Late Holocene solifluction lobe activity in the Mount Rae area, southern Canadian Rocky Mountains

Abstract

Solifluction lobes are tongue-shaped accumulations of sediment resulting from localized periglacial mass wasting. Radiocarbon records from beneath two turf-banked lobes in the Mount Rae area of the southern Canadian Rockies indicate that solifluction processes have been continuously active for at least the last 2000 years. The long-term rates of frontal movement at both sites average 0.49 cmlyear, but vary in magnitude from 0.35 to 1.50 cmlyear.Both lobes terminate above soil pedons progressively ovenidden by their advance. Estimates of the apparent mean residence time of the contemporary soil ranges from 962 + 100 years in one case to 1600 + 100 years in the other. This information was used to reconstruct a chronology of lobe activity. Collectively, the radiocarbon records indicate that solifluction lobes in this area were advancing quite rapidly between 1900-1750 years BP but declined to a much slower, but relatively constant, pace up until the present.Les langues de solifluxion sont des accumulations en saillie de sediment qui ksultent d'un mouvement de masse pkriglaciaire localisk. La datation au radiocarbone des matkriaux sous-jacents a deux lobes de solifluxion B bourrelets terreux dans la kgion de Mount Rae, dans le sud des Rocheuses canadiennes, kvble que les processus de solifluxion ont kt6 continuellement actifs durant au moins les deux demiers millknaires. La moyenne des taux a long terme de progression du mouvement frontal des deux cBtes est 0,49 cmlan, cependant les valeurs varient de 0,35 B 1 ,50 cmlan. L'extkmitk des deux lobes actifs a chevauchk progressivement les pkdons et les recouvrir. Les evaluations du temps moyen apparent de ksidence du sol contemporain varie de 962 f 100 ans pour un cas 1600 + 100 ans pour l'autre cas. Une reconstitution de la chronologie de l'activite des lobes est fondee sur ces renseignements. Un examen de l'ensemble des dkterminations des Lges au radiocarbone indique que les lobes de solifluxion dans cette kgion avan~aient assez rapidement durant l'intervalle 1900-1750 ans Av.P., et par la suite le taux de progression a diminuk considkrablement et de man2re relativement constante, pour finalement atteindre le taux actuel.[Traduit par la revue]Can.

Palaeoeskimo site burial by solifluction: Periglacial geoarchaeology of the tayara site (KbFk‐7), Qikirtaq Island, Nunavik (Canada)

“…The close grouping and lateral reproducibility of the dates (990-980, 1080-1050, and 1330-1310 yr B.P., Figure 2) is evidence of the reliability of the dating. The calculated mean annual rates of intra-site solifluction (1.68-2.33 cm/yr for calibrated ages over 350 years) are an order of magnitude greater than the long-term average rates obtained in the Canadian Arctic (Dyke, 1981;Blake, 1988;Friend, 1988), northern Labrador (Evans & Rogerson, 1988), Alaska (Reanier & Ugolini, 1983), the North American Cordillera (Benedict, 1970;Smith, 1987), and Norway (Matthews, Harris, & Ballantyne, 1986;Nesje, Kvamme, & Rye, 1989). These rates are generally less than 1 cm/yr.…”

Frontal advance of turf-banked solifluction lobes, Kluane Range, Yukon Territory, Canada

“…The closeness in age (overlapping 14 C dates), observed by many authors along extended segments of buried humus (1-5 m), have been interpreted as periods of accelerated lobe movement and tentatively attributed to changes in past climatic conditions (Benedict, 1966;Alexander and Price, 1980;Gamper, 1983;Ballantyne, 1986;Smith, 1987a;Elliot and Worsley, 1999). On the other hand, Matthews et al (1986) warned against the use of average rates of lobe advance, which they believed, are bhardly realistic if the underlying process is intermittentQ (Matthews et al, 1986, p.356).…”

“…Some researchers have dated the upper end of buried organic horizons to infer the onset of active solifluction (Worsley and Harris, 1974;Ellis, 1979;Nesje et al, 1989), and regional chronologies of solifluction activity during the Holocene have been developed based on compilations of these results (Morin and Payette, 1988; Matthews et al, 1993;Veit, 1993). In other studies, buried humus has been sampled at intervals along a continuous organic horizon to obtain a time series of individual lobe movements (Benedict, 1966;Costin et al, 1967;Alexander and Price, 1980;Gamper, 1983;Reanier and Ugolini, 1983;Matthews et al, 1986;Ballantyne, 1986;Smith, 1987a;Elliot and Worsley, 1999). Long-term rates of lobe advance obtained using this method range from 1 to 10 mm yr À 1 (Matsuoka, 2001).…”

Block and debris deposits in the high drakensberg, lesotho, southern africa: implications for high altitude slope processes

“…As the regolith is shallow on this slope, sediments may become saturated during heavy and prolonged rainfall events and/or rapid snowmelt and/or seasonal thaw events, thereby increasing the possibility of solißuction. However, the exposed section at the Njesuthi debris lobe does not show characteristics such as shear planes, inverted stratigraphy or buried soil/organic horizons, which are typical of many solißuction lobes (Worsley and Harris 1974;Matthews et al 1986;Smith 1987;Hirakawa 1989). While solißuction appears to have been operative on the slopes above the deposit, there is no morphological or sedimentological evidence to suggest that the deposit is a solißuction lobe.…”