Archaeocyathan limestone (Ajax Limestone, Lower Cambrian; Ajax Mine, South Australia) 2 : 無料・フリー素材/写真
Archaeocyathan limestone (Ajax Limestone, Lower Cambrian; Ajax Mine, South Australia) 2 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Fossiliferous limestone in the Cambrian of South Australia.Weathered rocky flats near the Ajax Mine in the South Australian Outback are composed of Cambrian-aged fossiliferous limestones. The rocks are full of archaeocyathans, formerly a mystery group of sessile, benthic, filter-feeding organisms (Phylum Archaeocyatha), but now known to be an extinct group of sponges (Phylum Porifera). Archaeocyathans are only known from Lower Cambrian rocks - the classic localities on Earth for these fossils are Siberia and Australia.The rocks here are part of the Lower Cambrian Ajax Limestone. The archaeocyathan biota in the Ajax Limestone is quite diverse, with over two dozen species (see Taylor, 1910). Studies show that the archaeocyathan skeletons have been transported - they are not in their living positions. The fossils in the Ajax Limestone here have been silicified - the original calcareous skeletons have been replaced by quartz.Stratigraphy: Ajax Limestone, Atdabanian and Botomian Stages, Lower CambrianLocality: rocky flats near the Ajax Mine, south of Leigh Creek & north of Beltana, South Australia (vicinity of 30° 40.317’ South latitude, 138° 26.356’ East longitude)---------------Reference cited:Taylor, T.G. 1910. The Archaeocyathinae from the Cambrian of South Australia with an account of the morphology and affinities of the whole class. Memoirs of the Royal Society of South Australia 2(2): 55-188, 16 pls. |
| 撮影日 | 2006-08-21 01:26:31 |
| 撮影者 | James St. John |
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