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Channel Rock Cavern
Channel Rock Cavern
Copyright 2009 by Greg Brick
Channel Rock Cavern is not a household name, but among local cavers it is legendary: it is the largest natural cave in the St. Peter Sandstone in Minnesota. (Fountain Cave is longer, but has a much smaller volume.) The following excerpt from "Subterranean Twin Cities" describes the cave. Some of the photos were provided courtesy of John Lovaas, who took them during an official inspection tour of the cave in 2008.
"In the summer of 1935, while constructing the Southeast Minneapolis Interceptor, workmen by chance dug into what remains the largest known cave under Minneapolis. (Several other sandstone caves, albeit smaller, were discovered during this same interceptor project in the 1930s, so it might even be dubbed the golden age of sewer caves.) Located near East 34th Street and West River Road, the cave is 800 feet long, 20 feet high, and 50 feet wide. In shape it’s roughly like a whale, or as I thought, like Moby Dick, arching back into one his poses in the classic Rockwell Kent illustrations. Although the name “Channel Rock Cavern” was suggested for it years ago, this name has no historical roots that I am aware of. Many cavers to this day simply call it the “34th Street Cave,” and leave it at that. Most of this cave lies within the St. Peter Sandstone, but its ceiling has collapsed upward into the overlying Platteville limestone. To the sandhogs, or tunnel workmen, the cave was a blessing in disguise because it gave them a convenient place to dump their sand as they continued digging the tunnel. Since the cave in ancient times had obviously opened onto the river banks, and had then slumped shut with material sloughing from the slopes above, it was fairly easy to create a “timbered work tunnel” out to the riverbanks.
"After the discovery of the great cavern, word got around and it attracted curious visitors. For a time, it was thought it might be converted into an underground city park. But it was finally decided to seal the timbered work tunnel on the river banks. Standing on the spot today, there is nothing whatever to suggest there’s a cave nearby. A new access point for the cave was created, a 52-foot shaft down from West River Road, capped with a hexagonal lid, and just under it, a heavy slab of concrete that required a winch to remove. The cave was only rarely visited after that, so that any visit became newsworthy, as in 1972, when sewer workers discovered “several fake graves” that someone had set up inside the cave, probably in the 1930s. In 1979, WCCO broadcasted the first televised visit to the cave on the “Moore-on-Sunday” show. In 1980, the National Speleological Society held its annual convention in the Twin Cities, and this cave was one of the featured stops, again generating newspaper publicity. There were several trips in the 1990s, for the benefit of visiting Canadian researchers, allowing them to collect samples of flowstone that had grown over the timberwork inside the cave, for the purpose of dating it. But any visit was a big production, because the road had to be blocked off temporarily so the lid could be safely removed."
