The Pilbara ragion of Western Australia is one of a handful of locations in the world where rocks older than 3.2 billion years are preserved at the surface of the Earth.
Other localities in South Africa, Canada and Greenland are of similar age (geologists call the period they were formed the "Early Archaean") but the Pilbara rocks are
the best preserved - they have not been sheared, compressed or heated significantly. This enables scientists to analyse the fabric of the Pilbara rocks for clues on the processes
that were operating on the Earth over 3.2 billion years ago. As a reference, the age of the Universe is estimated at 12 billion years, and the age of the Sun and the Earth and
the rest of our Solar system is around 4.6 billion years. So we're getting pretty close to the beginning of the period where earth was stable and no longer being hit by massive
planetesimals that were common when the solar system was first created.
No-one knows for sure when life first began on this planet. But looking at the rocks of the Pilbara, scientists have found signs that life may have been present when the rocks were
deposited - 3.2 billion years ago. The best signs currently available include structures known as stromatolites or "layered rocks". These rocks are formed when microbes create
sticky mats, which attract grains of sand. The microbes then grow through the sand and create another sticky mat on top, and the process repeats itself. This ends up forming a
cabbage-like structure that can be preserved in rocks, and later discovered by scientists.
Numerous stromatolites have been found in the Pilbara, in particular in an area called the North Pole Dome, which is close to the town of Marble Bar. (Marble Bar also holds the record
for the longest hot spell in the world - 160 days over 30 deg. C apparently). The North Pole Dome covers approximately 600 sq. km, and is made up of rocks that are mostly volcanic
lava flows, but also some relatively small areas of sedimentary rocks, and it is in these regions where stromatolites are found.
The "Trendall site" is a location in such a region, along a horizon known as the "Strelley Pool Chert". It is named for Alec Trendall, a former director
of the Geological Survey of Western Australia who discovered the locality. The stromatolites at this locality are the best preserved of this period.
This site gives you a chance to look at these stromatolites from the comfort of your living room! For those who would like to view the site closer up, please be aware that the site is
slated for preservation from human destruction by the creation of a world heritage site. We can't give out the exact location of the site for that reason. If you should chance upon
stromatolites "in the wild" so to speak, especially in somewhere like the Pilbara, the best course of action is to inform your local geological society and don't attempt to remove them.
It's critical for the future of research into early life that stromatolites be studied in situ, amongst the rocks where they were first deposited.
For further research, I recommend the following papers on the North Pole Dome. They are listed alphabetically by the first author's surname. If you feel I have omitted your favourite paper,
please feel free to email me! :-)
Awramik, S. M. (1986) New fossil finds in old rocks. Nature, 319, 446-447.
Awramik, S. M., Schopf, J. W. and Walter, M. R. (1983) Filamentous fossil bacteria from the Archaean of Western Australia. Precambrian Research, 20 (2-4), 357-374.
Awramik, S. M., Schopf, J. W. and Walter, M. R. (1988) Carbonaceous filaments from North Pole, Western Australia: Are they fossil bacteria in Archean Stromatolites? A discussion. Precambrian Research, 39, 303-309.
Brasier, M. D., Green, O. R., Jephcoat, A. P., Kleppe, A. K., Van Kranendonk, M. J., Lindsay, J. F., Steele, A. and Grassineau, N. V. (2002) Questioning the evidence for Earth's oldest fossils. Nature, 416 (6876), 76-81.
Buick, R. (1984) Cabonaceous filaments from North Pole, Western Australia: Are they fossil bacteria in Archaean stromatolites? Precambrian Research, 24, 157-172.
Buick, R., (1985) Life and conditions in the early Archaean: evidence from 3500 m.y. old shallow water sediments in the Warrawoona Group, North Pole, University of Western Australia, Perth, WA.
Buick, R. (1990) Microfossil recognition in Archean rocks: an appraisal of spheroids and filaments from a 3500 m.y. old chert-barite unit at North Pole, Western Australia. Palaios, 5 (5), 441-459.
Buick, R. (1992) The Antiquity of Oxygenic Photosynthesis - Evidence from Stromatolites in Sulfate-Deficient Archean Lakes. Science, 255 (5040), 74-77.
Buick, R. and Barnes, K. R. (1984) Cherts in the Warrawoona Group: early Archean silicified sediments deposited in shallow water environments. Univ. West. Aust. Geol. Dept. Univ. Extension Spec. Publ., 9, 37-53.
Buick, R. and Dunlop, J. S. R. (1990) Evaporitic sediments of early Archean age from the Warrawoona Group, North Pole, Western Australia. Sedimentology, 37, 247-277.
Buick, R., Dunlop, J. S. R. and Groves, D. I. (1981) Stromatolite recognition in ancient rocks: An appraisal of irregularly laminated structures in an Early Archaean chert-barite unit from North Pole, Western Australia. Alcheringa, 5, 161-181.
Buick, R., Groves, D. I. and Dunlop, J. S. R. (1995) Abiological Origin of Described Stromatolites Older Than 3.2 Ga - Comment. Geology, 23 (2), 191-191.
De Gregorio, B. T. and Sharp, T. G. (2003) Determining the Biogenicity of Microfossils in the Apex Chert, Western Australia, using Transmission Electron Microscopy, in LPSC XXXIV, LPI, Houston, TX.
Dunlop, J. S. R., (1978) Shallow-water sedimentation at North Pole, Pilbara block, Western Australia, in Geology Department and University Extension Publication No. 2, pp. 30-38, University of Western Australia, Perth, WA.
