Michael,
 
Why use the cheap stuff?  Get yourself some 10 guage copper wire:):):)
 
Dowsing aside:)  My experience with childrens graves has shown me that
they are rarely more than 1 meter deep and usually nuch shallower.  We
have to use the burial deposits of infants and children as vertical
control during mechanical stripping because they are typically the
shallowest feature on site.
 
On most sites I have worked 10 cm is awfully shallow for core sampling
because of natural deposition.  We usually have to strip at least two feet
of overburden to visually observe the primary graveshaft.
 
One method that I have used in smaller cemeteries is probing with a
ball-swaged probe.  I grid the cemetery off with a real tight grid and
generate a database by probing at every grid square corner and recording
depths to undisturbed substrata.  This works well in this region because
hard clayey subsoil is typically overlain by only 3 to 5 feet of soil and
many of the cemeteries we work are located on agriculturally unfavourable
land due to extremely shallow soils overlying bedrock.  The tighter the
grid you use the better.  This method has great potential for generating
sub surface maps with a minimal amount of intrusion.  I have never poked a
hole in a cranium yet but stay aware of the possibility (or probability:)
After I have systematically probed the cemetery I use that data to probe
somemore.  Not only do I recover grave locations, I also can get some
dimensional data from the feature as well as the locations of tap roots:)
 
Happy Hunting:)
 
Dan Sumner Allen IV
Staff Historical Archaeologist
Mortuary Specialist
DuVall & Associates, Inc. and Cumberland Research Group