Simplify the following text for a Grade 10 native English-speaking person.
Original: The southern mountains form a barrier between the San Fernando Valley and the Los Angeles Basin , separating `` the Valley '' on the north and west-central Los Angeles on the south ; and the northern mountains separate the Conejo Valley from Malibu .
Simplified: The mountains form a line between the San Fernando Valley and the Los Angeles Basin , separating `` the Valley '' on the north and west-central Los Angeles on the south .