Thomson, R. 1976 Waterfall Creek Road, relocation - engineering geology. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 252
Abstract: A proposal to relocate Waterfall Creek bridge, on State Highway 6, will involve substantial excavation on both approaches and some excavation for creek realignment. Most of the excavation will be in schist, but some glacial deposits occur where proposed cut slopes are low. Variably broken rock occurs along the existing road line. Natural exposures indicate the fragmented and potentially unstable material is superficial and will be removed by excavation. Local toppling of schist blocks may occur along the crest of the steep spur on the north side of the bridge.