OK, I'll show my ignorance on this topic - in the thread on the 1842 dollar it was noted that we expect to see die clashes in the fields, not the devices...sounds logical... but we do see bust coinage with clashes below Liberty's ear... I can't seem to wrap my mind around it. Can these two points actually come together and not leave marks anywhere else?
I would think that's because that area right under the ear, along the "chin line", is very shallow in relief and almost at the level of the fields
Found this nice example: http://www.ebay.com/itm/1834-25C-Ca...878480?hash=item5d681fe210:g:-UUAAOSwXrhXm5ii If you look at the fourth picture, you can see the area showing the clash is sunken to the level of the fields. The clash marks appear to go underneath as soon as they get to the more raised portions. So I think this is what's causing it on coins with this design
And on the bust halves what you typically see in the center of the obverse below the ear are the white stipes form the shield on the reverse and those ARE at the same level as the field. So you have on the obv a near field level feature opposite a feature that is field level. Add to that the fact that the dies are slightly convex. That makes those two areas even closer together.
