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Slope movements in the Lower Cambrian Cheshire Quartzite of the western Green Mountains in Vermont are characterized by block slides, rock falls, and more rarely by toppling failures. Slides and falls occur on steep hillslopes underlain by massive quartzite, whereas topples are unique to thinly bedded, tectonically deformed quartzite containing interbeds of graphitic schist. Freeze-thaw mechanisms dominate displacements of massive blocks, while rainfall induces toppling displacements. Movement of massive blocks occurs primarily in early spring and late fall. Bedrock discontinuties, including microfractures, joints, and bedding surfaces, are of primary importance in facilitating initial slope breakup and controlling the subsequent mode of downslope rock-mass movement. The preliminary results of investigations at three sites in the Cheshire Quartzite show that movement rates are controlled by structural conditions and slopedevelopment patterns. A typical freeze cycle during testing of a physical block model in the laboratory produced a displacement of 0.13 mm, which agrees reasonably well with the 0.26 mm annual displacements measured at two cliffedge blocks at a rockfall site. Gravity-induced toppling movements in much less massive quartzite are more rapid.

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