I just discovered this wonderful pic in the public domain of Capt. Simpson's crossing of the Carson on his successful exploration of a new route across Nevada (that was almost immediately put to use by the Pony Express!) This is just on the northeast edge of what is now Carson City heading up river towards Genoa, then still Utah Territory. Elinor, Jane Vaughan, John and John S. Lewis would have known this site and perhaps crossed here.
This is on the cover of a new book I just got today on the founding of Nevada. We'll see what else we can glean from inside the covers!
See Also, Peterson, Jesse G., A Route for the Overland Stage: James H. Simpson's 1859 Trail Across the Great Basin, (Utah State University, 2008) http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1113&context=usupress_pubs