I've recently undertaken some surface mining in DF, and I've having more collapses (and dead dwarves) than I ever did underground.
I have a ridge like
------
xxxxxx
---------------
xxxxxxxxxxxxxxx
which I designate for digging like so
------
dddddd
---------------
xxxxxxxxxxxxxxx
Somehow I'm still getting a huge collapse which is killing my miners. Is the "layer" dropping on my dwarves?
Legend:
x: stone of some sort-: the layerd: designated for digging: open space