Yes, this is true that a natural and free St Anthony Falls would gradually retreat upstream and eventually erode down to a stretch of rapids. However, it may be a beautiful and grand waterfall to behold for one or two thousand years until that happens. I find a lot of beauty in natural river rapids also - much more beauty than I usually find in artificial stream impoundments behind concrete.
Dave Stack Harrison > Karen Cooper wrote : >> I expect that's not possible. It's not the construction projects that have been the most damaging (although that tunnel under the river that collapsed was a Real Problem). The problem with "restoring" St. Anthony Falls is that the falls are created from a limestone cap over a layer of sandstone. The water erodes the softer sandstone, and the limestone cap, unsupported, breaks off. St. Anthony Falls thus retreats upstream, and has been doing so for 1,000s of years. The limestone cap gets increasingly thin as it is followed upstream. Shortly upstream of the place of the current St. Anthony Falls, the limestone peters out and disappears. Without that, St. Anthony Falls becomes a ripple in the river. The apron that is the current falls is protecting the remaining limestone. >> _______________________________________ Minneapolis Issues Forum - A City-focused Civic Discussion - Mn E-Democracy Post messages to: mailto:mpls@;mnforum.org Subscribe, Unsubscribe, Digest, and more: http://e-democracy.org/mpls
