Hadrophycus immanus. Archaean (ca 2.6 billion years old), 148 x 100 mm, an early example of a stromatolite. Libby Supergroup, Nash Fork Shear Zone, Libby Flats, Medicine Bow Range, Wyoming, USA. Late Archean (Neoarchean Era) stromatolites are about as common as in Proterozoic strata.

Hadrophycus immanus. Archaean (ca 2.6 billion years old), detail, an early example of a stromatolite. Libby Supergroup, Nash Fork Shear Zone, Libby Flats, Medicine Bow Range, Wyoming, USA.

Banded ironstone Formation, Palaeoproterozoic Era, Siderian Period (ca. 2.4 to 2.3 billion years old). Port Handford, Western Australia, 20 x 7 cm polished specimen. The fine-scale alternation of iron-rich and silica-rich bands is clearly visible in this specimen, interpreted to be a record of seasonal fluctuations in photosynthetic activity. Oxygen produced reacted with dissolved iron to precipitate iron oxides. The Siderian Period is named for the abundance of Banded Iron Formations, which peaked just after the Archaean-Proterozoic boundary.

Baicalia sp. Stromatolite. Mesoproterozoic Era, ca. 1.5 – 1.2 billion years. Wumishan Formation, near Beijing, China.

Domal stromatolite, 25 cm, viewed in an inverted position. Khufai Formation (Early Ediacaran Period, Neoproterozoic Era). from "Camp 2", Huqf, Oman.

Domal stromatolite, 25 cm, viewed in an inverted position. Khufai Formation (Early Ediacaran). from "Camp 2", Huqf, Oman.

Stromatolite, 15 cm, Khufai Formation (Early Ediacaran). from "Camp 2", Huqf, Oman.

Cloudina, Ara Formation, Ediacaran, Oman.

Goblet shaped macrofossils with approximately hexagonal symmetry occur nestled among the algal thrombolites of the late Ediacaran. Namacalathus in silicified thrombolite, Ediacaran, Fara Formation, Oman.

Cloudina, Driedoornvlagte thrombolite bioherm (approximately, Omkyk Member, Kuibis subgroup, Ediacaran, Nama Group (Zaris sub-basin), Namibia. Individual Cloudinas range up to 13 mm long and 5 mm in diameter.

Google Earth image of the Zaris sub-basin, Namibia, looking west towards the Namib Desert.

Google Earth image of Oman showing Ediacaran fossil localities: Khufai Formation (Camp 2, Huqf area) and Wadi Bani Awf in the north.

Khufai Formation stromatolite localities, Huqf area, Oman.

Google Earth view showing Wadi Bani Kharus, Wadi al Hijayr and Wadi Bani Awf Ediacaran sites.

20/3/2008. Wadi Bani Kharus. Permian on Ediacaran.

20/3/2008. Wadi al Hijayr. Permian on Ediacaran.