There was a huge expensive coffee table book called "the heyy baby days of beach music" that came out a few years ago which has info on tons of groups.
In a few words, I would describe the sound as mostly White garage-type bands (they were not like separate vocal groups) playing soul music.
Also, one thing that's different than the northern scene is that it seems like there's a continuity of the music where it continued to be made and new generations got into the scene continuously, even going into today.