Behind Birdie beach is a Coastal Barrier. 

 

This was a system of sand dunes that was built as the sea level rose between 12,000 and 6,000 BP.

 

Prior to that the sea level was approximately 120 m lower.

 

The barrier formed across a number of valleys and formed the lagoons of Tuggerah Lakes.

 

Most of the barriers were mined in the 1950s and 60s, mainly for rutile.