Here is the point at Pittsburgh. The Allegheny is bringing in ice from the top of your picture. the Mon is flowing in from the right. Both rivers empty into the Ohio off to the left. Somehow, Ice flowed up the Mon. THe current is low today with a slight wind blowing left to right on your picture. However, I'm supprised this amount of Ice came up river. My guess is at least 300 ft. Perhaps the Al is flowing slightly faster, creating an eddy on the mon side of the point?