Dough sets (gelates) first at the loaf surface (crust). Gases migrate =
away
from the thusly-impenetrable crust. They may exit through any beach=20
they find in the crust, resulting in a depression or dimple or collapse. =
=20
Otherwise a bubble, or bubbles, may form. Said bubble may fly the =
crust,=20
or breach it, causing local collapse.

Taking all of, or most of, the rise before baking is one solution.

(Roy, you don't like that, do you? Much too simple! Listen Roy --
bakers are not rocket scientists, nor should they expect to be.)

R.f.s.-group-googling "flying crust" (in the message texts) brings up a=20
pyrites gold mine of ancient mumblings.

Hey, the Library called to say the Hamelperson's book I ordered has
arrived. Tomorrow I will know everything. So ask me again.

--=20
Dick Adams
<firstname> dot <lastname> at bigfoot dot com
___________________
Sourdough FAQ guide at=20
http://www.nyx.net/~dgreenw/sourdoughfaqs.html