I spent a long day carefully removing some “overburden” ( unfossiliferous rock) from a small corner of the block adjacent to the smallish femur that I found recently. If the matrix didn’t change so quickly and there weren’t so many cracks in the rock and the bone didn’t have so many hairline cracks this would be a piece of cake! A lot of these bones are like icebergs, just some tips showing at first. I’m not sure what’s going on next to that femur.
The gray rock to the left is an upper layer of fine-grained mudstone, generally not as rich in bone as the greenish-blue sandy rock below. Most bone is covered with a sort of dappled dendritic overlay of orange-red iron oxide, presumably hematite. The half a dozen vertebra in the bottom of the picture is in the upper layer and has a much darker coating. The oxide often appears in a fraction of an inch zone of rock around the bone, sort of a halo that sometimes is useful for warning me a bone is near- but not always.
More to come next week.