spider,
look at the map provided by ngex, posted by sam. The blue areas are expected to contain potash, those southern holes were drilled on the white, no potash area and is to confirm the potash boundary of the southern end. They are too close to the border anyway.
If you look at the earliest map provided by STB, you will see question marks along those drill holes that yielded little potash. So is something we are fully aware of and expected.
