Accurate sample description is basic geologic work - the foundation upon which the entire structure of subsurface investigation rests. This manual has been compiled to furnish convenient reference data on standard stratigraphic procedures. Techniques of examining, describing, and logging well cuttings, cores, and outcrop samples are set forth.
Although the primary responsibility of the sample logger was once that of providing correlation points for structural mapping, it has become increasingly important for him to provide stratigraphic data. The source, transporting medium, environment of deposition, and post-depositional history of the sediments all can be determined by sample examination. Two elements are involved: logging to represent what is present in the samples, and interpretation of the geologic history from the material which is logged.
A description may become so detailed and voluminous as to obscure important characteristics; the stratigrapher must learn to be selective and report only significant details . Sample studies should be made carefully and attentively. The accuracy of a study is dependent upon the quality of the samples and the skill of the observer. Thorough and careful initial examination and description of samples will save time and avert the necessity for re-examination.
