There's an interesting article in the 30 July Science news regarding the use of ground penetrating radar on sucj locations as Omaha Beach.
It's worth the read.

Yup... it is an interesting development. If you ever get to see the series of "Time Team" you can get some awesome examples. Unfortunately this technique is not foolproof nor accurate enough to be definitive.

Actually, I watch that program when I can get a chance. I would love to go on some of those digs they've been on. I'd really enjoy tramping around in those areas. It almost seems as though anywhere you plant a spade you'll dig up an artifact!

I have been lucky enough to be able to participate in a few digs.... one stone-age, one first centuries BC and one Medieval...

It is weird, and in some way awesome to hold a flint scraping tool roughly 5000 years after it was made, and the thing still being sharp as a razorblade...

About nine years ago, while walking in our cattle pasture and after a heavy rain, I was messing around along a wash. I noticed this black object on the ground and thinking it was an old boot heel I kicked it. Out of the ground pops this stone knife blade! I was in shock. All my life I'd been hoping to find an arrowhead out there, but this was beyond my wildest dream! As luck would have it, I was attending a "paleo-picnic" and the state archeologist would be there. I took it along to show him and in hopes he could give me a rough idea as to its age. He thought perhaps it was at least 600 years old!

I know excatly what you mean by it being awesome to hold something that old. What's even better, is to imagine what the previous owner's life had been like and what circumstances led to that object being left there.

It's why I got into history

I'll dig that out and snap a shot of it and post it here so you can see it.

Take care
Steve