The Pine Rivers meetings I rode in the 70's were either at Kilcoy or Tivoli.
There was a somewhat of a motocross track that the Pine Rivers motorcycle club run on inside and around the Caboolture speedway track (before the motocross track was set up on the road to summerset dam).
There was also a couple of tracks that were riding and not racing tracks, one off Kremzow road at Strathpine and also another along side the now freeway at North lakes. don't recall either being race tracks.
There was also a track where the dam is at Samonvale whch had a seniors motocross track and a junior flat track but that was pre 1975.
John, did you ever ride the old Redcliffe motocross track that was near the areodrome? big down hill drop off and then you rode back up the same hill. After this closed the motocross club moved to the dump site at Duffield road.