So more then likely the 18 footer has been dipped. And could be as old as 1840's Well I am still going to get into the crawl space and take a look. Boy that would be great to find a sink hole or something down there. There might be enough room to use my 4' probe I hope. Also I will do some more probing towards the left side of the map on the outside. For a pit that old I would say its worth the effort. I will be sure to post any findings. Thanks for all the help everyone! Also for what it worth here is another pontil shard I found in the 18'er.