Exactly so, Cagey but can I describe them as :As I read the pictures, then, you are talking about the shape of the arrangements of stones, not the shape of the individual stones. Some stones are arranged in a line that ends in stones arranged in an elliptical shape. Others are arranged in a line and that ends in stones arranged in the shape of a triangle.
Is this correct?
It is clear, Cagey.Thank you again.It is not the stones, but the arrangement of stones that have these shapes as their heads. I think you need to say that explicitly, otherwise people will think that each stone has that shape, as I did.
You don't have to use the word "arrangement", of course. There other ways to say it. For instance:
The stones are laid out in a linear pattern ....It will take more words than in your original sentence to explain it.