Research - Mr Walker's Caves Project - Tijou Reef Western Lagoon Wall Caves

During October 1995 I had the opportunity to dive in the lagoon at the southern end of Tijou Reef for the first time since 1973 when we 'found' this 40m deep lagoon. As I was about to begin my ascent from my dive I noticed a small slot between the talus slope sand and vertical wall at about 32m on the western side of the lagoon. Upon investigation I found an entrance to a cave which extended several metres into the reef and laterally for at least five to six metres.

Over the previous 22 years of GBR experience I, along with many others, always had the fantasy of discovering a cave which may have remains - indicating Aboriginal occupation during periods of low sea stands.

After discussing the cave location and lagoon morphology with Prof Peter Davies a leading reef geologist it was likely that:

  • the cave had been subjected to at least two periods of inundation

  • the reef to the seaward side appeared to be Pleistocene age
    i.e. more than 120000 years old, but this needs confirmation

  • there had been Aboriginal activity in this area as they moved south into Australia through this area which was dry from about 17000 to about 10000 thousand years ago

  • this would be possibly the only site on the GBR where such a site remained somewhat intact

I then discussed the cave with Dr Peter Veth (Archaeology and Anthropology JCUNQ) and he was similarly excited about such a prospect for an underwater cave with the incredibly unlikely chance of indications of Aboriginal occupation.

As a result of this interest I planned a return to the site and gained a permit from the GBRMPA to undertake mapping and photography of the site. In November 1996, February 1997 and April 2003 I had the opportunity to dive the site again.

I was also assisted in these dives by many individuals and as a result the whole western wall has now been looked at, albeit briefly. The caves extend almost from the southern end to about northwards. They vary from 7m deep, 20m along the wall and up to 7m high through to a simple concavity in the wall - classic wave cut notches into a reef front during a low sea stand. On the floor of the enclosed caves there is sediment.

The questions are - what is the age of the reefal material around the caves and does the sediment overlay terrestrial sediments laid down during the low sea stand period when the reef was dry 17-10,000 years ago.

UPDATE Feb 05:
As part of a 90 minute commercial TV documentary being done by Ushuaia Nature from TFN1 France I was able to spend three days coring in the base of Mr Walker's caves.

In addition to the coring we were able to survey the entire western wall of the lagoon and GPS fix each of the best caves for future reference/research.

We cored the base of the cave that offered the best promise in terms of highly protected sediments. We got sediment to 3m and it kept going! This is a bit of a problem as that depth of sediment was totally unexpected. The two cores resulting from the work will be taken to the UNE in Armidale for analysis. Results will be posted here as they come to hand. It is hoped that ultimately we may find an interface between marine and terrestrial sediments - those laid down during the last glaciation.

The cave system is named after Terry Walker a friend and great reefie who died at sea in the Gulf of Carpentaria doing what he loved - running around in small boats researching islands and birds. I miss him.

2007 Update
Dating from UNE shows sediments to be 3000 years old between 2-3m depth. Now that I am an Adjunct at James Cook University I am developing more links within the research community to continue the work from this base. We will be seeking grant funds from various sources.



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