Untitled Sighting

My son and I were hauling our gear down to the canoe after spending the night camping. We passed each other at the top of the hill and a few seconds later I heard through the woods, maybe 125 yards away, an extremely loud bellowing, kind of like a wounded grizzly, but really really loud, it lasted 10-15 seconds then there was a pretty loud muffled talking for maybe 20-30 seconds more. What I mean by loud muffled talking is it sounded like talking that was loud, but I couldn't understand what was being said, like a different language or something? I continued down to the canoe and headed back to the campgrounds and my son was coming back down and I said "what in the heck was that?". He said  " I don't know, but it was loud". It was a dead, calm day, about 3:30 in the afternoon. The sound came from a point on the river, I told my son to go down to the canoe and watch upstream towards the rapids that go around the point and I went and got the shotgun.  I went down to the point a way that I could move quiet, so I was slowly going down there and I was hedging to the left side of the point. I hadn't heard anything, I could start to see the pool of the river upstream from the rapids so I eased over to look in the pool for fish rising, when not very far ahead of me something starts moving through the brush. It is real thick in there, I couldn't see anything, it made a real heavy sound when it stepped, I could hear every step it took, thump, thump, thump, thump, I eased to my right as to make sure it couldn't circle around me, as the point isn't very wide and my son could see the downstream side as well. The thumping and moving through the brush went towards the rapids then they quit, I headed that way to see if I could get a glimpse of what it was, but I walked right to where the point hits the rapids, and saw nothing, there are exposed rocks in the water, there was no splashing on any of them, whatever crossed had to leap rock to rock to cross, the first one being about 8 feet from shore,it may be 30 yards wide there. The point is not very big, whatever was there walked very hard on the ground and could not have gone any place else but where I followed it, by sound, like I said it was a dead quiet day, all I could hear was it footsteps and brush moving and water faintly gurgling at the rapids. No animal I know of leaps rock to rock when pursued, they just splash across to get away. We set up a trail camera there for a month and did not get any pictures.