Site evaluation for foundations and earthworks requires more detailed investigation than that required for the preparation of general purpose engineering geological maps. It is generally best carried out in several stages, all of which must take account of the functional requirements of the structure planned at the site and the practical problems which may arise during construction. Of particular importance in the preliminary stages is the mapping of the detailed soil profile and the interpretation of its significance to the performance of structures built on it. The paper attempts to encompass and extend the many previous attempts at mapping soil profiles and to provide better bases for their interpretation. Firstly, it suggests locating trial pits and boreholes according to available geological and geomorphological evidence. Standardised methods of direct observation and measurement of soil fabric data from trial pits and large inspection boreholes are then presented. The need for careful interpretation of supplementary data obtained from continuous cores of near continuous intermittent samples is fully discussed. An overall assessment of the continuity of fabric features is shown to be essential and the usefulness of geological and geomorphological evidence in this respect is highlighted. The significance of various soil profile characteristics is illustrated by data collected during site investigations of a wide range of earthworks and foundations.