Read this: http://www.amazon.com/Landmark-Landscape-Photography-William-Ewing/dp/0500544336/
Thank you very much for mentioning this book. I am very glad I purchased it (after you mentioned it). I have not "read" it from cover to cover, but I think it has already given me some sense/hope/direction/guidance/food-for-thought...
Here is a link to a
video lecture given by the author/curator of the book which puts the collection of photographs and their groupings into perspective:
