Variables underpinning landslide classifications: movement: mechanism of, type of material (debris, amount of water present, rate of movement (moisture) factors to consider: (velocity, material, cohesion, climate, slope. Block slide is when rotational failure is when plane is concave up translational slide occurs parallel to slope consolidated, weathered material fails. Angle of repose determined by particle type and moisture content: courser sand= higher angle of repose, angle of repose increases as moisture increases until point. Surface tension of water holds grains together until of saturation pore water pressure pushes particles apart ledaclays: deposited when there was sea levels above areas of the st. lawrence region. Ledaclays fail when disturbed: salts can dissolve causing failure. Drainage control: surface and subsurface, controls pressure, material from top of slope is place near base thus reducing. We know the factors- material moisture and slope: slope and material are generally constants, thus the variable is moisture, which is what we measure.