Trenches are usually employed to expose steep dipping bedrock buried below shallow overburden, and are normally dug across the strike of the rocks or mineral zone being tested. Trenches are an excellent adjunct to RAB or RC drilling programs, where the structural data from trench mapping are needed to complement the lithological information obtained from the drill cuttings.

In some cases, it may be possible to completely strip shallow unconsolidated overburden to expose large areas of bedrock. This is done by bulldozing and/or by sluicing with high-pressure water hoses. The bedrock can then be mapped and sampled in great detail. Since the process is environmentally destructive, and rehabilitation would be expensive, extensive stripping would normally only be attempted when a prospective mineralized zone had been defined, and special sampling/geological problems were present that needed this kind of 100 % exposure for their