The earliest and longest era of geological time between about 4600 and 570 million years ago. It precedes the Palaeozoic era. Relatively undisturbed Precambrian rocks are found in North America, Australia, and South Africa and what fossil material there is has mostly been collected from these regions. Fossils resembling blue-green algae, fungal spores, and fungal hyphae have been preserved. Calcareous algae have been found in certain late Precambrian rocks in Labrador and Montana. Some cherts of the gunflint formation of Ontario (about 2000 million years old) and older cherts of Australia and Africa have been shown to contain * stromatolites. There is much controversy about the existence of certain of these fossil remains (especially the * chemical fossils ) and about the reason for the apparent gap between the few questionable life forms in the Precambrian and the comparative wealth of life forms in the Cambrian period. See geological time scale. |
