Bedrock Geology of the Vermilion Area (NTS 73E)

This map shows the bedrock geology of the Vermilion area (NTS 73E) in Alberta. Exposed bedrock in the area is composed dominantly of Upper Cretaceous clastic sedimentary rocks of the Bearpaw Formation, Belly River Group, and the Lea Park Formation. From west to east, there is a complex transition between nonmarine to marginal marine clastic rocks of the Foremost Formation and marine mudstone and siltstone of the Lea Park Formation.

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.

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.

As the regional structure of the area is gentle, map patterns are controlled to a large degree by topography on the bedrock surface.