In the main scarp, extensive oxide staining on the slip surfaces along foliation planes is conspicuously absent. This contrasts with the nearly ubiquitous staining and iron oxide mineralization along joint (fracture) surfaces. Staining and mineralization along these surfaces is evidence of infiltrating water; therefore, its absence suggests that the buildup of pore water pressure along the slip surfaces (foliations) over the long term was not a major contributing factor in triggering the rockslide. In contrast, precipitation infiltrating along the fractures followed by successive freeze and thaw cycles over the long term dilated the fracture openings and contributed to the instability.

The primary factor leading to the instability of the rock mass was the oversteepened slope that resulted from the quarry excavation. The triggering mechanisms for the February 17-18, 2001 rockslide are more difficult to infer because they operate over both the long and short term. Slow, gravitational creep can progress until the frictional resistance along weaker foliation planes decreases to the point where the rock mass fails catastrophically. Rock creep was observed in the upper two feet of the rock mass in the main scarp immediately below the soil zone as evidenced by foliation planes deformed in the down slope direction. Although not directly related to the rockslide, the near-surface rock creep does show the long-term gravitational effect on the weaker phyllite and schist units.