Era is a system of chronology. What are the eras?

The era is a large time period, a historical period. This is the name of the system of chronology, as well as the beginning of this chronology. The whole history of our planet can be conditionally divided into long periods. Between them, they are distinguished by certain climatic and geographic changes, as well as by a significant breakthrough in the development of the animal and plant world. Many are interested in what kind of era and what they are. Let's consider the main stages of the Earth's development.

Archean era

At this time our planet was formed, the period lasted about a billion years. Life on Earth was not yet, in the ocean chemical reactions between acids, alkalis and salts proceeded. The Archean era gave rise to protein matter. It was then that living organisms began to emerge.

The Proterozoic Era

The greatest period of development of the planet, which lasted about 2 billion years. At this time, algae and bacteria develop, organisms acquire their own organs, they become multicellular. The era is a time interval, when something new appears, the Proterozoic stage was distinguished by the formation of iron ore deposits. This period is characterized by the fact that all life processes take place in the ocean.

Palaeozoic

This period, distinguished by a constant change in climatic conditions, it is divided into 6 stages. At this time, the plant and animal world is developing, many species of fish appear. Along the banks grow coniferous trees, ferns. Approximately in the middle of the era the first amphibians appeared in the form of reptiles, beetles, grasshoppers. The period is characterized by constant cataclysms, changes in the forms of continents.

Mesozoic Era

Stage, consisting of the Triassic, Jurassic and Cretaceous periods. Mesozoic era is the emergence of land and sea turtles, frogs, shrimps, new varieties of corals. The dominant position is occupied by reptiles and dinosaurs. In the middle of the era, the first representatives of modern birds and insects appear. In the Cretaceous, there was an extinction of pterosaurs and dinosaurs.

At this time, climatic conditions are improving, as a result of which the earth is covered with greenery. On land, the first species of cypresses and pines appear, as well as flowering plants. The Mesozoic era begins to cooperate with insects and flora. During this period the continents acquire new forms and sizes, as a result of their division, islands are formed. The Atlantic Ocean increases in size, flooding large tracts of land.

The Cenozoic Era

"How many years does this last for the period in which humanity lives?" - people often ask such a question. The Cenozoic era (it lasts to this day) began about 66 million years ago. She distinguished herself by the appearance of modern birds, mammals, angiosperms and, of course, humans. By the middle of the era, almost all the main groups of wildlife kingdoms had already formed. At this time there are steppes and meadows, new types of grasses, shrubs. Also in nature, the main types of agrocenoses and biogeocenoses are formed. Man begins to adapt to the environment, use nature to meet personal needs. It was people who later changed the organic world. The Cenozoic era consists of three periods: Paleogene, Neogene and Quaternary. It continues today.

The considered eras are divided by climatic and geographic features. But there are other systems of chronology. For example, saying "our era", many imply a stage that originates from the Nativity of Christ. Also people distinguish industrial, technotronic and other periods that have distinguished themselves in something, changed people's perception of the world, changed attitudes towards living organisms.