From the Information Board: Bingi Bingi is well known for its unusual rocks. Two different types of volcanic rocks were placed as "magma' 10km below the surface 380 million years ago. The magmas did not mix well, showing up now as bits of dark rock included in the lighter surface. A prominent 4m wide pink aplite band near the end of the point would have been injected through wide cracks. 30 million years ago, basaltic magma, possibly from Gulaga, forced itself into the cracks in the rocks to form black dykes. Uplift and erosion has produced the rocks we see todav.
Of interest: "Gulaga was once an active volcano, with the first of many eruptions occurring about 94 million years ago. Back then it would have been nearly 2,000m higher than its current 797 m. What remains today is the inner core of the original volcano. It has been dormant since end of the Cretaceous 65 million years ago."