Fig 6. Summary of the weight of backfill deposited in each host layer, and its layer of origin.

The area of the circles is proportional to the weight of sand, with the largest circle representing 286 g. Backfill originating within the same host layer as deposition was excluded from these calculations. Upward displacement greatly exceeded downward displacement, with greatest deposition tending to be in the next higher layer. "Native" was the sand weight of deposits that could not be accounted for as the diluent in the colored mixtures. Purple and yellow were combined because they occupied the same depth.