7.0 Methodology III: Field Work

7.1 Objective

Field work is carried out in order to confirm or correct the pretyped terrain data, and in particular, to check those characteristics of surficial materials, such as texture, that cannot be adequately interpreted from air photos. Additional data may be collected if required by project objectives.

7.2 Time Required for Field Work

The field time necessary for a project is based on the TSIL that was specified according to project objectives (Section 5.1), and hence the number of polygons that must be checked. The average length of time required per field-checked-polygon will depend upon the following conditions:

• Terrain characteristics; polygons of complex terrain, such as ice-disintegration moraine with kames and pockets of glacial lake sediments, may require extensive checking and the establishment of more than one "observation site" (see Section 7.4).
• The time required to travel from one observation site to the next; this will be greatest where travel is on foot through dense forest without trails and least when a vehicle or helicopter can be used.
• The amount and type of information to be collected at each site; descriptions of natural or artificial exposures where stratigraphic features are visible will require more time than soil pit observations.
• If the terrain mapper is part of a group collecting multi-disciplinary information, such as during biophysical mapping (e.g., terrain, vegetation and wildlife specialists working together), then time per site will be determined by the group member who is collecting the most information, and this is not usually the terrain specialist.

Depending on the above conditions, rates of progress range from about 4 to 10 polygons per day. Additional polygons may be checked briefly as the mapper travels from one observation site to the next, see for example Section 7.5. Potential delays due to bad weather should be included in time estimates.

7.3 Initial Procedures

An experienced mapper will begin field work in an area with which she/he is not familiar by carrying out rapid reconnaissance traverses and examining major exposures of Quaternary materials. Information so gathered provides input to the model of the area's geomorphological history that was constructed during preliminary air photo interpretation. If logistics permit, this preliminary work will be done before detailed checking of specific polygons commences. Otherwise, exposures should be examined when the mapper is in the vicinity.

7.4 Observation Sites

In order to collect information about the surficial materials in the polygons that are to be checked, the mapper should, where possible, designate "observation sites" where materials are well exposed, such as road cuts, river banks and landslide headscarps. If exposures are not present, sites will consist of pits or trenches excavated with shovels or mechanical equipment, or auger holes. Sites may also be designated where surface observations are sufficient to confirm (or modify) pretyping, such as on talus slopes and active floodplains. The use of site description forms is discussed in Section 7.6.

Minimum Requirement: Observation sites shall be numbered, marked on the air photo and shown on the completed terrain map.