> actually yes david

Hear hear. That mid-Atlantic ridge with asthenosphere welling up from
below to form new lithosphere looks like a crustal discontinuity to
me, too.

> but i think grants imminent global toposcopy should clarify all
> this stuff very nicely anyway while also redirecting our attention
> to the points we all share in common

Gad, you're overinvesting there, though. It's just a list of
boundaries and a few notes. Detail is notable only by its absence.

Grant