Based upon the pattern and blog notes of Stephanie Blaisure (http://www.ravelry.com/patterns/library/grannies-and-ripples ), there are also some very helpful hints about the combination of grannies and ripples at: http://www.caron.com/projects/ss/ss69_baby_granny_stripes...

A photo of one particular antique Navajo rug design is the inspiration of this pattern, but a web search reveals hundreds of examples that could lend themselves to this interpretation.