[Rockhounds] Giant lava flow hiding in plain sight in Michigan

[Kreigh Tomaszewski]

When people think of volcanoes, they don’t typically think of Michigan. But
volcanic activity was the driving force behind some of Michigan’s key
resources and landmarks.

Ancient volcanic activity
<https://www.nps.gov/parkhistory/online_books/geology/publications/pp/754-C/sec2.htm>
is
the reason why the Upper Peninsula is so rich in minerals. The evidence is
hiding in plain sight.

What we see as Isle Royale and the Keweenaw Peninsula is actually part of
the one of the largest known lava flows on Earth.

The Midcontinent Rift System
<https://geonarrative.usgs.gov/mrs_mineral_deposits/> is a massive break
within the continental plate of North America. It first formed
approximately 1.1 billion years ago, with arms stretching roughly from
metro Detroit up through Michigan, Lake Superior and into northern Ontario,
then west over to Minnesota, then south down through parts of Iowa,
Missouri and Kansas.

https://www.woodtv.com/news/michigan/giant-lava-flow-hiding-in-plain-sight-in-michigan/