Anfibio=Older Coins

Just an observation: Since getting my Anfibio Multi this year, I have not had much time to use it. However, I have noticed the coins I find are older than what I have found in the past. This year, the average date of the Wheat Cents I have found is 1919.75. The average date of the Mercury Dimes I have found is 1929.5. I think this is because I am hunting parks that have been pounded by me and others in the past, and all that is left is the deeper and usually older coins. The average date on Indian Cents is 1902, so that is not a significant difference. I'm sure this is a trend that would hold true with any detector that is able to reach the coins still left in "hunted out" areas. It certainly has been fun finding the deeper coins, that have been passed over many times in the past. I'm hoping to get in some more detecting in the next couple of months.