Here's a true story that will help.... In 1998, my wife and I were visiting my in-laws in PA. A neighbor walked over and saw my metal detector and told an interesting story. In 1960, his two boys were fighting and one of them threw his brother's silver dollar across the road into tall grass. They couldn't find it and I said if I found it, his son would get it back. The grass was now short and after a few sweeps, my detector indicated a dollar was down 6". So after 38 years, it was down 6".
1970 COMPASS-
WHITES SILVER EAGLE-
WHITES DFX, 4X6DD COIL, 6X8DD COIL, 950 COIL, 10X12SEF COIL-
GARRETT PRO POINTER AT, GARRETT AT PRO , MINELAB EXPLORER SE with 8.5x12.5 Cors coil
Portlynn,
Welcome to Treasure Net !!
By now your lost item could be in my collection case; four feet above ground.
Due to too many other variables to consider, the exact answer is not possible.
Don.......
Welcome from Colorado. Interesting question, and hard to say. Alongside a road, may not even be in the area, could have been washed far away. It pretty much depends on the geology of the area I guess. I found an 1876 dime a half inch below the surface. I found military artifacts from the 1850's on the surface. I found a 10,000 year old mammoth tusk 10 ft. below the present surface. Depends a lot on the type of erosion in an area.