"The Cosmic Children" is a movie that was filmed by the famous surf movie maker Hal Jepsen. This portion of the film shows life on Topanga Beach. This was released in 1970.
These are the actual people that the family would of been hanging out with when they were at Lower Topanga Canyon (aka The Snake Pit). This is probably a good representation of what life in the area would of been like and why it got the reputation that it did. It's easy to see what the attraction would of been for Charlie and the family members.