Neoglacial history of the Coast Mountains near Bella Coola, British Columbia

Desloges, Joseph R.; Ryder, June M.

doi:10.1139/e90-027

Cited by 59 publications

(52 citation statements)

References 15 publications

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“…This history is based on lichenometic and dendroglaciological investigations undertaken during the summer of 1997. Previous work in this region showed that most LIA terminal moraines date from the period between 1860 and 1900 (Desloges, 1987;Desloges and Ryder, 1990). Our data supplements these observations, adding to our knowledge of the LIA in coastal British Columbia.…”

Section: Introductionsupporting

confidence: 82%

“…5). This curve provided an opportunity to reconsider the findings of Desloges (1987) and Desloges and Ryder (1990).…”

Section: Discussionmentioning

confidence: 93%

“…Based on dendrochronological studies of sixteen LIA moraine systems surrounding the Monarch Icefield, Desloges and Ryder (1990) showed that most terminal moraines were deposited in the 19th century. During reconnaissance investigations, however; Desloges (1987) also noted three sites (Borealis, Deer Lake and Fyles Glaciers) where fresh-appearing moraines bordered a more weathered moraine.…”

Section: Discussionmentioning

confidence: 99%

“…Carte de localisation du site à l'étude dans la région côtière centrale de la Colombie-Britannique. points 8, 11 and 12 were derived from the diameter of the largest Rhizocarpon geographicum measured on three LIA moraines found around the Monarch Icefield 50 km to the south (Desloges and Ryder, 1990). The minimum age assigned to each of these lichens was determined from the age of the oldest tree found growing on the same moraine (Desloges, 1987).…”

Section: Lichenometrymentioning

confidence: 99%

“…Records from coastal British Columbia and nearby Alaska indicate that there were three main episodes of LIA glacial activity (Wiles et al, 1999 ;Luckman and Villalba, in press). In the early-LIA, radiocarbon and dendrochronological evidence illustrates that glaciers advanced throughout the 13th and 14th centuries (Ryder and Thomson, 1986;Ryder, 1987;Desloges and Ryder, 1990;Wiles et al, 1999). This episode was followed by a hiatus, until late-LIA glacial advances in the 17th and 19th centuries (Ryder and Thomson, 1986;Ryder, 1987;Desloges and Ryder, 1990;Clague and Mathewes, 1996;Calkin et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

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Little Ice Age history of Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia

Smith¹,

Desloges²

2002

gpq

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This paper describes licheno- metric and dendroglaciological investigations of Little Ice Age (LIA) deposits at Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia. The glacier originates from an ice- field on the northeast flank of Tzeetsaytsul Peak and terminates in a moraine-dammed lake. A stream draining the lake has incised the moraine dam and flows through nested moraines into a second lake. Two end moraines near the lower lake record separate advances, with numerous morainic ridges found between the two lakes. A locally calibrated Rhizocarpon geographicum growth curve was constructed and provides relative ages for all the moraines. Absolute dates from wood fragments collected from within the morainic debris were determined by matching their annual growth ring patterns to a local Abies lasiocarpa tree-ring chronology. The outermost terminal moraine was deposited by a 17th century advance that culminated in ca. 1700. Following subsequent recession, Tzeetsaytsul Glacier readvanced to build a second terminal moraine by the mid-1800s. Recession of this glacier occurred within 40 years and by 1935 the glacier was beginning to calve into the uppermost lake. The research shows that the most recent LIA advance of Tzeetsaytsul Glacier was not the most extensive, and that multiple events characterized the late-LIA. Application of the Rhizocarpon growth curve indicates a previously unreported 17th century advance at other glaciers in the region. These findings serve to reinforce the synchroneity of late-LIA glacier fluctuations within the coastal cordillera of NW North America suggesting that they record regional climate forcing.

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Section: Introductionsupporting

confidence: 82%

“…5). This curve provided an opportunity to reconsider the findings of Desloges (1987) and Desloges and Ryder (1990).…”

Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Lichenometrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Little Ice Age history of Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia

Smith¹,

Desloges²

2002

gpq

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Dating young geomorphic surfaces using age of colonizing Douglas fir in southwestern Washington and northwestern Oregon, USA

