Thirty-seven spicule-dominated clasts from limestone breccia in the lower part of the Upper Ordovician Malongulli Formation of the Cliefden Caves area, central New South Wales, have yielded a collection of 2657 conodonts. These have been assigned to 48 species, dominated by Belodina confluens Sweet, Besselodus sp., Dapsilodus mutatus (Branson and Mehl)?, Drepanoistodus suberectus (Branson and Mehl), Oistodus cf. venustus Stauffer, Panderodus gracilis (Branson and Mehl), Paroistodus? sp. A Nowlan and McCracken, Scabbardella altipes subsp. B Orchard and Walliserodus amplissimus (Serpagli). Two new species are described, Pseudobelodina? anceps and Taoqupognathus tumidus. This allochthonous assemblage is a mixture of North American Midcontinent and North Atlantic-type pelagic elements, reflecting derivation from warm shallow and cooler deeper zones of the low-latitude, offshore Malongulli site . These spicule-dominated clasts probably formed initially as periplatform-ooze deposits at the outer margins of an island platform, then were incorporated in debris flows and transported basinward to become associated with the basal, in situ, graptolitic siltstone-shale Malongulli succession. The graptolite horizons are late Eastonian in age (Zone of Dicranograptus hians kirki). There is little evidence of reworking of the conodonts from older horizons. Twelve species have close North American Midcontinent affinities and may be correlated, using graphic methods, with the lower half of the Zone of Oulodus velicuspis, i.e. within the North American mid-upper Edenian Stage. This establishes upper limits for the age of the underlying pre-Malongulli carbonate succession, and confirms the Malongulli Formation as distinctive and much younger than the Darriwilian-early Gisbornian Malongulli-type succession to the east of Cliefden Caves.
