The2325 hectare CERRA Reserve is part of a system of protected areas in the Upper Clarence, which include Richmond Range, Koreelah, Yabbra, Border Ranges and Toonumbar National Parks.

The Reserve is relatively undisturbed, with a history of limited selective logging and low levels of public use.

Located within an overlap zone between bioregions,the fauna is predominantly Torresian (subtropical) with some Bassian (temperate) species. The Reserve also supports species commonly associated with habitats from both coastal and Tableland regions of north east NSW.

The Reserve is part of the south-west orientated Koreelah Range, a volcanic remnant of the Focal Peak shield volcano. This volcano produced a series of basalt flows 23 million years ago. The basalt flows eroded to give rise to fertile kraznozem and chocolate soils on the plateaus. The basalt flows overlaid older sedimentary rocks of the ClarenceMorton Basin formation which are 150 million years of age.

Four creek systems drain the reserve: Captains Creek, Cullens Creek, Little Cullens Creek, and Rocky Waterholes Creek. These all drain into Koreelah Creek and form part of the headwaters of the Clarence River.