Porphyry Island is the last island in a chain stretching southwest from the Black Bay Peninsula. It is generally flat to rolling with little relief and the rugged shoreline offers little shelter. The rocks of the peninsula and the island are of Late Precambrian age and consist of more than 300 distinctive lava flows. These ancient volcanic flows are typically grey-green basalt intermixed with minor amounts of sedimentary rocks. Geologists call these rocks the Osler Group. The island and nature reserve take their name from the characteristic quartz and feldspar crystals, or porphyries found in the volcanic rocks. The nature reserve is on the southern margin of the boreal forest. Its interior supports a mixed forest dominated by white birch in the south and balsam fir in the north. Wetlands with concentrations of black spruce are also found here. Lichens are commonly seen draping mature trees and as barrens intermixed with hardy flowering plants along rocky shorelines. The rocky shores also support arctic species, like encrusted saxifrage, insectivorous butterwort and the sedge. Of greater interest is the presence of devil’s club in the forest. Populations of this thorny shrub here, and on adjacent islands, are the only known occurrences east of the Rocky Mountains.
Park Facilities and Activities: This nature reserve is managed to protect its significant biological and geological values. There are no visitor facilities and the islands remote location makes visitation difficult. The unauthorized collection of rare plants and other natural objects from the nature reserve is prohibited. Anyone wishing to conduct scientific research must obtain an approved research application.
Location: The southern end of the Black Bay Peninsula, in Lake Superior, east of Sleeping Giant Provincial Park.