Shallow inter-reefal structure of the Capricorn group, southern Great Barrier Reef

276 km of continuous seismic reflection profiles have been obtained from the inter-reef areas of the Capricorn Reefs. Five reflectors were identified, three being widespread: reflector A, the shallowest, is found only close to modern reefs; reflector C is widespread and varies from flat-lying to irregular; the deepest reflector, D, is limited to the area north and west of Heron Island, where it is flat-lying. All the reflectors are assumed to represent erosional surfaces, and the ages of the intervening sequences are not known. Either reflector C, or the present sea bottom and reflector A, represent the surface of the Holocene transgression.