How much would new dredge material dig into and displace existing beach structure?
Could the material dropped on Tena Bar in 74 have displaced money already there? To what depth?
And how would you distinguish something older from something newer, five years later?
I don't think it would do anything. they simply placed the sand over the existing area.
my guess would be that you would have to have samples of sediments for each year in question to determine when certain deposits were placed on the shoreline. I did find that a sample of the riverbed was taken right in front of T-bar and is very close to the layer above the dredge layer Palmer identifies in the chart that you have provided several times in the past. if not mistaken it was taken from mile marker 98? the Fazio's are known for good quality sand, and they get it right off T-bar..
It's possible the money was on the beach before the spoils, but they would have to remove all the new material to expose the original shoreline. since the spoils could be seen for several years after the fact, it's hard to say whether or not they went underneath the spoils when they moved, or spread the material..the placement of the spoils tell me that lots of material went right back into the river being so close to the shoreline. I tend to believe it flooded a large portion of the area's surrounding the spoils.