Re: My interpretation
Jeff,
I grew up on the Juniata river. Floated it many times from Lewistown down through Mifflintown. Once Lexis crossed the Tuscarora mountain, he described a rock overlooking the river. He also later stated that someone floating a canal raft downstream might find it to his dismay. I am not sure if the canal was present when Lewis was in the area. I think if they were the canals were just completed. I have not verified this.
I do know that there are few places on the Juniata where a rock outcrop would look over the river and be susceptible to flooding. First the PRR has tracks on that side of the river. There are few places that meet this description. The RR did not do much mass excavation/blasting. There are three spots that meet this criteria....the first is at the fish commission access area in Mifflintown. On rt 22 west of town 2-3 miles. This is just downstream of the river where it comes out of the narrows. A place to possibly get caught. On the opposite side of the river from the access is a rock overlook. Legend says a wagon with people were lost in the deep hole. Legend also says of dangerous whirlpool/current. I cannot verify, only state what I knew as a youngster. The RR does not go to near the river here due to the elevation. That is why I think this the best of the three. The second place is downriver of Milfflin on the Mifflin side. across the river from the Empire Kosher Chicken Plant.
Bye the way land near the Chicken plant was a fairground for approximately 10-15 years in late 1800's. This are is scheduled for a new bridge to be started in a year or two. 1/4 mile south of Mifflintown on lands of Parker. I have not identified Parkers land yet. It was said to be riverside, but I believe it may be on top of the hill close to the Tuscarora Junior High.
The rail road is close to the river in this area and may have covered any possibilities in this spot. the third spot is below Port Royal, approaching Mexico. again the RR has run through there and may have buried the area. The canal on this section of river is on the northeastern side while boaters would have utilized the opposite side during high water to go downstream.