By D. A. (Midwested) on Monday, August 17, 2026 - 09:03 pm:
That area of the UP rivals the Keweenaw for it's wonderful outdoor attractions. In addition to Black Slate Falls and Quarzite Falls on the Black Slate River. There also is the Silver River, the Huron River and it's mouth. There's Mt Arvon and Arvon Slate Quarry. The black board you remember from childhood may have come from here.
In this photo of the Black Slate River, that's not a timber sunken in the river. It's a quartzite vein.