We found it easily with help from this web site: Movie Making Locations

Here is the famous rock as it still stands in 2003:

Here's a big shot of the whole area showing THE ROCK as well as the "cliffs of Nyoka."  According to one web site, William S. Hart often pitched his tent within the steel semicircle in the foreground.  Also seen is the recent development in the immediate area and the access road. Quick-Hands Hannah in the foreground: