Archaean (about 2.5 billion years ago)

Archean is the oldest and longest generation in geological age, that is, primitive crust, primitive atmosphere, hydrosphere, sedimentary circle and the initial stage of biological occurrence and development.

2) Proterozoic (2.5 billion-600 million years ago)

In Proterozoic, the continental crust gradually changed from small to large, from thin to thick, volcanic activity decreased relatively, and lithology changed from basic to acidic. There is a huge debris accumulation in the Lower Proterozoic, which is conducive to strong granitization and the formation of large intrusions. Due to the decrease of CO2 concentration in the atmosphere and the increase of Ca and Mg ions in water, chemically deposited carbonate rocks began to appear. It will directly affect the evolution of magmatic process and lead to the emergence of alkali source rocks. With the increase of free oxygen in the atmosphere, the oxidation environment began to appear. Therefore, oolitic hematite and sulfate minerals and the first batch of red beds were produced in the later stage. The appearance of organisms has little impact on the environment, so there is not a lot of biochemical deposits in Proterozoic. At the end of Proterozoic, moraine was also found, which was the product of the first global ice age.

At this time, prokaryotes have evolved into eukaryotes, anaerobic organisms have been transformed into aerobic organisms (this turning point is called Yuri point, which occurs when the oxygen content in the atmosphere increases to one thousandth of the current oxygen concentration in the atmosphere), and the number of species has also increased from less to more. At this time, the plant kingdom on the earth developed for the first time, and a large number of primitive lower plants appeared, such as green algae, charophytes, brown algae, red algae and so on. These microfossils can be used for stratigraphic division and correlation. In the late Proterozoic, primitive animals also appeared. For example, the Ediacaran fauna in Australia includes aquatic invertebrates such as sponges, jellyfish, arthropods, flatworms and soft corals. Sponge spicule fossils have also been found in North America.

(3) Paleozoic (600-230 million years ago)

Paleozoic includes Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. In CAMBRIAN, the division of Pangu continent led to transgression, the continental shelf was widely distributed, and marine invertebrates flourished unprecedentedly. Among them, trilobites of arthropods account for 60% of the total fossils, brachiopods account for about 30%, and others only account for 10%. At this time, marine plants also showed signs of transition to terrestrial plants. For example, algae coal found in Cambrian strata in China is an example. The Ordovician seabed expanded in a large area, and brachiopods, hornstones, graptolites, nautilus and corals became worldwide species. The primitive fish-jawless fish (turtle) also appeared. During the Silurian period, marine animals continued to develop in large numbers. Later, due to the violent crustal movement and environmental changes, marine animals entered the fresh water area of the mainland, and real fish-jawed fish and vascular plants with water-transporting tissues suitable for coastal growth were born. Since the Late Paleozoic after Devonian, the continents have tended to merge, regressions have occurred constantly, and the habitats of many marine invertebrates have disappeared, so their species and numbers have been greatly reduced. On the contrary, fish are in full bloom, and terrestrial plants are flourishing day by day. Since then, the earth's surface has ended a desert ozone-free era. In Carboniferous and Permian, it became the heyday of amphibians, and the plant kingdom also developed from spore plants to gymnosperms. In Carboniferous and Permian continents, there were large forests dominated by ferns, which became an important coal mining period in geological history.

(4) Mesozoic (230-70 million years ago)

Mesozoic includes Triassic, Jurassic and Cretaceous. Gymnosperms, which appeared at the end of Paleozoic, have become the most prosperous species in Mesozoic. They reproduce by seeds, and the fertilization process is completely independent of water, which is more suitable for terrestrial habitats. This is another leap in plant evolution. The large-scale development of terrestrial plants such as Cycas, Ginkgo biloba and conifers not only created favorable conditions for coal formation (such as Jurassic coal seams widely distributed in the world), but also provided a rich food base for the development of reptiles.

Throughout the Mesozoic era, reptiles became the most prosperous chordates at that time. There are herbivorous and carnivorous dinosaurs on land, ichthyosaurs and plesiosaurs on the sea and pterosaurs in the air. At the same time, lizards, turtles, turtles, crocodiles, frogs and insects also appeared.

(5) Cenozoic (70 million years ago-now)

Cenozoic, including Paleogene, Neogene and Quaternary, is the latest generation. In the plant kingdom, the Paleogene was characterized by the great development of angiosperms, and the plant community changed from monotonous coniferous forest to evergreen broad-leaved forest with rich flowers and fruits. When the climate tends to be dry and cold, drought and biochemical phenomena occur in vegetation in many places. Grassland dominated by monocotyledonous herbs appeared at the beginning of Neogene, and tundra appeared in Quaternary. The animal kingdom is characterized by the unprecedented prosperity of mammals, so the Cenozoic era is also called the era of mammals. The lush angiosperms in the hot and humid forest region have greatly promoted the development of mammals. The prosperity of insects is also related to the development of angiosperms. The wide distribution of angiosperms and insects has promoted the prosperity of birds. When the grassland area expanded, many herbivorous grassland dwellers appeared among ungulates and rodents, and the number of carnivores also increased.