The Golden Mile Dolerite (GMD) is a differentiated gabbroic sill, with a thickness ranging from 600 to 940 m. * The Paringa Basalt (PB) consists of pillowed to massive basalts with minor thin interflow sediments, approximately 850 m thick. * The Black Flag Beds (BFB) are a sequence of sediments and felsic volcanics with a thickness of up to 1000 m. The thickness is reduced in the vicinity of the Golden Mile due to the influence of folding. * Porphyry Dykes (PD) crosscut all formations in the stratigraphic sequence and range from 0.5 to 10 m in width in the study area.
1.3. Data collection
Geotechnical data were required in order to design a major part of the eastern wall in the Fimiston open pit and details of the data collected are discussed elsewhere [2]. However, the following provides a summary: * Ten linear scanlines were undertaken, in which a total of 349 m of scanline were mapped for a total of 770 discontinuity measurements. Scanline mapping provided a significant amount of valuable geotechnical information and was particularly well suited to the study area where significant lengths of wall exposure are available. * A total of 1022 m of diamond drill core were logged with 1795 discontinuity measurements taken. Most holes are oriented at relatively high angles to the dominant structures, which helped to minimised bias. Samples for laboratory shear testing were selected from these holes.