Maybe it's an efficiency thing with the game, but I find it odd that I can place dirt over water, poison green water, and lava and it destroys the liquid/magma. You can dig through the lava by replacing it by dirt, see attached picture for an example. I feel we shouldn't be able to destroy the "liquids" by placing dirt on top of them. Just in case you wanted to try, once you reach the bottom, through the lava, and jump down....you will die.
