7.8 Collection of Samples and Laboratory Analysis
Project objectives may require data from laboratory analyses. For example, particle size analyses are commonly performed on a limited number of samples in order to confirm hand texturing done in the field. Atterberg limits (plasticity), bulk density and natural moisture content may be determined for fine grained materials when terrain analysis is carried out in conjunction with geotechnical work. Petrological and geochemical soil analyses of surficial materials are included in reports related to drift prospecting. Appropriate procedures for sampling and sample storage should be determined before field work begins.
Confirmation of field determinations of the texture of fine materials, such as till matrix, is recommended for major projects with extensive field checking, when field checking is being done by relatively inexperienced persons, and when experienced mappers commence work in an unfamiliar area.
Minimum Requirements:
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If bedrock information is relevant to project objectives or a related project, then data about bedrock characteristics and the locations of rock outcrops can be plotted on air photos and maps, and hand specimens collected. This will be most useful in areas where no bedrock map exists, where bedrock mapping is being carried out concurrent with terrain mapping, and in drift-covered areas where bedrock outcrops are rare (cf. Bridgland, 1986).
Terrain mapping on air photos should be corrected according to field observations as soon as possible after field work in order to take advantage of the mapper's recollection of the field sites. If possible, this should be done in the field during evenings. It is advantageous to select field accommodation that provides space for the use of a mirror stereoscope and adequate illumination. Field notes can also be entered into computer storage each evening if facilities are available.
Figure 7. Example of data form used for site descriptions.
