Bedrock Base Map Location 5
As the Earth’s early crust stabilized, the bedrock underwent multiple cycles of erosion and weathering by wind and water. This process destroyed the more fragile mineral fragments found in the rock, leaving behind only the sturdy and highly resistant mineral quartz. These quartz-dominated sediments became widespread on the early continents during the Proterozoic Eon (approximately 2.5 billion years ago to 540 million years ago). Upon burial they were eventually subjected to high temperature and pressure which resulted in the recrystallization of the quartz grains into a singular solid mass of the metamorphic rock known as quartzite. The faint red colored zones in the rocks comes from trace amounts of iron. Intrusions of younger quartz veins (caused by quartz-rich fluid filling cracks in the rocks) can also be seen in some rocks.
Northeast Ontario | Paleoproterozoic | 2.3 billion years old