1968-S Columns

Looks like some dude is being stalked by the 'Hound of the Baskervilles'.

Looks like strong die polishing to cover/remove die clash marks from the obverse die. Looks like the area targeted was the removal of the under the jaw lines created during the clash. Happens a lot. But stronger examples warrant a modest premium usually from beginning collectors. Always nice to know why the marks are there. You might ask how would marks inside those columns be affected. When viewing a die, the fields are the outside of the die. The devices are sunken (Mirror image of coin) Thus the removal of the clash marks (made in the fields) are polished/remove from the die touching only the outside edge of the die, which is the field.