Nikumaroro: Challenges to Doing Archaeology - 4

The surface sorts itself, so that there's a sort of "armor" on the very surface, made up of biggish (say, finger-sized and bigger) pieces of coral, through which smaller stuff filters, generally concentrating at about 10 cm. depth.  So the surface "armor" obscures smaller items (even things like fire features made up of charcoal and ash, to say nothing of bottle shards, rouge fragments, ferrous items, and so on).

This is the stratigraphy in the north wall of our deepest unit; the logs across the top are to minimize collapse.  Again, a 50 cm. scale (and 20 cm. North Arrow).