MAP COMPILATION

Procedures used if source maps existed

The following steps were taken when maps were compiled from existing soil maps and legends

1. Generalized small-scale maps were compiled using the most recently available, larger- scaled, soil survey source maps and their reports.
2. Using the source map scale, the size of the area that reduced to 1 x 1 cm (100 km2) at a scale of 1:1 million was established. This was selected as the smallest mappable area; most areas were larger. There were, however, a few exceptions where generalized map polygons at 1:1 million scale were smaller than 1 cm2 (e.g., narrow, elongated features and drainage patterns, strongly contrasting soil landscapes, and small islands). Map symbols were attached to these smaller polygons by use of a leader (a straight line), assuming the polygon density adjacent to these areas had room for the extra symbol and leader.
3. Translucent material with a matte surface (Chronoflex) was overlaid and registered on the soil survey source map.
4. The major drainage pattern, major physiogrpahic features, and large, uniform, soil landscape areas were delineated on the source map.
5. The source map symbols and legend information were translated to the generalized small-scale map symbol format and assigned unique polygon numbers. A change in any one differentiating property class limit on the source map resulted in a separate generalized polygon.
6. Where necessary, smaller source map polygons (similar or dissimilar) were grouped to form a composite dominant portion of the generalized polygon. Its map symbol was composed and assigned a unique polygon number.
7. Small islands with a minimum map size of 0.25 cm2 (at the 1:1 million scale) were coded as a polygon. Where small islands were situated close together in a group, a line was drawn around them to form a polygon. The portion of such a polygon that was water was estimated and indicated as a percentage on the coding form.
8. The above procedures were continued until most areas of the source map were generalized. Any remaining small areas were reviewed and a decision was made as to which generalized polygons they should most sensibly be combined with, based on similarity of the major attributes.
9. The generalized polygons and their map symbols were reviewed and compared with the source information.
10. The attributes of the soil landscape portion of the generalized polygon were coded into the database.
11. Polygon boundaries and map symbol attributes along adjacent source maps and along provincial boundaries were correlated.
12. The compiled maps on the Chronoflex overlays were reduced photo-mechanically to 1:1 million scale, processed onto clear material, formed into mosaics and registered on an appropriate 1:1 million scale map base.
13. This mosaic was carefully edited to ensure that all boundaries and map symbols were correlated between adjoining maps.
14. A map positive at a scale of 1:1 million was preprared.

Procedures used if no source maps existed:

1. Although much soil information is currently available for some northern areas, little is available for those areas where no soil surveys have been carried out (e.g., Baffin Island and some of the other arctic islands). In many cases there is also a lack of geomorphological data concerning such features as regional landforms, surficial materials, and local surface forms. This lack of information and the inaccessibility of the terrain necessitated the development of survey methodology based on LANDSAT imagery to provide both detailed information on a site-specific basis and general information in the form of small-scale soil landscape maps (Tarnocai 19771). This mapping is carried out most efficiently by a pedologist experienced in the northern environment.
2. The following survey methodology was used for most of the Northwest Territories and all of the Yukon Territory, northern British Columbia and northern Ontario. In the remainder of the Northwest Territories (primarily on some of the arctic islands) and northern Quebec and northern Labrador the same methodology was used, but ground truthing was not carried out.
3. A base map of the project area (1:1 million scale) was acquired or compiled.
4. The 1:1 million scale, cloud-free, high quality, black and white LANDSAT mosaics (controlled) were interpreted manually with the aid of panchromatic photographs, colour LANDSAT imagery and other relevant information.
5. Features most readily and consistently observable on LANDSAT imagery, including regional landforms, surficial materials, local surface forms, water bodies, wetlands, vegetation, and patterned ground were identified and grouped into polygons.
6. The smallest polygon on the map was approximately 1 x 1 cm in size; exceptions included small islands or distinct, elongated soil landscape features.
7. Translucent material with a matte surface (Chronoflex) was overlaid and registered on the LANDSAT mosaic and all polygon boundaries were transferred to the Chronoflex.
8. A unique number was assigned to each polygon.
9. The attributes of the polygon were correlated between adjoining maps.
10. Using these maps, data from existing ground truth sites was reviewed and compiled on coding forms; these existing sites had been inspected during earlier systematic traverses of the area by fixed-wing aircraft or by helicopter. The traverses were carried out during related studies to verify characteristic soil and landscape features observable on LANDSAT imagery or panchromatic photographs. Detailed information relating to terrain and vegetation were collected during ground stops, and soils were sampled and described. As much detailed information as possible was collected at these sampling sites as this data was often the only information available for the soils, terrain, and vegetation of the area.
11. The attributes of the polygon were coded into the data base.
12. Finalized map polygons with their unique numbers were transferred from the Chronoflex overlay to the base map.

Source: Shields et al., 1991 Contact: Peter Schut