Iroquois Shoreline (trca)

TRCA hydrogeology staff created the layer in Viewlog 4.0 by creating nodes at irregular intervals (perhaps 100 m intervals where the contours were tight and up to 1000 m where the break in slope was obvious and the surficial geology showed a till/sand contact). The interpretation largely relied upon Dr. Rick Gerber's rule of thumb of 135 m asl for the elevation of Lake Iroquois (established in the Duffins Watershed) but geological judgment was used where the OGS Surficial Geology and break in slope appeared to deviate from the rule of thumb. In addition, specific boreholes, such as the one installed by TRCA hydrogeology staff at West Deane Park along Mimico Creek where sands associated with the Iroquois shoreline were discovered, were relied upon to justify following the contours up river valley where erosion makes interpretation from surficial geology difficult. The layer was then exported as a shapefile.