[agrandis]

My WAG on the lines: they are looking for things(?) that would fit between those lines, so are going to dig trenches along the lines and find all the things.

[DoughtyOne]

It's a gridwork so that they are very sure the metal detector scans every inch of ground. Without the grid, it would be hit and miss.

[blam]

"My WAG on the lines: they are looking for things(?) that would fit between those lines, so are going to dig trenches along the lines and find all the things."

No, that's they way you do a grid search and lay things out on a map.

[HoustonCurmudgeon]

My WAG on the lines: they are looking for things(?) that would fit between those lines, so are going to dig trenches along the lines and find all the things.

The lines are a search pattern for hand held metal detectors or ground penetrating radar. The distance a man can swing one with comfort.