Keweenawan

Keweenawan refers to a geological period and the associated rock formations found primarily in the Lake Superior region of North America. This period, the late Neoproterozoic era, is characterized by extensive volcanic and sedimentary activity. The Keweenawan Supergroup, the largest known sequence of terrestrial rift-related igneous rocks on Earth, is the most prominent geological feature attributed to this time.

These rocks are predominantly basaltic lava flows and thick sequences of sandstone and conglomerate. The sheer volume of lava erupted during the Keweenawan period is staggering, forming the bedrock of much of the Keweenaw Peninsula in Michigan and extending into Wisconsin, Minnesota, and Ontario. The formation of these rocks is linked to the breakup of the supercontinent Rodinia, which created a massive rift valley system.

The Keweenawan period is also significant for its rich mineral deposits, most notably copper. The native copper found in the Keweenaw Peninsula is a direct result of the volcanic and hydrothermal processes active during this geological epoch. These copper deposits were historically important and are still of interest today. The geological evidence of the Keweenawan period provides crucial insights into plate tectonics and the early history of Earth's crust.