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Surface mining of coal can involve extensive footwall slopes parallel to shallow to moderately dipping coal measures strata. Footwall failure mechanisms typically invoke bedding-parallel defects but also require either the existence of flatter structures, which cross-cut bedding, or require break-out through the rock mass to allow failure surfaces to emerge.Permian-aged Baralaba Coal Measures of the Bowen Basin, Queensland, are prospective for coal with extraction by open-pit methods. The Baralaba Coal Measures contains multiple seams within an interburden sequence comprising sandstone, siltstone, mudstone and carbonaceous variations. The coal measures sequence has been deformed into a complex pattern of NW-striking folds which has resulted in bedding dip ranging from 15° to 60°. Bedding has been classified as shallow (10–30°) to moderate (30–60°).Geotechnical investigations conducted to support coal extraction up to depths of 200 m suggest that structural controls strongly influence footwall slope design. For the purpose of footwall slope design, a distinction can be made between deposit areas of relatively simple structure (uniformly dipping bedding on fold limbs) and structurally complex areas (where layer-parallel shortening close to fold hinges has resulted in a system of low-angle thrusts and asymmetrical minor folds).

The geologic framework and sand resources of Trinity Shoal were assessed for their suitability as construction aggregate and beach replenishment material. The study of Trinity Shoal was conducted in two phases. First, potential sand deposits on Louisiana’s continental shelf were identified from published nautical charts and bathymetric maps. A regional seismic survey was then conducted in the area, in which about 800 line-km of high-resolution seismic profiles were acquired and interpreted. The second phase of the study involved acquisition of vibracores. The vibracore locations were chosen from preliminary interpretation of the seismic data, and through analysis of historical and current coastal geomorphology. From analysis of the seismic and core data, an isopach map, geologic cross-sections, and grain texture analyses were made. Texture, primary physical structures, and sequence associations were used to characterize sediment facies. Six depositional environments were delineated from the core and seismic data. The regressive depositional environments include: (1) prodelta; (2) delta fringe; and (3) distributary channel. The transgressive depositional environments include: (1) lagoon; (2) barrier; and (3) shoal. The shoal environment is represented by the marine sand body that caps Trinity Shoal, and is derived from reworking the underlying barrier facies. In contrast, the barrier environment is comprised of recurved spit, tidal inlet, washover, and sand sheet sub-environments. Seismic profiles and core logs were integrated to calibrate the seismic facies with shoal and barrier environments interpreted from core analysis. The geologic cross-sections and the isopach map show the shoal and barrier sand thickness trend thinning in a general west to east direction across the study area. Shoal and barrier sand thickness exceed 8 m on the southern or seaward flank of Trinity Shoal. The shoal’s transgressive sand facies offer the best source of material for coastal erosion control projects in terms of volume and quality, with a calculated volume of about 2 billion m3.