[quote=K-97]
It's likely that Ghazan was using friction to melt the rocks into lava, I imagine it would work like rubbing you legs to warm them up or rubbing two sticks together to produce a fire. Except instead of two sticks you are rubbing every individual ''rock particle'' in the targeted area together in order to generate massive amounts of heat; the result of which melts the rock into lava.
[/quote]

That's a point I hadn't really thought about, I actually like this theory a lot. Though, as Sloth said that doesn't explain Bolin, but that's a whole other mess of "why". As far as Larfleeze's concept of genetics goes: I've always liked the idea, but I haven't seen much of it made sense of in the continuity. I mean that would've made Kya have an entirely unique style of waterbending if 1+1=2 but then again maybe it's not always a 100% hybrid bending gene or whatever? I don't know, it's a mess.

I still don't like waterarms or combustion girl in any form.