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: Ansley A. Charbonneau, Dan J. Smith
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis Group 2018
• Subjects: rock glacier; british columbia coast mountains; periglacial; permafrost; tree rings; geo; envir; British Columbia; Canada; Antarctic and Alpine Research; Arctic; Ice
• Online Access: https://doi.org/10.1080/15230430.2018.1489026; https://doaj.org/article/958928ed4eae4ef5b548b76c99b92a79

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.