[2] In 1857, at the age of 43, Clark contracted a severe lung infection that was diagnosed as consumption (as tuberculosis was called in his time).

Doctors gave him six months to live, as they had no antibiotic treatment at the time, but counseled rest and outdoor air.

He contributed to the writing and passage of legislation to protect the area, gaining support of US Senator John Conness from California.

The legislation was to protect Yosemite Valley and the Mariposa Grove of Giant Sequoias for "public use, resort, and recreation ... to be left inalienable for all time."

He left out his personal role in the discovery, popularization, and protection of the Mariposa Grove of Big Trees.

Clark spent some time living in Summerland, a Spiritualist colony in Southern California, near Santa Barbara.

He was buried at a spot near Yosemite Falls which he personally selected and dug decades prior to his death.