Hunt’s Guide to the UP has this to say about the Lower Harbor Ore Dock in Marquette:
Once rail cars moved onto this massive sandstone dock to unload iron ore into the holds of waiting ore carriers via “pockets” or chutes. After a 1971 strike the Lake Superior & Ishpeming rail line through downtown was no longer used. The newer ore dock by Presque Isle was enough to meet later needs. As part of a plan to redevelop the Lower Harbor and South Rail Yards, the 3,000-foot trestle approaching the docks was torn down, removing a longtime landmark across Front Street and opening up a long waterfront corridor for public use.
via the YouTube you can see a super-sweet video of a stand up paddleboarder making a complete circuit of the ore dock
More Marquette on Michigan in Pictures.