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Basal gravel and sand mantling the bedrock floors of buried valleys throughout the Canadian Interior Plains, and conformably overlying proglacial lacustrine sediment, comprise the Empress Group. While previously conceptualized as stratigraphically equivalent deposits of preglacial rivers prior to the first and most extensive continental and montane glaciations, subsequent stratigraphic studies indicated that buried valley basal gravel must have been deposited between, or during, progressively more extensive continental glaciations and could not be stratigraphically equivalent throughout the buried valley network. However, in the general absence of formation-rank stratigraphic description of basal gravel units that might better inform the geologic history of the deposits, most workers simply consider Empress Group sediments time-transgressive. In this paper, we examine basal gravel at provincial and regional scales to understand its genesis and geologic history. At the provincial scale, we map basal gravel in three dimensions using a novel machine learning approach. At the regional scale, we formally define basal gravel formations at either end of the largest buried valley system in Alberta, which informs its glacial history and physiographic development and shows the importance of formation-rank stratigraphic description. Our results indicate that the buried valley network across Alberta is palimpsest in genesis and basal gravel units within it are chronostratigraphically intercalated between tills. We advocate that the Empress Group definition be extended across Alberta with modifications to improve its clarity and utility, and formally define the Old Fort, Unchaga, Ipiatik, and Winefred formations as part of the Empress Group. [ABSTRACT FROM AUTHOR]

During many decades, the town of Moulay Yacoub underwent an important urban expansion to meet the high demand on housing fuelled by tourism activities, which constitute the backbone of the town's economy. Unfortunately, the majority of buildings, both private and public, suffer from varying levels of damage related to the lithological, climate, and geomorphic settings of the area. In fact, the town is built on a marly hill prone to various types of mass movements, ranging from shallow soil creep to large slides. In addition, vertical displacement related to swelling/shrinkage behaviour of these Miocene marls is widespread in the area. The present paper presents a multi-disciplinary approach to investigate the activity and the interaction between slow-moving urban landslides and expansive soils within the urban perimeter of Moulay Yacoub. In fact, the severe seasonal contrast characterised by intense rainfall over short periods constitutes the main triggering factor of the instability phenomena in the region. Moreover, the desiccation cracks affecting marly soils are indicators of their expansive behaviour, which is very obvious in geotechnical tests results. The other geotechnical parameters obtained from laboratory tests show that the shallow marl samples are severely weathered compared with those of the compact material extracted at greater depth. The borehole data and seismic noise survey allows the detection of several impedance contrasts corresponding to the weathered layer – bedrock boundary, which in some cases corresponds to the rupture surface of the inventoried landslides. The very slow but perennial activity of the later processes is well documented by the inclinometers, the PS-InSAR monitoring, and building damage assessment surveys. Indeed, this case study highlights the complementarity of techniques used in this multi-disciplinary approach that give a multi-faceted understanding of slope instability processes and should provide a blueprint for future site-specific studies in the region. [ABSTRACT FROM AUTHOR]