Hello Joe. Some sites are just like that, full of trash and enough to send you and your detector bonkers. While reading your post, I remembered a WW2 plane crash site that I detected a couple of years ago. the crash occured in 1938, and the ground was strewn all over with melted pieces of aluminium and other metal rubbish. There were bits of air line hoses, fuel lines, nuts and bolts, and the ground was infested with melted bits of metal from the surface down to about 12 inches in depth. The site was also located on a fairly steep hill side, so balancing yourself and detecting properly was a bit fustrating to say the least.
Getting back to your site, it sounds like some of the typicaly trashy sites I've also had the pleasure of detecting! First of all, what are you running in? What is your sensitivity set to? Are you in trash mode? Are you using a smaller coil, like the 7.5 inch coil for the Quattro? I've found, if you hunt with some form of discriminationin really trashy ground, don't be mistaken, you will still get a transfer of signals from one target to another. You also may get falsing if the ground is mineralised or iron infested from building materials that have rusted in the ground over the years, or even a nulling over targets, as in ground like this, the Quattro is slower to re-set between targets as there's so much in close proximity to each other. I'm trying to visualise the type of ground your in, from what you've said, so please bear with me.
Pick a piece of ground that isn't so concentrated with rubbish, and change to All Metal Mode. This will help prevent all the falsing, and you won't get nulling over targets. The trick here is to firstly slow down your sweep speed greatly, just using slow deliberate movements, little sweeps. I would remove the first layer, say an inch or two in about a 4 by 4 foot square bit of ground, and just concentrate on that piece of ground for now. As you sweep over the ground, throw a relic down that you've already found, and listen to the signal. You'll find that with a very slow sweep speed, and listening for the signal, it will jump out at you differently from other signals. Do this as you go with a variety of relics, like any old coins you found, and bury a few of them just an inch or two, and sweep again, locating the targets. Your mind will then begin to determine the type of signals that wanting to listen for. Each site may present different types of relics, so try to use a few relics from this particular site, as the relics will have been changed in composition somewhat, and give signals that are conducive to that site, in the type of ground they were originally buried in. With a bit of practice, you start to pick up on what I mean about the signals you are listening for.
If you just concentrate on one small area, it won't seem so mind boggling. As you work the area, taking off a thin layer at a time, the ground becomes less infested, and you should be able to pick up a variety of targets as you go. But with the ground that you removed, there could be keepers in that too. So if you're willing to see it through, and determined to locate All targets, then you would go through that soil, by picking out what rubbish you can see with your hands, and then swiping the coil over that. Always mark the area you work in, however small it is, with perhaps wooden pegs or twigs, so you know what you've covered. You can get it down pat to the point you aren't hearing any targets at all, in the area you were working on.
I have a site which I'd been working on for months using this method. Like yours, the ground was full of rubbish like roofing nails which give a great signal, and the signal is almost identical to a silver shilling! By working small areas of the ground, taking layers off the top as I go, I retreived many relics this way. It's been well over a year now, and still, I will find something I missed. Another thing you can do is, put all the rubbish into a bucket and take it away with you when you leave. That way, you're not picking up the same rubbish you threw down somewhere. Be as organised and neat as possible. This might seem like a lot of work, and it can be. But if you're determined to hunt properly, these are just some of the tricks that will see you through.
To be honest Joe, I kind of envy your old site. You country is so much older than mind, and you might be surprised that some of the artifacts you find will pre-date 1835!
All the best with it. Golden