I have discovered a Thornton Carothers in Bear River, Yuba, Calfornia in the 1860 US Census. He is the right age to be the brother of my direct ancestor Clark Carothers. The census records the following information about Thornton:
Age: 23 years
Occupation: farm laborer
Born in Illinois
Thorton was among 8 men working as farm laborers on the farm of Henry Reed, age 67.
In 1860, Clark's brother Thornton would be about 23 years old. The more I learn about my Carothers relations, the more I discover how many of them came to Calfornia.