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We use aerial and underground adit laser scanning and photogrammetry to characterize the geometry of the landslide. Structural geology, and particularly the morphology of the lower shear zone, strongly controls the deformation and, in turn, the observed internal and surficial slope damage features. In this paper, we investigate slope damage at the Downie Slide, a very large landslide in British Columbia, Canada, that is slowly moving along two shear zones subparallel to the ground surface. Studies of these features provide insight into the mechanisms responsible for the deformation. The displacement of a large slow-moving landslide is accompanied by slope damage, such as fractures, tension cracks, and slope bulging. Units 8,9, and 10 comprise a 600 m thick succession of quartzites, quartzo-feldspathic grits and Correlation with regional stratigraphy of Frenchman Cap confirms this interpretation (Brown and Psutka 1979 Brown 1980). The presence of graded grits in units 4,5, and 6, lack of repetition of stratigraphic units, and unfaulted and generally gradational contacts are evidence that units 3-7 comprise a right-way-up stratigraphic succession. 4) confirms stratigraphic continuity across the Columbia River. An impure marble bed within unit 7 traced from the east bank to the vicinity of the adit and north to Fissure Creek (Fig. 4) the contact trends north parallel to the river, but swings westward and crosses the river somewhere near the centre of the slide and is exposed in the adit, implying stratigraphic continuity across this part of the Columbia River. However, our mapping just north of the slide and in adit 2 has shown that the contact is conformable but gradational over a distance of tens of metres. The contact between units 6 and 7 (these units are referred to by British Columbia Hydro as "West" and "East Series" respectively) has been the focus of attention for a long time as it was interpreted as a faulted contact, with the fault following the trace of the river valley.
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It contains calc-silicates, impure and graphitic marbles, quartzites, and minor pelites. Combined stratigraphic and structural cross section through Pettipiece Ridge which lithologically distinguishes it from unit 6.