Board Thread:Lore Discussion/@comment-10209824-20130530153039/@comment-6003396-20131009050822

My above post wasn't meant to be taken too literally or seriously. It was only meant to illustrate that many different substances, some as common as water, can have varying forms depending on their surroundings and some of these forms can coexist under precise circumstances.

In relation to the Abyss – and this is all speculative – this could mean that during the events of Oolacile, the surroundings and/or the "maturity" of the Abyss itself lent to it certain properties. For example, the solidified stalagmite-like stones that are found in the Royal Wood which turn into a gas-like substance when broken up and exposed to the air. Back to the time of the main events of Dark Souls: the Abyss has fully matured and the surroundings under New Londo Ruins might cause it can take on other forms.