Chapter Highlights18.1 Introduction18.2 Planning the Ground Investigation Programme18.3 Types of Soil and Rock Samples18.4 Indirect Methods of Sub–Surface Exploration18.5 Semi-Direct Methods of Sub–Surface Exploration18.6 Direct Methods of Sub–Surface Exploration18.7 Routine Field Tests18.8 Recording of Field Data18.9 Location, Spacing, and Depth of BoringsPoints to RememberQuestionsExercise Problems