Many engineering geologists devote a significant proportion of their time to the logging of boreholes and, specifically, to the interpretation of rock cores in engineering terms. A variety of techniques have been devised for logging such cores but in the United Kingdom the systems which have been adopted are often inadequate in relation to modern requirements. The Code of Practice for Site Investigations (C.P. 2001 1957, 94) provides a minimal statement on the methods of preparing logs from borings; no specific advice is given on rock core description. It is apparent, also, that the maximum potential yield of data from many boreholes is not attained and, in consequence, the benefit from drilling not fully realized.
This Working Party of the Engineering Group of the Geological Society of London was set up with the objective of recommending methods which can be used in the logging of rotary cored boreholes sunk primarily for civil engineering purposes. It was agreed that the report should deal with the description of cores, and methods of handling and storage; only aspects of the drilling technique and programme relevant to the appreciation of the ground conditions would be included. Detailed consideration of drilling, in-situ testing and borehole inspection methods would be omitted.
The Report is intended to provide a review of the information which can be obtained from borehole cores and guidance as to the manner in which this information can be recorded. The Report has not the authority