Could be J, There IS a lot of marine material in that creek. In her youth, Badger found a perfect vertebrae from the X fish there.
Before the flood control dams were built and nature ruled.. some of those gravel bars perfectly classified
out various density of materials in long rows...we once found about 20 ray teeth ( 1/4 inch ) all along one
I was surprised by a similar classification at C3 last week..in a rapids area about 15 inches deep I found 2 concentrated areas of just pure hemetite ( iron )