Digital versions of 68 existing maps were combined with new mapping data to produce an Alberta-wide GIS dataset. We processed the data as follows:
1. Existing digital data from 68 previously published maps were combined into an Alberta-wide GIS dataset. These features were classified as moraine ridge, overridden moraine ridge, ice-thrust ridge, meltwater channel (major and minor), streamlined bedform, esker, crevasse-filling, or dune ridge.
2. A DEM dataset was assembled, consisting of shaded-relief images produced from 5 m resolution, bare-earth LiDAR digital elevation models (DEMs). Areas of the province currently without LiDAR coverage were supplemented by shaded relief images produced from a 25 m Alberta Environment and Sustainable Resource Development (ESRD) DEM.
3. Multiple shaded-relief images from differing light source directions were generated in areas exhibiting a complex linear landform assemblage, using both the LiDAR data and ESRD DEM. These images were reduced into a three-band image using principal components analysis (PC1, PC2, PC3) to eliminate any potential directional bias in the visibility of linear features.
4. The compiled glacial landform digital data were overlain on the LiDAR DEM and/or ESRD DEM to confirm whether they had any distinct topographic expression. Any inconsistencies in previous mapping and classification were either corrected, or if hypothesized features exhibited no topographic expression, they were not included in this dataset. In areas where compiled line features occurred as closely spaced or segmented lines, individual lines were either selectively removed or connected until the pattern and continuity of individual landforms became visible. A small proportion of landforms were defined by polygons on the original maps. These features were remapped as a new line feature that corresponds to the central axis or crestline of the landform.
5. Additional data sources, consisting of reports and published research papers were consulted, scanned and georeferenced where appropriate. Because much of the data in these sources were presented as small-scale figures, these sources of information were used as a guide for delineating additional landforms by using the LiDAR and/or ESRD-DEM to re-trace the previously identified landforms where visible on our imagery sources.
6. New digitization of landforms was performed across areas of the province which were previously unmapped, using the LiDAR DEM and/or ESRD DEM. In addition, for areas of the province that were previously mapped using airphotos but where LiDAR data coverage now exists, we assessed the reliability of the previously published landform mapping and augmented these maps with new landform mapping based on interpretations from the LiDAR imagery.