Dunlop, J. S. R. and Buick, R., (1981) Archaean epiclastic sediments derived from mafic volcanics, North Pole, Pilbara Block, Western Australia, in Special Publication of the Geological Society of Australia, edited by D. I. Groves and J. E. Glover, pp. 225-233, Geological Society of Australia, Perth, WA.
Dunlop, J. S. R., Muir, M. D., Milne, V. A. and Groves, D. I. (1978) A new microfossil assemblage from the Archaean of Western Australia. Nature, 274, 676-678.
Grotzinger, J. P. and Knoll, A. H. (1999) Stromatolites in Precambrian carbonates: Evolutionary mileposts or environmental dipsticks? Annual Review of Earth and Planetary Sciences, 27, 313-358.
Grotzinger, J. P. and Rothman, D. H. (1996) An abiotic model for stromatolite morphogenesis. Nature, 383 (6599), 423-425.
Groves, D. I., Dunlop, J. S. R. and Buick, R. (1981) An early habitat of life. Scientific American, 245 (4), 56-65.
Hickman, A. H. (1983) Geology of the Pilbara Block and its environs, pp. 268, Geological Survey of Western Australia, Perth, WA.
Hofmann, H. J., Grey, K., Hickman, A. H. and Thorpe, R. I. (1999) Origin of 3.45 Ga coniform stromatolites in Warrawoona Group, Western Australia. GSA Bulletin, 111 (8), 1256-1262.
Lindsay, J. F., Brasier, M. D., McLoughlin, N., Green, O. R., Fogel, M., McNamara, K. M., Steele, A. and Mertzman, S. A. (2003) Abiotic Earth - Establishing a baseline for Earliest Life, Data from the Archean of Western Australia, in LPSC XXXIV, LPI, Houston, TX.
Lowe, D. R. (1980) Stromatolites 3,400-Myr old from the Archaean of western Australia. Nature, 284, 441-443.
Lowe, D. R. (1983) Restricted shallow-water sedimentation of early Archean stromatolitic and evaporitic strata of the Strelley Pool Chert, Pilbara Block, Western Australia. Precambrian Research, 19 (3), 239-283.
Lowe, D. R. (1994) Abiological Origin of Described Stromatolites Older Than 3.2 Ga. Geology, 22 (5), 387-390.
Lowe, D. R. (1995) Abiological Origin of Described Stromatolites Older Than 3.2 Ga: Reply. Geology, 23 (2), 191-192.
McNaughton, N. J., Compston, W. and Barley, M. E. (1993) Constraints on the Age of the Warrawoona Group, Eastern Pilbara Block, Western-Australia. Precambrian Research, 60 (1-4), 69-98.
Nijman, W., de Bruijne, K. H. and Valkering, M. E. (1998) Growth fault control of Early Archaean cherts, barite mounds and chert-barite veins, North Pole Dome, Eastern Pilbara, Western Australia. Precambrian Research, 88 (1-4), 25-52.
Schopf, J. W., Kudryavtsev, A. B., Agresti, D. G., Wdowiak, T. J. and Czaja, A. D. (2002) Laser-Raman imagery of Earth's earliest fossils. Nature, 416 (6876), 73-76.
Schopf, J. W. and Packer, B. M. (1987) Early Archean (3.3-billion to 3.5-billion-year-old) microfossils from Warrawoona Group, Australia. Science, 237 (4810), 70-73.
Van Kranendonk, M. J. (2000) Geology of the North Shaw 1:100 000 Sheet, Geological Survey of Western Australia, Department of Minerals and Energy, Perth, WA.
Van Kranendonk, M., Webb, G. E. and Kamber, B. S. (2003) Geological and trace element evidence for a marine sedimentary environment of deposition and biogenicity of 3.45 Ga stromatolitic carbonates in the Pilbara Craton, and support for a reducing Archaean ocean. Geobiology, 1, 91-108.
Vearncombe, S., Barley, M. E., Groves, D. I., McNaughton, N. J., Mikucki, E. J. and Vearncombe, J. R. (1995) 3.26 Ga Black Smoker-Type Mineralization in the Strelley Belt, Pilbara-Craton, Western-Australia. Journal of the Geological Society, 152, 587-590.
Walter, M. R., (1978) Recognition and significance of Archaean stromatolites, in Archaean cherty metasediments: Their sedimentology, micropalaeontology, biogeochemistry, and significance to mineralization, edited by J. E. Glover and D. I. Groves, pp. 1-10, University of Western Australia, Perth, WA.
Walter, M. R., (1983) Archaean stromatolites: Evidence of the Earth's earliest benthos, in Earth's Earliest Biosphere - It's origin and evolution, edited by J. W. Schopf, pp. 187-213, Princeton University Press, Princeton, New Jersey.
Walter, M. R., (1994) Stromatolites: The main geological source of information on the evolution of the early benthos, in Early Life on the Earth, edited by S. Bengston, pp. 270-286, Columbia University Press, Ney York.
Walter, M. R., (1996) Ancient hydrothermal ecosystems on Earth: A new palaeobiological frontier, in Evolution of Hydrothermal Ecosystems on Earth (and Mars?), pp. 112-130.
Walter, M. R., Bauld, J. and Brock, T. D. (1972) Siliceous Algal and Bacterial Stromatolites in Hot Spring and Geyser Effluents of Yellowstone National Park. Science, 178, 402-405.
Walter, M. R., Buick, R. and Dunlop, J. S. R. (1980) Stromatolites 3400-3500 Myr old from the North Pole area, Western Australia. Nature, 284, 443-445.