From Australian Oceans Data Network
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Drowned dolines - the blue holes of the Pompey Reefs, Great Barrier Reef

Created 23/01/2026

Updated 23/01/2026

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Blue holes occur at Cockatoo and Molar Reefs, in the Pompey hard line reefs. These two holes are roughly circular in shape, between 240-295 m in diameter, and 30-40 m deep. They are completely (Cockatoo) or partially (Molar) rimmed by profuse living coral and surrounded by lagoonal depths of 5-10 m. The inner slopes of the Cockatoo blue hole are 60-70° down to a depth of 25 m, below which coalescing sediment fans markedly reduce this angle. At the Molar blue hole, slopes are mainly gentler (45°) and sediment fans and terraces occur below 16 m. Distinct biological/sedimentary associations occur in both holes. Seismic refraction studies across the rim of the blue holes show a shallow (8.5-11 m) pre-Holocene surface beneath the rims. The balance of evidence suggests that the blue holes represent collapsed dolines which may have taken more than one low sea-level period to form. The original surface structures have been modified by subaerial solution processes, and subsequent sediment infill and coral growth following the Holocene transgression.

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Additional Info

Field Value
Title Drowned dolines - the blue holes of the Pompey Reefs, Great Barrier Reef
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/0fd7a0c1-564a-49e4-a8c6-a5096aaa4673
Contact Point
Australian Ocean Data Network
clientservices@ga.gov.au
Reference Period 20/04/2018
Geospatial Coverage
Map data © OpenStreetMap contributors
{
  "coordinates": [
    [
      [
        150.0,
        -21.75
      ],
      [
        152.0,
        -21.75
      ],
      [
        152.0,
        -20.25
      ],
      [
        150.0,
        -20.25
      ],
      [
        150.0,
        -21.75
      ]
    ]
  ],
  "type": "Polygon"
}
Data Portal Australian Oceans Data Network

Data Source

This dataset was originally found on Australian Oceans Data Network "Drowned dolines - the blue holes of the Pompey Reefs, Great Barrier Reef". Please visit the source to access the original metadata of the dataset:
https://catalogue.aodn.org.au/geonetwork/srv/eng/csw/dataset/drowned-dolines-the-blue-holes-of-the-pompey-reefs-great-barrier-reef4