It's hard to describe it any other way since I don't rightly know what it is! Actually, I hardly have a clue what it might be. You probably wouldn't remember it, it's such a minor detail in the story, but it was described in the very first chapter of Obernewtyn:
An eastward bend in the path led us around the edge of a natural stone wall, and there we suddenly came upon a thing that was unmistakably a product of the Oldtime. A single unbroken gray stone grew straight up into the sky like the trunk of a tree, marked at intervals with bizarre symbols, an obelisk of the ancient past. (pg 10)
It's also mentioned much later in the Keeping Place, when Elspeth compares the gypsy monument to the battle in the White Valley with this Beforetime pillar, although it didn't clarify the previous explanation all too much for me:
[It was] a pale pillar at the end of the mounds. It reminded me eerily of a Beforetime column that stood on the way from the Kinraide orphan home to the Silent Vale and had always caused our Herder escort to gibber prayers and make fierce warding-off signs. I went closer to read the lettering and realized the stone was finely carved into an intricate stylization of fire. (pg 509)
I thought maybe it's a streetlamp or something, but it couldn't be that with the "bizarre markings" and no description of bulbs or what on it. I tried to think of things resembling a very tall pillar that are used for measurement, but uhhhhh, I don't know of any such thing. ._.
What do you guys think? Any ideas...?