QUATERNARY GEOLOGY OF ST. JOSEPH ISLAND, ALGOMA DISTRICT.

Mapping has been completed of St. Joseph Island in northwestern Lake Huron, Canada. The chief economic product of Quaternary age in this study area is sand and gravel from the extensive raised beach deposits. Large reserves remain, with most of the gravel finding only local use. The gravel is petrographically of good quality, being dominantly of Precambrian rock types, but the abundance of boulders makes crushing commonly necessary for most purposes. Substantial volumes of clay are present but have not been exploited.