Kalimna Limestone Member of Fossil Hill Limestone.
1.2 m thick sheet-like biostrome.
Large (60x30 cm) Tetradium cribiforme colonies (Tabulate). 3 % of biovolume composed of Nycropora (T) and Cystistroma (S). 1.5 % composed of Bajgolia (T), Hillophyllum (R) and encrusting Dualites (T).
1 % are bryzoans.
Collection of Miller

Abstract ref. 1597:
The Cliefden Caves area of central New South Wales has a well preserved Late Ordovician sedimentary succession that formed in an offshore, near-equatorial, volcanic island setting. Initially fringing deposits (the Fossil Hill Limestone) accumulated, with occurrences of corals such as Tetradium cribriforme, Nyctopora, Bajgolia, Dualites, Hillophyllum, and stromatoporoids like Cystistroma, Rosenella and Stratodictyon. These were particularly characteristic of the shoal-type, mid-shelf T. cribriforme biofacies, and were contributors to a number of bioherms and biostromes. The succeeding, massive Belubula Limestone accumulated mainly in shallow lagoonal phases of the planated island with only sparse heliolitine corals, Aulopora, Bajgolia?, the stromatoporoids Cystostroma and Alleynodictyon? and the sphinctozoan sponge Belubulaia. The overlying deeper platform carbonates of the Vandon Limestone have a more diverse fauna with T. cribriforme, numerous heliolitines, Palaeophyllum, the sphinctozoan Cliefdenella, and stromatoporoids (Ecclimadictyon, Clathrodictyon), but no indubitable 'reefs'. Deep water assemblages of the overlying Malongulli Formation include reworked and in situ siliceous sponge associations. Limestone breccias include: (1) clasts with corals (Favistina and favositids) and rare silicified sphinctozoans, presumed to be derived from the adjacent shallow platform; and (2) clasts eroded from the slopes, with a diverse assemblage of demosponges, hexactinellids and discrete spicules. The in situ Malongulli assemblage occupied a lower slope/basin position, and includes undescribed hexactinellids and abundant spicules. A striking onshore-offshore faunal differentiation exists, with (1) the corals and stromatoporoids, most diversified and abundant in the mid-shelf island settings above wave base, (2) the sphinctozoans, rare constituents of lagoonal to subtidal 'level bottom' carbonate platform habitats, (3) the demosponges, most common and diversified in the upper slope, and (4) the hexactinellids, well represented in both upper and lower slope /basin habitats.