Mining engineers are involved in the extraction of minerals from ore bodies that often incorporate deposition seams. Civil engineers may also need an understanding of slopes associated with earthworks on sloping terrain. Typical use could be on bulk earth structures such as water reservoir dam walls, tank bunds and the like. The ability to calculate depths and directions of drill holes, the slopes of drives and the calculation of inclined angles is not well covered in most surveying texts. This chapter attempts to show some of the simple calculation techniques available for use in the field, or as an adjunct to normal mine planning software. Field measurement of strike and dip of an exposed seam can be made using Total Stations, automatic levels or geologists’ compasses, e.g., the Brunton type. There are few references to strike and dip. Schofield and Breach (2007). Shepherd (1968, 1981) covers the subject in detail. Most field exploration by geologists will be with compass and inclinometer, the Brunton and like instruments. Thus, dip and strike directions will be measured in degrees magnetic which is converted to true azimuth by the application of magnetic declination (from maps or on-line resources).