The island is part of the Solitary Islands Marine Park established 2 January 1998 and managed by the New South Wales Maritime Parks Authority.
[1] Rocks on North West Solitary Island consist of repeating beds of sillicaceous argillite, mudstone and sandstone.
The argillite probably formed from volcanic ash falls.
The mudstone shows cleavage at an angle steeper than the bedding planes by 20°.
This New South Wales geography article is a stub.