I can help you out with your question somewhat.
The beaver tail soft drink tabs (pull and toss tabs) came to be in 1965 they ended in 1975.
The modern square tab (actually is called a sta-tab) replaced the pull and toss rings.
Now the soft drink pull and toss is not to be confussed with other pull rings like potted meat, vienna sauges, ect.
Yes! I like to find the pull and toss tabs, that tells me a lot about the site, I know that for the most part silver (fresh dropped) will mainly be below that layer of beaver tail tabs. And they are a pretty good sign of how deep the good coins are going to be. The layer of them in our local park is 3" to 5" (and there is a bed of them for sure! Thousands and Thousands of them there). So that means if your going to get to the 1960 stuff and older (here) then you'll need to at lest get down to 6" (of dirt).
Here is something to think about,
If the top of the pull ring layer is 3" to 3.5" and that's 1975's then how many inches per-year are they settling?
Now if the area is a known park that opened in 1920 about how deep is the 1930 stuff?
Its not exact, but it gives you an idea. Keep in mind that with the above I'm thinking of fresh dropped coins (fresh dropped, I mean a 1930 quarter being dropped in 1930!) Its possible for a minted coin to have been dropped YEARS after it was minted.
I found a old golf course where pull rings where less than 2" deep, some could be seen still at the surface, the silver that we found was less than 3".
So, every area is different. What's sad is I found an area around here that I know dates back to the mid 1800's but I was finding aluminium Pepsi cans at 7"
So, I knew that it was hopless trying to find the old stuff there.
Hopes this helps.
Mark
