UNDERWATER DISSOLUTIONAL PITTING ON DOLOSTONES, LAKE HURON-GEORGIAN BAY, ONTARIO

This paper examines underwater dissolutional pitting along the dolomitic shorelines of the Bruce Peninsula around Tobermory, Ontario. Research was conducted from the modern spray and swash zone to depths of 25 m at four sites: Little Cove, Big Tub, Marr Lake, and Cove Island. The morphology of sample pits was measured, rock samples were collected, and comprehensive water analyses were completed. The most striking result to emerge from this work was a strong positive relationship (r2 = .93) between pit depth and water depth. Variations in the physical lithology obscured all other relationships between the morphological parameters that were studied. The detailed variations of lithology between sites and between water depths at a given site are difficult to quantify and were not attempted in this project. The Tobermory sites are distinct because they have been both totally emerged and totally submerged during the last 12,000 years. A model to explain pit genesis including initiation and enlargement incorporating this post glacial lake level history is proposed. [Key words: karren, pitting, littoral, dolostone.]