Pierson

2006

Earth Surf Processes Landf

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Dating of dynamic, young (< < < < <500 years) geomorphic landforms, particularly volcanofluvial features, requires higher precision than is possible with radiocarbon dating. Minimum ages of recently created landforms have long been obtained from tree-ring ages of the oldest trees growing on new surfaces. But to estimate the year of landform creation requires that two time corrections be added to tree ages obtained from increment cores: (1) the time interval between stabilization of the new landform surface and germination of the sampled trees (germination lag time or GLT); and (2) the interval between seedling germination and growth to sampling height, if the trees are not cored at ground level. The sum of these two time intervals is the colonization time gap (CTG). Such time corrections have been needed for more precise dating of terraces and floodplains in lowland river valleys in the Cascade Range, where significant eruption-induced lateral shifting and vertical aggradation of channels can occur over years to decades, and where timing of such geomorphic changes can be critical to emergency planning.Earliest colonizing Douglas fir (Pseudotsuga menziesii) were sampled for tree-ring dating at eight sites on lowland (< < < < < 750 m a.s.l.), recently formed surfaces of known age near three Cascade volcanoes -Mount Rainier, Mount St. Helens and Mount Hood -in southwestern Washington and northwestern Oregon. Increment cores or stem sections were taken at breast height and, where possible, at ground level from the largest, oldest-looking trees at each study site. At least ten trees were sampled at each site unless the total of early colonizers was less. Results indicate that a correction of four years should be used for GLT and 10 years for CTG if the single largest (and presumed oldest) Douglas fir growing on a surface of unknown age is sampled. This approach would have a potential error of up to 20 years. Error can be reduced by sampling the five largest Douglas fir instead of the single largest. A GLT correction of 5 years should be added to the mean ring-count age of the five largest trees growing on the surface being dated, if the trees are cored at ground level. This correction would have an approximate error of ± ± ± ± ±5 years. If the trees are cored at about 1·4 m above the ground surface (breast height), a CTG correction of 11 years should be added to the mean age of the five sampled trees (with an error of about ± ± ± ± ±7 years). Published inDating of many types of young (<500 years), dynamic, geomorphic landforms (such as mass-movement erosional tracks and deposits, river terraces, floodplains, tsunami impact zones, etc.) for purposes of hazard assessment and mitigation commonly requires greater dating precision than is available through radiocarbon methods. Post-eruption geomorphic responses in channels of rivers draining volcanoes can be particularly rapid and complex of tens of metres and lateral adjustments of hundreds of metres can occur over periods of only days to decades (e.g. Rodolfo et al., 199...

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Development of the critical zone environment in the highly dynamic landscape of the Forni Glacier forefield: Winds, tree vegetation, pedogenesis and surface waters after glacier retreat

Leonelli,

Masseroli,

Trombino

et al. 2024

Earth Surf Processes Landf

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The expansion of glacier‐free forelands after glacier retreat is emerging as a typical climate change‐dependent feature that is widely studied for assessing biogeomorphic feedbacks and analysing the vertical processes and changes occurring in the critical zone (CZ). However, the horizontal processes occurring in the CZ environment are still poorly understood. Here, we comprehensively analyse the development of the CZ environment over time in the Forni Glacier forefield, Italian Alps, since the end of the Little Ice Age (LIA) by considering different sectors (air, forest, water and soil) in two portions of the glacier forefield: the lower portion, which occurs below the glacier‐forefield treeline (GFT), where a fully functioning CZ environment has developed, and the upper portion, which occurs above the GFT, in the proglacial area (PA), where only an incipient CZ exists. The early stages of CZ development in the PA are highly influenced by katabatic winds, which impact the colonisation patterns of saplings and young trees, and characterised by high‐energy geomorphic processes that cause sediment reworking and initial stages of soil development. Below the GFT, the minimum tree ecesis interval after glacier retreat reaches a median value of 38 years (n = 8), and the fully developed CZ environment (with trees reaching at least 2 m in height after 20 years) formed after ~60 years following glacier retreat and is characterised by forest cover, soils organised in a chronosequence and contrasting isotopic signatures of surface and running waters. The correlation with the isotopic signatures of tree rings allowed us to estimate a groundwater flow period of approximately 2 months from the slopes into the CZ of the valley floor. By analysing the horizontal processes driving the geomorphic and biotic evolution patterns of a glacier forefield, this work introduces a novel approach for assessing the development of the CZ environment over time.

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Neoglacial history of the Coast Mountains near Bella Coola, British Columbia

Cited by 59 publications

References 15 publications

Little Ice Age history of Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia

Little Ice Age history of Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia

Dating young geomorphic surfaces using age of colonizing Douglas fir in southwestern Washington and northwestern Oregon, USA

Development of the critical zone environment in the highly dynamic landscape of the Forni Glacier forefield: Winds, tree vegetation, pedogenesis and surface waters after glacier retreat

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