Keewatin Series

The Keewatin Series refers to a division of Precambrian rocks found in Ontario and northern Minnesota, dating back to approximately 2.6 billion years ago. These rocks are primarily sedimentary and have undergone varying degrees of metamorphic alteration.1

While some geologists believe the Coutchiching Series underlies the Keewatin Series, others dispute this, and further study is needed to clarify their stratigraphic relationship. It is likely that much of the Coutchiching Series is interbedded with lava flows assigned to the Keewatin Series, suggesting they may be partly equivalent in age. The Seine Series, which overlies the Keewatin Series, is separated by an unconformity, indicating a significant period of erosion before its deposition.12