Aspects of project evaluation which come within the ambit of engineering geologists and soils engineers arise from the physical setting of the project. They are, firstly, concerned to observe and infer the distribution of soil and rocks and the ground water regime, secondly, to assess their implications for the construction of foundations for the structures which comprise the project. The first is geology and the second is foundation engineering. Foundation engineering is a subtle combination of geology and soil mechanics with the intuitive art of judgement and innovation where experience plays an important role. The role of the engineering geologist and the soils engineer is to ensure that the appropriate combination of geology and soil mechanics is used in the assessment of foundation engineering problems.
In the early days, theoretical methods of soil mechanics combined with improved techniques of exploration promised to eliminate the necessity for depending on geological information. For a period engineers felt that it was only a question of time until all the problems in the field of sub-surface engineering, like those in steel and concrete design, could be solved by theoretical methods using values determined by laboratory tests. However, the practical application of soil mechanics, coupled with field observation of performance, often showed large discrepancies between the forecast and the actual events. Re-assessment of case histories invariably showed that such discrepancies were essentially dependent on the geological characteristics of the soils and rocks.
Blind exploration of sites gave way to planned site investigations based on the