Surficial Geology of Southern Ontario

The Surficial Geology of Southern Ontario data set is a GIS based geological map that shows the
distribution and characteristics of surficial units across Southern Ontario. It illustrates surficial deposit types, material types,
geological features (e.g. drumlins, eskers) and general bedrock types and outcrops. The surficial
geology of southern Ontario consists largely of varying types and thicknesses of deposits
emplaced primarily during the Quaternary period. These surficial deposits overly a bedrock terrain
consisting mainly of Phanerozoic sedimentary rocks that overlie older Precambrian rocks of the
Canadian Shield. The data used in generating the map was derived from Quaternary maps,
primarily at a scale of 1:50 000, completed by the OGS and Geological Survey of Canada (GSC)
for most of southern Ontario over the past 40 years. A total of 125 maps, 36 of which belong to the
GSC, were used to create the seamless coverage. These original, tiled maps existed as either digital
vector or raster format. The raster images were rubber sheeted to a geographic base and digitized
(head' s up) according to standards established for the project. Polygonal, point and line
information was captured as part of the automation process. Coverages created include; sgu_poly,
sgu_point, sgu_line, sgu_mor, sgu_misc, ogs_pits and sgu_anno. Attribute tables were built and
populated with various geological related information. The original maps contained legends of
varying detail and terminology, therefore, a single, standard legend suitable for a 1:50 000 compilation was constructed. This legend, created using Microsoft ®Access Database software,
was used to translate all original map units to the new standard legend. Each of the map attribute
tables was joined to the translation table using a unique key. A series of additional attributes, for
instance, primary material and genesis were extracted from each map sheet and included in this
table.