An inventory of rock glaciers in the central British Columbia Coast Mountains, Canada, from high resolution Google Earth imagery

• Published in: Arctic, Antarctic, and Alpine Research
• Main Authors: Charbonneau, Ansley A., Smith, Dan J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Arctic, Antarctic, and Alpine Research 2018
• Subjects: British Columbia; Canada; Antarctic and Alpine Research; Arctic; Ice; permafrost
• Online Access: http://hdl.handle.net/1828/12630; https://doi.org/10.1080/15230430.2018.1489026

Little is known about the presence, distribution, age, or activity of rock glaciers in the British Columbia Coast Mountains of western Canada. Reflecting debris accumulation and mass wasting under a periglacial climate, these rock glaciers describe a geomorphic response to permafrost regimes that may or may not presently exist. An inventory of rock glacier landforms in the eastern front ranges of the Coast Mountains, using high-resolution Google Earth imagery, documented 165 rock glaciers between lat. 50°10ʹ and 52°08ʹ N. The majority of these rock glaciers occur at sites positioned between 1,900 and 2,300 m above sea level, where rain shadow effects and continental air masses result in persistent dry, cold conditions. Morphology and field observation suggest that these features contain intact ice. The rock glaciers occupy predominately northwest- to northeast-facing slopes, with talus-derived rock glaciers largely restricted to north-facing slopes. Glacier-derived features outnumber talus-derived features by a ratio of 5:1. Several of the inventoried rock glaciers were located up valley from presumed Younger Dryas terminal moraines, indicating that they formed after 9390 BP. Dendrogeomorphological investigations at one rock glacier record contemporary activity that resulted in 1.3 cm/yr of frontal advance since AD 1674. This inventory is the first to document the presence of rock glaciers in the Coast Mountains and supports preliminary understandings of permafrost distribution in the southwestern Canadian Cordillera. Research funding was provided by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant to Smith. We thank Øyvind Paasche and an anonymous reviewer for their thoughtful insights and suggestions for improvement on an earlier version of the manuscript. Special thanks are offered to Bryan Mood and Vikki St-Hilaire for their assistance in the field. Faculty Reviewed