May 2024
Written in preparation for a visit…
The Keweenaw Fault
The Keweenaw Fault is a ~100 mile reverse fault that bisects the Keweenaw Peninsula of the Upper Peninsula of Michigan and marks the boundary between the Mid-continent rift and continental rocks. The fault is a reverse fault that thrusts lava flows of the Midcontinent Rift System onto sedimentary rocks of the Jacobsville Sandstone, and is part of the inversion of the Midcontinent Rift where a region that had previously undergone extension experienced significant contraction during the final stages of the Grenville orogeny. There are few (no) surface indications of the fault; but the Pilgrim river runs along the sandstone side of the fault trace.
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