I found this Hadrosaur Tibia in a flat area of the chocolate shale strata. Only the small 3″x3″ bleached out knob was exposed at first. The fossil was just under the surface layers of shale and so it had ben exposed to yearly weather changes. This made the top bone veneer very friable and unstable. I needed to use a lot of CA glue to stabilize the surface. The remaining portions were very were sound. I added a support bar to the cast to keep it that way in transport.