Warning SCIENCE content:I tested falling dwarves in arena mode [31.18] and got interesting results. On impact, the ground generates a semi-random number of blunt attacks (2-9) against random body parts. Most clothing doesn't appear to protect against this damage. The damage usually breaks bones in the area, or heavily bruises tissue (turning organs cyan). More attacks appear to be generated when you fall from a greater height.
On average, 20% of fallers die of brain damage on impact, and 15% die of suffocation due to upper/middle spine fracture. 35% average death rate for heights between 2z and 8z. 1z falls suffer no injury. I couldn't test more than 8z in the arena. You'd need a fort to test greater heights.
A dwarf can fall 2z, land on his head, and die. A dwarf can also fall 8z and live, though all survivors have broken bones and are unconscious from the pain.
Odd stuff:
-only breastplates and greaves appear to deflect the damage
-helms do nothing to protect against brain damage from falls
-each "ground attack" trains armor user and dodger skill
-armor user and dodger skills don't reduce/avoid damage
-heavy animals don't suffer more than light animals
-hard materials like teeth, tusks, and bronze are often severed
-creatures with many body parts fare better than ones with few body parts
-GCS are boneless, painless, have many spare legs, making excellent drop troops
Raw data:
1z:
20 dropped, no injury
_____________________________________________________
2z:
20 dropped
3 died after colliding with an obstacle (skull fractured into brain)
2 suffocated in short order (both had middle or upper spine damage, no lung damage!)
15 unconscious with broken bones, vomiting
number of "ground attacks"
1
2xxx
3xx
4xxxxxxx
5xxxxx
6xxx
7
_____________________________________________________
3z:
20 dropped
2 died cwo (skull=>brain)
6 suffocated (spine broken)
12 survivors
1
2
3xxxxx
4xxxxxx
5xxxx
6xxx
7xx
_____________________________________________________
4z:
20 dropped
5 died cwo (skull=>brain)
1 suffocated (spine)
14 survivors
1
2
3x
4xxxxxxxxx
5xxxxx
6xxx
7xx
8
_____________________________________________________
5z:
20 dropped
5 died cwo (skull=>brain)
2 suffocated (spine)
13 survivors
1
2
3x
4xx
5xxxxxxx
6xxxx
7xxxxx
8x
_____________________________________________________
6z:
20 dropped
3 died cwo (skull=>brain)
3 suffocated (spine)
14 survivors
1
2
3
4
5xxxx
6xxxxxxxx
7xxxx
8xx
9xx
_____________________________________________________
7z:
20 dropped
6 died cwo (skull=>brain)
4 suffocated (spine)
10 survivors
1
2
3
4xx
5x
6xxxxxx
7xxxxxxx
8x
9xxx
_____________________________________________________
8z:
20 dropped
5 died cwo (skull=>brain)
1 suffocated (spine)
14 survivors
1
2
3
4
5xxx
6xx
7xxxxxx
8xxxxx
9xxxx
______________________________________________________
9z+: need to test in a fort, not arena