The Regional Synthesis Map ( Maps - GeoServ ) was compiled in a digital format from material published at different scales, in different format and having different legends. Consequently, the accuracy of the map varies with the scale of the source document and the contacts between formations were adjusted to the more recent and larger scale documents. Paleozoic formations located in Ontario were compiled from recent maps at 1:50k and the legend follows closely the one used by Williams, 1991. Precambrian formations were compiled from paper maps at scales of 1:50 000 and 1:250 000 in the central and southern part of the study area, and from a map at 1:1 million in the northern part. The Precambrian formations were grouped according to genesis due to the complexity of the geology and to accommodate the different legends used on the original documents. See Geological history or click on each rock polygon on the map for a description of rock formations and characteristics.