Also I thought that it would have been a lot deeper; picture tells a thousand words; with the depths we have been getting on the bores...we've really just looked licked the top of the iceberg.
I know some others in the past; thought that because it had been mined for so long that a significant percentage of the spod had already been dug out....yes large pit, but clearly massive resource!
The wide flat base also suggests that they weren't burrowing in pockets around the pit due to varying quality; they were able to clean cut!