[MichaelJ]

It's a long and complicated story. Parents taking their kids up the cog don't like the moonscape, as do some folk. Others laugh it off, and the stories go that the engineers would throw coal back at the hikers.

The hikers are generally mooning the cog because it's a nasty, disgusting polluter belching enormous black clouds of coal smoke into the ski. It has since also become AT through-hiker tradition.

The cog has been building a new engine that's, I believe, biodiesel-fueled, so hopefully once that's in service they can copy it and get all the coal engines off the tracks. But it's still going to take time and until then, there will be sideways-smiling protesters.