Saddling is also caused by *wear*. Scale is an abrasive and over many years it will polish it's way down---you can see anvils with wear saddles that do not have the bottom of the face plate sagging as would be evident for settling.
You can see anvils with *both* causes evident.
One common abuse mode is to use a chisel or a hot cut on the face of the anvil---too hard a hit or angling it too far can leave a mark on the face. ALWAYS use a "saddle" or cutting plate!
I have a large anvil that was in very good shape until a welding shop used it for a fixture. it now has gouges into a nice flat face---arghhhhh
Thomas
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Thomas
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