The spell description for Wall of Stone states:
It must, however, merge with and be solidly supported by existing stone.
My group was adventuring on a plain, where the ground was made of dirt. Presumably there was rock below us somewhere, but we didn’t really have any way of knowing exactly how far down that was. We were trying to make a shelter using the spells that we had, and Wall of Stone looked good, except for that one line. Our GM ended up houseruling that as long as the structure could generally support itself, it didn’t need to actually merge with stone, but I’m interested to know how other people would handle it.
In your game, do you require Wall of Stone to merge with existing stone, as the spell description states? Do you allow walls to be created on dirt, wood, or other materials? Am I just reading this description wrong?