Hale Dixon Tharp was born in Ohio on July 8, 1835. He was the son of Nathaniel Tharp and Lucinda Zane. Came to CA about 1852 during the gold area. There me met and married a widow, Mrs. Edward J. Swanson (Chloe Ann Smith) and her four sons. They married in El Dorado County on December 5, 1853 and lived in Placerville (Hangtown) for a short period of time. They moved to Tulare County, CA into the Sierra-Nevada foothills east of Visalia about 1857. They settled on the confluence of Wild Horse Creek and the Kaweah River. This area was a popular spot for Indians and Hale Tharp became friends with the locals. It is said that he owned more horses than cattle and due to the lack of adequate pasture for his animals, he was told by the local Indian Chief that he would take him into the mountains to the east and show him places where his animals could find abundant feed and water during the hot dry summer months.So he did marry, probably didn't have any children, liked to hang out with the natives, and spent every summer living in a log. Now all I can think of is the Lorax wearing a cowboy hat.
The Indian Chief took Hale Tharp up into the mountains as promised and it was there that he found the groves of giant Sequoia Trees. It is thought that he was the first white man to see these trees. He brought his animals up for summer pasture and while there, he found a fallen Sequoia log that was hollow and big enough for him to live in. This hollow log is still there and is an attraction within the Sequoia National Park ... it is today known as "Tharp's Cabin."
Hale Tharp is also known to have given the name to another Tulare County landmark, Hospital Rock on the Kaweah River. His stepson, Geroge Swanson named a large outcropping of rocks within the Park ... it is called Morro Rock.
Because of his early experiences and knowledge of the "high country", he was often consulted by visitors such as John Muir who later helped establish Sequoia National Park.
Hale Tharp died in Visalia, CA on November 28, 1912. His ranch now lies under the waters of Lake Kaweah but in late summer as the waters are drained for irrigation, the land resurfaces and can be seen.
I am not familar with the book that you mention but will try to find it to add to what little I know about this man and his family. My connection is through George W. Swanson, stepson of Hale Tharp.
For some reason I find this guy fascinating. He doesn't have a wikipedia page, but here's some info I found on a geneology forum: