As to the natural occurrence of "volcanic " material on the Wisconsin and Michigan Peninsulas. Not unless it was imported for barbecues! I've never seen a brecciated volcanic bomb and I don't think it exists by definition. (Note Mark's post on magmas and xenoliths even if he did not call them that) There is more smelting slag in the Great Lakes area than another place I know of. It was used to pave roads, build railroad ballast, even dumped into the lakes. ( Anyone remember the emerald material left by aliens recovered on the lake floor some guy was selling on the internet?)
Impact breccia could, in theory, have been transported from any of several craters on the Canadian Shield.--by glaciers or as a part of some smelting ore transport. NON impact related Breccia lenses can occasionally be found along contact faces of faults and are occasionally brought to surface in mining operations. Impact breccias look like melts or rocks that have been roasted. Other breccias likely to be found near you are more likely to have a limestone/calcium content..which will effervesce in hydrochloric acid. They will most likely contain clasts which look sedimentary.
I hope this helps to exclude volcanic bombs as a source...
Be it remembered that one or two lunar meteorites have been found with a vessiculated fusion crust ( just to keep you on needles)
Regards, Elton
* There may be a couple of islands in the arctic circle but those are associated with the icelandic system and not the North American Plate.
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