• Barrier-front deposits consist of predominantly crinoid-bryozoan grainstone with a suite of sedimentary structures indicative of a lower to middle shoreface setting (planar laminae, cross-laminae, rare HCS and a mixed Skolithos-Cruziana ichnofauna). The barrier-top facies consist of closely juxtaposed very high- and low-energy deposits, representing barred upper shoreface to beach environments and slackpond or intertidal mudflat. The high-energy facies consist of bryozoan-pelecypod-Solenopora-oncoid grainstone and rudstone. Sedimentary structures include low-angle, truncating planar laminae and locally dense clusters of small Skolithos burrows. Low-energy deposits are sparsely fossiliferous (ostracodes, green algae, gastropods and Tetradium) calcisiltite with probable fenestrae and very rare desiccation cracks. Small (<50 cm deep), storm-breach channels filled by bioclastic-intraclastic rudstone are incised into the calcisiltite. Most of the lagoon deposits are Tetradium and green algae-rich mudstones. Pelloidal grainstone are interpreted as representing small sand shoals/beaches around the fringes of the lagoon. Lenses of bioclastic-intraclastic rudstone, with grain-types characteristic of both the barrier-top and lagoon, are interpreted as storm washover deposits. (Kiernan & Dix 2002. The Hull Limestone (Upper Ordovician) of Eastern Ontario: A Lower Paleozoic Carbonate Barrier-and-Lagoon System)