Shawnah Foster was jailed for investigation corporal injury to a child.
San Bernardino County Sheriff's investigators said the 31-year-old woman took her daughter to the Mojave Desert park on Oct. 5 to fight the other 12-year-old girl.
When they arrived, the girls began fighting.
Witnesses say that when her daughter appeared to be losing, Foster jumped in and pulled the other girl away by her hair. Foster then allegedly slapped the other girl in the face.
The fight was captured on home video.