One of the reasons I like this image so much is it is about as close to pure abstraction as Adams ever goes. While it is a farily straight forward image of a boulder field and distant mountains, I think the shapes and modulation of the light and shadow on the boulders resonates with the viewer more then the "factual" elements of the work.
The great problem with Adams is that even though he wrote several books about photography, he was all in all a pretty poor comunicator. As Mr. Cardwell so ably points out, Adams work was his interpretation of reality and through choice of lenses, filters and printing manipulations, his final results more often then not departed greatly from a factual rendering. yet many photographers who try to emulate his style believe he was a great proponent of straight photography. He was part of the time, especially with regards to the F64 period, but his nature work was his own abstract take on what he saw and felt.
There are dozens of landscape photographers today who sell and publish work that technically puts Adams to shame. They have out Adamsed Adams! But how many produce work with the same emotional content?