Dan -
 
I've been out of the cellar arena for a long time, and this may be a well
known truism...but the shape of a root cellar might have a lot to do with the
type of flooring as well as the function.  I've always wondered how one could
hope to hide a large, conspicuous trap door in the floor of a small cabin.  A
long linear cellar along the wall might be a reflection of the need to use
the floor boards for a covering, while a central cellar could indicate less
concern with concealment.  Do contents indicate any differences in intent
between the two shapes?