly higher on open-slopes following conventional cable logging. Consequently, landslides appear to have a greater potential to occur in open-slope terrain following conventional logging, but differences in gullied polygons are less likely. Increased post-logging landslide rates in conventionally logged, open slopes are more likely the result of undetected road-related drainage changes than differences between helicopter and conventional yarding-related ground disturbance. (C) 2004 Elsevier B.V. All rights reserved. DOI
4.Ward, BC; Thomson, B.Late Pleistocene stratigraphy and chronology of lower Chehalis River valley, southwestern British Columbia: Evidence for a restricted coquitlam stade.Can. J. Earth Sci., 2004, 41: 881-895 Late Pleistocene stratigraphy and chronology of lower Chehalis River valley, southwestern British Columbia: Evidence for a restricted coquitlam stade
Sediments in lower Chehalis valley span middle Wisconsin (Olympia nonglacial interval) to Holocene time. Sediments are divided into six units with chronological control provided by 14 new radiocarbon ages. Fluvial gravel spans the transition from the late Olympia nonglacial interval to the early Fraser Glaciation. Glaciolacustrine sedimentation represents the first definitive glacial activity in the valley and indicates that Vashon ice in the Fraser Lowland blocked the mouth of the Chehalis valley at ca. 18-17 ka BP. Ice then flowed down the Chehalis valley. The Chehalis valley deglaciated while ice persisted in the Fraser Lowland, forming another lake. After this lake drained, terraces and fans formed. This style of glaciation-deglaciation is typical of many watersheds peripheral to the Fraser Lowland in that local valley ice was slightly out of phase with ice in the lowland. This resulted in glacial lakes forming during both advance and retreat phases. However, in contrast to watersheds in the northwestern Fraser Lowland, no definitive evidence of a Coquitlam ice advance was found within the Chehalis valley. Although glaciers in the area were likely active and advancing, data from the Chehalis valley indicates that they were not as extensive as previously thought. Since ice source areas in the northeastern Fraser Lowland are in the leeward area of the Coast Mountains, it is suggested that lower precipitation resulted in limited glacier activity there during the Coquitlam Stade. DOI
3.Ward, BC; Wilson, MC; Nagorsen, DW; Nelson, DE; Driver, JC; Wigen, RJ.Port Eliza cave: North American West Coast interstadial environment and implications for human migrations.Quat. Sci. Rev., 2003, 22: 1383-1388 Port Eliza cave: North American West Coast interstadial environment and implications for human migrations
The timing of Late Pleistocene glacial advance, retreat, relative sea level and environmental viability between 25 and 12.5 ka (C-14 yrs BP) remain a key issue in the feasibility of a coastal migration route for the first North Americans. This is discussed on the basis of stratigraphic, radiometric and faunal data for Port Eliza cave, a raised sea cave, on the west coast of Vancouver Island, British Columbia. Ice cover is indicated by the occurrence of 2m of laminated clay, representing deposition in a subglacial take. From immediately below this clay a diverse vertebrate fauna of marmot, vote, marten, cervid and various species of birds and fish was recovered, yielding ages of 18-16 ka. These dates and others from the region show that ice cover on the outer coast was brief, from ca 15.5-14ka.. The fish species indicate that relative sea level was close to the cave and that salmon runs were likely present. The terrestrial vertebrate fauna is consistent with a cool, open parkland environment with maximum summer temperatures cooler than present; these conditions lasted until at least 16 ka. With a diverse fauna and favorable climate, humans could have survived here on a mixed marine-terrestrial diet, confirming the viability of the coastal migration hypothesis for this portion of the route. (C) 2003 Elsevier Science Ltd. All rights reserved. DOI
2.Ward, B; Rutter, N.Deglacial valley fill sedimentation, Pelly River, Yukon Territory, Canada.Quat. Int., 2000, 68: 309-328 Deglacial valley fill sedimentation, Pelly River, Yukon Territory, Canada
A thick sequence of deglacial valley fill was studied along the Pelly River, Yukon Territory. Late Wisconsinan deglaciation was by regional stagnation of the Cordilleran Ice Sheet, resulting in complex sequences of sediments deposited in glacial lakes, many above stagnant ice. More than 30 sections were described and measured and eight facies were recognized and interpreted. The distribution of sediment reflects control by several systems: (1) ice depositing basal tills: (2) debris flows in glacial lakes depositing diamicton; (3) meltwater streams depositing sorted sediment; and (4) melting of underlying ice remobilizing and deforming previously deposited sediment. A model is constructed that helps to explain sedimentation along Pelly River. Material was deposited into lakes from melting ice, valley slopes and adjacent valleys. Basal tills are relatively rare with most diamictons representing deposition by sediment gravity flows. The presence of large thicknesses of highly disturbed sediments indicates that the sediments were deposited onto ice and subsequently failed. Undisturbed glaciolacustrine sediments were deposited either in more distal parts of the basin or after most of the ice had ablated. The adjacent topography and the height of the glacial limits also influenced sedimentation: steeper topography provided coarser sediments for deposition; while low elevation of glacial limits reduced the availability of sediment even if steep slopes were present. This study further contributes to models of supraglacial sedimentation by documenting that sedimentation was in several lake basins, that lateral gradations in grain size are present, and that fairly significant amounts of diamicton can be present. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved. DOI
1. WARD, BC; JACKSON, LE.Late Wisconsinan glaciation of the Glenlyon Range, Pelly Mountains, Yukon Territory, Canada.Can. J. Earth Sci., 1992, 29: 2007-2012 Late Wisconsinan glaciation of the Glenlyon Range, Pelly Mountains, Yukon Territory, Canada
Airphoto analysis, identification of erratics, and stratigraphic and geomorphic investigations were used to determine the nature of McConnell (Late Wisconsinan) age glaciation in the Glenlyon Range, Yukon Territory. Most of the peaks of the Glenlyon Range were nunataks within the Selwyn Lobe of the Cordilleran Ice Sheet. The configuration of local and Selwyn Lobe moraines indicates that local glaciers did not extend beyond the cirques and made no contribution to the Selwyn Lobe. These conclusions are confirmed by the character of sediments examined in sections along Little Sheep Creek and by the distribution of erratics in one of the cirque valleys. Aridity limited local ice growth; large glaciers did not grow because of insufficient precipitation. DOI
