This GIS dataset is part of a digital compilation of the bedrock geology of NTS areas 72E, 72L, 73D, and 73E. It is one of the datasets used to produce Alberta Geological Survey (AGS) Maps 567, 568, 569, and 570.
This dataset represents the compilation of existing geological maps and original geological mapping by AGS staff. Mapping included field observations and creating three-dimensional models of subsurface stratigraphy based on the interpretation of geophysical logs from oil and gas wells. Each three-dimensional formation surface was projected to a model of the bedrock surface, and the intersection formed the first approximation of the position of the geological contact at the base of the surficial deposits. We adjusted these preliminary contacts to honour outcrop data and the interpretation of the bedrock unit immediately below surficial deposits in individual wells.
The data were created in file geodatabase format and output for public distribution in shapefile format.
AGS Open File Reports 2010-10 and 2011-13 present additional information on data sources related to this dataset.
This dataset represents the compilation of existing geological maps and original geological mapping by Alberta Geological Survey staff.
The Belly River Group is comprised of the Foremost, Oldman, and Dinosaur Park formations. South of Twp. 5, the Dinosaur Park and Oldman Formations cannot be differentiated based on well logs. Selected bedrock units (Dinosaur Park, Oldman, Foremost, and Pakowki formations) were mapped in the subsurface using downhole geophysical well logs.
Other bedrock units were mapped in the subsurface using downhole geophysical well logs. Additional data points were obtained from outcrop sections, previously published maps and air photo interpretation. Elevation data for outcrop locations were obtained using topographic contour data.
To produce this dataset, we combined digital versions of existing and several newly mapped areas into one GIS dataset. We processed the data as follows:
1. Collected and assessed input data. This involved collecting datasets from various sources, assessing quality, and standardizing the attribute table in the ArcGIS environment. When necessary, we corrected datasets that were digitized by third parties.
2. Created a standard schema to house selected original and new map attributes.
3. Merged input data into one seamless layer, edge-matched the boundaries.
4. Generalized the dataset (reducing number of polygons) by eliminating small polygons not applicable to the 250 000-scale map and dissolved the boundaries between adjacent polygons representing the same geological unit.
5. Ran a topology check on the entire dataset to ensure no gaps, overlaps, slivers, or blank polygons were present.
All data were modelled using ArcGIS Geostatistical Analyst® to create structure surfaces for the top of each stratigraphic unit. The intersection of each surface with a model of bedrock topography provided the preliminary map trace for each unit. Structure surfaces were also intersected with a digital elevation model for comparison. Map traces were modified to honour the control data as best as possible.