This GIS dataset is a compilation of existing surficial map information for Alberta, edited for mapping continuity and generalized to make it suitable for presentation and use at 1:1,000,000 scale. It is the dataset used to create Alberta Geological Survey Map 601: Surficial Geology of Alberta. The data were prepared from an intermediate dataset (Alberta Geological Survey DIG 2013-0001), which was edgematched and then the boundaries between similar polygons were ‘dissolved.’ The residual dataset was then generalized selectively using the Geological Survey of Canada’s GeoScaler software. We then added attributes describing the generalized polygons, including unit description, texture, genetic group, and geological age.
The data were created as an Esri file geodatabase feature class and exported for public distribution as an Esri shapefile called Surf1M_py_ll.shp. The layer file Surf1M_py_ll.lyr is also included for the convenience of Esri software users (version 9.2).
Alberta Geological Survey (AGS) dataset DIG 2013-0001, Surficial Geology of Alberta: Ungeneralized Digital Mosaic (GIS data, polygon features), is an interim dataset produced while generating this dataset and AGS Map 601. Starting with AGS DIG 2013-0001 as the input source, we followed these steps:
1. Dissolved surficial mosaic input data on MAP_LABEL.
2. Eliminated polygons < 450,000 square metres, but excluded units classified as fluvial (F), fluvioglacial (FG), or colluvial ©.
3. Reclassified all glacier polygons to undifferentiated moraine. Dissolved all areas originally mapped as lake or anthropogenic.
4. Ensured reclassification is correct.
5. Fixed discrepancies along individual map area boundaries by reclassifying and, in some cases, re-mapping border areas to produce a smoother transition between them.
6. Clipped out and generalized subareas using GeoScaler software; tiled the results back together. This was a subjective, iterative process. Depending on the nature of the geography of a given subarea, we needed different parameters to produce a desirable outcome. The GeoScaler polygon generalization parameters used for the cellular automata (CA) model vary across the province. The input areas were prepared at cell sizes ranging between 150 m and 500 m. Generalization parameter values used were Moore’s neighbourhood radius = 2 in all cases, CA iterations = 5 in all cases, and minimum polygon output size ranged between 10 and 20 grid cells.
7. 'Permanent snow and ice' features were extracted from CanVec data. We generalized these 50,000-scale polygons using GeoScaler. Vector data were converted to a 150 m cell-size grid. Generalization parameter values used were Moore’s neighbourhood radius = 2, CA iterations = 10, and minimum polygon output size = 20 grid cells. We deleted polygons less than 1,000,000 square metres in the generalized result.
8. The generalized results from Step 6 were updated with the generalized glaciers from Step 7.
9. Output from step 8 were updated with generalized outlines of Lakes Claire and Athabasca taken from million-scale National Framework data, and classified as 'Lacustrine'.
10. Attributes were added to the feature class, which we then exported as a shapefile for public distribution.
All GIS work was performed using ArcGIS v. 9.3 software.