The Oak Ridge Moraine runs east-west through the centre of Durham Region.  The lands immediately north of Lake Ontario are heavily urbanized.  The few undeveloped shoreline areas are occupied by provincially signficant coastal marshes.

Between the south edge of the moraine and the present urban limits of Ajax, Whitby, and Oshawa lies the Lake Iroquois Shoreline.  This is a ridge of sands and glacial lake deposits (silts and clays) that marks the shoreline of Lake Ontario (glacial Lake Iroquois) left behind after the last glaciers melted 10,000-12,000 years ago.  It performs an important groundwater recharge/discharge funchtion, providing baseflow to the many Level 3 creeks and rivers that flow south to Lake Ontaro. 

For a high resolution PDF of the map, go to Associated Documents below.

For more information on The State of Greenlands Protection in South-Central Ontario report click here.