Hmmm… I guess metal detectors are useful when one is trying to sift through either objects being dug up, or to pinpoint the location of shallow metal object once the site is found (in a large grave site, for instance). I should’ve made my point more clear. I meant that metal detectors are not as useful when one is trying to locate possible historical or archaeological sites, as opposed to narrowing down to a particular spot to excavate once that site is found.

I disagree mildly with how aerial survey is discounted. I believe that it does provide a very inexpensive first clue as to where some possible sites could be. For places where vegetation covers the ground most of time, soil coloring might not be as readily visible (at least not when people do not have any reasons to look for the difference). By using aerial survey, the archaeologists get a better idea on where to conduct the preliminary tests, which would yield a lot more definite information about the site once these tests are performed. Without it, it would not only be difficult to find a starting point, but would also become expensive as a lot more preliminary tests would be required before a “positive” detection is found (of course, not if one is really lucky).

I guess what I am saying is that aerial survey is valuable if one is looking for clues about possible site locations, as opposed to doing verifications on a site that is already suspected to be interesting in a historical or archaeological sense.