I have seen pics of Redwall Cavern @
http://www.kaibab.org/gc/wallpapr/gc_wall.htm
Is there such a thing as a 1/2 day trip to that area or anywhere near the north rim would be ok.
Thanks a Bunch
Jan

ttt

ttt

ttt

ttt

I've reread your question several times and I'm still not sure what your asking, but I'll give it try since no one else is.

Oh and all of my advice is on my assumption that Redwall is near Marble Canyon. So if I'm wrong, just ignore everything!

If you want time estimate from the North Rim to Redwall Cavern, I would think 1/2 day is too conservative to really enjoy that area. Here's a map that might help.
http://www.nps.gov/grca/pphtml/maps.html

If you staying in the south rim and would like to go to the Redwall or the north rim I'm not sure if 1/2 day is do-able. I think someone has given the time and distance before. Try searching that.

If you went to a water rafting website for the Colorado River, they might be able to give more info.
Good Luck