Basically this means that the gold veins they are mapping out do not end at the measurements they have given. So if they've said the vein is 1.3km long and 70m deep thats only what they have uncovered so far. After they hit the 70m depth they were still finding gold but stopped drilling.

The reason they wouldn't just keep drilling further is that they're only trying to understand the shape of the gold structure at this point. Until they know and understand what the gold deposit looks like they don't want to wast money drilling in random locations. It costs a fortune to drill deep and their property is absolutely massive. So they've done shallow drilling and will follow that up with less expensive survey(airborne magnetic surveying) to see where they should drill deeper. This also speeds up the exploration process because drilling deep holes takes a lot of time as well.

So essentially they are doing everything as cost effective and systematic as possible to follow their strategy of "maximizing shareholder wealth"

Hope that helps.
Gamblor.