GoWaterfalling’s page on Gabbro Falls has directions to this western Upper Peninsula waterfall and begins:
Gabbro Falls is on the Black River and is as impressive, if not more impressive, than its more celebrated neighbors downstream along the Black River Scenic Byway. This is a largely wild waterfall with no fences or barriers of any kind. It consists of three separate drops. When the water is high there is a fourth drop that is the height of the other three combined. The main drop falls into a narrow crevice between two large rock formations.