We are going to be looking at the geological and biological history of the Earth through the last 500 million or so years. A wonderful source of information on the geological history of the earth is a site at Northern Arizona University.
Photographs are of the Grand Canyon, taken looking north from the South Rim.
Arrows approximately mark the time period given in the captions. One can actually go to the appropriate geological strata and find fossils of the animals that lived at that time period. First vascular plants. Evolution of invertebrates. Trilobites, early arthropods which are now extinct, appeared.