It has been some time since I read the Bible, but I do not recall either Boulder or Magmar being in it. I assume Russell Crowe knows better than me though! Is this a faithful depiction of Rock Lords though, or just a cheap cash-in to grab the money of the Rock Lord fan base?
The Rock Lords transform!
The Rock Lords in the film are certainly made of rock. They're animated with a neat stop-motion gait, though all of them are the same grey colour, and look more alieneqsue - more like a race of Pulver-Eyes than Boulders! They even transform from rock mode to humanoid, as depicted in one scene where the Rock Lords surprise some villains to help Russell Crowe look like a bad-ass!
The Rock Lords turn into rocks, in an especially hard to screencap scene!
The Rock Lords in this film are pretty weak. Despite being giants made from rock, they seem to die to primitive humans quite easily, and their role is very much playing second fiddle to Russell Crowe, eventually sacrificing themselves for him. There aren't even any Narlies in the film (unless you count Emma Watson). Surely while bringing the animals on board the Ark, Noah could have left room for two Narlilions?
In conclusion, while the Rock Lord content in this film is quite accurate, there is little in it. You would be best to just watch the sections with the Rock Lords, and in doing so learn more about how Rock Lords have shaped our planet. Will Russell Crowe put more Rock Lords in his future films? I hope so!