A brush fire burned nearly 1.5 acres between the intersection of Fallon-Two Rock and Gericke Roads, just south of Valley Ford, Tuesday afternoon. A witness reported seeing two teenagers driving adjacent to the area in a white pickup. Firefighters contained the fire within half an hour after it was reported, and found no evidence of its origins. “I think it was set by these teenagers, either unintentionally or intentionally,” Marin County Fire Marshal Scott Alber…