First off, the mint mark was moved to the obverse prior to 1977. It appears to me to be an area that took a hit causing the metal to be pushed up. Of course, it could be a die chip, but with the way it sticks out I wouldn't think so. I believe the coin took a hit.
HH
enamel7
I know the mint mark moved, thats why I took pictures of both. the coin has damage, but as far as being pushed, this does not appear to have any missing material to explain the build up...