P39, P45


These archaeocyath fossils fluoresce weakly under SW, but by using a suitably long exposure time the fluorescence can be appreciated.

“The former Ajax copper mine is the location of one of the most significant finds of archaeocyath fossils in the world. Archaeocyaths (ancient cups) were some of the earliest known marine sponges with mineral skeletons. They lived in the Lower Cambrian period, around 525 million years ago. These organisms proved highly successful, and over a 10 million year period diversified into a huge array of different forms and over 100 species, playing a dominant role in constructing the Earth’s first reefs. The large ridge of fossiliferous limestone located near the former mine is known throughout the world as the Ajax Limestone. Remarkably in the context of such finds, the Ajax Limestone contains a sample of almost every archaeocyath species known to have existed within the Australian-Antarctic province, and has a diversity which is far in excess of any other assemblage in the province. In addition to this representativeness, the limestone also contains over 100 type species – species that define a genus. This means that the site is one of the key points of reference for those studying the earliest stages of development of Life on Earth.” (SA Heritage Council Place Nº 26390)

For photos and a detailed description of the site itself, click here , then click on Page 2, then go to photos 9 & 10.

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