Geologic Time Scale. Fossils in Rock. Trace fossils. Molds and casts. Index fossils. Fossils in amber. Frozen Fossils-wooly mammoth is an example. Fossils in tar/asphalt. Petrification. RelativeDating Fossils. Origin of the Earth and Life. Nebula hypothesis-Earth creation. Miller-Urey experiment. Meteorite hypothesis. Iron sulfide bubbles hypothesis. From Soup to Cells - the Origin of Life. When did life originate?
Evidence suggests that life first evolved around 3.5 billion years ago. This evidence takes the form of microfossils (fossils too small to be seen without the aid of a microscope) and ancient rock structures in South Africa and Australia called stromatolites. Stromatolites are produced by microbes (mainly photosynthesizing cyanobacteria) that form thin microbial films which trap mud; over time, layers of these mud/microbe mats can build up into a layered rock structure — the stromatolite. Complex life. Endosymbiosis. Cyanobacteria.